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Biology 9th Class Biology

Chapter 8 Nutrition – 9th Class Biology Notes

Chapter 8 Nutrition – 9th Class Biology Notes

Question#1) Define the following terms?

I) Nutrition. II) Nutrients. III) Autotrophs.  IV) Heterotrophs.

Answer: I) Nutrition: The process in which food is obtained or prepared, absorbed and converted into body substances for growth and energy, is called nutrition.

II) Nutrients: Nutrients are the elements and compounds that an organism obtains and uses for energy or for the synthesis of new materials.

III) Autotrophs or autotrophic organisms: The organisms that prepare their own food by photosynthesis are called autotrophs.

IV) Heterotrophs or heterotrophic organisms: Organisms that obtain their food from other organisms and used it for growth and energy are called heterotrophs.

RECALLING: Every organism needs food for growth and energy and to function normally.

 

Question#2) Why organisms need food?

Answer: Everything in this universe needs energy to do some job. Similarly living organisms requires energy to carry out their life activities. This energy is produced by the digestion food during respiration process.

 

Question#3) Write a note on mineral nutrition in plants? OR What are the type and role of nutrients in the life of plants?

Answer: Mineral nutrition in plants: plants prepare their own food by photosynthesis. Plants get carbon, hydrogen and oxygen from CO2 and water. Plants require some nutrients for proper functioning. These nutrients are micronutrients and macronutrients.

I) Macronutrients: The nutrients which are required in large quantities are called macronutrients e.g. carbon, hydrogen, oxygen, nitrogen, magnesium, potassium etc.

II) Micronutrients: The nutrients which are required in small quantities are called micronutrients e.g. iron, molybdenum, boron, chlorine, zinc etc.

 

Question#4) Describe the role of important nutrients in plant life?

Answer: Role of important nutrients in plants life

MacronutrientsRole in plant life
PhosphorusComponent of ATP, nucleic acids, and coenzymes, necessary

for seed germination, photosynthesis, protein formation etc

PotassiumRegulates the opening and closing of the stoma,

reduces water loss from the leaves

SulphurComponent of proteins, vitamins and enzymes
CalciumActivates enzymes, is a structural component of

cell wall, influences water movement in cells

 

 

 

MicronutrientsRole in plant life
IronNecessary for photosynthesis, activates many enzymes
MolybdenumComponent of the enzyme that reduces nitrates to ammonia,

important in building amino acids

BoronImportant in sugar transport, cell division, and synthesizing

certain enzymes

CopperComponent of several enzymes
ManganeseInvolved in enzyme activity for photosynthesis,

respiration, and nitrogen metabolism

ZincRequired in a large number of enzymes
ChlorineInvolved in osmosis of water
NickelRequired in a nitrogen metabolism

 

Question#5) Describe the role of nitrogen in plant life?

Answer: Roles of Nitrogen in plant life:

Plants get nitrogen in the form of nitrates. Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth. Too much nitrogen can delay flowering and fruiting. Deficiencies of nitrogen can reduce yields, cause yellowing of the leaves and stunt growth.

 

Question#6) Describe the role of magnesium in plant life?

Answer: Magnesium is a structural component of chlorophyll. It is also necessary for the functioning of plant enzymes to produce carbohydrates, sugars and fats. It is used for fruit and nut formation and essential for germination of seeds. Deficiency of magnesium causes yellowing and wilting of leaves..

 

For your information:Carnivorous plants have evolved mechanisms for trapping and digesting small animals. The products of this digestion are used to supplement the plant’s supply of nitrogen.

 

Question#7) How are organic and inorganic fertilizers important in agriculture?

Answer: Fertilizer: Any of the chemical or natural substance added to soil or land to increase its fertility is called fertilizer.

Types of fertilizers: fertilizers are of two types:

  • organic fertilizers. 2) inorganic fertilizers.

1) organic fertilizers and its importance : The Fertilizers obtain from plants and animal materials, wood ash, manure, etc. Are called organic fertilizers. Organic fertilizers are derived from plant and animal materials.

They are more complex and take time to be broken down into forms usable by plants. Manure and compost are used as organic fertilizers. They can also increase soil drainage, aeration and the ability of the soil to hold nutrients.

2) inorganic fertilizers and its importance: inorganic fertilizer is comprised of synthetic, artificial ingredients manufactured and ready to use on plants. Naturally occurring inorganic fertilizers include rock phosphate, elemental sulfur and gypsum.

These are not chemically modified. If nitrogen is the main element, they are called nitrogen fertilizers. Most inorganic fertilizers dissolve readily in water and are immediately available to plants for uptake.

 

For your information:The distinction between the organic and inorganic fertilizers is not always clear-cut. Urea, for example, is an organic compound, but chemically synthesized urea is generally grouped with inorganic fertilizers.

 

Question#8) What are the different environmental hazards related to use of fertilizers?

Answer: Environmental hazards related to fertilizers use:

  • The massive quantities of inorganic fertilizers affect the soil nutrient-holding capacity.
  • Their high solubilities also degrade ecosystems through eutrophication (increase in chemical nutrients in an ecosystem).
  • Storage and application of some nitrogen fertilizers may cause emissions of the greenhouse gas nitrous oxide.
  • Ammonia gas may be emitted from the inorganic fertilizers. This extra ammonia can also increase soil acidity.
  • Excessive nitrogen fertilizers can lead to pest problems by increasing their reproduction rate.
  • Excessive amounts of organic fertilizers cause environmental problems due to nitrate leaching or run off of soluble organic compounds.

Question#9) Why the nutrient contents of soil is necessary to checked before the use of fertilizers?

Answer: It is recommended that the nutrient content of the soil and nutrient requirements of the crop should be calculated before the application of inorganic fertilizers because excessive use of fertilizers lead to various environmental problems like eutrophication , pollution , etc.

Question#10) What are the basic components of human food?

 

Answer: Components of human food: The nutritional requirements of human and other animals are relatively complex as compared to plants. Like other animals, the nutrients used by humans include carbohydrates, lipids, nucleic acids, proteins, minerals, vitamins. Besides these nutrients, they also require water.

 

Question#11) What are carbohydrates? Write down its sources and uses?

Answer: Carbohydrates: They are organic compounds composed of polyhydroxy aldehydes and polyhydroxy ketone. They are found in all organisms. They are commonly known as sugars. They contain three elements carbon, hydrogen and oxygen in which hydrogen and oxygen exists in 2:1 ratio that is why they are called hydrates of carbon or carbohydrates. One gram of carbohydrates provides 4 kilo calories of energy.
Forms of Carbohydrates:
Carbohydrates occur in three forms.
1. Monosaccharide
2. Disaccharides
3. Polysaccharides
1. Monosaccharides
Monosaccharides are simple sugars. Their common example is glucose. Glucose is main source of energy in our body cells.
2. Disaccharides
Disaccharides are formed by condensation of two monosaccharide units e.g. sucrose is formed by the combination of glucose and fructose. Maltose is another disaccharide.
3. Polysaccharides
Why many monosaccharides link together, they form polysaccharides. A single polyusaccharide may have many hundred units of monosaccharides. The common examples of polysaccharides are glycogen and starch. Glycogen occurs in animals and starch in plants. Another polysaccharide is cellulose, present in the cell walls of plants. It is the most abundantly occurring carbohydrate.
Sources of Carbohydrates
Carbohydrates containing starch are obtained from cereals and their products like wheat, rice, maize, bran, pastas, oats and barley. They are also obtained from carrots, radish, turnip, beet, beet root and potatoes. Simple sugar called glucose is obtained from grapes. The sugar derived from fruit is called fructose. Then from beet and sugar cane is called sucrose and that from milk is lactose.
Importance of Carbohydrates in Human Body
One gram carbohydrate food provides 3800 calories (4 kcal energy) to our body. The Carbohydrates are the cheapest and easy source of energy. Surplus carbohydrates are stored as glycogen in the liver and muscles, or converted to fats and stored in the fat cells beneath the skin and causes obesity.
Children, laborers and people, involved in physical labor need more carbohydrates in their daily diet whereas other should avoid them because their excess in the body can cause blood pressure, diabetes, obesity and heart diseases, therefore, carbohydrate products should be taken with care.

Question#12) Write a short note on lipids?

Answer: Lipids: Organic compounds composed of fatty acids and glycerol are called lipids.

Sources: Lipids are obtained from two sources:
Animal Sources
Ghee, butter, cream, animal fat and fish oil.
Plant Sources
Oils from mustard, olives, coconut, maize, soya beans, sunflower and peanuts.
Types of lipids: There are two types of lipids.

Saturated fatty acids: Saturated fatty acids have all of their carbon atoms bonded to hydrogen atoms. The lipids containing saturated fatty acids are solid at room temperature. For example butter contains nearly 70% saturated and 30% unsaturated fatty acids thats why these are solid at room temperature.

Unsaturated fatty acids: Unsaturated fatty acids have some of their carbon atoms double-bonded in place of a hydrogen atom. The lipids containing unsaturated fatty acids are liquid at room temperature.  For example: sunflower oil contains nearly 75% unsaturated fatty acids and 25 % saturated so these are liquid at room temperature.

 

Importance of Lipids
1. The use of fat rich products increase in winters because they provide double the amount of energy as compared to carbohydrates.
2. They provide 9000 cal/gm energy to the body.
3. In plants fats are stored in seeds, and in animals, they are found beneath the skin and around the kidneys where they are not only stored but also protect these parts.
4. They provide materials for building new protoplasm and cell membrane.
5. Some fatty acids are essential for man.
6. Saturated fats (animal fats) should be used with, great care in our diet as they lead to rise in the cholesterol level, which accumulates in the blood vessels, and thus affects the flow of blood in the arteries This can result in heart attack.

Question#13) Write a detailed note on Proteins?

Answer: Proteins: The biopolymers of amino acids are called proteins. Proteins are very important organic compounds found in all organisms. Proteins contain carbon, hydrogen, oxygen and nitrogen and sometimes some amount of sulphur.

A protein molecule is composed of many building units linked together to form a chain. A chain of amino acids is called polypeptide. Amino acids are building units of a protein molecule. About twenty different amino acids occur in nature that combines in different manners to make different type of proteins. Proteins are structural part of the cell membrane.

Some proteins are fibrous. They form different structures in the body like muscles, bones and skin. They also occur in our blood and cells. The enzymes which control different chemical reactions in the body are also proteins in nature. As a result of protein catabolism, energy is released. One gram of protein produces 4 kilo cal of energy which is used to synthesize ATP.

 Sources of Proteins
Following are the sources of proteins:
Animal Sources e.g. meat, fish, chicken, milk and cheese.
Plant Sources e.g. legumes, pulses, dry fruit and cereals.

Importance of Proteins in Human Body
1. Proteins are essentially required for growth and development.
2. Growing children ,pregnant women and lactating mothers need a lot of proteins.
3. An adult requires 50-100 gms of proteins daily.
4. Protein deficiency in children and cause a disease called Kwashiorkor.
5. Proteins play an important role in the building of cellular protoplasm.
6. They also play an important role in the building of muscles and connective tissues.
7. Many proteins are required for making enzymes, hormones and antibodies.
8. If proteins are eaten in excess than needed by body, the excessive amino acids are converted into carbohydrates by the liver, which are either oxidized to release energy and converted into glycogen and fat and stored.

For your Information:Carbohydrates are the most common source of energy. Proteins and lipids are vital building components for body but they can also be used for energy.

 

For your information: Saturated fatty acids can increase a person’s cholesterol level. An increased cholesterol level may eventually result in the clogging of arteries and, ultimately, heart disease.

 

Question#14) Draw a table to show the role of various minerals?

Answer: MINERALS: Minerals are inorganic elements that originate in the Earth and cannot be made in body. They play important roles in various body functions and are necessary to maintain health.

Most of the minerals in human diet come directly from plants and water, or indirectly from animal foods. Minerals are categorized into major and trace minerals. Major minerals are required in the amounts of 100 mg (milligrams) or more per day, while trace minerals are required in amounts less than 100 mg per day. The role of major and minor minerals in human body are given in following table.

 

Table : Important minerals in human diet and their roles
MineralsRole in body
Major minerals
SodiumFluid balance in the body

Helps in absorption of other nutrients

 

 

Important for muscle contraction, nerve impulse

transmission, heart function, and blood pressure

PotassiumFluid balance in the body

Acts as cofactor for enzymes

ChlorideFluid balance in the body

Component of hydrochloric acid

CalciumDevelopment and maintenance of bones and teeth blood clotting
Magnesium &

Phosphorus

Development and maintenance of bones and teeth

 

 

 

Trace minerals
IronOxygen transport and storage 

Act as enzyme cofactors support immune function

ZincAids insulin action

Helps in growth and reproduction

CopperActs as enzyme cofactor
ChromiumHelps in insulin action
FluorideStabilizes bone mineral and hardens tooth enamel
IodineEssential for normal thyroid function

 

For your information: On the nutritional label of a packaged food the word “Calorie” is equal to a kilocalorie.

Question#15) which foods contain calcium and iron and what role these minerals play in our bodies?

Answer: Role of Calcium ; Calcium is essential for the development and maintenance and strengthening of bones and teeth. It is also needed for maintaining cell membranes and connective tissues and for the activation of several enzymes. Calcium also aids in blood clotting.

Sources: Humans get calcium from milk, cheese, egg yolk, beans, nuts, fruit, cereals, cabbage etc. Deficiency problems: Deficiency of calcium causes spontaneous discharge of nerve impulses which may result in tetany, bones also become soft, blood clots slowly and wounds heal slowly.

 

Role of iron: Iron plays a major role in oxygen transport and storage. It is a component of haemoglobin in red blood cells and myoglobin in muscle cells. Cellular energy production also requires iron. It acts as cofactor for many enzymes of cellular respiration. Iron also supports immune function.

Sources: Humans get iron from red meat, egg yolk, whole wheat, fish, spinach, mustard, peanuts, etc.

Deficiency problems: Its deficiency is the most common nutrient deficiency worldwide. Iron-deficiency causes anaemia.

 

 

For your information: Good calcium nutrition, along with low salt and high potassium intake, prevents from hypertension and kidney stones.

 

For your information: Cooking or heating destroys the water soluble vitamins more readily than the fat-soluble vitamins.

For your information: Fat-soluble vitamins are much less excreted from the body as compared to water-soluble vitamins. This means that levels of water-soluble vitamins in the body can decrease more quickly, leading to vitamin deficiency.

Question#16) Define vitamins? How are vitamin A, C and D important in our diet?

Answer: VITAMINS

Vitamins are the chemical compounds that are required in low amounts but are essential for normal growth and metabolism.

Vitamins are very complicated compounds. When vitamins were discovered, their chemical nature was not well known. Therefore, they were denoted with English letters as A, B, C, D, E and K. Now it is known that vitamin B is not a single vitamin but a group of vitamins called as vitamin B complex.

 

Classification of vitamins: Vitamins may be divided into two groups: the fat-soluble vitamins (vitamins A, D, E, and K) and the water-soluble vitamins (vitamins B and vitamin C).

The fat soluble vitamins can be stored along with fat while the water soluble vitamins cannnot be stored so their intake is required continuously.

Vitamin A (Retinol):

Vitamin A was the first fat-soluble vitamin identified (in 1913).

Functions or Importance of vitamin A: It combines with a protein called opsinto form rhodopsin in rod cells of the retina of eye. When vitamin A is inadequate, the lack of rhodopsin makes it difficult to see in dim light.

It is also involved in cell differentiation, a process through which embryonic cells transform into mature cells with specific functions. Vitamin A also supports bone growth and immune functions.

Sources: Humans get vitamin A from leafy vegetables (spinach, carrots), yellow/orange fruits (mango), liver, fish, egg, milk, butter etc.

Deficiency problems: Deficiency of vitamin A is the leading cause of blindness in children worldwide. One of the symptoms of vitamin-A deficiency is night blindness. It is a temporary condition, but if left untreated it can cause permanent blindness. Vitamin-A deficiency can also cause a condition in which hair follicles become plugged with keratin, giving dry texture to skin.

 

 

Vitamin B:

** The vitamin B complex consists of several vitamins that are grouped together because of the loose similarities in their properties, distribution in natural sources, and physiological functions.

** All the B vitamins are soluble in water.

** Most of the B vitamins have been recognized as coenzymes, and they all appear to be essential in facilitating the metabolic processes of all forms of animal life.

** The complex includes B1 (thiamine), B2 (riboflavin), niacin (nicotinic acid), B6 (a group of related pyridines), B12 (cyanocobalamin), folic acid, pantothenic acid, and biotin.

 

Table: Functions, deficiencies and sources of important vitamins
VitaminSourcesFunctionsDeficiency symptoms
Vitamin

A

Leafy vegetables

(spinach, carrots)

Yellow fruits

Fish

Liver

Egg, milk and butter

Vision in dim light

Cell differentiation

Growth

Immunity

Poor growth

Blindness

Dry skin

Vitamin

C

Citrus fruits

Leafy green vegetables

Beef liver

Collagen formation

Healing of wounds

Functioning of immune system

Scurvy:

Fatigue, poor wound healing

Bleeding gums & joints

Vitamin

D

Fish liver oil

Milk

Ghee and butter

Synthesized by skin

Maintenance of the concentrations of calcium and phosphorousRickets in children

Osteomalacia in adults

 

VITAMIN C (Ascorbic acid)

Vitamin C is essential for:

It is needed in many reactions.

In the synthesis of collagen (a fibrous protein) in connective tissue.
Healing of wounds & fractures
Facilitates absorption of iron.
Helps in hemoglobin formation.
Formation of steroid hormones
Reduces the chances of infections
prevents from scurvy
Antioxidant
For healthy gums.

SOURCES: Orange, lemon, guava , strawberries, Pineapple, grape fruit, tomato, cabbage, cauliflower,etc.

DEFICIENCY

Decrease in body resistance to infection
Bleeding of teeth.
Scurvy (Symptoms of scurvy include muscle and joint pain, swollen and bleeding gums, slow wounds healing, and dry skin.).
Anaemia
poor wound healing
painful joints.

Daily Dose

60 mg per day

Over dose

Diarrhea
Painful urination
Flatulence
Skin rash

Remember

heavy dosages of vitamin C leads to stone formation.
Vitamin C is easily destroyed by heat, washing of vegetable and improper cooking in Iron & copper utensils.

Minute quantities of vitamin C are present in muscles.Since meat consists of muscles so it is not a good source of vitamin C.

Vitamin D

The best-known function of vitamin D is to help regulate blood levels of calcium and phosphorous. Vitamin D increases the absorption of these minerals from intestine and their deposition in bones. Also helps in strengthening of teeth.

Sources: Vitamin D is mainly found in fish liver oil, milk, ghee, and butter,egg yellow, etc. It is also synthesized by skin when ultraviolet (UV) radiations from the Sun are used to convert a compound into vitamin D.

 

Deficiency problems: Long-term deficiency of vitamin D affects bones. In children, vitamin-D deficiency leads to rickets, a condition in which bones weaken and bow under pressure. In adults, vitamin-D deficiency causes osteomalacia, or “softening of bones,”increasing the risk for fractures in bones. Deficiency of vitamin D also leads to tooth decay.

Over dose: Extra heavy doses of vitamin D are harmful and cause loss of appetite ,Softness of tissues and calcification of joints.

 

Question#17) Why are water and dietary fibres considered important in our diets?

Answer:  EFFECTS OF WATER AND DIETARY FIBRE

Strictly speaking, water and dietary fibre are not considered as nutrients, but they do play important role in life.

Role of Water

Water
Water makes approximately 60% of the body tissues of an adult. It is an essential component of the protoplasm. One can live without food for more than a week but a person can die within two to three days due to lack of water.
Sources: Important sources of daily water intake are natural water, milk, juicy fruits and vegetables.

 

Daily requirement: The estimated water requirement of an average adult is two litres per day.

Importance of Water
1. It plays an important role in digestion.
2. It helps in transport of digested food and other materials in dissolved form.
3. All the chemical reactions inside the cell take place in the presence of water.
4. It helps in excretion of urine, removal of faeces.
5. Enzymes become more active in solution form.
6. It keeps the blood thin and so that it can be easily circulated.
7. Water regulates the body temperature.
8. Its deficiency in tbe body causes dehydration, which can prove fatal.
9. Plants cannot photosynthesize without water.
10. The people living in hot and dry places need more water. By breathing, sweating and urination about 2-3 liters of water is lost per day.

 

Dietary Fiber (Roughage)
it is the part of food that is indigestable and provide fibers to our body.
Sources of Dietary Fibers
All fruit and vegetables provide fibers to the body for example, citrus fruits, cereals, spinach, cabbage and salads. The cell wall in plant cells are largely made of cellulose which cannot be digested by man. Bacteria living in the gut of ruminants digest the cellulose and convert it into fatty acids, which renders it absorb-able.
Importance of Dietary Fibers
1. Roughage adds bulk to the food enabling the muscles of the alimentary canal to grip it and keeps the food moving by peristalsis.
2. Absence of roughage in our diet may lead to constipation and related disorders.
3. Fibers keep the intestines in a healthy condition, thus our daily diet must contain a lot of fruit and vegetables.

4) Insoluble fibre speeds up the movement of carcinogens (cancer causing agents) from intestine.

  • Soluble fibre helps in lowering blood cholesterol and sugar levels.

 

Question#18) Define balanced diet. How would you relate it with age, gender and activity?

Answer: Balance Diet: Diet which contains all the essential nutrients in correct proportion for the normal growth and development of body is called Balanced diet.

The degree to which any particular meal is adequate in providing energy from food depends on the nature of the job of a person.
A common man’s diet is said to be suitable if it provides 50% calories from carbohydrates, 40% from fats, and 10% from proteins.

The following chart shows some of the common foods, taken in Pakistan, and the percentage of carbohydrates, lipids and proteins in each of them.

Common foods and the percentage of nutrients
FoodCarbohydratesLipidsProteins
Bread (Roti)52%03%09%
Rice23%0.1%2.2%
Potato19%0.1%02%
Apple12.8%0.5%0.3%
Eggs0.7%12%13%
Milk04%04%03%
Butter0.4%81%0.6%
Chicken011%20%

 

Relation of balanced diet with age, gender and activity:

During growth period of the body, there is higher metabolic rate in body cells and so body needs a balanced diet that contains more energy. Adults need less proteins per kilogram body weights, but a growing boy or girl needs more proteins per kilogram weight. Similarly children need more calcium and iron for their growing bones and red blood cells respectively.

 

Gender has an impact on the requirements of a balanced diet. Women have comparatively less metabolic rate than men of the same age and weight. So men need a balanced diet that provides comparatively more energy.

Different people have different lifestyles and varied nature of work. A man with sedentary habits does not require as much energy as the man who is on his feet for most of the day.

 

Quotation: “Let thy food be thy medicine”:  HIPPOCRATES.

 

Table : Estimated energy requirements (in Kilocalories) according to age, gender and activity
GenderAge

(years)

Activity Level
SedentaryModerately

active

Active
Child

Male/Female

2-31,0001,000-1,4001,000-1,400
Female4-81,2001,400-1,6001,400-1,800
9-131,6001,600-2,0001,800-2,200
14-181,8002,0002,400
19-302,0002,000-2,2002,400
31-501,8002,0002,200
50+1,6001,8002,000-2,200
Male4-81,4001,400-1,6001,600-2,000
9-131,8001,800-2,2002,000-2,600
14-182,2002,400-2,8002,800-3,200
19-302,4002,600-2,8003,000
31-502,2002,400-2,6002,800-3,000
50+2,0002,200-2,4002,400-2,800

 

 

 

Question#19) Describe how protein energy malnutrition, mineral deficiency diseases and over intake of nutrients are the major forms of malnutrition?

 

Answer: PROBLEMS RELATED TO NUTRITION (MALNUTRITION)

Problems related to nutrition are grouped as malnutrition. OR Lack of proper nutrition is called malnutrition.

It often refers to undernutrition resulting from inadequate consumption, poor absorption, or excessive loss of nutrients. Malnutrition also includes over-nutrition, resulting from overeating or excessive intake of specific nutrients.

Most commonly, malnourished people either do not have enough calories in their diet, or eat a diet that lacks protein, vitamins, or trace minerals. Malnutrition weakens the immune system, impairs physical and mental health, slows thinking, stunts growth and affects fetal development.

Common forms of malnutrition include protein-energy malnutrition (PEM), mineral deficiency disease (MDD), and over-intake of nutrients (OIN).

 

For your information: According to the United Nations Children’s Fund (UNICEF), malnutrition contributes to the deaths of more than 6 million children (under age five) each year.

 

a- Protein-Energy Malnutrition

Protein-energy malnutrition means inadequate availability or absorption of energy and proteins in the body. It is the leading cause of death in children in developing countries. It may lead to diseases such as Kwashiorkor and marasmus.

 

  1. Kwashiorkor is due to protein deficiency at the age of about 12 months when breastfeeding is discontinued. It can also develop at any time during a child’s growing years. Children may grow to normal height but are abnormally thin.
  2. Marasmususually develops between the ages of six months and one year. Patients lose all their body fat and muscle strength, and acquire a skeletal appearance. Children with marasmus show poor growth and look small for their age.

B) Mineral deficiency diseases (MDD): Diseases resulting from the deficiency of a mineral are called mineral deficiency diseases. These are relatively rare among humans. Some examples are given below;

 

  1. Goiter is a disease of thyroid gland that is caused by an insufficient amount of iodine in diet. Iodine is used by thyroid gland to produce hormones that control the body’s normal functioning and growth. If sufficient iodine is not available in a person’s diet, thyroid gland becomes enlarged and it results in swelling in neck. This condition is known as goitre.

 

  1. Anemia is a disease of blood that is caused when the number of red blood cells is reduced than the normal. Or Anemaia is a condition that develops when blood lacks enough healthy red blood cells or hemoglobin. The term anemia literally means “a lack of blood. Anemia is the most common of all mineral deficiency diseases.

Causes: Inadequate amount of iron in the daily diet is the main cause of anemia.

Effects: Hemoglobin molecule contains a single atom of iron at its centre. If body fails to receive sufficient amounts of iron, adequate number of hemoglobin molecules are not formed. In this case, there are not enough functioning of red blood cells. The patient is weak and there is shortage of oxygen supply to body’s cells.

Treatment of anemia: Iron deficiency anemia is easily treatable with diet changes and use of iron supplements.

c- Over-Intake of Nutrients

Over-intake of nutrients (OIN) is a form of malnutrition in which more nutrients are taken than the amounts required for normal growth, development and metabolism. The effects of over-intake of nutrients are usually intensified when there is reduction in daily physical activity (decline in energy expenditure).

Over-intake of nutrients causes a number of health problems. For example high intake of carbohydrates and fats leads to obesity, diabetes and cardiovascular problems. Similarly, high dose of vitamin A causes loss of appetite and liver problems. Excess intake of vitamin D can lead to deposition of calcium in various tissues.

EFFECTS OF MALNUTRITION

An extended period of malnutrition can lead to problems like starvation, heart diseases, constipation and obesity.

 

Starvation is a severe reduction in nutrient and energy intake and is the most horrible effect of malnutrition. In humans, prolonged starvation causes permanent organ damage and eventually results in death.

 

Heart diseases are also increasing on the global level. One of the causes of heart diseases is malnutrition. People who take unbalanced diet (high in fats) are more exposed to heart problems.

 

Constipation: Malnutrition often leads to situations where people cannot schedule their meals. This irregularity results in many health problems including constipation.

 

Obesity means becoming over-weight and it may also be due to malnutrition. People who take food that contains energy more than their requirement and do very little physical work can become obese. Obesity is known as the mother-disease and may lead to heart problems, hypertension, diabetes etc.

 

For your information: According to the Food an Agriculture Organization of the United Nations, more than 25,000 people die of starvation every day. On average, every five seconds a child dies from starvation.

 

For your information: The World Health Organization (WHO)estimates that, within the next few years, diseases due to malnutrition will become the principal global causes of mortality.

Question#20) What do you know about drought, Famine and Flooding? How would you advocate the unequal distribution of food as the major factor that contributes to famine?

Answer;

FAMINE – THE MAJOR CAUSE OF MALNUTRITION

Famine means the lack of enough food to feed all people living in an area. The most terrible famines of the twentieth century are the Ethiopian famine (1983-85) and the North Korean famine (1990s). The major causes of famine are unequal distribution of food, drought, flooding or increasing population.

 

Unequal distribution of food (main cause of famine) : The achievements in science have enabled human beings to produce better food in terms of quality and quantity. Today the agricultural practices produce more than enough food that can be supplied to every one on the Earth.

But due to political and administrative problems, food is not equally distributed to different regions of the world. The result is that there is always surplus food in countries like America, UK, and Canada etc. and at the same time people have nothing to eat in countries like Ethiopia, Somalia etc. This unequal distribution of food lead to famine in some areas of the world and this is how unequal distribution is the major factor of famine.

 

For your information: Famines may also be due to the problems created by humans e.g. wars and wrong economic policies.

 

For your information: The World Food Program (WFP) is the food aid branch of the United Nations. It is the world’s largest agency providing food to more than 90 million people in 80 countries.

 

Analysing and interpreting: In the comparative chart of daily diet and balanced diet requirements, mention the visible symptoms caused by nutrient deficiencies.

Drought

A drought is a period of time when there is not enough water to support agricultural and human needs. Drought is usually due to a long period of below-normal rainfall. Droughts decrease or even stop the crop yields and it results in famine.

 

Flooding

It occurs due to more than normal rainfall or due to weak water distribution system. Rivers and canals overflow their banks and destroy the soil quality of agricultural lands. It becomes impossible to grow crops immediately after flooding. In this way, flooding may be a reason for short-term famine.

 

Increasing population

In spite of the global increase in food production, millions of human beings are undernourished. In the over-populated regions of world, large populations overuse natural resources to grow maximum food in order to meet the problems of food shortage. It leads to dry and infertile lands and depletion of resources. In such situations crops can no longer be grown and famines result.

 

Question#21) Why the process of digestion is necessary in human beings?

Answer: Importance and need of digestion: Amino acids, simple sugars and fatty acids are rare in our environment. Such substances are usually parts of larger molecules like proteins, polysaccharides and lipids, which cannot cross the membranes. There is a need of converting such large and non-diffusible molecules into smaller and diffusible molecules (that can cross the membranes).

This is achieved through the process of digestion.

After digestion, the diffusible molecules from the digestive system reach body cells through blood. Here, they are assimilated (to get energy and to synthesize our own structures). At the same time, the indigestible part of food is eliminated out of body through the process of defecation.

Phases of nutrition: The nutrition in humans comprises of the following phases.

 

1- IngestionThe process of taking in food.
2- DigestionThe process of breaking up complex substances into simpler substances.
3- AbsorptionDiffusion of digested food into blood and lymph.
4- AssimilationConversion or incorporation of absorbed simple food into the complex substances constituting the body.
5- DefecationElimination of undigested food from the body.

 

 

For your information: We eat mutton and digest its proteins into amino acids. These amino acids are used to synthesize our proteins.

 

Digestion
Digestion is the process in which the insoluble and non-diffusible components of food are broken down and by the action of enzymes are converted into soluble and diffusible substance to be absorbed into the blood stream. OR Digestion is the process in which the non-diffusible molecules of food are changed to diffusible ones by the action of enzymes.

Types of Digestion
1. Mechanical digestion
2. Chemical Digestion
1. Mechanical Digestion
In mechanical digestion, the food consisting of large sized particle is broken into fine pieces by cutting, grinding, chewing and churning up, so that enzymes can act upon it efficiently and effectively. Mechanical digestion of food takes place in the mouth and stomach.
2. Chemical Digestion
In chemical digestion, the digestive enzymes mix with the food and act upon it to break it down further into simple and diffusible chemical forms. The enzymes act on carbohydrates, proteins and fats separately. Chemical digestion takes place in all the major parts of the digestive system. The digestive glands such as liver and pancreas also play very important role in this digestion.

 

Digestive system: All the organs which take part in digestion process make a system which is called the digestive system.

Human digestive system: The human digestive system consists of two parts.

  • Alimentary canal: The digestive system of human consists of a long tube that extends from mouth to anus.This tube is called alimentary canal. Its main sections are oral cavity, pharynx, esophagus, stomach, small intestines and large intestine.

Peristalsis
The muscles of alimentary canal produce rhythmic waves of contraction which is called peristalsis. Due to this process, food is carried through various parts of the alimentary canal.

2) Secretory glands: In addition to the alimentary canal, there are some glands that secrete digestive enzymes. These glands are of three types. a) Salivary glands b) Pancreas c) Liver.

Question#22) Describe structures and functions of the main regions of alimentary canal? Briefly describe swallowing and peristalsis?

Answer:  Main sections of alimentary canal are oral cavity, pharynx, esophagus, stomach, small intestines and large intestine.

Oral cavity – Selection, grinding, partial digestion

Oral cavity is the space behind mouth and has many important functions in the whole process of digestion. Here three important processes takes place.

  1. A) Selection: When food enters the oral cavity, it is tasted and felt. if the food is fit for our health it is selected and if not fit then it is rejected.
  2. B) Mastication or chewing: he grinding of food by teeth is called mastication. By combined function of tongue and mouth. It converted food into small pieces, so that it can easily pass from
  3. C) The saliva is continuously secreted by the three pairs of salivary glands in response to the presence of food in the buccal cavity.
    Saliva is alkaline and contains an enzyme amylase.This enzyme converts starch into sugar (maltose) and helps in semi digestion of starch. The morsel of food after being chewed and thoroughly mixed with the saliva is called a bolus. It is rolled down by the swallowing action into the esophagus which conveys it to the stomach by the wave of peristalsis. The end of stomach lined with esophagus is called cardiac end.

Ingestion
The food of animals and human is in the solid form and may be bulky. Taking in of the food in the oral cavity and swallowing is called ingestion.

Mechanical Digestion

 

For Your Information

 

Teeth

Teeth
God has blessed animals and human beings with teeth. They help in breaking and chewing of the food. They are present in oral cavity.Teeth are attached to the upper and lower jaws.
Kinds of Teeth
Humans have two sets of teeth during their lives.
Milk Teeth
The first set of teeth begins to come through the gums when the baby is about six months old. these are called the milk teeth and all twenty teeth are formed over a period of two years.
Permanent Teeth
The milk teeth begin to drop out at the age of six years and are gradually replaced by the second set of teeth called the permanent teeth. In man the milk teeth do not fall off simultaneously, they fall off one by one and similarly permanent grow one by one as well. Healthy teeth are strong and give a beautiful and lustrous look. You must brush your teeth at least twice a day.
Structure of a Tooth
A tooth has two permanent parts, the Crown and the Root. The crown is that part of tooth which projects out of the gum and jaws. The root the the tooth is embedded into the gums and is therefore, hidden.
Enamel
This is the outer most part of tooth which is very hard and lustrous. It is deposited on the outside of the crown of the tooth by cells in the gum. The enamel is a non-living substance. It is made up of calcium salts. It imparts beauty to the tooth and protects the tooth. If the enamel gets removed then the teeth start decaying.
Dentine
It is the part of teeth present under the enamel which is hard. But it wears off if the enamel gets removed. Running through the dentine are strands of cytoplasm arising from the cells in the pulp. These cells keep on adding more dentine to the inside of the tooth.
Pulp
The innermost part of the tooth is hollow and is made up of soft connective tissue which is called the pulp. The strands of cytoplasm in the dentine derive their food and oxygen from the pulp which enables the tooth to live and grow. The pulp contains sensory nerves and blood capillaries. These nerve endings are sensitive to heat and cold and can produce the sense of pain e.g. toothache.
Cement
Cement is a thin layer of very hard material which covers the dentine at the root of the tooth. the fibers holding the tooth in the jaw are embedded in the cement at one end and in the jaw at the other. In this way teeth remain firmly embedded in the jaws.

 

 

Pharynx and Oesophagus – Swallowing and Peristalsis

Swallowing : During swallowing following activities takes place.

Bolus is pushed to the back of mouth by tongue.

The soft palate also moves upward and to rear. In this way, the opening of nasal cavity is closed.

When swallowed, the bolus passes pharynx to enter oesophagus. Pharynx has adaptations to prevent the entry of bolus particles in trachea (wind pipe to lungs). During swallowing, larynx (the top of trachea) moves upward and forces the epiglottis (a flap of cartilage) into horizontal position. Thus glottis i.e. the opening of trachea is closed. The beginning of swallowing action is voluntary, but once food reaches the back of mouth, swallowing becomes automatic.

After being swallowed, food enters the tube called oesophagus, which connects pharynx to stomach. Neither pharynx nor oesophagus contributes to digestion and the previous digestive actions of saliva continue.

 

 Peristalsis: The waves of contraction and relaxation in the smooth muscles of alimentary canal walls is called peristalsis. Peristalsis moves food from oral cavity to rectum.

 

For your information: In adult human, esophagus is about 25 cm long.

Stomach – Digestion, churning and melting

Stomach is a dilated part of alimentary canal. It is J-shaped, located in the left of abdomen, just beneath diaphragm.

 

Parts of Stomach: Stomach has two main portions.

Cardiac portion of stomach is present immediately after esophagus.

pyloric portion is located beneath cardiac portion.

 

SPHINCTERS OF STOMACH: The opening of the stomach which are guarded by muscles are called sphincters. Stomach has two sphincters.

Cardiac sphincter is between stomach and esophagus. Bolus enters stomach from oesophagus through cardiac sphincter.

pyloric sphincter is between stomach and small intestine.

Digestion in stomach:

When food enters stomach following processes takes place.

Gastric juice secretion: The gastric glands found in the stomach wall are stimulated to secrete gastric juice. Gastric juice is composed chiefly of mucous, hydrochloric acid, and a protein-digesting enzyme pepsinogen.

Hydrochloric acid converts the inactive enzyme pepsinogen into its active form i.e.pepsin. HCl also kills microorganisms present in food. Pepsin partially digests the protein portion of food (bulk of mutton) into polypeptides and shorter peptide chains.

Stomach

 

 

Churning: In stomach, food is further broken apart through a process of churning. The walls of stomach contract and relax and these movements help in thorough mixing of gastric juice and food. The churning action also produces heat which helps to melt the lipid content of food.

The starch in our bite of bread and the protein in mutton have been partially digested and the food has been converted to a soup-like mixture called chyme. After it, the pyloric sphincter allows a little mass of chyme to enter duodenum.

 

Intresting information: An interesting problem is raised here. Pepsin is a powerful protein-digesting enzyme. Why does not it digest the stomach walls, which are mostly proteins? We saw that pepsin is not released in its active form. Rather it is secreted as inactive pepsinogen, which requires HCl for activation.

The mucous of gastric juice forms a thick coating over the inner walls of stomach and neutralizes the HCl there. It makes pepsinogen difficult to be activated and to attack stomach walls.

For your information: Some quantity of gastric juice is always present in stomach. When bite is in oral cavity, brain sends messages to stomach walls to secrete some gastric juice. When food reaches stomach, more gastric juice is secreted according to needs. If there is little or no protein in food, stomach does not secrete more gastric juice.

On the other hand, if more proteins are present in food, abundant gastric juice is secreted. In this case, already present gastric juice begins the digestion of huge proteins into peptides. These peptides stimulate some cells of stomach walls to release a hormone called gastrin. This hormone enters blood and is distributed to all parts of body. In stomach, it has specific effect and stimulates the gastric glands to secrete more gastric juice.

Small Intestine – Complete digestion and absorption

Duodenum: Duodenum comprises of the first 10 inches (25 cm) of small intestine and it is the part of alimentary canal where most of the digestive process occurs. Here, food is further mixed with 3 different secretions.

  1. Bile from liver helps in the digestion of lipids through emulsification i.e. by keeping the lipid droplets separate from one another.
  2. Pancreatic juice from pancreas contains enzymes trypsin,pancreatic amylase and lipase which digest proteins, carbohydrates and lipids respectively.

 

  1. Intestinal juice from intestine walls contains many enzymes for the complete digestion of all kinds of food.

Jejunum: Next to the duodenum is 2.4 meters long jejunum. It is concerned with the rest of the digestion of proteins, carbohydrates and lipids of our bite.

Ileum: Last 3.5 meters long part of small intestine is ileum. It is concerned with the absorption of digested food. There are circular folds in the inner wall of ileum. These folds have numerous finger-like projections called villi (singular: villus).Villi increase the surface area of the inner walls and it helps a lot in the absorption of digested food.

Each villus is richly supplied with blood capillaries and a vessel of lymphatic system, called lacteal.The walls of villus are only single-cell thick. The digested molecules i.e. simple sugars and amino acids are absorbed from intestine into the blood capillaries present in villi.

Blood carries them away from small intestine via the hepatic portal vein and goes to liver for filtering. Here, toxins are removed and extra food is stored. From liver, the required food molecules go towards heart via the hepatic vein. Fatty acids and glycerol, present in small intestine, are absorbed into the lacteal of villus. Lacteal carries them to the main lymphatic duct, from where they enter in bloodstream.

 

For your information: Bile also contains pigments that are the by-products of red blood cell destruction in liver; these bile pigments are eliminated from body with faeces.

For your information: A non-functional finger-like process called appendix arises from the blind end of cecum. Inflammation of appendix due to infection causes severe pain. The infected appendix must be removed surgically otherwise it may burst and inflammation may spread in abdomen.

Chapter 8 Nutrition - large intestine image

 

Large intestine – Absorption of water and defecation

After the digested products of our bite have been absorbed in blood, the remaining mass enters large intestine. It has 3 parts;

1) Caecum (cecum): (or pouch that forms the T-junction with small intestine), pouch or large tube like structure in the lower abdominal cavity that receives undigested food material from the small intestine and is considered the first region of the large intestine.

The main functions of the cecum are to absorb fluids and salts that remain after completion of intestinal digestion and absorption and to mix its contents with a lubricating substance, mucus. The internal wall of the cecum is composed of a thick mucous membrane through which water and salts are absorbed. Beneath this lining is a deep layer of muscle tissue that produces churning motions.

2) Colon: It is the second part of large intestine that is responsible for absorption of water into the blood. From colon. As water is absorbed, the solid remains of food are called faeces.

Faeces mainly consists of the undigested material. Large number of bacteria,sloughed off cells of alimentary canal, bile pigments and water are also part of faeces.

 

3) Rectum: It is the third and last part of the small intestine. Faeces are temporarily stored in rectum, which opens out through anus. Under normal conditions when the rectum is filled up with faeces, it gives rise to a reflex and anus is opened for defecation. This reflex is consciously inhibited in adults but in infants it is controlled involuntarily. During growth, child learns to bring this reflex under voluntary control.

 

For your information: Many bacteria live in colon.They produce vitamin K, which is necessary for the coagulation of blood.

 

Role of liver: Liver is the largest gland of body, a spongy mass of wedge-shaped lobes that has many metabolic and secretory functions.

Morphology: It is multi-lobed and dark reddish in appearance.

Location: It lies beneath the diaphragm on the right side of abdomen.

Mass: In an adult human, it weighs about 1.5 kg and is the size of a football. A pear-shaped greenish yellow sac i.e. gallbladder lies along the right lobe of liver on ventral side.

Function: Liver secretes bile, which is stored in gallbladder. When gallbladder contracts, bile is released into duodenum through common bile duct. Bile has no enzymes but contains bile salts for the emulsification of lipids. It helps the lipid-digesting enzymes to attack on lipids. Besides digestion, liver carries out a number of other functions, some of which are summarized here;

  • Removes amino groups from amino acids (de-amination).
  • Converts ammonia to a less toxic form i.e urea.
  • Destroys the old red blood cells.
  • Manufactures blood clotting proteins called fibrinogen.
  • Converts glucose into glycogen and, when required, breaks glycogen into glucose.
  • Converts carbohydrates and proteins into lipids and produces cholesterol.
  • Produces heat to maintain body temperature.
  • Stores fat-soluble vitamins (A, D, E, and K) and mineral ions, such as iron.

 

Analyzing and Interpreting:

Identify the villus, epithelium, capillary network and lacteal while examining the transverse sections of small intestine (like the one given on right).

For your information: There is a growing concern about the harmful effects of carbonated soft drinks. They are very acidic and make our bodies poor in oxygen. They contain phosphoric acid which dissolves calcium out of the bones. This results in bones weakening. The caffeine present in colas increases the heart rate and raises blood pressure.

 

Question#23) Briefly give the signs and symptoms, causes, treatments and prevention of diarrhea, constipation, and ulcer?

Answer: DISORDERS OF GUT

Diarrhea, constipation and ulcer are the most common disorders of the gut that affect a number of people in Pakistan.

 

DIARRHOEA

Definition: Diarrhea is a condition in which the sufferer has frequent watery, loose bowel movements.

Symptoms: This condition may be accompanied by abdominal pain, nausea and vomiting. It occurs when required water is not absorbed in blood from colon.

Causes: The main causes of diarrhea include lack of adequate safe water. Diarrhea is also caused by viral or bacterial infections of large intestine.

Prevention , Care and Treatment; If sufficient food and water is available, the patient of diarrhea recovers in a few days.

However, for malnourished individuals diarrhea can lead to severe dehydration and can become life-threatening. The treatment for diarrhea involves consuming adequate amounts of water (to replace the loss), preferably mixed with essential salts and some amount of nutrients. Antibiotics may be required if diarrhea is due to bacterial infection. Prevention’s of diarrhea include taking clean water and essential salts, eating regularly and taking hygienic measures.

 

CONSTIPATION

Definition: Constipation is a condition where a person experiences hard faeces that are difficult to eliminate.

Causes: The main causes of constipation include excessive absorption of water through colon, insufficient intake of dietary fibre, dehydration, use of medicines (e.g. those containing iron, calcium, and aluminum) and tumors in rectum or anus.

Symptoms: Delayed passage of waste through the lower portion of the large intestine, with the ultimate discharge of dry, hardened feces from the anus.

Treatment and Prevention: Treatment of constipation is with a change in dietary and exercise habits. The medicines called laxatives (e.g. paraffin) are used for treatment. Constipation is usually easier to prevent than to treat. One should take the required quantities of water and dietary fibers.

 

ULCER

Definition: Ulcer (peptic ulcer) is a sore in the inner wall of gut (in oesophagus, duodenum or stomach). Ulcer of stomach is called gastric ulcer.

Effects: In ulcer, the acidic gastric juice gradually breaks down the tissue of the inner wall.  Causes: The causes of ulcer include excess acid, infection, long term use of anti-inflammatory medicines (including aspirin), smoking, drinking coffee, colas, and eating spicy foods.

Signs and symptoms: The signs and symptoms of ulcer include abdominal burning after meals or at midnight. Severe ulcers may cause abdominal pain, rush of saliva after an episode of regurgitation, nausea, loss of appetite and weight loss.

Prevention and Treatment; Ulcer is treated with medicines, which neutralize the acidic affects of gastric juice. Spicy, acidic foods and smoking should be avoided as preventive measures.

Question#24) What are the health risks if we take more saturated fatty acids in our diet?

Answer; Saturated fatty acids are not good for human health because they increase cholesterol level in the body. They cause narrowing of blood vessels which may result in heart attack.

Question#25) What are the effects of the lack of nitrate and magnesium ions on plant growth?

Answer: Effects of Lack of nitrogen: When nitrogen is deficient plants concentrate it in the youngest leaves. So the older larger leaves turn pale and in severe cases fall from plant body. Overall coloration of plant is yellow and growth is stunted. It also reduce the yields of plants.

Effects of lack of magnesium: Deficiency of magnesium causes chlorosis (yellowing of leaves) and wilting of the leaves. Chlorosis first occur in older leaves and then in younger leaves with the passage of time. Magnesium is an activator for many enzymes such as RUBISCO which is involved in fixation of carbon dioxide. So photosynthesis process slows down or stops. Plant deficient in magnesium produces smaller and woodier fruits.

Question#26) How are vitamins A, C and D important in our diets?

Answer:

Functions or importance of vitamin A: It combines with a protein called opsinto form rhodopsin in rod cells of the retina of eye. When vitamin A is inadequate, the lack of rhodopsin makes it difficult to see in dim light. It is also involved in cell differentiation, a process through which embryonic cells transform into mature cells with specific functions. Vitamin A also supports bone growth and immune functions.

Functions or importance of Vitamin C:

It is needed in many reactions.

In the synthesis of collagen (a fibrous protein) in connective tissue.
Healing of wounds & fractures
Facilitates absorption of iron.
Helps in haemoglobin formation.
Formation of steroid hormones
Reduces the chances of infections
prevents from scurvy
Antioxidant
For healthy gums.

Functions or importance of  Vitamin D:

The best-known function of vitamin D is to help regulate blood levels of calcium and phosphorous. Vitamin D increases the absorption of these minerals from intestine and their deposition in bones. Also helps in strengthening of teeth.

Question#27) How can the deficiency of vitamin A cause blindness?

Answer: Vitamin A is a component of light sensitive parts, the rods and cones. So it allows the night vision or for seeing in dim light, that,s why deficiency of vitamin A cause blindness.

Question#28) How will you differentiate between bolus and chyme?

Answer: Difference between bolus and chyme: Chyme is a semi liquid mass of partially digested food that passes from the stomach through the pyloric sphincter into the duodenum. Bolus is a small round soft mass chewed food.

Question#29) Which sphincters play role in the movement of food in and out of stomach?

Answer: Pyloric sphincter controls the movement of food out of stomach into the small intestine (duodenum). While lower esophageal sphincter present in the cardiac region between esophagus and stomach controls the movement of food into the stomach.

 

Question#30) Stomach is an organ of the digestive system, but it also secretes a hormone. What hormone is it and what function it performs?

Answer: A group of hormone called gastrointestinal (related both to stomach and intestine) hormones are secreted by stomach and small intestine that controls digestion of food. Some gastrointestinal hormones like secretin, cholecystokinin were found to play a role in neuro-transmission.

 

Question#31) Draw a table that can show sources, energy values and functions of carbohydrates, proteins and fats?

Answer:

Food ComponentSourcesFunctionsEnergy value
KJ/gKCal/g
1Fats (lipids)Animal Sources
Ghee, butter, cream, animal fat and fish oil.
Plant Sources
Oils from mustard, olives, coconut, maize, soya beans, sunflower and peanuts.
1. The use of fat rich products increase in winters because they provide double the amount of energy as compared to carbohydrates.
2. They provide 9000 cal/gm energy to the body.
3. In plants fats are stored in seeds, and in animals, they are found beneath the skin and around the kidneys where they are not only stored but also protect these parts.
4. They provide materials for building new protoplasm and cell membrane.
  37  9
2ProteinsAnimal Sources meat, fish, chicken, milk and cheese.
Plant Sources :  legumes, pulses, dry fruit and cereals.
1. Proteins are essentially required for growth and development.

2. Proteins play an important role in the building of cellular protoplasm.
3.They also play an important role in the building of muscles and connective tissues.

4. Many proteins are required for making enzymes, hormones and antibodies.

5. If proteins are eaten in excess than needed by body, the excessive amino acids are converted into carbohydrates by the liver, which are either oxidized to release energy and converted into glycogen and fat and stored.

   17   4
3carbohydratesCarbohydrates containing starch are obtained from cereals and their products like wheat, rice, maize, bran, pastas, oats and barley.

They are also obtained from carrots, radish, turnip, beet, beet root and potatoes. Simple sugar called glucose is obtained from grapes. The sugar derived from fruit is called fructose. Then from beet and sugar cane is called sucrose and that from milk is lactose.

One gram carbohydrate food provides 3800 calories (4 kcal energy) to our body. The Carbohydrates are the cheapest and easy source of energy.

Surplus carbohydrates are stored as glycogen in the liver and muscles, or converted to fats and stored in the fat cells beneath the skin and causes obesity.

174

 

Each gram of ethanol drink contain 29 KJ  OR  7 kcal of energy while fiber contain 8 KJ  OR  2 Kcal of energy per gram.

 

QUESTION#32) Define the following terms?

Answer: Amylase: An enzyme that act on carbohydrates and degrade it is called amylase.

Anemia: A disease of blood in which the blood is deficient in red blood cells, hemoglobin, or in total volume is called anemia.

Appendix: A narrow blind tube usually about three to four inches (8 to 10 centimeters) long that extends from the cecum in the lower right-hand part of the abdomen.

Assimilation: The incorporation of the products of digestion into the body,for energy, growth and repair of tissues is called assimilation.  OR  Conversion or incorporation of absorbed simple food into the complex substances constituting the body.

Balanced diet: Diet which contains all the essential nutrients in correct proportion for the normal growth and development of body is called Balanced diet.

Bolus: A soft mass of chewed food is called bolus.

Sphincter: An annular(ring like) muscle surrounding and able to contract or close a bodily opening.

Cardiac sphincter: The valve between the distal end of esophagus and the stomach is called cardiac sphincter.  OR   the lower esophageal sphincter which residues at the top of stomach is called cardiac sphincter.

Chyme: The semi fluid mass of partly digested food expelled by the stomach into the duodenum is called chyme.

Colon: The part of the large intestine that extends from the cecum to the rectum is called colon.

Constipation: Constipation is a condition where a person experiences hard faeces that are difficult to eliminate.

Diarrhoea: Diarrhea is a condition in which the sufferer has frequent watery, loose bowel movements.

Dietary fibre: It is the part of food that is indigestible and provide fibers to our body.

Digestion: Digestion is the process in which the insoluble and non-diffusible components of food are broken down and by the action of enzymes are converted into soluble and diffusible substance to be absorbed into the blood stream. OR Digestion is the process in which the non-diffusible molecules of food are changed to diffusible ones by the action of enzymes.

Duodenum: The first part of the small intestine extending from the pylorus to the jejunum where most of the digestion takes place.

Emulsification: The break down of large globule (a tiny globe or ball especially of a liquid) into smaller uniformly particles is called emulsification.

Epiglottis: A thin plate of flexible cartilage in front of the glottis that folds back over and protects the glottis during swallowing is called epiglottis.

Famine: Famine means the lack of enough food to feed all people living in an area.

Fat soluble vitamins: Vitamins that are soluble in fats only are called fat soluble vitamins.

Fertilizer: Any of the chemical or natural substance added to soil or land to increase its fertility is called fertilizer.

Gastric juice: A thin watery acid digestive fluid secreted by glands in the mucous membrane of the stomach.

Gastrin: Any of various polypeptide hormones that are secreted by the gastric mucosa and induce secretion of gastric juice.

Gastric mucosa (mucous membrane): membrane rich in mucous glands that lines body passages and cavities which communicate directly or indirectly with the exterior.

Goiter: A disease in which the thyroid gland becomes enlarged due to less use of the iodine.

Ileum: The longest and last part of the small intestine extending between the jejunum and large intestine where food is completely digested and absorbed is called ileum.

Intestinal juice: clear to pale yellow, watery secretion composed of hormones, digestive enzymes, mucus, and neutralizing substances released from the glands and mucous-membrane lining of the small and large intestines. Intestinal juice neutralizes hydrochloric acid coming from the stomach; releases gastrointestinal hormones into the bloodstream; and contains digestive enzymes that facilitate the digestion and absorption of food.

Jejunum: The first, larger and thicker walled portion of the small intestine is called jejunum.

Kwashiorkor: severe malnutrition in infants and children esp. of impoverished regions caused by a diet low in protein.

Lacteal: Any of the lymphatic vessels arising from the villi of the small intestine and conveying chyle(Milky fat like digestive juice) to the thoracic duct.

Laxatives: Medicines that producing bowel movements and relieving constipation.

Lipase: Enzymes that act on lipids and digest them are called lipases.

Liver : A large very vascular glandular organ of vertebrates that secretes bile is called liver.

Malnutrition: Problems related to nutrition are grouped as malnutrition. OR Lack of proper nutrition is called malnutrition.

Marasmus: A condition of chronic undernourishment occurring esp. in children and usu. caused by a diet deficient in calories and proteins is called marasmus.

Mineral deficiency diseases: Diseases resulting from the deficiency of a mineral are called mineral deficiency diseases.

Nutrition: The process in which food is obtained or prepared, absorbed and converted into body substances for growth and energy, is called nutrition.

Oesphagus: A muscular large tube of digestive system in between the stomach and pharynx is called esophagus.

Oral cavity: The cavity of the mouth is called oral cavity or buccal cavity.

Over-intake of nutrients (OIN): Over-intake of nutrients (OIN) is a form of malnutrition in which more nutrients are taken than the amounts required for normal growth, development and metabolism.

Pancreas: Large gland located in the abdomen near the stomach which produces pancreatic juice for digestion and the hormone insulin.

Pancreatic juice: A clear alkaline secretion of pancreatic enzymes (as trypsin and lipase) that flows into the duodenum and acts on food already acted on by the gastric juice and saliva.

Pepsin: A protease enzyme of the stomach that breaks down most proteins to polypeptides is known as pepsin.

Pepsinogen: A granular zymogen (inactive protein) of the gastric glands that is readily converted into pepsin in a slightly acid medium.

Pertistalsis : The involutary movement of the esophagus and small intestine is called peristalsis.

Pharynx : The muscular tubular passage of the vertebrate digestive and respiratory tracts extending from the back of the nasal cavity and mouth to the esophagus.

Protein energy malnutrition: Protein-energy malnutrition means inadequate availability or absorption of energy and proteins in the body.

Pylorus: The muscular opening from the vertebrate stomach into the intestine.

Sphincter: An annular muscle surrounding and able to contract or close a bodily opening is called sphincter.

Pylorus: The muscular opening from the vertebrate stomach into the intestine is called pylorus.

Pyloric sphincter: A ring of smooth muscle fibers around the opening of the stomach into the duodenum is called pyloric sphincter.

Rectum : The terminal part of the intestine from the sigmoid colon to the anus is called rectum.

Saliva : Fluid secreted by glands in the mouth which moistens ,softens and semi-digest food is called saliva.  “OR”   A slightly alkaline secretion of water, mucin, protein, salts, and often a starch-splitting enzyme (as ptyalin) that is secreted into the mouth by salivary glands, lubricates ingested food, and often begins the breakdown of starches.

Starvation: widespread or generalized atrophy (wasting away) of body tissues either because food is unavailable or because it cannot be taken in or properly absorbed.

Stomach: A dilatation of the alimentary canal of a vertebrate communicating anteriorly with the esophagus and posteriorly with the duodenum.

Swallowing : The taking of food through the mouth and esophagus into the stomach is called swallowing.

Trace minerals: Minerals that are required in very minute quantities to living organisms are called trace minerals.

Trypsin: A proteolytic enzyme that is secreted in the pancreatic juice in the form of trypsinogen, is activated in the duodenum, and is most active in a slightly alkaline medium.

Ulcer : Ulcer (peptic ulcer) is a sore in the inner wall of gut (in oesophagus, duodenum or stomach). Ulcer of stomach is called gastric ulcer.

Villus (villi) : Minute hair like projections which cover the lining of the small intestine ; provide surface area for absorption.

Vitamins : Organic substances which are essential in small amounts to regulate the metabolism and maintain the immune system are called vitamins.

Water soluble vitamins: Vitamins that are only soluble in water are called water soluble vitamins.

 

UNDERSTANDING THE CONCEPTS –

Chapter 8 Nutrition

  1. What are the effects of the lack of nitrate and magnesium ions on plant growth?

Answer: Please see answer of question number 25.

  1. How are inorganic and organic fertilizers important in agriculture?

Answer: Please see answer of question number 7.

  1. Draw a table that can show sources, energy values and functions of carbohydrates, proteins and fats.

Answer: Please see answer of question number 31.

  1. How are vitamins A, C and D important in our diets?

Answer: Please see answer of question number 26.

  1. Which foods contain calcium and iron and what role these minerals play in our bodies?

Answer: Please see answer of question number 15.

  1. Why are water and dietary fibers considered important in our diets?

Answer: Please see answer of question number 17.

  1. Define balanced diet. How would you relate it with age, gender and activity?

Answer: Please see answer of question number 18.

  1. Describe how protein energy malnutrition, mineral deficiency diseases and over intake of nutrients are the major forms of malnutrition?

Answer: Please see answer of question number 19.

  1. How would you advocate the unequal distribution of food as the major factor that contributes to famine?

Answer: Please see answer of question number 20.

  1. Describe structures and functions of the main regions of alimentary canal.

Answer: Please see answer of question number 22.

  1. Describe swallowing and peristalsis.

Answer: Please see answer of question number 22.

  1. Briefly give the signs and symptoms, causes, treatments and prevention of diarrhea, constipation, and ulcer?

Answer: Please see answer of question number 23.

 

SHORT QUESTIONS – Chapter 8 Nutrition

  1. What are the health risks if we take more saturated fatty acids in our diet?

Answer: Please see answer of question number 24.

  1. How can the deficiency of vitamin A cause blindness?

Answer: Please see answer of question number 27.

  1. How will you differentiate between bolus and chyme?

Answer: Please see answer of question number 28.

  1. Which sphincters play role in the movement of food in and out of stomach?

Answer: Please see answer of question number 29.

  1. Stomach is an organ of the digestive system, but it also secretes a hormone. What hormone is it and what function it performs?

Answer: Please see answer of question number 30.

 

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