Chapter Number 13 Support and Movement – 10th Class Biology Notes

Question 1: Define Support, movement and locomotion?

Answer: Support: support means to stand erect.

 

Movement: Movement” is a general term meaning the act of changing place or position by entire body or by its parts.

Locomotion: Locomotion is the movement of an animal as a whole from one place to another.

 

Question 2: What is skeleton? What are the different types of skeleton?

Answer: Skeleton: Skeletal system or skeleton is defined as the framework of hard, articulated structures that provide physical support, attachment for skeletal muscles, and protection for the bodies of animals

Types of skeleton: There are two types of skeleton.

1) Exoskeleton: The skeleton system that is at the outside of the body is called exoskeleton. Example: The skeletal system of some invertebrates e.g. arthropods.

2) Endoskeleton: The skeleton system that is on the inside of the body is called endoskeleton. Example: Skeleton in man.

 

Question3: What type of skeleton human being possess? What are the basic functions or roles of skeleton?

Answer: Human skeleton: Skeletal system or skeleton is defined as the framework of hard, articulated structures that provide physical support, attachment for skeletal muscles, and protection for the bodies of animals. Like other vertebrates, the human skeleton is on the inside of body and is called endoskeleton. In the living body, the skeleton is very much alive. Bones and cartilages are made of living cells and also have nerves and blood vessels in them. They grow and have the ability to repair themselves.

 

Role of Skeletal System:

The big functions of skeletal system are protection, support and movements. In our body, skeleton works very closely with the muscular system to help us move. Similarly, skeleton provides protection to many internal organs e.g. skull protects brain, vertebral column protects spinal cord and ribs protect most of our other internal organs. Vertebral column also provides the main support to our body mass.

 

Question4: Write a detailed note on components of human skeleton?

 

Answer: Components of human skeleton: Overall, the human skeleton is made of bony framework but in certain parts, this framework is supplemented by cartilage.

 

  1. Cartilage

Cartilage is a dense, clear blue-white firm connective tissue (but less strong than bone). The cells of cartilage are called chondrocytes. Each chondrocyte lies in a fluid space called lacuna present in the matrix of cartilage. The matrix of cartilage contains also collagen fibres. Blood vessels do not enter cartilage. Cartilage contain one type of cells.

 

Figure : Chondrocytes in cartilage matrix

 

 

Types of cartilage: There are three types of cartilage.

1) Hyaline cartilage: Hyaline cartilage is strong yet flexible. It is found covering the ends of the long bones, in the nose, larynx, trachea and bronchial tubes.

2) Elastic cartilage: Elastic cartilage is similar in structure to hyaline cartilage. It is also quite strong but has elasticity due to a network of elastic fibres in addition to collagen fibres. It is found in epiglottis, pinna etc.

3) Fibrous cartilage: Fibrous cartilage is very tough and less flexible due to large number of thick collagen fibres present in knitted form. It is found in intervertebral discs.

 

  1. Bone

Bone is the hardest connective tissue in body. Bone Like cartilage, the matrix of bones also contains collagen. But it also contains minerals e.g. calcium and phosphate. Bones contain different types of cell. The mature bone cells are called osteocytes.

 

 

Recalling
Cartilage and bone are types of connective tissue in animals. Most connective tissues contain collagen fibres in a matrix.
Recalling
Tendons and ligaments are other connective tissues that contain tightly packed collagen fibres.

 

 

Figure: Hyaline cartilage

 

Figure: Fibrous cartilage

 

 

 

Component of bone: There are two main components of the bone.

  1. a) Compact bone:The hard outer layer of a bone is called compact bone.
  2. b) Spongy bone:The interior of bone is soft and porous and is called spongy bone. Spongy bone contains blood vessels and bone marrow.

Role of bone: Bones not only move, support and protect the various parts of body but also produce red and white blood cells and store minerals.

 

Figure : Compact and spongy bone

 

 

 

 

Figure: The internal structure of bone.

 

 

Interesting information:

Babies are born with about 300 soft bones. Some of these bones later fuse together, so that the adult skeleton has 206 hard bones.

 

Intresting information:

Andreas Vesalius (1514-1564) is honoured for developing modern anatomical studies. Vesalius was born in Brussels, Belgium. He made many discoveries in anatomy, based on studies made by dissection of human dead bodies. His book contained the most accurate depictions of the whole skeleton and muscles of the human body.

 

 

Question5: What are the main components of the axial skeleton and the appendicular skeleton of human?

 

Answer: Components of Human Skeleton

The 206 bones in the adult human skeleton are organized into a longitudinal axis i.e. axial skeleton, to which appendicular skeleton is attached.

 

  1. Axial skeleton

Axial skeleton consists of the 80 bones in the head and trunk of body. It is composed of five parts.

Skull bones: Skull contains 22 bones out of which 8 are cranial bones (enclosing the brain) and 14 are facial bones.

Ear bones: There are 6 middle ear ossicles (3 in each ear).

Neck bone: There is also a hyoid bone in neck.

Vertebral column bones: Vertebral column contains 26 bones (vertebrae).

Chest and ribs bones: The chest is made of a chest bone called sternum and 24 (12 pairs) ribs.

 

 

  1. Appendicular Skeleton:Appendicular skeleton is composed of 126 bones.

Shoulder bones: Pectoral (shoulder) girdle is made of 4 bones.

Arms: Arms have 6 bones.

Hands: Both hands have 56 bones.

Pelvic girdle: Pelvic girdle (hips) has 2 bones.

Legs: Legs have 8 bones.

Feet: Both feet have 56 bones.

 

Figure: Human skeleton

 

 

 

Question6: Name the longest and smallest bones in human body?

Answer: The thigh bone (femur) is the longest bone in our body which is 19.9 inches long and is ¼ of the height of an adult. While the stapes or stirrup is the shortest bone which is 3 mm long.

 

Question7: Describe the types of joints and give examples.

 

Answer:  Joint: A joint is the location at which two or more bones make contact.

Function of joints: They allow movement and provide mechanical support.

 

TYPES OF JOINTS:

Joints can be classified on the basis of the degree of movement they allow.

  1. a) Immoveable (Fixed) joints:Such joints allow no movement e.g. the joints between the skull
  2. b) Slightly moveable joints:Such joints allow slight movements e.g. joints between the vertebrae.

 

Figure: Fixed and slightly moveable joints

 

 

  1. c) Moveable joints:They allow a variety of movements e.g. shoulder joint, hip joint, elbow joint, knee joint etc. There are many types of moveable joints in body. The main types are hinge joints and ball-and-socket joints.
  2. i) Hinge joints:Hinge joints  move back and forth like the hinge on a door and allow movements in one plane only. The knee and elbow are hinge joints.
  3. ii) Ball-and-socket joints:Ball-and-socket joints allow movement in all directions. The hip and shoulder joints are ball-and-socket joints.

 

 

Figure : Two types of moveable joints.

 

 

The neck joint between vertebral column and head allows movements side to side. Can you think what would have happened if it were a ball-and-socket joint?

Answer: If it were a ball and socket joint, then it will allow movements in all directions.

 

Question8: What are ligaments and tendons? What function do they perform?

 

Answer: Tendons and Ligaments: Tendons and ligaments are bands of fibrous connective tissue (made of collagen).

 

Tendons (sinew): Tendons are tough bands and attach muscles to bones.

Function of tendon: Tendons attach muscles to bones. When a muscle contracts tendon exerts a pulling force on the attached bone, which moves as a result.

Ligaments: Ligaments are strong but flexible bands and join one bone to another at joints.

Functions of ligaments: They attach one bone to another at joint and prevent dislocation of bones at joints.

 

Question9: Explain antagonism in muscle action selecting biceps and triceps as example?

 

Answer: MUSCLES AND MOVEMENT: When bones move at joints, they produce movements. The movements in bones are brought about by the contractions of skeletal muscles, which are attached with them by tendons.

 

Origin: The end of a skeletal muscle attached with some immoveable bone is called origin.

Insertion: The end of muscle that is attached with a moveable bone is called the insertion.

Role of skeletal muscles: When a muscle is stimulated by a nerve impulse, it contracts to become shorter and thicker. Due to this contraction, it pulls the moveable bone (at insertion).

Antogonistic muscles: Muscles having opposite functions, the contraction of one neutralizing the contraction of the other. OR Muscles that occurs in pairs and oppose the functions of each other, if one contract the other relaxes and vice versa. The phenomenon is called antagonism (antagonistic action).

 

Explanation: Skeletal muscles are usually in pairs of antagonists. In an antagonistic pair, both muscles do opposite jobs. When one muscle contracts the other relaxes and vice versa. Flexor: When a muscle contracts and bends the joint, it is known as flexor muscle and the movement is called flexion.

Extensor: When a muscle contracts and straightens the joint, it is known as extensor muscle and the movement is called extension. 

 

Example: Following is an example of the antagonistic action of a pair of skeletal muscles.

Biceps is a flexor muscle on the front of the upper arm bone while Triceps is an extensor muscle on the back of arm.

Both these muscle have their origin at pectoral girdle and insertion at one of the two bones of forearm. When biceps contracts, the

forearm (insertion end) is pulled upward. It is the flexion of elbow joint. During this flexion, triceps muscle relaxes. When triceps muscle

contracts, forearm is pulled down. It is the extension at elbow joint. During it, biceps muscle relaxes.

In this way, biceps and triceps make up an antagonistic pair of muscles. Similar pairs, working antagonistically across other joints, provide for almost all the movements of skeleton.

It is important to remember that muscles can only pull or contract, not push.

 

Most activities in our body like standing,walking,running, playing etc.require combined action of several muscles.

 

 

Question10: Write a note on osteoporosis and arthritis?

 

Answer: DISORDERS OF SKELETAL SYSTEM:

The following disorders of skeletal system are important.

Osteoporosis: Osteo means bone and porosis means pores so osteoporosis is the weakening of the bones or pores formation in the bones due to excessive loss of calcium.

Causes of Osteoporosis: Osteoporosis is a bone disease in adults, especially in old people. It is more common in old women. In osteoporosis, there is a decrease in the density of bones due to loss of calcium and phosphorus. It may be due to malnutrition (lack of proteins and Vitamin C), lack of physical activities or deficiency of estrogen hormone. In old age, there is decreased secretion of growth hormones and it also leads to decreased deposition of minerals in bone matrix.

Symptoms: Osteoporosis itself does not usually cause noticeable symptoms.However, weakened bones that are no longer able to support body weight can break even under slight pressure. Such fractures most commonly occur in the hipbones, wrists, or spine. Another symptom caused by osteoporosis is chronic back pain. This pain can worsen even when you are making small movements such as regular activities around the house, or while coughing, laughing, or sneezing. You may even feel pain when you are standing still.

Treatment and Prevention: J Regular intake of calcium containing food is useful.

J Weight bearing exercises, such as walking, weight training or climbing stairs play a role in strengthening bones and preventing fractures.

J Selective estrogen receptor modulator (SERMs; e.g ralaxofene) is used to treat osteoporosis in women.

J Testosterone: This is not recommended for the treatment of osteoporosis in most men. However, in some cases where osteoporosis in men is the result of hypogonadism, which is a condition of low levels of the male hormone testosterone, testosterone replacement therapy (androgen) may be used alone or with a bisphosphonate.

J Parathyroid hormone analogues (e.g., teriparatide): This class of medication builds new bone faster than it breaks it down, and can be used to treat severe osteoporosis.

Arthritis:

Arthritis means “inflammation in joints”. It is also very common in old age and in women. It is characterised by pain and stiffness in joints (particularly in the weight bearing joints e.g. hip joint, ankle joint etc.). The treatment of arthritis includes pain killer and anti inflammatory medicines. There are many types of arthritis, for example:

  1. Osteo-arthritis:It is due to degeneration in the cartilage present at joints or due to decreased lubricant production at joints. In this arthritis, fusion of the bones at joint may occur and joints may become totally immoveable.
  2. Rheumatoid arthritis:It involves the inflammation of the membranes at joints. Its symptoms include fatigue, low-grade fever, pain and stiffness in joints.
  3. Gout:It is characterised by the accumulation of uric acid crystals in moveable joints. It generally attacks the toe joints.

 

 

Can you do it?
Aquatic animals need less skeletal support than land animals of similar size. Propose an explanation for this fact.

 

Because of buoyancy. Buoyancy is a force caused by fluid pressure. Buoyancy can cancel out gravity, so that an animal living in the water does not even need limbs to support its body weight. Dolphins and whales, for example do not need any limbs. They have turned their front limbs into flippers and their rear limbs have almost disappeared entirely.

 

 

For your Information:

It is one of the functions of esterogen to deposit minerals in bones. When the reproductive cycle stops in females, not enough esterogen is secreted.

 

 

UNDERSTANDING THE CONCEPT:

 

  1. What are the main components of the axial skeleton and the appendicular skeleton of human?

Answer: Please see answer of question no.5.

 

  1. Describe the types of joints and give examples.

Answer: Please see answer of question no.7.

  1. What are ligaments and tendons? What function do they perform?

Answer: Please see answer of question no.8.

 

  1. Explain antagonism in muscle action selecting biceps and triceps as example

Answer: Please see answer of question no.9.

 

SHORT QUESTIONS

 

  1. Differentiate between cartilage and bone.

Answer: Difference between cartilage and bone:

1) Cartilages are soft while bones are hard.

2) The cellular components of the cartilages are chondrocytes that contain called chondrin. The cellular matrix of the bones are Osteocytes that contain ossein protein.

3) Cartilage contains one type of cells while bones consists of different type of cells.

4) Cartilage is avascular (not supplied with blood vessels), Bones are vascular (supplied with blood vessels).

 

  1. What is the role of skeleton in support and movement?

Answer: Role of Skeletal System:

The big functions of skeletal system are protection, support and movements. In our body, skeleton works very closely with the muscular system to help us move. Similarly, skeleton provides protection to many internal organs e.g. skull protects brain, vertebral column protects spinal cord and ribs protect most of our other internal organs. Vertebral column also provides the main support to our body mass.

 

  1. How would you differentiate between osteoporosis and arthritis?

Answer: Osteoporosis affects the bones while arthritis effect the joints.

In osteoporosis bones become fragile and finally fracture (Break or damage) while in arthritis the joints become immobilized and deform.

 

  1. Label the biceps and triceps in the following diagrams and also mention their contracted or relaxed states.

 

 

 

 

Answer:

 

 

 

THE TERMS TO KNOW:

 

Antagonism: Muscles having opposite functions, the contraction of one neutralizing the contraction of the other. OR Muscles that occurs in pairs and oppose the functions of each other, if one contract the other relaxes and vice versa. The phenomenon is called antagonism (antagonistic action).

Appendicular skeleton: The division of the skeleton that includes arms, hands, legs, feet pectoral girdle and pelvic girdle.

Arthritis: A disease of the inflammation of joints.

Axial skeleton: The division of the skeleton that includes the skull, vertebral column, ribs and breastbone.

Ball-and-socket joint: The joint that allows movement in all directions e.g. hip and shoulder joints.

Biceps: A flexor muscle on the front of the upper arm bone.

Bone: Hard connective tissue; moves, supports and protects the various organs of the body.

Cartilage: Cartilage is a dense, clear blue-white firm connective tissue (but less strong than bone).

Chondrocyte: The cells present in the cartilage are called chondrocytes.

Compact bone: The hard outer layer of bones is called compact bone.

Cranial bones: The bones of the cranium are known as cranial bones.

Extensor: When a muscle contracts and straightens the joint, it is known as extensor muscle and the movement is called extension. Example: Tricep.

Fibrous cartilage: The cartilage that has large number of fibres in the matrix e.g. the cartilage in intervertebral disc.

Flexor: When a muscle contracts and bends the joint, it is known as flexor muscle and the movement is called flexion. Example: Bicep.

Gout: A type of arthritis; characterised by the accumulation of uric acid crystals in the moveable joints.

Hinge joint: A joint that permits movement of bones in one plane e.g. elbow and knee joints.

Hyaline cartilage: The cartilage that has collagen fibres in its matrix; found covering the ends of the long bones, in the nose, larynx, trachea and bronchial tubes.

Insertion: The end of the muscle that is attached with a moveable bone.

joint: The location at which two or more bones make contact.

Lacuna: The fluid filled space in bone and cartilage, where their cells are present.

Ligament: Strong but flexible connective tissue that joins one bone to bone at the joints.

Origin: The end of the muscle that is attached with a immoveable bone.

Osteoarthritis: Inflammation in joints due to degeneration in the cartilage present at the joints or due to decreased lubricant production at the joints.

Osteocyte: The mature bone cells are called osteocytes.

Osteoporosis: A bone disease in adults, especially in old age; there is a decrease in the density of bones due to loss of calcium and phosphorus.

Rheumatoid arthritis: Painful inflammation of the membranes at the joints.

skeleton: The framework of hard, articulated structures that provide physical support, attachment for skeletal muscles, and protection for the bodies of animals.

spongy bone: The soft and porous interior of the bone; contains blood vessels and bone marrow.

Sternum: The chest bone is called sternum.

Tendon: Tough connective tissue that attaches muscles to bones.

Triceps: An extensor muscle on the back of the upper arm bone.

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