Q1. Write the functions of human skeleton.
Ans. The functions of human skeleton are :-
1. It supports the body by giving a framework and gives a definite shape.
2. It protects the several delicate organs such as brain, kidney, heart, spinal cord, lungs etc.
3. It helps in movement and locomotion.
4. It gives a leverage movement by the joints which increases the speed of the movement.
5. It helps in the formation of blood such as white bone marrow makes the white blood cells while the red bone marrow makes red blood cells.
6. Bone is a storehouse of calcium and phosphorous.
Q2.What does the human skeleton consist of?
Ans. It consists of bones, cartilages, tendons and ligaments.
Q3.Define:-
1. Declacified bones:-
Ans. When the bone is kept in weak hydrochloric acid {HCl} it removes its calcium and phosphate such a bone is called decalcified bone. It is soft and flexible.
2. Oxidized bones:-
Ans. If the bone is burnt in the air it loses its organic matter while the mineral part is left. Such a bone is called oxidized bone which is brittle and can break easily. Generally old people in their old age loose their organic part of the bone hence the bones becomes weak and become fragile which can break easily.
Q4. Write in short the structure of a bone.
Ans. The structure of bone is as follows:-
1. Bone is a highly calcified hard and rigid connective tissue.
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2. It consists of bone cells called oesteocytes.
3. These cells have collagen fibers, deposits of calcium and phosphorous.
4. The external surface of the bone is covered with a membrane called periosteum. While the inner layer is richly supplied with blood vessels.
5. Bone has white {white blood cells} and red {red blood cells} bone membranes.
Q5. Write the shapes of bones and their location.
Ans. The shapes of the bones and their location are as follows:-
1. Long bones:-present in arms, legs and ribs.
2. Short bones:-present in ankles and wrists.
3. Flat bones: – present in shoulder blades, sternum and skull.
4. Irregular bones:-present in face and vertebra.
Q6.write the two main divisions of the human skeleton:-
Ans. The two main divisions of the human skeleton are:-
1. Axial skeleton:-Includes skull, vertebral column, ribs and sternum.
2. Apendicular skeleton:-Includes limbs {hands and legs} and griddles.
1:- Axial skeleton
1. Skull:-
* The skull is called cranium or brain box which protects the brain.
* It is made up of eight immovable bones, permanently fixed.{8}
* Other part if the skull forms the face made up of fourteen bones.{14}
* Skull also contains bones of upper jaw maxilla and lower jaw mandible.
* At the back part of the skull there is a large hole called foremen magnum for the emerging of the spinal cord.
2. Vertebral column:-
* Consists of 33 vertebrae.
* The first 7 vertebrae are called neck or cervical vertebrae. The first one is called atlas and second one is called axis.
* The next twelve vertebrae are called thoracic vertebrae. It has a long spinous processes projected backwards. Their transverse process bares extremity of facet.
* Next five vertebrae are called lumbar vertebrae. They have well developed transverse and spinous process.
* They have five sacral vertebrae that are fused together and forms sacrum. {Hip bone attributes}.
* It contains four coccigeal vertebrae fused together to form coccyx which was a rudimentary tail of the human body.
3. Ribs:-
* There are twelve pairs of ribs with thoracic vertebrae which makes the rib cage.
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Calcium helps to keep bones strong but just drinking milk doesn’t mean that you won’t get osteoporosis. You may be genetically inclined to get it even though you drink milk every day. There are also many other things that contribute to getting osteoporosis, like not eating enough calcium, doing steroids causes bones to become weak and look like sponges when looking at it under a microscope. ...
* The first seven pairs of ribs are called true ribs attached to the sternum called breast bone.
* Eighth, ninth and tenth pair are united together by the cartilage and are called false ribs.
* Eleventh and twelfth pair is also false ribs but they are not attached to sternum and hence are called floating ribs.
4. Sternum:-
* It is also called breast bone. It is flat, lying in the middle of the chest.
2. Appendicular skeleton:-
1. Bones of limbs {hand}
* Forelimbs contain single long bones in upper arm called humorous.
* There are two long bones in the lower arm. The first one faces the thumb called radius. The next one is called ulna.
* There are eight wrist bones called carpals.
* There are five metacarpals in palm.
* There are fourteen phalanges.
2. Hind limbs {legs}:-
* It contains long bone called femur or thigh bone which is the longest and strongest in the skeleton.
* There are two long bones called tibia and fibula in the lower leg.
* There are seven tarsal bones in the ankle, five in metatarsal {long} in the middle foot and fourteen phalanges.
* There is also a knee cap called platella.
3. Girdles {develops from tendons}{an additional bone joint at the lower end of the femur}
* They are the parts of skeleton which connect {articulate} the limbs to the main axial skeleton.
* They are of two types:-
1} shoulder girdle [pectoral girdle]
2} hip girdle called pelvic girdle.
* Pectoral girdle- It is flat, triangular in shape also called shoulder blade. It has a cup shaped cavity called glenoid cavity for joining the limbs. It also has a curved collar bone.
Q7.Name three types of muscles?
Ans. The three types of muscles are:-
1. Voluntary muscles-they are under our own control. For example legs and hands.
2. Involuntary muscles-they are not in control of our own will. For example muscles of stomach, liver etc.
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3. Cardiac muscle-they are also involuntary muscles which are present in heart and never get tired.
Q8.lever mechanism of joints?
Ans. The joints in the human body show the action of lever as follows:-
1. First order lever-fulcrum is in between weight and power. Such joints are fixed in elbow while arms, skull {in 1st and 2nd neck vertebrae}.
2. Second order liver-weight is in between fulcrum and power. Present in toes and heels, while lifting up the heels.
3. Third order lever-power is in between weight and fulcrum present in bicep muscles while stretching the arm.
Q9. Functions of Synovial fluid.
Ans. Functions of synovial fluid are:-
1. Synovial fluid is present in the synovial sac of the synovial joint such as knee and elbow.
2. It is a lubricating fluid which prevents the friction between the two bones, also keeps the bones in proper position.
Q10.Functions of glenoid Cavity.
Ans. Functions of Glenoid cavity are:-
1. The outer apex of the shoulder girdle has a large cup-shaped cavity called glenoid cavity. It helps in the fitting of the rounded upper head of humerous.
Q11. Function of acetabulum.
Ans. It is a cup shaped cavity of the pelvic girdle which fits the large rounded head of the femur{thigh bone}.
Q12. Function of foramen magnum.
Ans. The back part of the cranium {skull} has a large hole called foramen magnum which helps the spinal cord to immerge from the brain and continue in the back bone.
Q12. Structure of vertebrae.
Ans. The structure of vertebrae is as follows:-
1. A vertebra is a ring like structure.
2. Central solid cylindrical bone is called Centrum.
3. At the side of the Centrum there are spines called neural spines.
4. There are two transverse processes for each vertebra. There is a difference between the dorsal vertebrae and the upper vertebra.
Q13. Differentiate between True ribs and Floating ribs.
True ribs Floating ribs
1. There are seven pairs of true ribs The eleventh and twelfth pair of ribs which are
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Osteoporosis Osteoporosis is a significant health problem that affects more than 25 million women in the United States and potentially 200 million worldwide. This disease is characterized by diminishing the structure of the skeleton (particular the " spongy' bone). This results in an increased risk of fracture. Osteoporosis develops silently over a period of years, eventually progressing to a ...
attached to the sternum. not attached to the sternum are called floating
ribs.
2. They are attached to the sternum and They are not attached to the sternum and hence
hence called true ribs. are called floating ribs.
Q14. Differentiate between coccyx and sacrum.
coccyx sacrum
1. The last section of backbone is made up The large bone formed by fusion of five vertebrae
of few fused vertebrae is called coccyx. Which articulates the hip bone.
Q15. Structure of vertebra.
Ans. The structure is as follows:-
1. Each vertebra is somewhat in ring like structure its solid body of bone called as Centrum.
2. On the opposite side of centrum there is a neural canal through which the spinal cord passes.
3. This neural canal has two neural centres at the side of the centrum which meet at the upward projection forming neural spine.
4. On the sideward of this projection there are transverse processes which extends from neural path.
5. Neural arch also bears articular facets which joints the vertebra.
6. Between each vertebra there is cusion of cartilage known as invertebral disc or gristle which acts like a shock absorber.
