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Q1. How do compact bone and spongy bone differ in structure?
Answer
In the inner region of bone called endosteum, there are two further regions.
i) Peripheral part called compact bone.
ii) Inner bone mass called spongy bone. Most of spongy bone is present in terminal broad parts of bone called epiphysis.
Q2. Name three functions of the bones.
Answer
i) Support and Shape
Bones support soft tissues and serve as attachment sites for most muscles and provide shape to the body
ii) Protection
Bones protect critical internal organs such as brain, spinal cord, heart, lungs and reproductive organs.
iii) Movement
Skeletal muscles attached to bones help to move the body
Q3. Which bones form the pectoral girdle?
Answer
Pectoral girdle is composed of three bones:
i) Ileum
ii) Ischium i Pubis which form coxa
Q4. List six different types of freely moveable joints?
Answer
i) Hinge joint
ii) Pivot joint
iii) Ball & socket joint
iv) Saddle joint
v) Condyloid jint
vi) Gliding joint
Q5. Name three disorders of human skeleton.
Answer
i) Slipped disc (Herniation)
ii) Spondylosis
iii) Arthritis
Q6. What are the symptoms of arthritis?
Answer
i) Inflammation of joints.
i) Pain after walking which may later occur after even at rest.
ii) Creaking sounds in joints
iv) Difficulty in getting up from chair and pain on walking up and down stairs.
v) Redness of skin around the joints.
Q7. How a broken bone is repaired?
Answer
Repairing Process
There are four stages in the repairing process which are as follows
Hematoma Formation of Clot Formation
As soon as there is a fracture in bone, the blood vessels of the bone and surrounding are tom which results in hemorrhage. A mass of clotted blood is formed at that place which is called hematoma. After sometime a swelling occurs which creates lot of pain.
Fibrocartilaginous Callus Formation
The next step is callus formation which is soft. This takes 3-weeks. The place where hematoma was formed now is provided with capillaries and debris is also cleared.
Fibroblast and the bone forming cells osteoclasts now move to that place to form bone
Bony Callus Formation or Callus Ossification
Along with osteoblasts, osteoclasts also move to the place of fracture converting the soft callus into bony callus. After 3-4 weeks of injury bone is formed while 2-3 months is required for firm bony union.
Bone Remodelling
After several months, bony callus is remolded by excess material on outside of bone.
Final structure of remolded area resembles that of original unbroken bone because it responds to same set of mechanical stimuli.
Q8. What are first-aid treatment for joint dislocation and sprain?
Answer
i) A dislocated joint usually can only be successfully "reduced" into its normal position by a trained medical professional, Surgery may be needed to repair or tighten stretched ligament
ii) Sprain can be usually treated with treatment such as icing and physical therapy.
Dressing, bandages, or ace-wraps should be used to immobilize the sprain and provide support.
Q9. What is remodelling bone?
Answer
After several months bony callus is remodelled by the excess material on the outside of bone. Final structure of remodelled area resembles that of the original unbroken bone because it response to the same set of mechanical stimuli.
Q10. What changes occur in sarcomere during muscle contraction?
Answer
In muscle fiber there are alternative dark and light bonds. Microscopic study clearly shows that bands are due to regular thick and thin filaments. Transversing the middle of each l-band is a dark line called Z-line
The section of myofibril between two Z-lines is called sarcomere which is a contractile unit. From ZHine actin filaments extend in both directions, whilst in the centre ofsarcomere are found myosin filament.
Q11. Differentiate between bone and cartilage.
Answer
Bone
Bone is a rigid form of connective tissue, which forms the endoskeleton of vertebrates Bone is a living hard (resists compression) and strong (resists bending) structure. It consists of a hard ground substance or matrix and cells. In the adult human, the matrix consists of about 65% inorganic matter (calcium phosphate, carbonate etc.) and about 35% organic substances (protein, collagen). The cells are embedded in the matrix.
Cartilage
Cartilage is a type of connective tissue consisting of cells called chondrocytes and a tough, flexible matrix made of type II collagen. Unlike other connective tissues, cartilage does not contain blood vessels and the chondrocytes are supplied by diffusion.
Because of this, it heals very slowly
Q12. How thin and thick myofilaments are arranged in myofibrils?
Answer
Ultrastructure of Myofilament
Thick and thin filament combines to form myofilament. The central thick filament extend the entire length of A band the thin filament extend across the I band and partly into A band. The diameter of thick filament is 16mm. It is composed of myosin Myosin molecule has tail terminating in two globular heads. Myosin tail consists of two long polypeptide chain coiled together. The head are called cross bridge.
Thin filaments are composed of acting molecules which are 7-8 mm thick. The actin molecules are arranged in two chain which twist around each other like twisted double strand of pearls. Twisting around the actin chains are two strands of protein tropomyosin. The other major protein in thin filament is troponin.
Q13. You raise your hand to answer a question in class. Example the role played by your bones and skeletal muscles in this movement.
Answer
As we know that skeletal muscles are attached with bones so as to bring the movement.
When you want to raise your hand, skeletal muscles contract which result in lifting of bones attached to them. As a result your arm moves up.
Q14. What is the composition of thick and thin filaments?
Answer
Thick Filament
The thick filament which is about 16 mm in diameter is composed of myosin. Each .myosin molecule has tail terminating in two globular heads. Myosin tail consists of two long polypeptide chain coiled together. The heads are sometimes called cross bridges because they link the thick and thin myofilaments together during contraction.
Thin Filaments
Thin filaments are 7-8 mm thick and composed of chiefly actin molecule. The actingmolecules are arranged in two chains which twist around each other, like twisted double strand of pearls. Twisting around the actin chains are two strands of another protein tropomyosin. The other major protein in thin filament is troponin. It is actually three polypeptides complex (Troponin-T, Troponin-C & Troponin-I). One binds to actin, another binds to tropomyosin while third binds to calcium ions. Each myosin filament is surrounded by six actin filaments on each end
Q15. Differentiate between tetany and tetanus.
Answer
Tetany
Tetany is a symptom characterized by muscle cramps, spasms or tremors. These repetitive actions of the muscles happen when muscle contract uncontrollably. Tetany may occur in any muscle of the body, such as those in face, fingers or calves. The muscle cramping associated with tetany can be long lasting and painful. A common cause of tetany is very low levels of calcium in the body.
Tetanus
Tetanus is infection of the nervous system with the potentially deadly bacteria Clostridium tetani. Spores of the bacteria C. tetani live in the soil and are found around the world. In the spore form, C. tetani may remain inactive in the soil, but it can remain infectious for more than 40 years. Infection begins when the spores enter the body through an injury or wound. The spores release bacteria that spread and make a poison called tetanospasmin. This poison blocks nerve signals from the spinal cord to the muscles, causing severe muscle spasms. The spasms can be so powerful that they tear the muscles or cause fractures of the spine.
Q18. Name the bones of Thoracic Cage.
Answer
Rib Cage or Thoracic Cage
In man there are twelve pairs of ribs, one pair articulating with each of the thoracic vertebrae forming a cage that encloses the heart and lungs. Ten pairs of ribs are connected anteriorly with the sternum. Seven pairs out of these ten pairs are directly connected with the sternum and are known as 'true ribs, while the other three pairs are indirectly connected with the sternum through costal arch and are known as 'false ribs'. The lower two pairs of ribs are not attached in front and are known as the "floating ribs".
Q19. Name the bones of upper and lower limb.
Answer
Hind Limbs
Each hind limb consists of thigh, shank, ankle and foot. In the hind limb there is a single femur in the thigh, a pair of bones, the tibia and fibula, in the shank, 8 anklebones, followed by five longer metatarsals in the foot and finally five rows of fourteen phalanges in the toe.
Forelimbs
The forelimbs consist of a humerus in the upper arm region; a radius and an ulna in the lower arm region: 8 carpals in the wrist and 5 metacarpals in the palm of the hand and 14 phalanges.
Q20. What are the parts of the vertebral column and what are its curvatures?
Answer
Vertebral Column
Vertebral column extends from skull to the pelvis to form backbone, which protects the spinal cord. Normally the vertebral column has 4 curvatures, which provide more strength than the straight column. The vertebral column consists of 33 vertebrae. The vertebrae are named according to their location in the body, vi., cervical, thoracic lumbar and pelvic
Cervical Vertebrae
These are seven vertebrae which lie in the neck region. The first two cervical vertebrae are Atlas vertebra and Axis vertebra.
Thoracic Vertebrae
There are twelve thoracic vertebrae located in the thoracic region.
Lumbar Vertebrae
There are five vertebrae in lumbar region.
Sacrum
Sacrum is formed by the fusion of anterior five vertebrae present in the pelvic region
Coccyx
Coccyx is formed by the fusion of four posterior vertebrae present in the pelvic region.
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