Chapter # 16

SUPPORT AND MOVEMENT

Multiple choice questions.

(i) The disorder in which bones are porous and thin but bone composition is normal is;

(a) osteomalacia (b) osteoporosis

(ii) The organic portion of bone's matrix is important in providing all but;

(a) tensile strength (b) hardness

(iii) The remodeling of bone is a function of which cells?

(a) chondrocytes and osteocytes

(b) osteoblasts and osteoclasts

(d) osteoblasts and osteocytes

(iv) In skeletal muscle, calcium facilitates contraction by binding to

(a) tropomyosin (b) actin.

(v) Which of the following statements concerning the role of Ca2+ in the contraction of skeletal muscle is correct?

(a) The mitochondria act as a store of Ca++ for the contractile process

(b) Ca+2 entry across the plasma membrane is important in sustaining the contraction of skeletal muscle

d) The tension of a skeletal muscle fibre is partly regulated by G proteins muscle

(vi) The function of the T tubules in muscle contraction is to

(a) make and store glycogen

(b) release Ca2+ into the cell interior and then pick it up again

(d) to hamper the the nerve impulse

(vii) The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes are the:

(a) neuromuscular junctions (b) sarcomeres

(viii) Myoglobin has a special function in muscle tissue.

(a) it breaks down glycogen.

(b) it is a contractile protein

(d) none of these

Short Questions

Q1. Name the cranial and facial bones

Ans. The 28 Bones of the skull are tabulated here.

Skull	Unpaired Bones	Paired Bones
Cranium 8 Bones	Frontal Occipital Sphenoid Ethmoid	Parietal Temporal
Facial bones (face) 14 bones	Mandible Vomer	Maxilla Zygomatic Lacrimal Nasal Inferior concha Palatine
Auditory ossicle (ear bones) 6 Bones		Malleus Incus Stapes

Q2. What is the function of the intervertebral discs?

Ans. The inter vertebral discs are protective shock absorbing pads between the bones of vertebrae. They remain in stable position with the help of the cartilaginous portion of disc & the gel portion present among the discs. Any damage to disc or infection than causes disc defects & disc thus can not keep themselves stable.

Q3. Distinguish between the anulus fibrosus and nucleus pulposus regions of a disc.

Ans.

i. Vertebral column is a bony tube made up of vertebrae, connected with each other by mean of intervertebral discs.

ii. The discs act as shock absorber during walking running or jumping etc.

iii. The outer part of the disc is called annulus fibrosis and its internal part is the nucleus pulposus.

iv. Slipped disc or herniation occurs most commonly in those areas of vertebral column where a mobile part joins a relatively immobile part, on occasions like bending forward, while lifting a heavy load,

v. In these areas the posterior parts of annulus fibrosis of the disc ruptures and the central nucleus pulposus is forced out.

vi. This may press one or more nerve roots and thus results in the onset of pain.

Q.4 Briefly describe the impairment of function seen in cleft palate.

Ans. Clef palate is the abnormal union of palate bone during its development as a result of the birth the defect of palate cancers malfunction for the new born. In speech, eating habits & in swallowing.

Extensive Questions

Q1. Describe the structure of bone.

Ans. Bone:

i) Introduction: Bone is a rigid form of connective tissue, which forms the endoskeleton of vertebrates.

ii) Nature: Bone is a living hard (resists compression) and strong (resists bending) structure.

iii) Composition: 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.

iv) structure: The structure of bone is specially designed to withstand the compression strains falling upon it and to resist pressure.

v) Bone Cells: Bones are composed of cells for example; osteoblasts (cells that to help form bone), and osteoclasts (cells that help eat away old bone).

In addition, bone contains cells called osteocytes, which are mature osteoblasts that have ended their bone-forming capacity. These cells engage in metabolic exchange with the blood that flows through the bones.

Osteoblasts:

i. The osteoblasts are mononucleate cells. Osteoblasts produce a matrix which is composed mainly of Type I collagen.

ii. They are also responsible for mineralization of this matrix.

iii. Osteoblasts are the immature bone cells, and eventually become entrapped in the bone matrix to become osteocytes- the mature bone cell.

Osteocytes:

i. They are mature bone cells.

ii. They cease to generate mineralized matrix.

iii. Osteocytes have many extensions that reach out to meet osteoblasts and other osteocytes for the purposes of communication.

vi. They are responsible for the maintenance of bone and calcium.

v. They also regulate the bone's response to stress and mechanical load.

Osteoclast:

i. Osteoclasts are large, multinucleated cells that remove bone tissue by removing its mineralized matrix and breaking up the organic bone.

ii. This process is known as bone resorption.

iii. They are equipped with phagocytic-like mechanisms similar to circulating macrophages.

Q2. Describe major divisions of human axial skeleton

Ans. Axial Skeleton:

Axial skeleton consists of skull, vertebral column and cular skeleton ribs.

1. Skull:

i. The skull consists of cranium (or facial bones), ear bone (or auditory ossicles) and hyoid bone.

ii. The primary function of skull is the protection of brain. The human skull is composed of 22 bones, besides 6 tiny ear bones and one hyoid bone.

iii. At the time of birth several of the bones of the cranium are not completely formed.

iv. If the bones of cranium were completely formed at the time of birth, great difficultly would have been experienced in the birth canal.

2. Vertebral Column:

i. The vertebral column forms a more or less rigid rod.

ii. It extends through the length of the trunk on the dorsal side and form the backbone.

iii. It houses and protects the spinal cord.

iv. It is a place of attachment of pelvic and pectoral girdle.

v. In man, there are 33 vertebrae.

vi. Seven cervical vertebrae in the neck region; in the thorax region 12 thoracic vertebrae; in the lower back region 5 lumber vertebrae; in the sacral region 5 sacral vertebrae (to which the pelvic girdle is attached ) and at the end of the vertebral column is the coccyx or tail bone which consists of 4 small fused vertebrae.

vii. The coccyx is man's vestige of a tail.

3. Ribs:

i. 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.

ii. Ten pairs of ribs are connected anteriorly with the sternum.

iii. 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'.

iv. The lower two pairs of ribs are not attached in front and are known as the “floating ribs”.

Q3. What are types of fractures? Describe the repair process of a simple fracture.

Ans. Bone fractures:

i. A fracture is the medical term for a broken bone.

ii. They occur when the physical force exerted on the bone is stronger than the bone itself. So bones break when they cannot withstand a force or trauma applied to them.

iii. Simple fracture: Closed (simple) fractures are those in which the skin is intact.

iv. Compound fracture: The fracture is an open (compound) fracture if the bone ends penetrate the skin and form a wound.

Repair of a fractured bone:

i. A fracture is treated by reduction, the realignment of the broken bone ends.

ii. In closed or external reduction, the bone ends are coaxed into position by the physician's hands. In open (internal) reduction, the bone ends are secured together surgically with pins or wires.

iii. After the broken bone is reduced, it is immobilized by a cast to allow the healing process to begin.

iv. For a simple fracture the healing time is six to eight weeks for small or medium-sized bones in young adults, but it is much longer for large, weight-bearing bones and for bones of elderly people (because of their poorer circulation).

v.Stages; Repair in a simple fracture involves four major stages;

Heamatoma formation:

i. When a bone breaks, blood vessels in the bone, and perhaps in surrounding tissues, are torn and hemorrhage occur.

ii. As a result, a heamatoma, a mass of clotted blood, forms at the fracture site.

iii. Soon, bone cells deprived of nutrition die, and the tissue at the site becomes swollen, painful, and inflamed.

Fibrocartilaginous callus formation:

i. Within a few days, several events lead to the formation of soft granulation tissue, also called the soft callus.

ii. Capillaries grow into the hematoma and phagocytic cells invade the area and begin cleaning up the debris.

iii. Meanwhile, fibroblasts and osteoblasts invade the fracture site and begin reconstructing the bone.

iv. The fibroblasts produce collagen fibers that span the break and connect the broken bone ends, and some differentiate into chondroblasts that secrete cartilage matrix.

v. Within this mass of repair tissue, osteoblasts begin forming spongy bone, but those farthest from the capillary supply secrete an externally bulging cartilaginous matrix that later calcifies.

vi. This entire mass of repair tissue, now called the fibrocartilaginous callus, splints the broken bone.

Bony callus formation:

i. Within a week the fibrocartilaginous callus is gradually converted to a bony (hard) callus of spongy bone.

ii. Bony callus formation continues until a firm union is formed about two months later.

Bone remodeling:

i. Beginning during bony callus formation and continuing for several months after, the bony callus is remodeled. The compact bone is laid down to reconstruct the shaft walls.

ii. The final structure of the remodeled area resembles that of the original unbroken bony region because it responds to the same set of mechanical stressors.

Q4. Compare smooth, cardiac, and skeletal muscles.

Ans. Types of muscles:

Based on their location, three types of muscles are skeletal, cardiac, and smooth.

1. Skeletal Muscles:

i. Location: Skeletal muscles are attached to and cover the bony skeleton.

ii. Striations: Skeletal muscle fibers are multinucleated, the longest muscle cells having obvious stripes called striations and are under voluntary control.

iii. Working power: They can contract rapidly, but get tire easily and must rest after short periods of activity, or fatigued. Nevertheless, it can exert tremendous power.

iv. Function (a) Skeletal muscles are also remarkably adaptable. For example, hand muscles can exert a force of a fraction of an ounce to pick up a dropped paper clip and the same muscles can exert a force of many pounds to pick heavy loads like a bucket full of water.

(b) Skeletal muscles are primarily involved in locomotory actions and changes of body postures.

2. Cardiac Muscles:

i . Location: Cardiac muscles occur only in the heart where they constitute the bulk of the heart walls.

ii. Arrangement: Cardiac muscle cells are arranged in a characteristic branching pattern.

iii. Nature: Like skeletal muscle cells, cardiac muscle cells are striated, but are involuntary and have single nucleus.

iv. Working power: Cardiac muscles usually contract at a fairly steady rate set by the heart's pacemaker, but neural controls allow the heart to “shift into high gear” for brief periods.

v. Function: Rhythmic contraction of cardiac muscles in atria and ventricles of the heart pump blood throughout the body.

3. Smooth Muscles:

i. Location: Smooth muscles are found in the walls of hollow visceral organs, such as the stomach, urinary bladder, respiratory passages, and blood vessels.

ii) Shape: Smooth muscle cells are spindle shaped.

iii) Natural: They have one centrally placed nucleus per cell. They have no striations, and are not subjected to voluntary control.

iv. Function: Voluntary muscles control the movement of substances through hollow organs.

Q5. Explain the ultra-structure of human skeletal muscles.

Ans. Structure of Skeletal Muscles:

i. Location: The skeletal muscles are attached to the skeleton.

ii. Muscle fibres: The skeletal muscle consists of muscles bundle, which are further composed of huge elongated cells called muscles fibre.

iii. Natural of ii. Muscle fibres: These muscles fibres are cylindrical, unbranched and with a diameter of 10 –100μm.

iv. Sarcoplasm: Each fibre consists of a semi fluid matrix, the sarcoplasm or cytoplasm, containing many nuclei and a large number of mitochondria.

v. The nuclei are located near the periphery of each fibre.

vi. Each fibre is surrounded by a membrane sarcolemma.

vii. T-tubule: The sarcolemma of muscle fibre cell penetrates deep into the cell to form hollow elongated tube, the transverse tubule, T-tubule.

viii. lumen (a) of T-TubeThe lumen of which is continuous with the extracellular fluid.

(b) The T-tubule and terminal portion of the adjacent envelope of sarcoplasmic reticulum (a modified type of endoplasmic reticulum that store calcium) form triads at regular intervals along the length of the fibril.

(c). The nerve impulse is carried through the T-tubule to the adjacent sarcoplasmic reticulum.

ix. Colour of fiber: Fibre may be red, due to the presence of the myoglobin- an oxygen storing pigmented protein.

xii. Composition of fiber: It also contain large amount of stored glycogen.

xi. Myofibrils: The sarcoplasm of the fibre contains many contractile elements called myofibrils, which are 1 –2μm in diameter.

xii. Structure of myofibrils: Each myofibril has alternate light and dark bands, which give the fibre its “striped” appearances.

It is because of this, that the skeletal muscles are also called striated or striped muscles.

Q6. Explain the sliding filament theory of contraction using appropriately labeled diagrams of a relaxed and a contracted sarcomere.

Ans. Muscles Contraction:

i. Contractility: Contractility or the ability to contract is a fundamentals characteristic of living substance.

ii. Use of c Contractility: It is essential to all kinds of movements, except growth and cytoplasmic streaming.

iii. Sliding filament Hypothesis: The currently popular model of muscle fiber contraction is called the sliding filament hypothesis

(a) Discovery: It was proposed by H .E. Huxely and A. F. Huxely.

They observed that when the muscle contracts, the thick and thin filaments of the muscles fibre slide past each other but are not changed in length.

(b) Statement: According to this model, the release of calcium ions from the sarcoplasmic reticulum causes a reorientation of certain components in the thin actin filaments, permitting them to bind with extensions (heads) from the thick myosin filaments.

Each myosin head then binds and splits an ATP molecule and the energy released powers the head forward to the next binding component on the actin filament.

As this occurs, the actin filament moves one "notch" past the myosin filament.

viii. As long as calcium ions and ATP are available in the cytoplasm, the myosin heads continue to "crawl" along the actin filaments, thereby contracting the sarcomere and muscle.

Recovery: Muscle Fibre Relaxation:

i. When the electrical impulses reaching a muscle fibre cease, the sarcoplasmic reticulum begins to re-accumulate the calcium ions by active transport.

ii. Once most of the calcium is sequestered in the sarcoplasmic reticulum sacs, which takes only milliseconds, the binding between the myosin heads and the actin filaments can no longer occur.

iii. As a result, the thick and thin filaments slide past one another, returning to their relaxed state of minimal overlap.

iv. The sarcomeres (and muscle fibres) once again achieve their maximal length and stretchability.

Control of Muscle Contraction:

i. The contraction of a muscle fibre is normally an all-or- none phenomenon.

ii. Once it is stimulated, a muscle fibre will contract to a set length, regardless of intensity of the stimulus above the threshold level.

iii. The question then arises: If fibre contraction is an all-or- none phenomenon, how do we manage the fine control of muscular activity that permits us to lift a pencil on one occasion and a bowling ball on another?

iv. Part of the answer has to do with the physical relationship between motor neurons and muscle fibres.

v. The axon of a motor neuron has many branches, each branch terminating at a single muscle fibre. Thus, depending on how many branches it has, one neuron can stimulate several to many different muscle fibres.

vi. All the muscle fibres triggered by a single neuron contract simultaneously as a single motor unit.

vii. Since a particular muscle may consist of many motor units, the total amount of muscle contraction depends on the number of motor neurons conducting impulses to their motor units in that muscle. If many neurons carry impulses at once, many motor units within the muscle will contract.

viii. This causes a stronger over all contraction of the muscle than if only a few motor units are activated.

Q7. Describe the structure of a sarcomere and indicate the relationship of the sarcomere to the myofilament.

Ans: Sarcomere(i)

Myofibrils consist of smaller contractile units called sarcomere.

ii Structure: In each sarcomere a series of dark and light bands are evident along the length of each myofibril.

(b). The dark bands are A band (anisotropic) and the light band are I band (isotropic).

(c). Each A band has a lighter strip in its midsection called H-zone (hele for bright) which inturn is bisected by M –line (medial line).

(d) The I band have midline called Z –line (zwish meaning between). A sarcomere is the region of a myofibril between two successive Z –line.

iii) Relationship of sacrcomere to myofilametn(i) The region of myofibril is the sarcomere, which is the functional unit of the contraction process in the muscles.

(ii). Each myofilament is made up of central thick filament surrounded by thin filament, which are linked together by cross bridges. The thick filament contains a protein, myosin.

(iii). Thin filament is composed of a protein actin as its main component besides it also has tropomyosin and troponin proteins.

(iv) The myosin and actin help in contraction of the muscles.

(v) Thick filament has a tail terminating in two globular heads, which are also called as cross bridges and these link thin and thick filaments during contraction.

Analyzing and interpreting

Q1. Identify the bones of the pelvic girls, pectoral girdle, arms and leg by using the model of human skeleton.

Ans.

Q2. Compare the structure of skeleton, smooth and cardiac muscles with the help of prepared slides.

Ans.

Q3. Draw a diagram of sarcomere and label its parts.

Ans.

Q4. Justify how the main functions of the skeleton are to act as a system of rods and levers, which are moved by the muscles.

Ans. Muscles and bones act together to form levers. A lever is a rigid rod (usually a length of bone) that turns about a pivot (usually a joint). Levers can be used so that a small force can move a much bigger force. This is called mechanical advantage.

There are four parts to a lever – lever arm, pivot, effort and load. In our bodies:

bones act as lever arms
joints act as pivots
muscles provide the effort forces to move loads
load forces are often the weights of the body parts that are moved or forces needed to lift, push or pull things outside our bodies.

Levers can also be used to magnify movement, for example, when kicking a ball, small contractions of leg muscles produce a much larger movement at the end of the leg.

Levers are able to give us a strength advantage or a movement advantage but not both together.

Q5. Justify why do the muscles pull but do not push.

Ans. Skeletal muscles move bones by pulling on them. Because we control this movement, they are called voluntary muscles. Muscles can pull but not push, so skeletal muscles are often arranged in pairs that pull bones in opposite directions.

The body has some 640 skeletal muscles, accounting for about 40 percent of body weight. Skeletal muscles are attached to bones by tough fibrous connections called tendons.

Initiating and Planning

Q1. Relate the bipedal posture of man with his skeleton and musculature.

ANS. Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs.

Science, Technology and Society Connections

Q1. Name the techniques for joint transplantation.

Ans. 1.Meniscus transplant:

The meniscus is the cartilage in the knee which separates the thigh bone (femur) from the lower leg bone (tibia). A meniscus transplant consists of taking out a worn or damaged meniscus and replacing it with a new one from a donor. The meniscus to be transplanted is taken from a cadaver, and, as such, is known as an allograft. Meniscal transplantation is technically difficult, as it must be placed accurately and secured to the tibial plateau. As of 2012, only a few surgeons have significant volume of experience in meniscus transplantation world wide

2. Microvascular joint transplantation with epiphyseal growth

Q2. Justify the use of calcium in teenage and twenties can be a preventive action against osteoporosis.

Ans. Osteoporosis is a disease of the bones. It happens when we lose too much bone, make too little bone or both. As a result, our bones become weak and may break from a minor fall or, in serious cases, even from simple actions, like sneezing or bumping into furniture.

Osteoporosis means “porous bone.” If we look at healthy bone under a microscope, we will see that parts of it look like a honeycomb. If we have osteoporosis, the holes and spaces in the honeycomb are much bigger than they are in healthy bone. This means our bones have lost density or mass and that the structure of our bone tissue has become abnormal. As our bones become less dense, they also become weaker and more likely to break.

No doubt use of calcium in teenage and twenties can be preventive action against oestiopores because calcium in early years strengthens bones.

How Calcium Helps Prevent Osteoporosis

Calcium makes bones strong. In fact, bones and teeth contain 99% of the body's total calcium, with the remaining 1% in intracellular and extracellular fluids. Bones act as a storehouse for calcium, which is used by the body and replaced by the diet throughout a person's life. If enough calcium is not consumed, the body takes it from the bones. If more calcium is removed from the bones than is consumed in the diet, the bones become fragile and weak as a person gets older, leading to osteoporosis and fractures.

Osteoporosis prevention begins during childhood and adolescence by getting enough exercise and the proper nutrients, including calcium and vitamin D. However, adults can help prevent osteoporosis in the same ways.

The importance of calcium in developing and maintaining bone mass (bone density) varies throughout a person's life. At times of rapid and significant bone growth (during the teenage years) or rapid bone loss (after age 50 years), calcium is more important. Therefore, to reduce the risk of osteoporosis, calcium intake should be the highest during adolescence and after 50 years of age.

Q3. Reason out the rigor mortis.

ANS. Rigor mortis (Latin: rigor "stiffness", mortis "of death") is one of the recognizable signs of death, caused by chemical changes in the muscles after death, causing the limbs of the corpse to become stiff and difficult to move or manipulate. In humans, it commences after about three to four hours, reaches maximum stiffness after 12 hours, and gradually dissipates from approximately 24 hours after death.

A few hours after a person or animal dies, the joints of the body stiffen and become locked in place. This stiffening is called rigor mortis. Depending on temperature and other conditions, rigor mortis lasts approximately 72 hours. The phenomenon is caused by the skeletal muscles partially contracting. The muscles are unable to relax, so the joints become fixed in place.

More specifically, what happens is that the membranes of muscle cells become more permeable to calcium ions. Living muscle cells expend energy to transport calcium ions to the outside of the cells. The calcium ions that flow into the muscle cells promote the cross-bridge attachment between actin and myosin, two types of fibers that work together in muscle contraction. The muscle fibers ratchet shorter and shorter until they are fully contracted or as long as the neurotransmitter acetylcholine and the energy molecule adenosine triphosphate (ATP) are present. However, muscles need ATP in order to release from a contracted state (it is used to pump the calcium out of the cells so the fibers can unlatch from each other). ATP reserves are quickly exhausted from the muscle contraction and other cellular processes. This means that the actin and myosin fibers will remain linked until the muscles themselves start to decompose.

Rigor mortis can be used to help estimate time of death. The onset of rigor mortis may range from 10 minutes to several hours, depending on factors including temperature (rapid cooling of a body can inhibit rigor mortis, but it occurs upon thawing). Maximum stiffness is reached around 12-24 hours post mortem. Facial muscles are affected first, with the rigor then spreading to other parts of the body. The joints are stiff for 1-3 days, but after this time general tissue decay and leaking of lysosomal intracellular digestive enzymes will cause the muscles to relax. It is interesting to note that meat is generally considered to be more tender if it is eaten after rigor mortis has passed.

Q4. Relate improper posture to bone/joint problems.

Ans..

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Extra Questions

Q1. What do you know about cartilage?

Ans.

Cartilage:

1. Introduction: Cartilage is a type of connective tissue consisting of cells called chondrocytes and a tough, flexible matrix made of type II collagen.

2. Properties: Unlike other connective tissues, cartilage does not contain blood vessels and the chondrocytes are supplied by diffusion.

Because of this, it heals very slowly.

3. Early emplacement by bones: Although the human skeleton is initially made up of cartilages and fibrous membranes, most of these early supports are soon replaced by bones.

4. Location: A few cartilages that remain in adults are found mainly in regions where flexible skeletal support is needed.

Types: There are three types of cartilage tissue in human body:

a. hyaline, b. elastic c. fibrocartilage.

Q2. Explain Structural classification of joints?

Ans. Structural classification of joints is based on the material binding the bones together and whether or not a joint cavity is present. There are three types of joints, the fibrous, cartilaginous, and synovial joints.

1. Fibrous joints:

1. Introduction: In fibrous joints, a thin layer of fibrous connective tissue holds the bones firmly in position.

2. Joint Cavity: There is no joint cavity between the bones.

3. Immovable nature: In general fibrous joints are immovable.

4. Function: Fibrous joints are formed between the bones of skull, between sacrum and iliac of pelvic girdles, and between the bones of pelvic girdle.

5. Oceurence: These joints provide strength and support for the body, and have protective role for the delicate structures.

ii. Cartilaginous joints:

1. Introduction: Cartilaginous joints are connected entirely by fibrocartilage or hyaline cartilage.

2. Joint cavity: Joint cavity is absent.

3. Gliding movement: Bones can glide over each other to a limited extent.

4. Occurrence: Cartilage forms a flexible connection so that these joints

allow slight movement.

5. Function: Such joints are formed between vertebrae, and between wrist and ankle bones.

Synovial joints:

1. Nature: Synovial joints are those in which the articulating bones are separated by a fluid-containing joint cavity (synovial cavity).

2. Free movement: This arrangement permits freedom of movement, and all synovial joints are freely movable.

(3) Ligaments: Synovial joints are reinforced and strengthened by a number of band like ligaments.

1. These ligaments hold the bones in position.

2. Based on the shape of their particular surfaces, the synovial joints have different structural plan.

3. This structural plan determines the type of movement allowed.

4. Types: The synovial joints can be classified into two major categories; hinge and ball and socket joints.

Hinge joints: (a)

1. Structure: In hinge joints, a cylindrical projection of one bone fits into a trough shaped surface on another.

2. Function: These joints permit movement in one plane that is, permit

(a) flexion and extension only.

(b) Hinge joints are capable of bearing heavy loads.

Examples: Examples are elbow and knee joint.

Ball-and-Socket Joints: (b)

1. Nature: In ball-and-socket joints the spherical or hemispherical head of one bone articulates with the cuplike socket of another.

2. Free movement: These joints are the most freely moving synovial joints.

Example: The shoulder and hip joints are examples.

Q3. Explain the disorders of skeleton?

Ans.

Although human skeleton is hard and strong, yet deformities do occur resulting in reduced movement or complete immovability. Deformities of skeleton may be genetic, hormonal or due to the effects of nutrient deficiency

(a) Disc slip:

1. Location: The discs are protective shock-absorbing pads between the bones of the spine (vertebrae).

2. Intervertebral disc: The discs of the spine are also referred to as intervertebral discs.

Although they do not actually "slip," a disc may split or rupture.

Effected: (a) This can cause the disc cartilage and nearby tissue to fail (herniate), allowing the inner gel portion of the disc to escape into the surrounding tissue.

(b) This leaking jelly-like substance can place pressure on the spinal cord or on an adjacent nerve to cause symptoms of pain either around the damaged disc or anywhere along the area controlled by that nerve.

This condition is also known as a herniated disc.

(4) Factors involved slip or causes: Factors that lead to a slipped disc include aging with associated degeneration and loss of elasticity of the discs and supporting structures; injury from improper lifting, especially if accompanied by twisting or turning; and excessive strain forces associated with physical activities.

(b) Spondylosis:

1. Introduction: Spondylosis (spinal osteoarthritis) is a degenerative disorder that may cause loss of normal spinal structure and function.

2. Causes: Although aging is the primary cause, the location and rate of degeneration is individual.

3. Effected areas: The degenerative process of spondylosis may affect the cervical (neck), thoracic (mid-back), or lumbar (lower back) regions of the spine.

(c) Sciatica:

1. Introduction: Sciatica refers to pain, weakness, numbness, or tingling in the leg.

2. Causes: It is caused by injury to or pressure on the sciatic nerve.

This nerve starts in the lower spine and runs down the back of each leg.

Common causes of sciatica include:

Slipped disc, piriformis syndrome (a pain disorder involving the narrow muscle in the buttocks), pelvic injury or fracture and tumors.

(d) Arthritis:

i) Introduction: The arthritis is joint inflammation and it can affect joints in any part of the body.

ii) Causes: Arthritis is the leading cause of disability in those over the age of 65

(3) Symptoms: some of the symptoms of arthritis are:

ô Joint pain and swelling.

ô Stiffness particularly in the mornings.

ô The feeling of warmth around a joint.

ô Redness of skin around the joint.

ô Inability to move the joint easily.

Some of the causes of arthritis are broken bone, infection in the area, an autoimmune disease and general wear and tear on joints.

Q4. What do you know about joint injuries? Explain.

Ans: Introduction:

1. A dislocated joint is a joint that slips out of place.

2. It occurs when the ends of bones are forced away from their normal positions.

3. When a joint is dislocated, it no longer functions properly.

4. A severe dislocation can cause tearing of the muscles, ligaments and tendons that support the joint.

b) Symptoms: Symptoms include; swelling, intense Pain, and immobility of the affected joint.

c). Causes: i)The most common causes are a blow, fall, or other trauma to the joint.

(ii). In some cases, dislocations are caused by a disease or a

defective ligament.

(iii) Rheumatoid arthritis can also cause joint dislocation.

(d) Treatment: 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 ligaments.

(i) Sprain:

1. Introduction: A sprain is an injury to a ligament.

2. Injured parts: Commonly injured ligaments are in the ankle, knee, and wrist.

The ligaments can be injured by being stretched too far from their normal position.

The ligaments are to hold skeleton together in a normal alignment so ligaments prevent abnormal movements.

However, when too much force is applied to a ligament, such as in a fall, the ligaments can be stretched or torn.

The sprain should be rested.

3) Treatment: Sprains can be usually treated with treatments such as icing and physical therapy.

Dressings, bandages, or ace-wraps should be used to immobilize the sprain and provide support.

Q5. What do you know about “Energy of Muscle Contraction”. Explain muscle Problem?

Ans. Energy of Muscle Contraction:

1. Muscle contraction needs energy.

2. The immediate source of energy for the muscle contraction is ATP, stored in the muscle cells.

3. An enzyme ATPase, in the muscle cells breaks ATP to ADP, thus releasing energy for muscle contraction.

4. But much part of the energy comes from carbohydrates or glucose, stored as glycogen in the muscle cells.

5. When muscle contraction begins, glycogen is converted into glucose, which is then broken down to form ATP.

6. The muscle contraction then uses this ATP.

7. We know that in violent exercise, such as running, much energy is needed.

8. Apparently not, but the muscles cells of all vertebrates have a reserve of high-energy phosphate compound, called phosphocreatin.

9. During periods of intensive muscular activity, the phosphocreatin is broken into creatin and a high-energy phosphate group.

10. This group then unites with ADP to form ATP.

11. Of the total energy expended in muscles contraction, only about35% is utilized for the performance of work; the remaining is liberated in the form of heat, which is employed to maintain body temperature.

12. In cold weather the production of heat can be increased through voluntary muscular activity (walking, rubbing hand together etc) or involuntary by shivering.

13. Conversely, in warm weather, muscular activity is deliberately decreased to reduce heat production.

Q 6 What do you know about cramps?

Ans

Cramps:

1. Introduction: Muscle cramps are sudden, involuntary contractions or spasms in one or more muscles.

2. Time of Infection: They often occur after exercise or at night, lasting a few seconds to several minutes.

3. Temporary contractures: Writer's cramp is a familiar example of temporary contractures.

4. Causes: Muscle cramps can be caused by nerves that malfunction. Other causes are, straining or overusing a muscle, dehydration, lack of minerals in diet or the depletion of minerals in body, and not enough blood getting to muscles.

Q7 What do you know about Muscle fatigue?

Ans

Musle fatigue

1. Introduction: Muscle fatigue is a condition of the muscle in which its capacity to produce maximum contraction is reduced even though the muscle still may be receiving stimuli.

2. Causes (a) Availability of ATP declines during contraction and a total lack of ATP results in contractures states of continuous contraction because the cross bridges are unable to detach.

(b). Although excessive intracellular accumulation of lactic acid (which causes the muscles to ache and raises H+) alters contractile proteins, other ionic imbalances also contribute to muscle fatigue.

(c) In general, intense exercise of short duration produces fatigue rapidly via ionic disturbances, but recovery is also rapid.

(3) Recovery: In contrast to short-duration exercise, the slow-developing fatigue of prolonged low-intensity exercise may require several hours for complete recovery.

Q 8What do you know about Tetany?

Ans

TETANY

1. Introduction: Tetany is a symptom characterized by muscle cramps, spasms or tremors.

2. Time of action: These repetitive actions of the muscles happen when muscle contracts uncontrollably.

3. Occurrence: Tetany may occur in any muscle of the body, such as those in face, fingers or calves.

4. Time of muscle cramping: The muscle cramping associated with tetany can be long lasting and painful.

5. Causes: A common cause of tetany is very low levels of calcium in the body.

Q9 What isTetanus?Explain.

Ans

TETANUS
1. Introduction: Tetanus is infection of the nervous system with the potentially deadly bacteria Clostridium tetani.

2. Causative agent: 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.

3. Infection time: Infection begins when the spores enter the body through an injury or wound.

4. Tetanospasmin: 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.

utmanzai

Saturday, 19 July 2014

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