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Locomotion and movement

Movement is one of the significant features of living beings.
Animals and plants exhibit a wide range of movements. Streaming of protoplasm in the unicellular organisms like Amoeba is a simple form of movement.

Movement of cilia, flagella and tentacles are shown by many organisms. Human beings can move limbs, jaws, eyelids, tongue, etc.
Some of the movements result in a change of place or location. Such voluntary movements are called locomotion. Walking, running, climbing, flying, swimming are all some forms of locomotory movements.

Locomotory structures need not be different from those affecting other types of movements.

For example, in Paramoecium, cilia helps in the movement of food through cytopharynx and in locomotion as well.
Hydra can use its tentacles for capturing its prey and also use them for locomotion.
We use limbs for changes in body postures and locomotion as well. The above observations suggest that movements and locomotion cannot be studied separately. The two may be linked by stating that all locomotions are movements but all movements are not locomotions.

Methods of locomotion performed by animals vary with their habitats and the demand of the situation. However, locomotion is generally for search of food, shelter, mate, suitable breeding grounds, favourable climatic conditions or to escape from enemies/predators.

Types of movement

Cells of the human body exhibit three main types of movements, namely, amoeboid, ciliary and muscular.
Some specialised cells in our body like macrophages and leucocytes in blood exhibit amoeboid movement. It is effected by pseudopodia formed by the streaming of protoplasm (as in Amoeba).

Cytoskeletal elements like microfilaments are also involved in amoeboid movement. Ciliary movement occurs in most of our internal tubular organs which are lined by ciliated epithelium.
The coordinated movements of cilia in the trachea help us in removing dust particles and some of the foreign substances inhaled alongwith the atmospheric air.
Passage of ova through the female reproductive tract is also facilitated by the ciliary movement.
Movement of our limbs, jaws, tongue, etc, require muscular movement.
The contractile property of muscles are effectively used for locomotion and other movements by human beings and majority of multicellular organisms.

Locomotion requires a perfect coordinated activity of muscular, skeletal and neural systems. In this chapter, you will learn about the types of muscles, their structure, mechanism of their contraction and important aspects of the skeletal system.

muscle

Cilia and flagella are the outgrowths of the cell membrane. Flagellar movement helps in the swimming of spermatozoa, maintenance of water current in the canal system of sponges and in locomotion of Protozoans like Euglena. Muscle is a specialized tissue of mesodermal origin.
About 40-50 per cent of the body weight of a human adult is contributed by muscles.
They have special properties like excitability, contractility, extensibility and elasticity.

(i) Skeletal
(ii) Visceral and
(iii) Cardiac.

Skeletal muscles are closely associated with the skeletal components of the body. They have a striped appearance under the microscope and hence are called striated muscles. As their activities are under the voluntary control of the nervous system, they are known as voluntary muscles too. They are primarily involved in locomotory actions and changes of body postures.

Visceral muscles are located in the inner walls of hollow visceral organs of the body like the alimentary canal, reproductive tract, etc. They do not exhibit any striation and are smooth in appearance. Hence, they are called smooth muscles (nonstriated muscle). Their activities are not under the voluntary control of the nervous system and are therefore known as involuntary muscles. They assist, for example, in the transportation of food through the digestive tract and gametes through the genital tract.

Cardiac muscles are the muscles of heart. Many cardiac muscle cells assemble in a branching pattern to form a cardiac muscle. Based on appearance, cardiac muscles are striated. They are involuntary in nature as the nervous system does not control their activities directly.
Skeletal muscle ( structure and mechanism of contraction).
Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia.

Each muscle bundle contains a number of muscle fibres (Figure).
Each muscle fibre is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm.
Muscle fibre is a syncitium as the sarcoplasm contains many nuclei.
The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions.
A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils.
Each myofibril has alternate dark and light bands on it.
Striated appearance is due to the distribution pattern of two important proteins –
Actin and Myosin.

The light bands contain actin and is called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin. Both the proteins are arranged as rod-like structures, parallel to each other and also to the longitudinal axis of the myofibrils.
Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively.
In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it.
The thin filaments are firmly attached to the ‘Z’ line.
The thick filaments in the ‘A’ band are also held together in the middle of this band by a thin fibrous membrane called ‘M’ line.
The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils.
The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere (Figure).
In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments.
This central part of thick filament, not overlapped by thin filaments is called the ‘H’ zone.

Structure of Contractile Proteins
Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other.
Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins.
Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length.
A complex protein Troponin is distributed at regular intervals on the tropomyosin.
In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments (Figure).

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Each myosin (thick) filament is also a polymerised protein. Many monomeric proteins called Meromyosins (Figure 20.3b) constitute one thick filament. Each meromyosin has two important parts, a globular head with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter, the light meromyosin (LMM). The HMM component, i.e.; the head and short arm projects outwards at regular distance and angle from each other from the surface of a polymerised myosin filament and is known as cross arm. The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.

Mechanism of Muscle Contraction

Mechanism of muscle contraction is best explained by the sliding filament theory which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments.
Muscle contraction is initiated by a signal sent by the central nervous system (CNS) via a motor neuron. A motor neuron alongwith the muscle fibres connected to it constitute a motor unit. The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.
A neural signal reaching this junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma. This spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm. Increase in Ca⁺⁺ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.
Utilising the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge (Figure).
This pulls the attached actin filaments towards the centre of ‘A’ band. The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.
It is clear from the above steps, that during shortening of the muscle, i.e., contraction, the ‘I’ bands get reduced, whereas the ‘A’ bands retain the length (Figure).
The myosin, releasing the ADP and P1 goes back to its relaxed state. A new ATP binds and the cross-bridge is broken (Figure ).
The ATP is again hydrolysed by the myosin head and the cycle of cross bridge formation and breakage is repeated causing further sliding. The process continues till the Ca⁺⁺ ions are pumped back to the sarcoplasmic cisternae resulting in the masking of actin filaments. This causes the return of ‘Z’ lines back to their original position, i.e., relaxation.
The reaction time of the fibres can vary in different muscles. Repeated activation of the muscles can lead to the accumulation of lactic acid due to anaerobic breakdown of glycogen in them, causing fatigue.
Muscle contains a red coloured oxygen storing pigment called myoglobin.
Myoglobin content is high in some of the muscles which gives a reddish appearance. Such muscles are called the Red fibres.
These muscles also contain plenty of mitochondria which can utilise the large amount of oxygen stored in them for ATP production. These muscles, therefore, can also be called aerobic muscles.

On the other hand, some of the muscles possess very less quantity of myoglobin and therefore, appear pale or whitish. These are the White fibres.
Number of mitochondria are also few in them, but the amount of sarcoplasmic reticulum is high. They depend on anaerobic process for energy.

Muscle Fiber Contraction and Relaxation

The sequence of events that result in the contraction of an individual muscle fiber begins with a signal—the neurotransmitter, ACh—from the motor neuron innervating that fiber. The local membrane of the fiber will depolarize as positively charged sodium ions (Na⁺ ) enter, triggering an action potential that spreads to the rest of the membrane will depolarize, including the T-tubules. This triggers the release of calcium ions (Ca⁺⁺) from storage in the sarcoplasmic reticulum (SR). The Ca⁺⁺ then initiates contraction, which is sustained by ATP (Figure ). As long as Ca⁺⁺ ions remain in the sarcoplasm to bind to troponin, which keeps the actin-binding sites “unshielded,” and as long as ATP is available to drive the cross-bridge cycling and the pulling of actin strands by myosin, the muscle fiber will continue to shorten to an anatomical limit.

Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the voltage-gated calcium channels in the SR. Ca⁺⁺ ions are then pumped back into the SR, which causes the tropomyosin to reshield (or re-cover) the binding sites on the actin strands. A muscle also can stop contracting when it runs out of ATP and becomes fatigued (Figure).
The molecular events of muscle fiber shortening occur within the fiber’s sarcomeres (Figure ).
The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.

The region where thick and thin filaments overlap has a dense appearance, as there is little space between the filaments. This zone where thin and thick filaments overlap is very important to muscle contraction, as it is the site where filament movement starts.
Thin filaments, anchored at their ends by the Z-discs, do not extend completely into the central region that only contains thick filaments, anchored at their bases at a spot called the M-line.
A myofibril is composed of many sarcomeres running along its length; thus, myofibrils and muscle cells contract as the sarcomeres contract.

The Sliding Filament Model of Contraction

When signaled by a motor neuron, a skeletal muscle fiber contracts as the thin filaments are pulled and then slide past the thick filaments within the fiber’s sarcomeres. This process is known as the sliding filament model of muscle contraction (Figure).
The sliding can only occur when myosin-binding sites on the actin filaments are exposed by a series of steps that begins with Ca⁺⁺ entry into the sarcoplasm.
Tropomyosin is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. Tropomyosin binds to troponin to form a troponin-tropomyosin complex. The troponin-tropomyosin complex prevents the myosin “heads” from binding to the active sites on the actin microfilaments. Troponin also has a binding site for Ca⁺⁺ ions.

To initiate muscle contraction, tropomyosin has to expose the myosin-binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments. The first step in the process of contraction is for Ca⁺⁺ to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands. This allows the myosin heads to bind to these exposed binding sites and form cross-bridges. The thin filaments are then pulled by the myosin heads to slide past the thick filaments toward the center of the sarcomere.
But each head can only pull a very short distance before it has reached its limit and must be “re-cocked” before it can pull again, a step that requires ATP.

ATP and Muscle Contraction

For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc.
This repeated movement is known as the cross-bridge cycle. This motion of the myosin heads is similar to the oars when an individual rows a boat: The paddle of the oars (the myosin heads) pull, are lifted from the water (detach), repositioned (re-cocked) and then immersed again to pull (Figure
). Each cycle requires energy, and the action of the myosin heads in the sarcomeres repetitively pulling on the thin filaments also requires energy, which is provided by ATP.
Cross-bridge formation occurs when the myosin head attaches to the actin while adenosine diphosphate (ADP) and inorganic phosphate (P_I) are still bound to myosin (Figure). P_Iis then released, causing myosin to form a stronger attachment to the actin, after which the myosin head moves toward the M-line, pulling the actin along with it. As actin is pulled, the filaments move approximately 10 nm toward the M-line. This movement is called the power stroke, as movement of the thin filament occurs at this step (Figure). In the absence of ATP, the myosin head will not detach from actin.
One part of the myosin head attaches to the binding site on the actin, but the head has another binding site for ATP.
ATP binding causes the myosin head to detach from the actin (Figure). After this occurs, ATP is converted to ADP and P_I by the intrinsic ATPase activity of myosin. The energy released during ATP hydrolysis changes the angle of the myosin head into a cocked position (Figure ).
The myosin head is now in position for further movement.

When the myosin head is cocked, myosin is in a high-energy configuration. This energy is expended as the myosin head moves through the power stroke, and at the end of the power stroke, the myosin head is in a low-energy position. After the power stroke, ADP is released; however, the formed cross-bridge is still in place, and actin and myosin are bound together.
As long as ATP is available, it readily attaches to myosin, the cross-bridge cycle can recur, and muscle contraction can continue.

Each thick filament of roughly 300 myosin molecules has multiple myosin heads, and many cross-bridges form and break continuously during muscle contraction. Multiply this by all of the sarcomeres in one myofibril, all the myofibrils in one muscle fiber, and all of the muscle fibers in one skeletal muscle, and one can understand why so much energy (ATP) is needed to keep skeletal muscles working.
In fact, it is the loss of ATP that results in the rigor mortis observed soon after someone dies. With no further ATP production possible, there is no ATP available for myosin heads to detach from the actin-binding sites, so the cross-bridges stay in place, causing the rigidity in the skeletal muscles.

Sources of ATP ATP supplies the energy for muscle contraction to take place. In addition to its direct role in the cross-bridge cycle, ATP also provides the energy for the active-transport Ca⁺⁺ pumps in the SR. Muscle contraction does not occur without sufficient amounts of ATP. The amount of ATP stored in muscle is very low, only sufficient to power a few seconds worth of contractions. As it is broken down, ATP must therefore be regenerated and replaced quickly to allow for sustained contraction. There are three mechanisms by which ATP can be regenerated: creatine phosphate metabolism, anaerobic glycolysis, and fermentation and aerobic respiration.
Creatine phosphate is a molecule that can store energy in its phosphate bonds. In a resting muscle, excess ATP transfers its energy to creatine, producing ADP and creatine phosphate. This acts as an energy reserve that can be used to quickly create more ATP.
When the muscle starts to contract and needs energy, creatine phosphate transfers its phosphate back to ADP to form ATP and creatine.
This reaction is catalyzed by the enzyme creatine kinase and occurs very quickly; thus, creatine phosphate-derived ATP powers the first few seconds of muscle contraction.
However, creatine phosphate can only provide approximately 15 seconds worth of energy, at which point another energy source has to be used (Figure).

skeletal system

Skeletal system consists of a framework of bones and a few cartilages. This system has a significant role in movement shown by the body.
Imagine chewing food without jaw bones and walking around without the limb bones. Bone and cartilage are specialised connective tissues.
The former has a very hard matrix due to calcium salts in it and the latter has slightly pliable matrix due to chondroitin salts.

In human beings, this system is made up of 206 bones and a few cartilages.
It is grouped into two principal divisions –
the axial and the appendicular skeleton. Axial skeleton comprises 80 bones distributed along the main axis of the body. The skull, vertebral column, sternum and ribs constitute axial skeleton.
The skull (Figure ) is composed of two sets of bones –
cranial and
facial, that totals to 22 bones.

Cranial bones are 8 in number. They form the hard protective outer covering, cranium for the brain. The facial region is made up of 14 skeletal elements which form the front part of the skull.
A single U-shaped bone called hyoid is present at the base of the buccal cavity and it is also included in the skull.
Each middle ear contains three tiny bones –
Malleus, Incus and Stapes, collectively called Ear Ossicles.
The skull region articulates with the superior region of the vertebral column with the help of two occipital condyles (dicondylic skull).

Our vertebral column (Figure ) is formed by 26 serially arranged units called vertebrae and is dorsally placed.
It extends from the base of the skull and constitutes the main framework of the trunk.
Each vertebra has a central hollow portion (neural canal) through which the spinal cord passes. First vertebra is the atlas and it articulates with the occipital condyles.
The vertebral column is differentiated into cervical (7),
thoracic (12),
lumbar (5),
sacral (1-fused) and
coccygeal (1-fused) regions starting from the skull.
The number of cervical vertebrae are seven in almost all mammals including human beings.

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The vertebral column protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back.
Sternum is a flat bone on the ventral midline of thorax.
There are 12 pairs of ribs. Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end and is hence called bicephalic. First seven pairs of ribs are called true ribs.
Dorsally, they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilage.
The 8th, 9th and 10th pairs of ribs do not articulate directly with the sternum but join the seventh rib with the help of hyaline cartilage.
These are called vertebrochondral (false) ribs.
Last 2 pairs (11th and 12th) of ribs are not connected ventrally and are therefore, called floating ribs.
Thoracic vertebrae, ribs and sternum together form the rib cage (Figure).
The bones of the limbs alongwith their girdles constitute the appendicular skeleton. Each limb is made of 30 bones.
The bones of the hand (fore limb) are humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number) (Figure). The bones of the leg (hind limb) Femur (thigh bone – the longest bone),
tibia and fibula,
tarsals (ankle bones – 7 in number), metatarsals (5 in number) and phalanges (digits – 14 in number) are the bones of the legs (hind limb) (Figure).
A cup shaped bone called patella cover the knee ventrally (knee cap).
Pectoral and Pelvic girdle bones help in the articulation of the upper and the lower limbs respectively with the axial skeleton. Each girdle is formed of two halves. Each half of pectoral girdle consists of a clavicle and a scapula (Figure).

Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs. The dorsal, flat, triangular body of scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion.
The clavicle articulates with this. Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint. Each clavicle is a long slender bone with two curvatures. This bone is commonly called the collar bone.

Pelvic girdle consists of two coxal bones (Figure ). Each coxal bone is formed by the fusion of three bones – ilium, ischium and pubis. At the point of fusion of the above bones is a cavity called acetabulum to which the thigh bone articulates. The two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage.

Fibrous joints do not allow any movement. This type of joint is shown by the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures, to form the cranium. In cartilaginous joints, the bones involved are joined together with the help of cartilages.

The joint between the adjacent vertebrae in the vertebral column is of this pattern and it permits limited movements. Synovial joints are characterised by the presence of a fluid filled synovial cavity between the articulating surfaces of the two bones. Such an arragement allows considerable movement.
These joints help in locomotion and many other movements.

Ball and socket joint (between humerus and pectoral girdle), hinge joint (knee joint), pivot joint (between atlas and axis), gliding joint (between the carpals) and saddle joint (between carpal and metacarpal of thumb) are some examples.
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DISORDERS OF MUSCULAR AND SKELETAL SYSTEM
Myasthenia gravis: Auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle. Muscular dystrophy: Progressive degeneration of skeletal muscle mostly due to genetic disorder.

Tetany: Rapid spasms (wild contractions) in muscle due to low Ca++ in body fluid.

Arthritis: Inflammation of joints.

Osteoporosis: Age-related disorder characterised by decreased bone mass and increased chances of fractures. Decreased levels of estrogen is a common cause.

Gout: Inflammation of joints due to accumulation of uric acid crystals.

1. Draw the diagram of a sarcomere of skeletal muscle showing different regions.
2. Define sliding filament theory of muscle contraction.
3. Describe the important steps in muscle contraction.
4. Write true or false. If false change the statement so that it is true. (a) Actin is present in thin filament (b) H-zone of striated muscle fibre represents both thick and thin filaments. (c) Human skeleton has 206 bones. (d) There are 11 pairs of ribs in man. (e) Sternum is present on the ventral side of the body.
5. Write the difference between : (a) Actin and Myosin (b) Red and White muscles (c) Pectoral and Pelvic girdle
6. Match Column I with Column II : Column I Column II (a) Smooth muscle (i) Myoglobin (b) Tropomyosin (ii) Thin filament (c) Red muscle (iii) Sutures (d) Skull (iv) Involuntary
7. What are the different types of movements exhibited by the cells of human body?
8. How do you distinguish between a skeletal muscle and a cardiac muscle?
9. Name the type of joint between the following:- (a) atlas/axis (b) carpal/metacarpal of thumb (c) between phalanges (d) femur/acetabulum (e) between cranial bones (f) between pubic bones in the pelvic girdle
10. Fill in the blank spaces: (a) All mammals (except a few) have __________ cervical vertebra.
(b) The number of phalanges in each limb of human is __________
(c) Thin filament of myofibril contains 2 ‘F’ actins and two other proteins namely __________ and __________.
(d) In a muscle fibre Ca⁺⁺ is stored in __________
(e) __________ and __________ pairs of ribs are called floating ribs.
(f) The human cranium is made of __________ bones.

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21329--Pelvic girdle consists of - Ilium, ischium and pubis (A) Ilium(8) Ilium and ischium(C) Ilium, ischium and pubis(D) Ischium and pubis.
21330-- Joint between atlas and axis is - Pivot joint (A) Pivot joint (B) Saddle joint(C) Angular joint (D) Hinge joint .
21333-- Two halves of pelvic girdle are joined together by - Pubic symphysis (A) Pubic symphysis(B) Ischiac symphysis(C) Ischiopubic symphysis(D) By fusion.
21334-- Which one is incorporated in muscle fibres? - Myoglobin (A) Acetylcholine (B) Myoglobin(C) Histone (D) Cytochrome.
21336--Sutural joints are present between - Parietals of skull (A) Thumb and metatarsal(B) Humerus and radio-ulna(C) Parietals of skull(D) Glenoid cavity and pectoral girdle.
21338-- Coracoid is component of - Pectoral girdle (A) Fore limb (B) Skull(C) Pectoral girdle (D) Pelvic girdle.
21341-- Joint of sternum and ribs is - Cartilaginous (A) Cartilaginous (B) Fibrous joint(C) Angular joint (D) Hinge joint.
21344-- A simple crack in the bone when the two parts of the bone remain together is called - (A) Green stick fracture (B) Simple fracture(C) Comminuted fracture (D) Compound fracture.
21346-- Collar bone is known as - (A) Scapula(B) Coracoid (C) Patella (D) Clavicle.
21363-- Longest bone is that of - (A) Humerus(B) Stapes(C) Femur(D) Radio-ulna.
21368-- Which ion is essential for muscle contraction? - (A) Na(B) K(C) Ca(D) Cl.
21372-- Longest 'visceral' muscle occurs in - (A) Vas deferens '.
(B) Pregnant uterus(C) Normal uterus "(D) Abdomen.
21373-- Trochanters occur in - (A) Humerus(B) Femur(C) Radio-ulna (D) Tibio-fibula.
21379-- Total number of bones in the body of man is (A) 28(B) 206(C) 108(D) 218 21382-- .
Muscles causing movement of food in stomach are (A) Striated(B) Cardiac(C) Unstriated(D) Specialised.
21384-- Acetabulum forms (A) Hip joint (B) Shoulder joint (C) Knee joint (D) Elbow joint.
21385-- The only movable bone in the skull is (A) Maxilla (B) Frontoparietal (C) Mandible (D) Nasal.
21387-- Sutures present between various bones of skull are- (A) Cartil,agenous joints(B) Synovial joints(C) Hinge joints(D) Fibrous joints.
21389-- Foramen magnum and occipital condyles are found in- (A) Fronto parietal bone(B) Occipital bone(C) Prootic bones(D) Squamosal bone.
21390-- Synovial fluid is present in- (A) Spinal cavity(B) Cranial cavity(C) Freely movable joints(D) Fixed joints 21394-- In human beings, the second cervical vertebra helps in rotatory movements of head through knob- like process called- (A) Prezygapophysis (B) Postzygapohysis(C) Odontoid process(D) Metaphysis.
21402-- We move our hands while walking for- (A) Faster movement(B) Balancing (C) Increasing blood circulation(D) Relieving tension.
21403-- During strenuous exercise, glucose is converted into- (A) Glycogen (C) Starch(B) Pyruvic acid(D) Lactic acid.
21406-- Muscle contraction of shortest duration occurs In- (A) Eye lids (C) Intestine(B) Heart(D) Jaws.
21407-- Myoglobin occurs in- (A) White muscle fibres(B) Red muscle fibres (C) Involuntary muscles(D) All the above.
21409-- Major protein in the thick filaments of skeletal muscle fibre is- (A) Myosin(B) Actin (C) Tropomyosin (D) Troponin.
21410-- Substance that accumulates in a fatigued muscle is- (A) Pyruvic acid (B) Lactic acid(C) CO2 (D) ADP.
21411-- During muscle contraction- (A) Size of A-bands remains the same(B) Size of H-zone becomes smaller(C) Size of I-bands decreases(D) All the above.
21415-- Malleus is part of- (A) Reproductive system of cockroach (B) Skull of Man (C) Middle ear ossicles(D) Fore limbs.
21417-- An example of gliding joint is- (A) Humerus and glenoid cavity(B) Femur and tibio-fibula(C) Occipital condyle and odontoid process (D) Zygapophyses of adjacent vertebrae.
21419-- Glenoid cavity is found in-- (A) Pelvic girdle (B) Skull(C) Pectoral girdle (D) Sternum.
21420-- Ilium is part of- (A) Small intestine (B) Pectoral girdle(C) Pulmonary tract (D) Pelvic girdle.
21423-- Ribs are attached to- (A) Scapula(B) Sternum(C) Clavicle(D) Ilium.
21442-- Vertebra-arterial canal occurs in- (A) Cervical vertebrae(B) Lumbar vertebrae(C) Thoracic vertebrae(D) Sacral vertebrae.
21443-- Which vertebra has the odontoid process?- (A) 7th vertebra of Frog (8) Second vertebra of Frog(C) Second cervical vertebra of mammal (D) Second thoracic vertebra of mammal.
21454-- The number of pairs of false ribs is- (A) 2 (B) 3 (C) 4 (D) 7 21326-- Sarcomere is distance between - Two Z-lines (A) Two I-bands (B) A and I bands (C) Two Z-lines (D) Z and A bands 21455--The floating ribs are- (A) 11 and 12 (B) 9 and 10(C) 7 and 8 (D) 1 and 2.
21495-- Red muscles have abundant- (A) Lactic acid and acetic acid(B) Glucose and haemoglobin(C) Relaxin and myosin(D) Myoglobin and cytochrome (E) None of the above.
21499-- Which of the following vertebrae are fused- (A) Cervical (B) Sacrum (C) Lumbar (D) Thoracic.
21501-- Stimulus several times greater than threshold sinuous is provided to muscle fibre.
It will- (A) Contract with same force (B) Contract forcefully (C) Contract slightly(D) Undergo tetany.
21502--Sliding filament theory of muscle contraction was given by- (A) Arnon and Hill(B) Huxley and Pullman(C) Huxley and Huxley(D) Pullman and Pullman(E) Pullman and Huxley.
21503-- The reactions which change lactic acid into glycogen come under- (A) Calvin cycle (B) Cori cycle(C) Krebs cycle (D) Glycolysis(E) Glycolactic cycle.
21507-- Zygomatic is part of (A) Pelvic girdle (B) Skull(C) Pectoral girdle (D) Vertebral column.
21510-- Glycogen is degraded to lactic acid by enzymes in muscles and liver when the animal is (A) Exhausted (B) Starved (C) Killed(D) Defaecated (E) Copulated.
21512-- Surface for attachment of tongue is (A) Palatine(B) Sphenoid(C) Pterygoid(D) Hyoid apparatus.
21513-- Which of the following is Sesamoid bone (A) Pelvis(B) Patella (C) Pterygoid (D) Pectoral girdle.
21514-- Joint between atlas and axis is (A) Pivot (B) Hinge(C) Angular (D) Saddle.
21520-- Red muscle fibres are rich in (A) Golgi bodies (B) Mitochondria (C) Lysosomes (D) Ribosomes.
14198--Growthhormone (GH) or STH is secreted by (A) Adrenal(B) Anterior lobe of pituitary(C) Posterior lobe of pituitary(D) Sex organs 14,198.
00B.
Go Back to Start Go Back to Start 21354-- . Latissimus dorsal muscle is- (A) Chest muscle (B) Shoulder muscle (C) Leg muscle (D) Arm muscle.
21324-- Haversian canals occur in (A) All bones (B) Long bones ( C) Alimentary canal (D) None of the above
21327-- Sharpey's fibres occur inside (A) Collagen(B) Muscle(C) Bone (D) Skin
21332-- Olecranon process occurs in - (A) Femur(B) Radius(C) Humerus(D) Ulna.
21339-- Longest bone in lower arm is - (A) Ulna (B) Radius (C) Tibia (D) Femur.
21347-- Glenoid cavity is found in - (A) Humerus (B) Pectoral girdle(C) Pelvic girdle (D) Skull.
21349-- Acetabulum is part of - (A) Pelvic girdle (B) Pectoral girdle(C) Fore arm(D) Upper arm.
21353-- Epiphysial plate is involved in - (A) Formation of bone(B) Elongation of bone(C) Thickness of bone(D) All the above.
21361-- . Acromion process is part of - (A) Vertebral column (B) Pelvic girdle (C) Femur(D) Pectoral girdle.
21362-- . Ends of long bones are covered by - (A) Ligaments(B) Cartilage (C) Muscles(D) Blood cells
21365-- Joint between bones of human skull is - (A) Hinge joint(B) Synovial joint(C) Cartilaginous joint(D) Fibrous joint.
21370-- . Long bones function in - (A) Support(B) Support, erythrocyte and leucocyte synthesis(C) Support and erythrocyte synthesis (D) Erythrocyte formation.
21391-- Pelvic girdle of man consist of- (A) Ileum, ischium and pubis(B) Ilium, ischium and clavicle(C) Ilium, ischium and pubis(D) Coracoid, clavicle and scapula.
21392-- Part of .pelvic girdle joined by transverse process- (A) Ischium (C) Ilium (B) Ileum (D) Pubis
21404-- Coccygeal bone occurs in- (A) Skull(B) Pectoral girdle(C) Vertebral column(D) Pelvic girdle.
21430--Number of bones present in arm is- (A) 30(B) 32(C) 35(D) 40.
21433--Sigmoid notch is found in- (A) Tibio-fibula (B) Femur(C) Radio-ulna (D) Humerus.
21435-- Sesamoid bone is derived from- (A) Cartilage(B) Areolar tissue(C) Tendon .(D) Ligament
21440-- Each half of pelvic girdle is made of- (A) Ischium(B) Ilium (C) Pubis(D) All the above.
21444- Longest bone of Frog is- (A) Humerus(B) Tibio-fibula(C)Femur(D) Radio-ulna.