21. Name the different types of movement.
Types of movement:
The different types of movements that occur in the cells of our body are amoeboid, ciliary, flagellar and muscular movement.
1. Amoeboid movement:
Cells such as macrophages exhibit amoeboid movement for engulfing pathogens by pseudopodia formed by the streaming movement of the cytoplasm.
2. Ciliary movement:
This type of movement occurs in the respiratory passages and genital tracts which are lined by ciliated epithelial cells.
3. Flagellar movement:
This type of movement occurs in the cells which are having flagella or whip-like motile organelle. The sperm cells show flagellar movement.
4. Muscular movement:
The movement of hands, legs, jaws, tongue are caused by the contraction and relaxation of the muscle which is termed as the muscular movement.
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22. Name the filaments present in the sarcomere.
1. Thick filament - Myosin.
2. Thin filament - Actin.
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23. Name the contractile proteins present in the skeletal muscle.
1. Myosin - Thick filament.
2. Actin-Thin filament.
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24. When describing a skeletal muscle, what does "striated" mean?
1. Along the length of each myofibril there are a repeated series of dark and light bands.
2. The dark A-bands (Anisotropic bands) and the light I-bands (Isotropic bands) are perfectly aligned with one another.
3. This type of arrangement gives the cell a striated appearance.
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25. How does an isotonic contraction take place?
Isotonic contraction (iso-same, ton-weight/resistance):
1. In isotonic contraction the length of the muscle changes but the tension remains constant.
2. Here, the force produced is unchanged.
Eg: Lifting dumbbells and weight lifting
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26. How does an isometric contraction take place?
1.In isometric contraction the length of the muscle does not change but the tension of the muscle changes.
2.Here, the force produced is changed.
Eg: Pushing against a wall, holding a heavy bag.
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27. Name the bones of the skull.
Frontal(1), Parietals(2),
Temporal(2), Occipitals(1), Sphenoid(1), Ethmoid(1)
2. Facial bones(14):
Nasals(2), Maxillae(2), Zygomatics(2), Lachrymals(2), Palatines(2), Inferior nasals(2), Mandible(1), Vomer(1)
3. Hyoid bone(1):
U-shaped bone found at the floor of buccal cavity.
4. Ear ossicles(6):
Maleus(2), Incus(2), Stapes(2) (Left and Right ear)
2. It is the only bone without joint.
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29. List the three main parts of the axial skeleton
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30. How is tetany caused?
Rapid muscle spasms occur in the muscles due to deficiency of parathyroid hormone resulting in reduced calcium levels in the body. This disease is called tetany and is a disorder of muscular system.
Functions of skeletal system:
Support -It forms a rigid framework and supports the weight of the body against gravity.
Shape- It provides and maintains the shape of the body.
Protection- It protects the delicate internal organs of the body.
Acts as reservoir - It stores minerals such as calcium and phosphate. Fat (Triglyceride) is stored in yellow bone marrow and represents a source of stored energy for the body.
Locomotion -It acts as lever along with the muscles attached to it.
Strength -It can withstand heavy weight and absorbs mechanical shock.
As a haemopoietic tissue - Red and White blood cells are produced in the bone marrow of the ribs, spongy bones of vertebrae and extremities of long bones.)
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32. What are the different types of rib bones that form the rib cage?
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, hence called bicephalic.
True ribs:
The first seven pairs of ribs are called 'true ribs' or vertebro-sternal ribs.Dorsally they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilages.
False ribs:
The 8th. 9th and 10th pairs of ribs do not articulate directly with the sternum but joined with the cartilaginous (hyaline cartilage) part of the seventh rib. These are called 'false ribs' or vertebro-chondral ribs.
Floating ribs:
The last 11th and 12th pairs of ribs are not connected ventrally. Therefore, they are called as 'floating ribs' or vertebral ribs.
Formation of rib cage:
1. Thoracic vertebrae, ribs and sternum together form the ribcage.
2. Rib cage protects the lungs, heart, liver and also plays a role in breathing.
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33. What are the bones that make the pelvic girdle?
The pelvic girdle:
2. Each coxal bone consists of three fused bones, ilium, ischium and pubis. At the point of fusion of ilium, ischium, and pubis a deep hemispherical socket called the acetabulum is present on the lateral surface of the pelvis.
3. It receives the head of the femur or thigh bone at the hip joint and helps in the articulation of the femur.
4. The ilium is the superior flaring portion of the hip bone. Each ilium forms a secure joint with the sacrum posteriorly. The ischium is a curved bar of bone. The V-shaped pubic bones articulate anteriorly at the pubic symphysis.
The Lower limb:
1. The lower limb consists of 30 bones which carries the entire weight of the erect body.
2. The bones of the lower limbs are thicker and stronger than the upper limbs. The three segments of each lower limb are the thigh, the leg or the shank and the foot.
3. The femur is the single bone of the thigh. It is the largest, longest and strongest bone in the body. The head of femur articulates with the acetabulum of the pelvis to form the hip joint.
4. Two parallel bones, the tibia and fibula, form the skeleton of the shank. A thick, triangular patella forms the knee cap, which protects the knee joint anteriorly and improves the leverage of thigh muscles acting across the knee.
5. The foot includes the bones of ankle, the tarsus, the metatarsus and the phalanges or toe bones. The foot supports our body weight and acts as a lever to propel the body forward, while walking and running.
6. The tarsus is made up of seven bones called tarsals. The metatarsus consists of five bones called metatarsals. The arrangement of the metatarsals is parallel to each other. There are 14 phalanges in the toes which are smaller than those of the fingers.
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34. List the disorders of the muscular system.
Disorders of muscular system:
1. Myasthenia gravis:
An autoimmune disorder affecting the action of acetylcholine at neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscles.
2.Tetany:
Rapid muscle spasms occur in the muscles due to deficiency of parathyroid hormone resulting in reduced calcium levels in the body.
3. Muscle fatigue:
Muscle fatigue is the inability of a muscle to contract after repeated muscle contractions.
4. Atrophy:
A decline or cessation of muscular activity results in the condition called atrophy which results in the reduction in the size of the muscle and makes the muscle to become weak, which occurs with lack of usage as in chronic bedridden patients.
5. Muscle pull:
Muscle pull is actually a muscle tear. A traumatic pulling of the fibres produces a tear known as sprain. This can occur due to sudden stretching of muscle beyond the point of elasticity.
6. Muscular dystrophy: The group of diseases collectively called the muscular dystrophy are associated with the progressive degeneration of skeletal muscle fibres, weakening the muscles and leading to death from lung or heart failure.
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35. Explain the sliding- filament theory of muscle contraction.
Rolf Niedergerke Andrew F. Huxley proposed the sliding-filament theory to explain muscle contraction. According to this theory overlapping actin and myosin filaments of fixed length slide past one another is an energy requiring process resulting in muscle contraction.
1. Contraction is the creation of tension in the muscle and relaxation is the release of tension created by contraction.
2. Muscle contraction is initiated by a nerve impulse sent by the central nervous system (CNS) through a motor neuron.
3. The junction between the motor neuron and sarcolemma of the muscle fibre is called the neuromuscular junction or motor end plate. When nerve impulse reaches this junction acetylcholine is released.
4. An action potential is generated which initiates opening of multiple gated channels of sarcolemma.
5. This causes the flow of large quantities of calcium ions from sarcoplasmic reticulum. The Ca+ ions bind to the troponin of thin filaments. The active sites are exposed to the heads of myosin to form a cross bridge and phosphate ion is released.
6. Hydrolysis of ATP occurs and energy released helps the myosin head to rotate (90° angle with long axis of filament). In this position myosin binds to an actin and activates contraction relaxation cycle which is followed by a power stroke.
7. Power stroke (cross - bridge tilting) begins after rest of myosin binding sites are uncovered. Myosin head and hinge region tilt from 90° angle to 45° angle. Cross bridges are transformed into high - force bonds as myosin releases phosphate ions allowing myosin head to swivel.
8. At the end of power stroke, the myosin head releases actin and swivels back to bind to a new actin molecule to start another contraction cycle. The power stroke repeats many times until a muscle fibre contracts. The process continues as long as muscle receives stimuli and there is steady flow of calcium ions.
9. Myosin returns back to relaxed state and releases ADP. A new ATP then binds to the head of myosin and cross-bridge is broken. The cycle of cross-bridge formation and breakage repeatedly causes sliding of the filaments. similar to motion of oar on a boat.
10. Relaxation
i) Motor impulses stop.
ii) Calcium ions are pumped back into sarcoplasm.
iii) Masking of active sites of actin filament.
iv) Failure of binding of myosin head with active sites of actin.
v) The thin filaments assume their normal position and muscle is released.
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36. What are the benefits of regular exercise?
1. The muscles used in exercise grow larger and stronger.
2. The resting heart rate goes down.
3. More enzymes are synthesized in the muscle fibre.
4. Ligaments and tendons become stronger.
5. Joints become more flexible.
6. Protection from heart attack.
7. Influences hormonal activity.
8. Improves cognitive functions.
9. Prevents Obesity. Promotes confidence, esteem.
10. Prevents depression, stress and anxiety.
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