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Draw the diagram of a sarcomere of skeletal muscle showing different regions.



Define sliding filament theory of muscle contraction.

The sliding filament theory of muscle contraction states that contraction of a muscle, fibre takes place by the sliding of the thin filament over the thick filament.


Describe the important steps in muscle contraction.

The important steps in muscle contraction start with the signal sent by the central nervous system via a motor neuron. Then next step when the neural signal reaches the neuro muscular junction is the release of neuro transmitter (Acetyl choline) which generates an action potential in the sarcolemma.

The action potential spreads through the fibres and releases calcium ion into the sacroplasm. The Ca++ ions bind with a submit of troponin on the action filaments and remove the Masking Myosin. The myosin binds with the action to form a cross bridge which pulls the action filaments towards the centre of A1 band. The ā€˜Zā€™ line is pulled inwards and this shortens the sacromere which is the contraction of the muscle. The energy required for this purpose is obtained by the hydrolysis of ATP. When a new ATP which binds the cross bridge is broken, the muscle is relaxed followed by the cyclic contraction.


Name the type of joint between the following:-


(a) atlas/axis

(b) carpal/metacarpal of thumb

(c) Between cranial bones

(d) Between pubic bones in the pelvic girdle.


(a) Pivot joint

(b) Saddle joint

(c) Fibrous joint

(d) Cartilaginous joint


Write the differences between :

(a) Actin and Myosin

(b) Red and White Muscles

(c) Pectoral and Pelvic Girdle.





1. The light band in the myofibril contain actin protein The dark band in the myofibril contain myosin protein
2. Actin filaments are thin Myosin filaments are thick.

Red Muscles

White Muscles

1. Muscles which contain high amount of oxygen storing red colour pigment called myoglobin appear red. White muscles do not contain myoglobin. So they are white in colour.
2. They contain plenty of Mitochondria. The number of mitochondria is few.
3. These are aerobic muscles. They depend on anaerobic process for energy.

Pectoral Girdle

Pelvic Girdle

1. The pectoral girdle helps in the articulation of the upper limbs. The pelvic girdle helps in the articulation of the lower limbs.
2. The pectoral girdle consists of a clavicle and a scapula. The pelvic girdle consists of two coxal bones.


What are the different types of movements exhibited by the cells of human body?

The cells of the human body exhibit three main types of movements namely:

(1) Amoeboid movement

(2) Ciliary movement and

(3) Muscular movement.


How do you distinguish between a skeletal muscle and a cardiac muscle?


Skeletal Muscles

Cardiac Muscles

1. These muscles are associated with the skeletal components. These muscles are associated with the heart
2. These are voluntary muscles These are involuntary muscles.


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