Structure and Functions of Muscle

1. Jean Melanie Vincent Haymo
Physical Education Teacher
MPhil Scholar Punjabi
University ,Patiala
MPED L.N.I.P.E , Gwalior
Structure and
Function of
Skeletal
Muscle

2. Skeletal Muscle
– Human body contains over 400 skeletal muscles
– 40-50% of total body weight
– Functions of skeletal muscle
– Heat production during cold stress
– Force production for postural support
– Force production for locomotion and breathing
– The prime function of muscle is to convert chemical energy (ATP) into
mechanical energy.

4. Structure of Skeletal Muscle
– Epimysium
– The entire muscle is surrounded by connective tissue called epimysium.
– Perimysium
– The bundle or fasciculus is also surrounded by a connective tissue called
perimysium.
– Fascicles
– Endomysium
– Many muscle fiber found in muscle bundle. The individual muscle fiber is surrounded by
connective tissue called endomysium.
– Tendon
skeletal muscle is attaches to a bone with the help of connective tissue called tendon.

6. – Sarcolemma
Each muscle fiber contains sarcoplasm covered by membrane sarcolemma.in the sarcoplasm, ATP, CP, fat
droplets are present.
The sarcoplasmic reticulum (smooth endoplasmic reticulum) stores calcium, which is released into the
sarcoplasm during muscle contraction.
- Myofibrils
Threadlike strands within muscle fibers. It is the smallest unit of a muscle fiber. Myofibril has
dark and light bands in it. The dark band is known as A band and light one’s are as I band.
These bands consists of two types of protein filaments known as actin(thin) and myosin(thick).
Thin myofilaments are composed of 3 proteins: actin, tropomyosin, and troponin.
- Thick myofilaments consist myosin molecules.
A band consists of both actin and myosin filament and I band consist of only actin filament.

11. – Further divisions of myofibrils
– Z-line:-In the middle of A and I band, there is a Z line.
– Sarcomere:- The portion between two Z line is called sarcomere.
The sarcomere is the functional (contracting) unit of skeletal
muscle.
– H zone:-the area in the centre of the A band is called H zone.

14. Cross-Bridge Formation in Muscle
Contraction

15. Function of Skeletal Muscle:
– Motion -- Motion can be obvious body movements or less noticeable motions such as
heartbeat and gut movement.
– Stabilize body positions and regulate organ volume -- Sustained contractions of skeletal
muscle maintain body posture without creating noticeable movement. Sustained
contractions of smooth muscle prevent outflow from hollow organs and maintain them
at an appropriate volume.
– Thermogenesis -- A by-product of muscle contraction is heat production and is therefore
important in homeostasis of body temperature.

16. Properties of skeletal muscles
– Excitability:-This is the ability to receive and respond to certain stimuli by
producing electrical messages.
– Contractibility :- Contractility is the ability to shorten and thicken (contract),
thus generating force to do work.
– Extensibility:- Extensibility is the ability to stretch without damaging the
tissue.
– Elasticity:- It is the property of muscle to lengthens during stretching by
pulling force & can return again to its normal resting position.
– Muscle tone:- it refers to the partially contracted state of the muscle in a
constant state of readiness for action.