Muscle biophysics

1. Types of
Muscle

2. What are muscles?
 Muscle , are excitable tissue like the
nervous tissue
 There are about 700 muscles that are
connected to the bones of the body.
 About 40-50 per cent of the body weight
of a human adult is contributed by
muscles
 The Muscles are involved movement of
the body.

3. Types of muscle
 Based on their location, three types of muscles
are identified :
(i) Skeletal muscle
(ii) Visceral also called smooth muscle and
(iii) Cardiac muscle

5. Skeletal muscle
 When you think about your muscles, you are
probably thinking about skeletal muscle.
 Skeletal muscles is voluntary muscles.
 When you volunteer, you choose to do
something.
 It's the same for your skeletal muscles. Your
leg won't kick a soccer ball until you choose
to move it.

6.  Skeletal muscles are striated muscles, which is a
fancy way of saying they look striped when you
view them under a microscope.
 They're the only type of
muscle that is voluntary, so
any muscle that you can
move by thinking about it is a
skeletal muscle.

7. Structure of a skeletal muscle
 Attached to bones at both ends by tendons
 When you contract a skeletal muscle it
shortens, pulling the bone along with it and
thus causing movement.
 Fusiform in shape with tapering ends
 Has a belly & tendons on either side

9. Structure of a skeletal muscle
Myofibrils
Muscle
Fascicles
Muscle fibres
Muscle fibres
Myofibril

11.  The arrangement of thick and thin filaments in
the myofibrils results in the striated
appearance of muscle fibers

13. Properties of Skeletal Muscle
 The skeletal muscles have the following
properties:
 Extensibility: It is the ability of the muscles
to extend when it is stretched.
 Elasticity: It is the ability of the muscles to
return to its original structure when released.
 Excitability: It is the ability of the muscle
to respond to a stimulus.
 Contractility: It is the ability of a muscle to
contract when in contact with a stimulus.

14. 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.

17. Skeletal Muscle Function
The important skeletal muscle function:
 The skeletal muscles are responsible for body movements such as
typing, breathing, extending the arm, writing, etc. The muscles
contract which pulls the tendons on the bones and causes
movement.
 The body posture is maintained by the skeletal muscles. The
gluteal muscle is responsible for the erect posture of the body. The
sartorius muscles in thighs are responsible for body movement.
 The skeletal muscles also regulate body temperature. After a
strenuous exercise, the body feels hot. This is due to the
contraction of skeletal muscles which converts energy into heat.

18. Smooth Muscle
 Smooth muscle is the type of muscle that makes up
the walls of many internal organs and structures, like
your digestive tract, blood vessels, and bladder.
 Also called visceral muscle.
 The most striking feature is the lack of striations and
stripes. Compared to the other types, smooth muscle
looks like smooth sheets, hence the name.

19.  You don't have any control over these muscles, so
they are involuntary muscles.
 smooth muscles are always at work behind the
scenes, helping you do all kinds of things necessary
for survival.
 The smooth muscles found in your esophagus,
stomach, and intestines contract and relax to push
food through your digestive tract.
 Smooth muscles in the walls of your blood vessels
contract and relax to adjust how much blood flows
through them.

20. Structure of smooth muscle

21. Types of smooth muscle
 Single unit smooth muscle
 Muliti unit smooth muscle.

22. Single unit smooth muscle
 Single-unit muscle has its muscle fibers
joined by gap junctions so that the muscle
contracts as a single unit.
 Present in hollow viscera (organs) like GIT,
Uterus, Ureter, Urinary Bladder & Respiratory
tract.

23. Multiunit smooth muscle
 Multiunit smooth muscle cells rarely possess
gap junctions, and thus are not electrically
coupled.
 As a result, contraction does not spread from
one cell to the next, but is instead confined
to the cell that was originally stimulated.
 This type of tissue is found around large
blood vessels, in the respiratory airways, and
in the eyes.

24. Cardiac Muscles
 The cardiac muscles is a muscles tissue found in the
heart wherein it is performing and bringing about
coordinated contractions which enable the heart to
pump blood.
 Cardiac muscles are striated and involuntary
muscles.