1. Zulcaif Ahmad
Muscles

2. Specialized cells for movement which contains
numerous filaments of special protein actin and myosin

3. Muscles
These are the part of body which spots the
body functions.
More than 600 muscles present in our body

4. Muscles
Classification:
It based in three different factors:
 Depending upon striations
 Depending upon control
 Depending upon function

5. Muscles
1. Depending upon striations:
It is further divided into two groups
a) striated Muscles
Trasverse lines at regular intervals
(skeletal and cardiac musles)
a) non-striated Muscles
Without cross striations
(smooth muscles)

6. Muscles
2) Depending upon control:
Divided into two types:
a) Voluntry musles:
in our control - Skeletal muscles inervated by
somatic nerves
b) In-voluntry muscles:
Not in our control – Cardiac muscles and smooth
muscles inervated by autonomic nerves

7. Muscles
3) Depending upon functions/situation:
Further divided into three types
a) Skeletal Muscles (in association with bone forming skeletal
system – 40 – 50%)
b) Cardiac Muscles (forms musculature of heart)
c) Smooth Muscles (they are in association with viscera – internal
organs, GIT, Urinary system, respiratory system)

8. Muscles
Contractility:
Skeletal muscles gives response to a
stimulus in the form of contraction.
- Contraction:
The internal events of the muscles which are
menifested by change in either the length or
tension of the muscles fibers.
(Has two types)

9. Muscles
1. Isotonic contraction:
iso = same
tonic = tension
- Simple Flexion of arms
2. Isometric contraction:
- length same and tension increase
- pulling any heavy object

11. Changes during muscles
contraction
Introduction:
Muscles is contract when it is stimulated.
It is physical and mechanical event. Other changes
also occur.
Other changes:
a) electrical changes
b) physical changes
c) histological changes
d) thermal changes
e) chemical changes

12. Changes during muscles
contraction
 Electrical changes:
When muscles is stimulated, electrical changes occur
before the
onset of mechanical changes.
 Resting membrane potential (the electrical potential
difference across the cell membrane between inside and
outside the cell).
 Action potential (series of changes in membrane
potential - A wave of electrical discharge that travels along the
membrane of the cell).
It occurs in two phases
o Depolarization
o Repolarization

13. Changes during muscles
contraction
 Ionic bases of electrical changes.
Ionic imbalance
a) Sodium potassium pump
b) Selective permeability of cell
membrane

14. Changes during muscles
contraction
 Graded potential (stimulation of the
reseptors, synaps or nuromuscular junction
produces some mild changes in the membrane
potential, it losses its intensity as its starts
spreading)

15. Changes during muscles
contraction
 Physical changes:
Change in length of muscles fiber or change in tension
developed in muscle (contractility)
 Chemical changes:
o Liberation of energy (the energy neccesery for muscular
contraction is librated during the processes of breakdown and
resynthesis of ATP)
 Breakdown of ATP:
I. spread of action potential into the muscles
II. libration of calcium ion from sisternae of L-tubules into the
sarcoplasm
III. movement of myosin head
IV. sliding mechanism

16. Changes during muscles
contraction
 resynthesis of ATP:
ADP attaches with high energy phosphate
redical except
combining with Pi.
Sources for high energy phosphate
o Synthesis of ATP from creatine phosphate
ADP + CP ATP +
Creatine
o Synthesis of ATP By carbohydrates metabolism
Glycolysis, cori’s circle, Krebs cycles

17. Changes during muscles
contraction
Changes in pH:
o In resting condition.
reaction of muscle is alkaline with a pH of 7.3.
o During onset of contraction.
at the beginning of muscular contraction, the reaction
become acidic. The acidity is due to dephosphorylation
of ATP into ADP and Pi.
o During later part of contraction.
the muscle become alkaline, it is due to resynthesis of
ATP from Cl.
o At the end of contraction
the muscles become once again acidic, this acidity is
due to the formation of pyruvic acid and or lactic acid.

18. Changes during muscles
contraction
 Histological changes:
o acto-myosin complex (Bands)
o excitation contraction coupling
o role of troponin and tropomyosin
o sliding theory or ratchet theory

21. Changes during muscles
contraction
 Thermal changes:
During musclar contraction heat is produce not all the
heat is librated at a time it release in different stages
o Resting heat
o Initial heat
I. heat of activation (produce during the release of Ca ions from L-tubules)
II. heat of shortening (produce due to various structural changes in the muscle fiber like
movement of cross bridges and myosin heads)
III. heat of relaxation
o Recovery heat
Due to chemical processes involved resynthesis of chemical
substances
broken down during contraction

22. Refrence:
 Essentials of medical physiology by jaypee (4th edition)
ch#28,29,30,31 ( page
145,146,149,154,155,163,164,165,166,168,169,170,171,
172,173)
 Text book of physiology by guyton n hall ( 11th edition)
, ch#06(pg 72 to 79 )