muscular system .ppt

misicni sistem

2. The Properties of
Muscular System
•The stimulus is transmitted along the
muscle fibers
•The response to his stimulus is muscle
contraction and relaxation.
•Chemical energy is converted to
mechanical energy during the response
•Locomotion and support is provided.

3. Types of Muscles
•There are three types of muscles:
1.Smooth Muscle
2.Striated Muscle
3.Cardiac Muscle

4. SMOOTH MUSCLE
•Cell of smooth muscle has a single
central nucleus that consists of a
mebrnane, known as sarcolemma and
cytoplasm known as sacroplasm.
•Smooth muscles are controlled by the
Autonomic Nervous System (ANS).

5. •The Smooth muscles works involuntarily.
•Their funciton is generally irregular and
slow
•Smooth muscle cells participate in the
structure of internal organs of vertebrates
(Stomach, intestine) and the whole body
structure of invertebrates.
PROPERTIES OF
SMOOTH MUSCLE

7. Skeletal(Striated)
Muscle
•They are involved in the skeletal system and
are also known as skeletal muscles.
•They provide locomotion in cooperation with
the skeletal system.
•The structures of striated muscles are listed
in decreasing order of size as muscle bundles,
muscle fibers, small fibers and actin and
myosin proteins.

8. •Tendons connect skeletal muscles to
the bones.
•Muscles that act cooperatively in
same direction are known as synergic
•Muscles that act in the opposite
direction to each other termed
antagonistic.

11. Properties of Striated Muscles
1.Striated muscles work voluntary
2.It is controlled by Central Nervous
System
3.It contracts rapidly as compared to
smoot muscle
4.It is located in leg, arm, hand, foot etc.

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13. Cardiac Muscle
•Although it is structurally smilar to the
striated muscle, there are some differences.
•The cardiac muscles works involuntary.
•It is controlled by Autonomic nervous
system.
•It is located only in heart.

14. The Muscular Contraction
•The muscle is stimulated by impulses from
the brain, spinal cord and autonomic nervous
system.
•The point of attachment of muscle and a
motor neuron is known as motoneuron.
•The paint at which the nerve ending is
attached to muscle membrane is termed the
motor and plate.

15. •No contraction or movement is
observed in a muscle if it is excited by
only a weak impulse.
•If the potential is gradually increased
to the threshold level, on impulse is
generated when this level reached.
•The response of the muscle at a certain
threshold level is known as the
NON-OR-ALL RULE.

16. Muscular contraction occurs in three
phases:
1.Latent phase
2.Contraction phase
3.Relaxation phase

17. The Mechanism of Contraction
•The muscle contracts by actin and
myosin fibers sliding over each other.
•The muscle is in a relaxed state when
the actin and myosin fibers move apart.
•The Z Band narrows and returns to its
original position by the activities of
actin and myosin proteins.
•The Z and I bands narrow, however
there is no change in the A band.
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18. Chemical Changes
During Contraction
•When the impulse reach the sarcolemma, it
is transmitted to the innerportions of
muscles.
•Ca
++
ions in sarcoplasmic reticulum flow into
the cytoplasm, increasing its concentration.
•Troponin and Tropomyosin molecules are
sensitive to Ca
++
ions.

19. •Injection of Ca
++
ions into muscles fibers
therefore posses them causes them to
contract.
•The muscles relax if the Ca
++

concentration decreases within the
muscle fibers
•Decrease in concentration of Ca
++
occurs
by the replacement of Mg with Ca
++
ions
by the consumption of ATP molecules.

20. Energy Supply For Muscle
•The energy reserve in the muscle can
only supply energy for 5 seconds.
•After this period, Creatin Phosphate is
used as energy source.
•If it is found in muscle cells and
supplies 20 times more ATP energy.
•At rest, the muscle store the excess
energy that is unused in the form of
ATP in creatine molecules.

21. •To achieve this creatine is phosphated by
ATP and converted to creatine phosphate.
•When extra energy is needed, creatine
phosphate is hydrolized into creatine and
phosphate.
•The energy contained within creatine
phosphate is used to synthesize ATP
molecules.

22. Physiological Tetanus
•A muscle will remain in a contracted state if it is
stimulated 40 times in one minute.
•In such cases, the muscle loses its elasticity and
becomes rid.
•This stuation is known as tetanus.
•Frequent stimulation of a muscle in excess of that
under normal conditions results in an tetanus.
•Cramp for instance, is a type of tetanus.
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