Muscle Physiology-1 _ Dr Sachin.pptx.pdf

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2. Muscle Physiology - 1
Introduction

3. 24+ years Teaching Experience
10,00,000 Students & Teachers Mentored
Dr. Sachin Kapur
M.Phil, Phd.

AIR- 1 (AIIMS)
AIR - 1 (AIPMT)
AIR - 1 (DPMT)

4. mbbsdrsachink

6. Syllabus

7. ●Describe the structure of neuro-muscular junction and
transmission of impulses.
●Discuss the action of neuro-muscular blocking agents
●Describe the pathophysiology of Myasthenia gravis

Muscle Physiology

8. ●Describe the different types of muscle fibres and their structure.
●Describe action potential and its properties in different muscle
types (skeletal & smooth)
●Describe the molecular basis of muscle contraction in skeletal and
in smooth muscles
Muscle Physiology

9. ●Describe the mode of muscle contraction (isometric and isotonic)
●Explain energy source and muscle metabolism
●Explain the gradation of muscular activity
Muscle Physiology

10. ●Describe muscular dystrophy: myopathies
●Perform Ergography(Practical)
Muscle Physiology

11. ●Demonstrate effect of mild, moderate and severe exercise and
record changes in cardiorespiratory parameters(Practical)
●Demonstrate Harvard Step test and describe the impact on induced
physiologic parameters in a simulated environment(Practical)
Muscle Physiology

12. ● Describe Strength-duration curve
●Observe with Computer assisted
learning(Practical)
❖amphibian nerve - muscle experiments
❖amphibian cardiac experiments
Muscle Physiology

13. ●Neuromuscular Transmission
●Excitation Contraction Coupling
●Molecular basis of Skeletal Muscle Contraction.
●Chemical changes during Skeletal Muscle Contraction.
●Characteristics of Skeletal Muscle Contraction.
●Applied skeletal muscle physiology.
Muscle Physiology Topics

14. ❖About 40 percent of the body is skeletal muscle, and perhaps
another 10 percent is smooth and cardiac muscle.
❖Some of the same basic principles of contraction apply to all of
these muscle types
MusclesMuscles

15. Types of Muscles
Skeletal Muscles Cardiac Muscles Smooth Muscles

16. Skeletal Muscles Cardiac Muscles Smooth Muscles
❖Striated or
striped
❖Voluntary
❖Non-striated or
Unstriped
❖Involuntary
❖Striated or
striped
❖Involuntary

17. ❖Only the heart contains cardiac muscle tissue, which forms
most of the heart wall.
❖Cardiac muscle is striated, but its action is involuntary.
MusclesCardiac Muscles

19. ➔Their lipid content is high and these use
fatty acids for energy (do not get fatigued).
➔Cardiac muscle tissue is a contractile tissue
present in the heart wall (myocardium).
➔These are striated , uninucleate, branched
and involuntary.

Cardiac Muscles
Types of Muscles

20. ➔Communication junctions (intercalated discs)
at some fusion points allow the cells to
contract as a unit, i.e., when one cell receives a
signal to contract, its neighbours are also
stimulated to contract.
Cardiac Muscles
Types of Muscles

21. ➔The discs contain desmosomes, which hold
the fibers together, and gap junctions, which
allow muscle action potentials to spread from
one cardiac muscle fiber to another.
Cardiac Muscles
Types of Muscles

22. ➔These are highly vascular, i.e. surrounded by a
very rich capillary network.
➔They show well developed sarcoplasmic
reticulum with plenty of cytoplasm,
mitochondria.
Cardiac Muscles
Types of Muscles

23. ❖These are located in walls of hollow internal structures, like blood
vessels, airways, and most organs in the abdominopelvic cavity.
❖These are also found in the skin, attached to hair follicles.
❖These looks nonstriated, that’s why these are referred as smooth.
MusclesSmooth Muscles

24. ❖The action of smooth muscle is involuntary, and some smooth
muscle tissue, such as the muscles that propel food through your
gastrointestinal tract, has autorhythmicity.
MusclesSmooth Muscles

25. ❖These can remain contracted for relatively longer periods without
expenditure of much energy, a property that endows them with a
better metabolic economy
MusclesSmooth Muscles

26. ➔The action of smooth muscle is involuntary,
and some smooth muscle tissue, such as the
muscles that propel food through your
gastrointestinal tract, has autorhythmicity.
➔These are of two types:
Smooth Muscles
Types of Muscles
Single Unit Smooth Muscles
Multi Unit Smooth Muscles

27. Types of Muscles
Smooth Muscles
Multi Unit Smooth Muscles Single Unit Smooth Muscles

28. ➔Of the two types of smooth muscle tissue,
the more common type is visceral
(single-unit) smooth muscle tissue.
Single Unit Smooth Muscles
Smooth Muscles

29. ➔It is found in tubular arrangements that
form part of the walls of small arteries and
veins and of hollow organs such as the
stomach, intestines, uterus, and urinary
bladder.
➔Like cardiac muscle, visceral smooth muscle
is autorhythmic.
Single Unit Smooth Muscles
Smooth Muscles

30. ➔The fibers connect to one another by gap
junctions, forming a network through which
muscle action potentials can spread.
➔Stimulation of one visceral muscle fiber
causes contraction of many adjacent fibers.
Types of Smooth Muscles
Single Unit Smooth Muscles

31. ➔When a neurotransmitter, hormone, or
autorhythmic signal stimulates one fiber,
the muscle action potential is transmitted to
neighboring fibers, which then contract in
unison, as a single unit.
Types of Smooth Muscles
Single Unit Smooth Muscles

32. Types of Smooth Muscles

33. ➔These consist of individual fibers, each with
its own motor neuron terminals and with
few gap junctions between neighboring
fibers.
➔Stimulation of one multiunit fiber causes
contraction of that fiber only.
Multi Unit Smooth Muscles
Types of Smooth Muscles

34. These are found in
➔Walls of large arteries, airways to the
lungs.
➔Arrector pili muscles that attach to hair
follicles.
Multi Unit Smooth Muscles
Types of Smooth Muscles

35. ➔Muscles of the iris that adjust pupil
diameter.
➔Ciliary body that adjusts focus of the lens in
the eye.
Multi Unit Smooth Muscles
Types of Smooth Muscles

36. ❖All skeletal muscles are composed of numerous fibers ranging
from 10 to 80 micrometers in diameter.
❖In most skeletal muscles, each fiber extends entire length of
the muscle.
MusclesSkeletal Muscles

37. ❖Except for about 2 percent of the fibers, each fiber is usually
innervated by only one nerve ending, located near the middle
of the fiber
MusclesSkeletal Muscles

38. ❖These are so named because most skeletal muscles move bones
of the skeleton.
❖A few skeletal muscles attach to and move the skin or other
skeletal muscles.
❖Alternating light and dark bands (striations) are seen when the
tissue is examined with a microscope.
MusclesSkeletal Muscles

39. ❖These work mainly in a voluntary manner.
❖Its activity can be consciously controlled by neurons that are
part of the somatic (voluntary) division of the nervous system.
MusclesSkeletal Muscles

40. ❖Diaphragm continues to alternately contract and relax without
conscious control so that you don’t stop breathing.
❖You do not need to consciously think about contracting the
skeletal muscles that maintain your posture or stabilize body
positions.
MusclesSkeletal Muscles

49. Body Movement
Body Position Stabilization
Storage of Substances
Heat Generation
MusclesFunctions of Muscles

50. Excitability
Contractility
Extensibility
Elasticity
MusclesProperties of Muscles

51. ❖It is the ability to respond to certain stimuli by producing
electrical signals called action potentials.
MusclesExcitability

52. ❖It is the ability of muscular tissue to contract forcefully when
stimulated by an action potential.
MusclesContractibility

53. ❖It is the ability of muscular tissue to stretch without being
damaged.
❖It allows a muscle to contract forcefully even if it is already
stretched.
❖Normally, smooth muscle is subject to the greatest amount of
stretching.
MusclesExtensibility

54. ❖It is the ability of muscular tissue to return to its original length
and shape after contraction or extension.
MusclesElasticity

55. ❖Each skeletal muscle is a separate organ composed of
hundreds to thousands of cells, which are called muscle fibers.
❖Muscle cell and muscle fiber are same.
❖It also contains connective tissues surrounding muscle fibers
and whole muscles, and blood vessels and nerves.

MusclesStructure of Skeletal Muscle

56. MusclesStructure of Skeletal Muscle

57. Muscles

58. ❖Outermost layer, encircling the entire muscle, is epimysium.
❖Perimysium surrounds groups of 10 to 100 or more muscle
fibers, separating them into bundles called fascicles.
❖Many fascicles are large enough to be seen with the naked eye.
MusclesStructure of Skeletal Muscle

59. Muscles
Structure of Skeletal Muscle

60. ❖Plasma membrane of muscle fiber is sarcolemma.
❖Cytoplasm of muscle fiber is sarcoplasm.
❖Sarcoplasm includes a substantial amount of glycogen.
❖Glycogen can be used for synthesis of ATP.
Muscles
Ultrastructure of Skeletal Muscle Fibre

61. ❖It consists of a true cell membrane, called plasma membrane,
and an outer coat made up of a thin layer of polysaccharide
material that contains numerous thin collagen fibrils.
Sarcolemma

62. ❖At each end of the muscle fiber, the surface layer of
sarcolemma fuses with a tendon fiber .
❖The tendon fibers in turn collect into bundles to form the
muscle tendons that then connect the muscles to the bones.
Sarcolemma

63. ❖It contains a red-colored protein called myoglobin.
❖It binds oxygen molecules that diffuse into muscle fibers from
interstitial fluid.
❖Myoglobin releases oxygen when it is needed by mitochondria
for ATP production.
Muscles
Sarcoplasm

64. ❖Mitochondria (sarcosomes) lie in rows throughout the muscle
fiber, strategically close to the muscle proteins that use ATP
during contraction.

Muscles
Sarcosomes

65. ❖Surrounding the myofibrils of each muscle fiber is an extensive
reticulum, called the sarcoplasmic reticulum.
❖This reticulum has a special organization that is extremely
important in regulating calcium storage, release, and reuptake.
❖Rapidly contracting types of muscle fibers have especially
extensive sarcoplasmic reticula.
Muscles
Sarcoplasmic Reticulum

66. ❖Multiple nuclei of a skeletal muscle fiber are located just
beneath the sarcolemma (plasma membrane)
MusclesStructure of Skeletal Muscle

67. ❖Thousands of tiny invaginations of the sarcolemma, called
transverse (T) tubules, tunnel in from the surface toward the
center of each muscle fiber.
MusclesStructure of Skeletal Muscle

68. ❖T tubules are open to the outside of the fiber and thus are
filled with interstitial fluid.
❖Muscle action potentials travel along the sarcolemma and
through the T tubules.
❖This arrangement ensures that an action potential excites all
parts of the muscle fiber at essentially the same instant.
Muscles
Structure of Skeletal Muscle

70. Development of Muscle

72. Myoblasts
Myocyte
Many myoblasts fuse to form single
muscle fiber (Myocyte) covered by
endomysium.
Muscle forming cells in an embryo.
MusclesDevelopment of Skeletal Muscle

73. Muscle Fasciculus
Bundle of muscle fibers covered by
perimysium.
Muscle
Many muscle fasciculi group to form
muscle which is covered by
epimysium.
Muscles
Development of Skeletal Muscle

75. ❖Each muscle fiber contains several hundred to several thousand
myofibrils.
❖Each myofibril is composed of about 1500 adjacent myosin
filaments and 3000 actin filaments.
Muscles
Ultrastructure of Skeletal Muscle Fibre

76. ❖Within myofibrils are smaller structures called myofilaments.
❖Thin filaments are 8 nm in diameter and 1–2 μm long, while
thick filaments are 16 nm in diameter and 1–2 μm long.

Muscles
Ultrastructure of Skeletal Muscle Fibre

77. Neuromuscular Junction

78. ❖Junction between a nerve fibre and a muscle fibre is called
neuromuscular junction.
❖Neurons that stimulate skeletal muscle to contract are somatic
motor neurons.
Muscles
Neuromuscular Junction

79. ❖Each somatic motor neuron has a threadlike axon that extends
from the brain or spinal cord to a group of skeletal muscle fibers.
❖Axon of a somatic motor neuron typically branches many times,
each branch extending to a different skeletal muscle fiber.

Muscles
Neuromuscular Junction

81. ❖Skeletal muscle fibers are innervated by large myelinated nerve
fibers that originate from large motoneurons in the anterior
horns of the spinal cord.
❖Each nerve fiber, after entering the muscle belly, normally
branches and stimulates from three to several hundred skeletal
muscle fibers.
Muscles
Neuromuscular Junction

83. ❖Each nerve ending makes a junction with the muscle fiber near
its midpoint.
❖The action potential initiated in the muscle fiber by the nerve
signal travels in both directions toward the muscle fiber ends.
❖With the exception of about 2% of the muscle fibers, there is
only one such junction per muscle fiber

Muscles
Neuromuscular Junction

84. ❖Nerve fiber forms a complex of branching nerve terminals that
invaginate into the surface of the muscle fiber but lie outside the
muscle fiber plasma membrane.
❖The entire structure is called the motor end plate.
❖It is covered by one or more Schwann cells that insulate it from
the surrounding fluids.

Muscles
Motor End Plate

86. ❖Each single motor neuron and the muscle fibers it innervates
constitute a motor unit.

Muscles
Motor Unit

87. ❖Number of muscle fibers in a motor unit varies.
❖In muscles such hand and those concerned with motion of eye (ie,
muscles concerned with fine, graded, precise movement), each
motor unit innervates very few ( three to six) muscle fibers.
Motor Unit

88. ❖On the other hand, values of 600 muscle fibers per motor unit
can occur in human leg muscles.
Motor Unit

89. Motor End Plate
Secretion of Acetylcholine
Drugs affecting NMJ
Diseases of NMJ
MusclesNeuromuscular Transmission