This is about muscle and contraction

1. Maribel D. Ganeb Ph.DScience Education
Philippine Normal University
Science 621-Animal Physiology

4. Objectives
 Present the important concepts about the muscles
 Enumerate the three different types of muscles
 Compare the characteristic of each type of muscle
 Discuss the structure of the muscles
 Present the microscopic anatomy of muscles and its
function
 Present videos on muscle contraction, and movement
mechanisms of an amphibian, fish and bird
 Show the importance of Contraction
 Present how muscle contraction happens
 Discuss the two kinds of Contraction
 Present three diseases of the muscle

5. The MuscularSystem
 Muscles are responsible for all types of
body movement
 Three basic muscle types are found in the
body
 Skeletal muscle
 Cardiac muscle
 Smooth muscle

6. Characteristics of Muscles
 Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber)
 Contraction of muscles is due to the
movement of microfilaments
 All muscles share some terminology
 Prefixes m yo and m ys refer to “muscle”
 Prefix sarco refers to “flesh”

7. COMPARISON OF
SKELETAL, CARDIAC,
ANDSMOOTHMUSCLES

9. Table 6.1 (2 of 2)

10. Characteristics of the Skeletal Muscle
 Most are attached by tendons to bones
 Cells are multinucleated
 Striated—have visible banding
 Voluntary—subject to conscious control

11. Connective Tissue Wrappings of
Skeletal Muscle
 Cells are surrounded and bundled by
connective tissue
 Endomysium—encloses a single muscle fiber
 Perimysium—wraps around a fascicle (bundle) of
muscle fibers
 Epimysium—covers the entire skeletal muscle
 Fascia—on the outside of the epimysium

12.  Connected Tissue Wrappings of Skeletal Muscle
Figure 6.1

13. Skeletal Muscle Attachments
 Epimysium blends into a connective tissue
attachment
 Tendons—cord-like structures
Mostly collagen fibers
Often cross a joint due to toughness and
small size
 Aponeuroses—sheet-like structures
Attach muscles indirectly to bones,
cartilages, or connective tissue coverings

14. Skeletal Muscle Attachments
 Sites of muscle attachment
 Bones
 Cartilages
 Connective tissue coverings

15. Microscopic Anatomy of Skeletal
Muscle
 Sarcolemma—specialized plasma
membrane
 Myofibrils—long organelles inside muscle
cell
 Sarcoplasmic reticulum—specialized
smooth endoplasmic reticulum

16. Skeletal Muscle Functions
 Produce movement
 Maintain posture
 Stabilize joints
 Generate heat

17. Smooth Muscle Characteristics
 Lacks striations
 Spindle-shaped cells
 Single nucleus
 Involuntary—no conscious control
 Found mainly in the walls of hollow organs

18. Smooth Muscle Characteristics
Figure 6.2a

19. Cardiac Muscle Characteristics
 Striations
 Usually has a single nucleus
 Branching cells
 Joined to another muscle cell at an
intercalated disc
 Involuntary
 Found only in the heart

20. Cardiac Muscle Characteristics
Figure 6.2b

22. THE MUSCLE
STRUCTURE

24. Microscopic Anatomy of Skeletal
Muscle
Figure 6.3a

25. Microscopic Anatomy of Skeletal
Muscle
 Myofibrils are aligned to give distinct bands
 I band = light band
 Contains only thin filaments
 A band = dark band
 Contains the entire length of the thick
filaments

26. Microscopic Anatomy of
Skeletal Muscle
Figure 6.3b

27. Microscopic Anatomy of
Skeletal Muscle
 Sarcomere—contractile unit of a
muscle fiber
 Organization of the sarcomere
 Myofilaments
Thick filaments = myosin filaments
Thin filaments = actin filaments

28. Microscopic Anatomy of
Skeletal Muscle
 Thick filaments = myosin filaments
 Composed of the protein myosin
 Has ATPase enzymes
 Myosin filaments have heads (extensions, or
cross bridges)
 Myosin and actin overlap somewhat
 Thin filaments = actin filaments
 Composed of the protein actin
 Anchored to the Z disc

29. Microscopic Anatomy of Skeletal
Muscle
Figure 6.3c

30. Microscopic Anatomy of Skeletal
Muscle
 At rest, there is a bare zone that lacks actin
filaments called the H zone
 Sarcoplasmic reticulum (SR)
 Stores and releases calcium
 Surrounds the myofibril

31. Microscopic Anatomy of Skeletal
Muscle
Figure 6.3d

32. The Nerve Stimulus and Action
Potential
 Skeletal muscles must be stimulated by a
motor neuron (nerve cell) to contract
 Motor unit—one motor neuron and all the
skeletal muscle cells stimulated by that neuron

33. Figure 6.4a
The Nerve Stimulus and Action
Potential

34. The Nerve Stimulus and Action
Potential
Figure 6.5a

35. The Nerve Stimulus and Action
Potential
Figure 6.5b

36. Transmission of Nerve Impulse to
Muscle
 Neurotransmitter—chemical released by
nerve upon arrival of nerve impulse
 The neurotransmitter for skeletal muscle
is acetylcholine (ACh)
 Acetylcholine attaches to receptors on the
sarcolemma
 Sarcolemma becomes permeable to
sodium (Na+)

37. Transmission of Nerve Impulse to
Muscle
 Sodium rushes into the cell generating an
action potential
 Once started, muscle contraction cannot be
stopped

38. The Sliding Filament Theory
of Muscle Contraction
 Activation by nerve causes myosin heads
(cross bridges) to attach to binding sites on
the thin filament
 Myosin heads then bind to the next site of the
thin filament and pull them toward the center
of the sarcomere
 This continued action causes a sliding of the
myosin along the actin
 The result is that the muscle is shortened
(contracted)

39. The Sliding Filament Theory
of Muscle Contraction
Figure 6.7a–b

40. The Sliding Filament Theory
Figure 6.8a

41. The Sliding Filament Theory
Figure 6.8b

43. Muscle Contraction

44. Muscles and the Body
Movement

45. Muscles and Body Movements
 Movement is attained due to a muscle moving
an attached bone
 Muscles are attached to at least two points
 Origin
 Attachment to a moveable bone
 Insertion
 Attachment to an immovable bone

46. Muscles and Body Movements
Figure 6.12

47. Types of Ordinary Body
Movements
 Flexion
 Decreases the angle of the joint
 Brings two bones closer together
 Typical of hinge joints like knee and elbow
 Extension
 Opposite of flexion
 Increases angle between two bones

48. Types of Ordinary Body
Movements
Figure 6.13a

49. Types of Ordinary Body
Movements
 Rotation
 Movement of a bone around its longitudinal axis
 Common in ball-and-socket joints
 Example is when you move atlas around the
dens of axis (shake your head “no”)

50. Intramuscular Injection Sites
Figure 6.18, 6.19b, d

51. MOVEMENT OF
SELECTED
VERTEBRATES

52. THE BIRD

60. Movement of Snake
 Snakes use at least five unique modes of
terrestrial locomotion. The kind of locomotion
a snake uses in any particular instance
depends on several factors such as the kind of
surface it is crawling on and its speed.

61.  Simple undulation is characterized by waves
of lateral bending being propagated along the
body from head to tail. The bends push
laterally against surface objects, but do not
deform locally around them, and usually slip
out of contact quickly; in this way, simple
undulation differs from the more complex
Lateral Undulation of snakes

62. Lateral Undulation
 waves of lateral bending are propagated along
the body from head to tail.
 unique in that whenever a bend contacts a
surface object, such as a rock or stick, it
exerts force against it and deforms locally
around it.
 the large dorsal muscles are activated
sequentially along the body.

63. Side Winding
 Many snakes are crawling on smooth or slippery
surfaces, but is best known in the sidewinder
rattlesnake (Crotalus cerastes) and a few desert
vipers of Africa and Asia.
 Sidewinding is similar to lateral undulation in the
pattern of bending, but differs in three critical ways:
 the body sort of rolls along the ground from neck to
tail, forming a characteristic track (that is proportional
to body length) in sand;

64. Concertina locomotion
 Concertina locomotion involves alternately pulling up the
body into bends and then straightening out the body
forward from the bends.
 The front part of the body then comes to rest on the
surface and the back part of the body is pulled up into
bends again, and so forth.
 Concertina locomotion is used in crawling through
tunnels or narrow passages and in climbing.

65. Rectilinear locomotion
 Rectilinear locomotion is movement in a straight line. It
is used mainly by large snakes such as large vipers,
boas, and pythons. In rectilinear locomotion, the belly
scales are alternately lifted slightly from the ground and
pulled forward, and then pulled downward and
backward. But because the scales "stick" against the
ground, the body is actually pulled forward over them.

66. Slide pushing
 involves vigorous undulations of the body that slide
widely over the surface.
 used when a snake on a smooth surface is startled and
tries to escape quickly,
 irregular bends of the body and tail press vertically on
the surface at different points;
 snake progresses irregularly by slipping along the
ground. Sliding friction is most important in slide-
pushing, although there may be occasional moments of
static contact.


67. FISH

72. THE
CHEETAH

74. Cheetah's speed secrets are revealed
By Matt BardoReporter, BBC Nature

75.  Different types of muscle fiber are suited to
different activities, explained Dr Wada.
 Type I fibers produced a small force output but
were resistant to fatigue, making them best
suited to maintaining posture and slow
walking.
 Type II a fiber performance was best suited to
fast walking and trotting whereas Type II or
"fast" fibres created a high force output but
had low endurance and were key to fast
running or galloping.

76. Cheetah’s running
 A sprinting cheetah spends more than half its
time in the air
 "The forelimb muscles in the cheetah included
[the] most Type I muscle fibers of all three
animals... while the muscle of hind limb
muscles have many Type II fibers."
 "The functional difference between forelimb
and hind limb is the most remarkable in the
cheetah," said Dr Wada.

77. Results suggested the
following:
 Cheetah's hind legs, in the same way as a
rear wheel-drive car, according to Dr Wada.
 The digits of the cheetah's hindlimbs
contained no fast fibres, but the digits on the
front legs contained many of them.
 Dr Wada explained that this is because the
cheetah controls its balance by using its
forefeet to turn and slow down.

78. THE DRAGON
FLY

80. Amazing Dragon Fly
 Nature inspired human for many inventions,
but the abilities of the dragonfly are more
advanced than any other superior invention.
 Scientists say that till now they don't know how
that insect had got these abilities to perform
such complicated technique as the executed
motions are amazing, also they say that it
would be impossible for that insect to learn
itself and without the help of anyone.

81.  Scientists say that dragonflies use movement
for their camouflage, Camouflage is usually
associated with immobility as it occupies the
same spot in the retina of the victim. So that
the victim sees it stable when it is moving,
scientists say that this technique is
complicated and very strange.
 Scientists say that the brain of the dragonfly is
so small in comparison with the volume of the
executed complicated arithmetic operations
which produce that fast movement in the three

85. THE FROGS

88.  Frogs must generate a high level of mechanical power
when they jump.
 The muscular system of frogs that jump is presumably
designed to deliver these high powers
 The length changes and activation pattern that muscles
undergo during jumping were measured, and isolated
muscle bundles were driven through this in vivo pattern.
 During jumping, muscles generated maximum power.
Specifically, the muscle fibers (i) operated at optimal
sarcomere lengths, (ii) operated at optimal shortening
velocities, and (iii) were maximally activated during
power generation

90. MUSCLE CONTRACTION

91. Importance of Contraction
 Locomotion
 Prey Capture
 Eating
 Copulation
 Production of Sound

92. Contraction of Skeletal Muscle
 Muscle fiber contraction is “all or none”
 Within a skeletal muscle, not all fibers may be
stimulated during the same interval
 Different combinations of muscle fiber
contractions may give differing responses
 Graded responses—different degrees of
skeletal muscle shortening

93. Muscle Responses to Strong
Stimuli
 Muscle force depends upon the number of
fibers stimulated
 More fibers contracting results in greater
muscle tension
 Muscles can continue to contract unless they
run out of energy

94. Energy for Muscle Contraction
 Initially, muscles use stored ATP for energy
 ATP bonds are broken to release energy
 Only 4–6 seconds worth of ATP is stored by
muscles
 After this initial time, other pathways must be
utilized to produce ATP

95. Energy for Muscle Contraction
 Direct phosphorylation of ADP by creatine
phosphate (CP)
 Muscle cells store CP
 CP is a high-energy molecule
 After ATP is depleted, ADP is left
 CP transfers energy to ADP, to regenerate ATP
 CP supplies are exhausted in less than 15
seconds

96. Energy for Muscle Contraction
Figure 6.10a

97. Energy for Muscle Contraction
 Aerobic respiration
 Glucose is broken down to carbon dioxide and
water, releasing energy (ATP)
 This is a slower reaction that requires continuous
oxygen
 A series of metabolic pathways occur in the
mitochondria

98. Energy for Muscle Contraction
Figure 6.10b

101. Energy for Muscle Contraction
 Anaerobic glycolysis and lactic acid formation
 Reaction that breaks down glucose without
oxygen
 Glucose is broken down to pyruvic acid to
produce some ATP
 Pyruvic acid is converted to lactic acid
 This reaction is not as efficient, but is fast
 Huge amounts of glucose are needed
 Lactic acid produces muscle fatigue

102. Energy for Muscle Contraction
Figure 6.10c

103. Video Clip

104. Muscle Fatigue and Oxygen
Deficit
 When a muscle is fatigued, it is unable to
contract even with a stimulus
 Common cause for muscle fatigue is oxygen
debt
 Oxygen must be “repaid” to tissue to remove
oxygen deficit
 Oxygen is required to get rid of accumulated
lactic acid
 Increasing acidity (from lactic acid) and lack of
ATP causes the muscle to contract less

106. Types of Muscle Contractions
 Isotonic contractions
 Myofilaments are able to slide past each other
during contractions
 The muscle shortens and movement occurs
 Isometric contractions
 Tension in the muscles increases
 The muscle is unable to shorten or produce
movement

108. isometric contraction
The muscle contraction without appreciable shortening
or change in distance between its origin and insertion. This
contractions generate force without changing the length of the
muscle.
isotonic contraction
The muscle contraction without appreciable change in
the force of contraction; the distance between the origin and
insertion becomes lessened.
Isotonic contractions generate force by changing the length of
the muscle and can be concentric contractions or eccentric
contractions.

109. Effect of Exercise on Muscles
 Exercise increases muscle size, strength, and
endurance
 Aerobic (endurance) exercise (biking, jogging)
results in stronger, more flexible muscles with
greater resistance to fatigue
 Makes body metabolism more efficient
 Improves digestion, coordination
 Resistance (isometric) exercise (weight lifting)
increases muscle size and strength

110. Effect of Exercise on Muscles
Figure 6.11

112. DISEASES IN THE
MUSCLE

113. Muscular dystrophy is a group of
diseases that cause progressive
weakness and loss of muscle mass. In
muscular dystrophy, abnormal genes
(mutations) interfere with the
production of proteins needed to form
healthy muscle.
Muscular Dystrophy

116.  Muscular dystrophy is genetic. Symptoms may
start to develop as early as infancy or may not
present until later in adulthood. Duchenne
Muscular Dystrophy (DMD) is one of the
most common types of the disease. DMD
appears early in childhood and affects mostly
boys. There is no cure for muscular dystrophy. In
addition to exercise, physical therapy, and
respiratory care.

117. .
There are many different kinds of muscular
dystrophy. Symptoms of the most common
variety begin in childhood, primarily in boys.
Other types don't surface until adulthood.
Some people who have muscular dystrophy will
eventually lose the ability to walk. Some may
have trouble breathing or swallowing.
There is no cure for muscular dystrophy. But
medications and therapy can help manage
symptoms and slow the course of the disease.

118. Muscle Cramps
 Muscle cramps are sudden, involuntary
contractions or spasms in one or more of your
muscles. They often occur after exercise or at
night, lasting a few seconds to several minutes. It
is a very common muscle problem.
 Muscle cramps can be caused by nerves that
malfunction. Sometimes this malfunction is due to
a health problem, such as a spinal cord injury or a
pinched nerve in the neck or back.

119.  Straining or overusing a muscle
 Dehydration
 A lack of minerals in your diet or the depletion
of minerals in your body
 Not enough blood getting to your muscles
 Cramps can be very painful. Stretching or
gently massaging the muscle can relieve this
pain.

120. Myositis
 Myositis means inflammation of the muscles
that you use to move your body. An injury,
infection, orautoimmune disease can cause it.
Two specific kinds are polymyositis and
dermatomyositis. Polymyositis causes muscle
weakness, usually in the muscles

123.  Two specific kinds are polymyositis and
dermatomyositis. Polymyositis causes muscle
weakness, usually in the muscles closest to
the trunk of your body. Dermatomyositis
causes muscle weakness, plus a skin rash.

124. THANK YOU VERY
MUCH!!!
Other symptoms of myositis may include
Fatigue after walking or standing
Tripping or falling
Trouble swallowing or breathing
Doctors may use a physical exam, lab tests, imaging tests and a muscle biopsy to diagnose myositis. There is no cure for these diseases, but you can treat the
symptoms.