Download Skeletal Muscle Anatomy

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ATP-energy source for
muscle contraction and
relaxation
ATP is provided from
cellular
respiration (mitochondria)
The energy released from
ATP breaks down to ADP
Much of the energy forms
heat, which keeps our
bodies warm
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Anareobic:
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Areobic
 Lack of oxygen
 Oxygen present
 Produces 2 ATP & lactic acid
 Produces CO2 and H2O & 36
1 glucose = 2 ATP
Occurs in cytoplasm
Fast process
Inefficient ATP production
ATP
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1 glucose=36 ATP
Occurs in mitochondria
Slow process
Efficient ATP production
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Very important during times of limited oxygen availability
Only occur for a short period of time (2-3 minutes)
Some lactic acid can diffuse out of the cell; the rest can cause
short-term (a day or two) muscle pain
Anaerobic respiration is limited by depletion of glucose and
buildup of lactic acid
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During resting activities & long term exercise (long distance
running) fatty acids are used primarily for ATP production
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Creatine phosphate-high energy
which increases regeneration of
ATP
Stores energy that can be used
rapidly to maintain adequate
amounts of ATP
During inactivity: excess ATP is
synthesized into creatine
phosphate
During activity: reserves of ATP are
used first, then energy stored in
creatine phosphate is accessed to
produce ATP for muscle
contraction
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After a person dies ATP is not available, the cross bridges
that are formed are not released, causing the muscle to
become rigid.
Muscle Twitch = Contraction of entire muscle in response to
a stimulus
 Threshold = The minimal strength required to cause a
contraction
 All-or-none response = Muscle fiber contract maximally or
not at all. “Charlie Horse”
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3 phases to muscle twitch
1. Lag Phase
2. Contraction Phase
3. Relaxation Phase
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Tetanus: When muscles remain contracted without relaxing
 Tetanus is infection of the nervous system with the
potentially deadly bacteria Clostridium tetani
 Excess build up and release of Calcium
Muscle Fatigue: Results when ATP is used faster than can be
produced and lactic acid builds up faster than can be
removed. Muscle loses ability to contract and relax after
prolonged exercise or strain
 Muscle Cramp: a sustained involuntary contraction
 Oxygen Debt: oxygen is used to create ATP, during exercise
you may not have enough oxygen --> this causes Lactic
Acid to accumulate in the muscles
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Results when ATP is used faster than can be
produced and lactic acid builds up faster than
can be removed
 ATP levels can fall too low for muscle cells to
produce the maximum force of contraction
 During extreme fatigue muscles may not be able
to contract or relax; Physiological Contracture
 Most common type of fatigue is psychological;
perception of central nervous system
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After intense exercise
respiration rates & volume
remain elevated
Pays back oxygen debt
that occurred during
activity
 Converts lactic acid to
glucose
 Replenish depleted ATP
and creatine phosphate
stores
 Replenish oxygen stores in
lungs, blood and muscles
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Magnitude of oxygen debt
depends on the intensity &
length of time of exercise
and the physical condition
of the person
Exercise and training
improves the ability to
carry out both aerobic and
anaerobic respiration
Muscle Tone: Constant tension produced by muscles of the
body over long periods of time.
 Slow Fibers: Contract slowly and resistant to fatigue. Type I
myosin “Dark Meat”
 Fast Fibers: Contract quickly and fatigue quickly. Type IIa or
IIb myosin “White Meat”
 Muscle Memory: Muscle learn and remember contractions
and actions “shooting a basketball”
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Two points of attachment of each muscle are its origin and
insertion
 Origin = the immovable end of the muscle
 Insertion = the movable end of the muscle
 when a muscle contracts the insertion is moved toward the
origin
 Muscle are attached to bone with tendons
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Agonist = muscles working together to cause movement
 Example: Biceps brachii
Antagonist = muscles working in opposition to another
muscle
 Example: Triceps brachii
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Isometric
Isotonic
Concentric
Eccentric
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Front
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Back
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Side