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ATPenergy 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:
 Lack of oxygen
 Produces 2 ATP & lactic acid
1 glucose = 2 ATP
Occurs in cytoplasm
Fast process
Inefficient ATP production
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 Areobic
 Oxygen present
 Produces CO
2
ATP and H
2
O & 36
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

 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

 After a person dies ATP is not available, the cross bridges that are formed are not released, causing the muscle to become rigid.

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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”
3 phases to muscle twitch
1. Lag Phase
2. Contraction Phase
3. Relaxation Phase

 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

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 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

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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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