Term
What are graded responses? |
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Definition
Variations in the degree of muscle contraction and are required for proper control of skeletal muscle movement. |
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Term
How are responses graded? |
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Definition
Changing the frequency of stimulus and changing the strength of stimulus. |
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Term
A single stimulus results in a ______ contractile response. |
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Definition
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Term
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Definition
Frequenly delivered stimuli increases the contractile force. The muscle does not completely relax. |
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Term
What is the threshold stimulus? |
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Definition
The stimulus strength at which the first observable muscle contraction occurs. |
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Term
What happens when stimulus strength is beyond threshold? |
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Definition
Muscle contracts more vigorously as stimulus strength is increased. |
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Term
What is the force of contraction controlled by? |
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Definition
Multiple motor unit summation. |
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Term
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Definition
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Term
What is incomplete tetanus? |
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Definition
More rapidly delivered stimuli. |
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Term
What is complete tetanus? |
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Definition
If stimuli are given quickly enough. |
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Term
What is another word for treppe? |
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Definition
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Term
What is the staircase effect? |
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Definition
Increased contraction in response to multiple stimuli of the same strength. |
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Term
Why do contractions increase? |
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Definition
1.)Availability of Ca2+ increases 2.)More efficent because heat is increased as muscles contract |
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Term
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Definition
The constant, slightly contracted state of all muscles, which does not produce active movements. |
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Term
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Definition
Keeps muscles firm, healthy, and ready to respond. |
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Term
How do Spinal Reflexes account for muscle tone? |
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Definition
They activate one motor unit then another, and responds to activation of stretch receptors in muscles and tendons. |
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Term
What are isotonic contractions? |
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Definition
The muscle changes in length (decreases the angle of joint) and moves the load. |
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Term
What are the two types of isotonic contraction? |
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Definition
1.)Concentric - muscle shortens and does work. 2.)Eccentric - muscle contracts as it lengthens. |
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Term
What are isometric contractions? |
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Definition
Tension increases to the muscle's capacity, but the muscle does not change length. |
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Term
When does isometric contractions occur? |
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Definition
If the load is greater than the tension the muscle is able to develop. |
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Term
What is the only source used directly for contractile activity? |
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Definition
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Term
How are ATP molecules regenerated? |
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Definition
The interaction of ADP with creatine phosphate. |
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Term
What is anaerobic glycolysis? |
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Definition
When muscle activity reaches 70% of max: bulging muscles compress blood vessels, oxygen delivery is impaired, and Pyruvic acid is converted into lactic acid. |
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Term
What happens after pyruvic acid -> lactic? |
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Definition
The lactic acid diffuses into the bloodstream, is picked up by liver, kidneys and heart, and then is converted back into pyruvic acid by the liver. |
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Term
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Definition
The muscle is in a state of physiological inability to contract. |
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Term
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Definition
1.)ATP production cannot keep up with use. 2.)Deficit of ATP cuases contractures 3.)Lactic acid accumulates in muscle 4.)Ionic imbalance is present |
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Term
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Definition
the extra amount of 02 needed for restorative processes. |
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Term
How can a muscle return back to resting state? |
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Definition
1.)Oxygen reserves must be replenished 2.)Lactic acid -> pyruvic acid 3.)Glycogen stores must be replaced 4.)ATP and CP reserves must be resynthesized. |
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Term
What is the force of contraction affected by? |
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Definition
The number of muscle fibers contracting - more motor fibers = stronger, size of muscle - bulkier = greater strength, degree of stretch - muscles contract strongest when muscle fibers are 80-120% of their normal resting length. |
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Term
How is the speed of contraction determined? |
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Definition
The speed in which ATPases split ATP. |
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Term
What pathways do oxidative fibers use? |
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Definition
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Term
What pathways do glycolytic fibers use? |
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Definition
Use anaerobic glycolysis. |
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Term
What are the three catergories of oxidative and glycolytic fibers? |
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Definition
Slow oxidative, fast oxidative, fast glycolytic. |
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Term
What are slow oxidative fibers? |
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Definition
contract slowly, have slow acting myosin ATPases, and are fatigue restistant. |
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Term
what are fast oxidative fibers? |
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Definition
contract quickly, have fast myosin ATPases and have moderate resistance to fatigue. |
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Term
What are fast glycolytic fibers? |
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Definition
contract quickly, have fast myosin ATPases, are easily fatigued. |
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Term
What is smooth muscle composed of? |
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Definition
Spindle shaped fibers with a diameter of 2-10 mm and hudreds of cm in length. |
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Term
Does smooth muscle have connective tissue sheaths? |
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Definition
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Term
How is smooth muscle organized? |
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Definition
Two layers. Longitudinal and circular. |
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Term
Where is smooth muscle found? |
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Definition
Hollow organs except the heart. |
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Term
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Definition
Alternating contractions and relaxations of smooth muscles that mix and squeeze substances through the lumen of hollow organs. |
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Term
How do longitudinal layers move? |
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Definition
The organ dilates and contracts. |
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Term
How do circular layers move? |
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Definition
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Term
Does smooth muscle has neuromuscular junctions? |
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Definition
No. Varicosities - bulging swellings of nerves. |
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Term
What are synaptic clefts in smooth muscle called? |
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Definition
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Term
Does the sarcoplasmic reticulum create striations in smooth muscle? |
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Definition
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Term
Are there t tubules in smooth muscle? |
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Definition
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Term
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Definition
Pouch-like infoldings in the plasma membranes. |
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Term
Where is Ca2+ sequestered in smooth muscle? |
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Definition
The extracellular space near the caveoli. |
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Term
Are there thin and thick filaments in smooth muscle? |
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Definition
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Term
How does smooth muscle move? |
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Definition
Slow, synchronized contractions. In unison. |
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