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Final Exam - Graded Muscle Responses
N/A
51
Anatomy
Undergraduate 3
12/10/2012

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Term
What are graded responses?
Definition
Variations in the degree of muscle contraction and are required for proper control of skeletal muscle movement.
Term
How are responses graded?
Definition
Changing the frequency of stimulus and changing the strength of stimulus.
Term
A single stimulus results in a ______ contractile response.
Definition
Single - muscle twitch.
Term
What is wave summation?
Definition
Frequenly delivered stimuli increases the contractile force. The muscle does not completely relax.
Term
What is the threshold stimulus?
Definition
The stimulus strength at which the first observable muscle contraction occurs.
Term
What happens when stimulus strength is beyond threshold?
Definition
Muscle contracts more vigorously as stimulus strength is increased.
Term
What is the force of contraction controlled by?
Definition
Multiple motor unit summation.
Term
What is this called?
Definition
Recruitment.
Term
What is incomplete tetanus?
Definition
More rapidly delivered stimuli.
Term
What is complete tetanus?
Definition
If stimuli are given quickly enough.
Term
What is another word for treppe?
Definition
The staircase effect.
Term
What is the staircase effect?
Definition
Increased contraction in response to multiple stimuli of the same strength.
Term
Why do contractions increase?
Definition
1.)Availability of Ca2+ increases
2.)More efficent because heat is increased as muscles contract
Term
What is muscle tone?
Definition
The constant, slightly contracted state of all muscles, which does not produce active movements.
Term
What are its benefits?
Definition
Keeps muscles firm, healthy, and ready to respond.
Term
How do Spinal Reflexes account for muscle tone?
Definition
They activate one motor unit then another, and responds to activation of stretch receptors in muscles and tendons.
Term
What are isotonic contractions?
Definition
The muscle changes in length (decreases the angle of joint) and moves the load.
Term
What are the two types of isotonic contraction?
Definition
1.)Concentric - muscle shortens and does work.
2.)Eccentric - muscle contracts as it lengthens.
Term
What are isometric contractions?
Definition
Tension increases to the muscle's capacity, but the muscle does not change length.
Term
When does isometric contractions occur?
Definition
If the load is greater than the tension the muscle is able to develop.
Term
What is the only source used directly for contractile activity?
Definition
ATP
Term
How are ATP molecules regenerated?
Definition
The interaction of ADP with creatine phosphate.
Term
What is anaerobic glycolysis?
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.
Term
What happens after pyruvic acid -> lactic?
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.
Term
What is muscle fatigue?
Definition
The muscle is in a state of physiological inability to contract.
Term
When does it occur?
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
Term
What is oxygen debt?
Definition
the extra amount of 02 needed for restorative processes.
Term
How can a muscle return back to resting state?
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.
Term
What is the force of contraction affected by?
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.
Term
How is the speed of contraction determined?
Definition
The speed in which ATPases split ATP.
Term
What pathways do oxidative fibers use?
Definition
Aerobic pathways
Term
What pathways do glycolytic fibers use?
Definition
Use anaerobic glycolysis.
Term
What are the three catergories of oxidative and glycolytic fibers?
Definition
Slow oxidative, fast oxidative, fast glycolytic.
Term
What are slow oxidative fibers?
Definition
contract slowly, have slow acting myosin ATPases, and are fatigue restistant.
Term
what are fast oxidative fibers?
Definition
contract quickly, have fast myosin ATPases and have moderate resistance to fatigue.
Term
What are fast glycolytic fibers?
Definition
contract quickly, have fast myosin ATPases, are easily fatigued.
Term
What is smooth muscle composed of?
Definition
Spindle shaped fibers with a diameter of 2-10 mm and hudreds of cm in length.
Term
Does smooth muscle have connective tissue sheaths?
Definition
NO. Fine epimysium.
Term
How is smooth muscle organized?
Definition
Two layers. Longitudinal and circular.
Term
Where is smooth muscle found?
Definition
Hollow organs except the heart.
Term
What is peristalsis?
Definition
Alternating contractions and relaxations of smooth muscles that mix and squeeze substances through the lumen of hollow organs.
Term
How do longitudinal layers move?
Definition
The organ dilates and contracts.
Term
How do circular layers move?
Definition
The organ elongates.
Term
Does smooth muscle has neuromuscular junctions?
Definition
No. Varicosities - bulging swellings of nerves.
Term
What are synaptic clefts in smooth muscle called?
Definition
Diffuse junctions.
Term
Does the sarcoplasmic reticulum create striations in smooth muscle?
Definition
No. Is less developed.
Term
Are there t tubules in smooth muscle?
Definition
No.
Term
What are caveoli?
Definition
Pouch-like infoldings in the plasma membranes.
Term
Where is Ca2+ sequestered in smooth muscle?
Definition
The extracellular space near the caveoli.
Term
Are there thin and thick filaments in smooth muscle?
Definition
Yes.
Term
How does smooth muscle move?
Definition
Slow, synchronized contractions. In unison.
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