Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
PHYSIOLOGY QUIZ 6
| Question | Answer |
|---|---|
| recruitment | The process of progressive activation of motor units |
| When does muscle contraction stop? | When the nerve impulse to the muscle stops. |
| Arrange the events before and after Ca2+ release in muscle contraction, in the order that they occur. | depolarization of motor endplate wave depolarization flows across the sarcolemma wave of depolarization flows down the t-tubules Ca2+ released from SR Ca2+ binds to troponin and causes a shift in tryptomyosin |
| Frequency | refers to the number of action potentials delivered to a muscle within a set period of time. |
| How does an increase in recruitment and frequency affect the strength of muscle contraction? | As more motor units are recruited, the muscle contraction grows progressively stronger. |
| motor unit | a single motor neuron and all the muscle fibers that it innervates. |
| twitch | Skeletal muscle is similar to nerve tissue in that the fiber responds to a stimulus in an all-or-none fashion |
| Length-tension relationship of skeletal muscle | Describes the amount of tension that is produced by a muscle as a feature of it's length. When tested under isometric conditions, the maximal force produced or measured will be different as the muscle lengthens or shortens. |
| Summation | It occurs when stimuli are delivered rapidly enough so that the muscle fiber does not relax completely between stimuli. |
| Tetanus | a state of sustained maximal muscle contraction. |
| Incomplete tetanus | occurs if stimulation frequency is high, but at a rate that still allows partial relaxation of muscle between twitches. |
| What is a consequence of a single stimulus to a nerve supplying a skeletal muscle fiber? | It results in a single twitch. |
| What occurs when a single stimulus in a motor nerve arrives at a skeletal muscle fiber? | It causes the release of acetylcholine from the motor end plate. |
| Under conditions where skeletal muscle length is held constant, which statement is true? | It is said to be under isometric conditions. |
| If a skeletal muscle is stretched over 100% of its resting length, the total force of contraction at first decreases and then increases. What causes this increase in total force when the muscle is stretched beyond its resting length? | Increased passive force generated by the stretched elastic elements. |
| As stimulus strength is increased, the force of a twitch response increases. What does this represent? | Increased recruitment |
| How many action potentials are triggered in any individual muscle fiber by the electric pulse in the submaximal range or maximal range? | This is what we refer to as the threshold stimulus. Only one action potential happens and you have to activate a decent number of motor units to deliver recordable muscle tension. |
| Why did muscle twitch force increase as you increased the voltage of stimulus between threshold and maximal stimulus? | number of motor units recruited increased |
| Explain why is the threshold stimulus so much higher when you stimulate the muscle directly? | The threshold is higher when you stimulate the muscle directly because it has to penetrate the connective tissue of the muscle body. It is lower when you stimulate the nerve directly because it directly innervates each motor unit. |
| 1. When muscle is simply stretched there was in increase in passive muscle force. How do you explain this phenomenon? How is it different from active muscle tension or twitch force? | The exact length of the stretch that resulted in the highest contraction force will depend. a moderate stretch will result in the largest contraction force. At the highest stretch levels, the actin and myosin filaments overlap to little, contractile force |
Created by:
danielnichols