Term
| a muscle twitch is the response of a muscle to a single, brief ___ ___. |
|
Definition
|
|
Term
| 3 phases of a muscle twitch are: |
|
Definition
- latent period- first few milliseconds after stimulation when excitation contraction coupling is taking place
- contraction period- cross bridges actively form and muscle shortens
- period of relaxation- calcium is reabsorbed into SR and muscle tension goes to 0 |
|
|
Term
| for the extraocular eye muscle the time from stimulation to peak contraction is ___ msec. for the gastrocnemius it is __ msec. And for the soleus it is __ mssec. |
|
Definition
- 8 msec
- 40 msec
- 90 msec |
|
|
Term
|
Definition
- variations in degree of muscle contraction
- required for proper control of skeletal movement |
|
|
Term
| muscle responses are graded by: |
|
Definition
Changing the frequency of stimulation
Changing the strength of the stimulus |
|
|
Term
| a single stimulus results in a single contractile response called a ___ |
|
Definition
|
|
Term
| frequently delivered stimuli without complete relaxation b/w results in : |
|
Definition
| wave summation- increased contractile force |
|
|
Term
| more rapidlly delivered stimuli result in ___ ___. If stimuli are given quick enough you can get ___. |
|
Definition
- incomplete tetanus
- complete tetanus |
|
|
Term
|
Definition
increased contraction in response to multiple stimuli of same strength
- contraction increases b/c more calcium is available in the sarcoplasm
- muscle enzyme systems become more efficient b/c increased heat as muscle contracts
see slide 79 and 80 skeletal muscle lecture and know picture |
|
|
Term
| the force exerted by a contracting muscle on an object is referred to as: |
|
Definition
|
|
Term
| ___ occurs when the tension generated by cross bridging exceeds the forces opposing this. |
|
Definition
|
|
Term
|
Definition
- force you can measure in a relaxed muscle
- due to amount of stretch in muscle |
|
|
Term
|
Definition
| - relaxed msucles are almost always slightly contracted due to spinal reflexes activating motor units |
|
|
Term
|
Definition
| - weight or reciprocal force exerted by an object on a muscle |
|
|
Term
|
Definition
| load on muscle in relaxed state prior to stimulation |
|
|
Term
| the greater the preload, the greater the ___ ___, and the greater the ___ ___. |
|
Definition
- preload stretch
- passive tension |
|
|
Term
|
Definition
| load the muscle is trying to move or work against during stimulation |
|
|
Term
| if a muscle has a preload, then the afterload the muscle must generate upon stimulation = |
|
Definition
| afterload= preload tension+ additional tension of the weight |
|
|
Term
| look at slide 83 on skeletal muscle lecture for preload and afterload diagram |
|
Definition
|
|
Term
| With an isotonic contraction, the ___ stays constant but the muscle may __ or ___ during the contraction. this is common where? |
|
Definition
- tension
- shorten
- lengthen
- finger and hand movements |
|
|
Term
| concentric isotonic contraction: |
|
Definition
- the tension stays constant
- the muscle shortens and does work |
|
|
Term
| eccentric isotonic contractions: |
|
Definition
- the tension is constant
- the muscle contracts as it lengthens
- example= lowering weight during curls, putting down book, walking down hill, skiing |
|
|
Term
| with eccentric contraction you get delayed soreness and then ____. |
|
Definition
|
|
Term
|
Definition
| - tension increases to muscle capacity but the muscle does not shorten or lengthen |
|
|
Term
| isometric contraction occurs if the ___ is greater than the ___ the muscle is able to develop. |
|
Definition
|
|
Term
| no work is done with isometric contraction. these contractions are used to ___ and __ force. give example: |
|
Definition
- generate
- maintain
- postural muscles maintain a constant tension without changing length |
|
|
Term
|
Definition
- a mixture b/w iosmetric and isotonic
- first have an isometric contraction until enough force is generated, then you have an isotonic contraction where muscle is shortening at a constant force |
|
|
