# Review + Muscle Fatigue + Respiration Questions -> Answer to prep for introduction for the lab

1. What are motor units? Why do only recruit some motor units instead of using all our muscle fibers?
	* A motor unit is a group of muscle fibers that are attached to a neuron.
	* this allows for cycling of motor fibers so that they do not get worn out as much
2. What is the difference between aerobic and anaerobic respiration? (both inputs and outputs)
	* both : have glucose
	* aerobic : has air for input; makes a ton of atp
	* anerobic : does not have air for input; has atp and lactic acid
3. Describe the lactic acid cycle and the cori cycle. Why do we have/need each of these?
	* the cori cycle is the same as the lactic acid cycle. The process takes lactate and converts it back into glucose but uses a bunch of atp in the liver in order to make a little atp in the muscle. The two work together because they have similar inputs oand outputs that work in a loop
4. Describe muscle fatigue, why it occurs, and what happens to humans when fatigued.
	* muslce fatigue is the process in which a muscle is no longer able to fullfull its duties and then stops preforming said action. In humans this often is due to a lack of oxygen which will prevent the muscle from preforming cellular respiration
5. Compare and contrast type I, type IIa, and type IIx muscle fibers.

|                      | type I | type IIa | type IIx |
|--------------------- | ------ | -------- | -------- |
| structural metabolic | small muscle diameter. lots of oxygen. | largest diameter, highly valscular + high density of mitochondirea -> aerobic | intermediate diameter,l white/paleish pink, little valcularity, almost no aerobic respiration |
| metabolic            | longer to ccontract, myoglobin (oxygen) | glycolysis cast contraction -> moderate fatigue resistance | castest contractility, uses atp very quickly, fast but super low fatigue resistance |
| function             | low power (first to be used) posture etc | moderate power 2nd used, walking/sprinting (longer distances) | 3rd used, highest power strong but short fatigue resistace

6. Describe the effect of different types of exercies on muscle tone and function
	* as an exercise increases in utilization the types of muscles that are recuited for that activity will further develop because they are more needed