Term
| What 2 things constitute a motor unit? |
|
Definition
|
|
Term
| Describe the differences in motor units between extrinsic eye movement and limb movement |
|
Definition
Eye movement - High neuron/fiber ratio, leads to specialization for small, fine movements
Limbs - Lower neuron/fiber ratio, but many more muscle fibers then the eye. Specialization is for generation of significant force. |
|
|
Term
| How many neurons activate a muscle fiber? How many muscle fibers are activated by a neuron? |
|
Definition
Each muscle fiber is activated by ONE neuron
Each neuron, however, can activate numerous muscle fibers |
|
|
Term
| What two measurements characterize an individual twitch reaction? |
|
Definition
1. Twitch amplitude
2. Time-to-peak |
|
|
Term
| What two measurements characterize tetanic contractions |
|
Definition
1. Amplitude
2. Fatigability |
|
|
Term
|
Definition
| The lowest current injection that will generate an action potential |
|
|
Term
| What is afterhyperpolarization? How does it relate to potential firing frequency? |
|
Definition
1. Polarization below resting potential after an action potential is generated
2. Shorter afterhyperpolarization times are fibers that can fire at higher frequencies |
|
|
Term
| What is the relationship between rheobase current, excitability, and firing frequency? |
|
Definition
Lower rheobase --> more excitible --> lower firing frequency
larger rheobase --> less excitable --> higher firing frequency |
|
|
Term
| Describe the relationship between twitch contraction summation and unit force output |
|
Definition
| As individual twitch contractions begin to summate, you enter a linear region in the firing frequency vs. unit force plot, so the summation of signals leads to a fairly linear region of unit force increase |
|
|
Term
| Describe the 2 different types of muscle fibers in terms of appearance and energy source |
|
Definition
Type 1 - Red, oxidative, high mitochondria and use ATP for energy source, slow twitch fibers
Type 2B - white, glycolytic, non oxidative metabolism, use glycogen as an energy source, fast twitch fibers |
|
|
