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slow twitch neuron vs fast twitch
- SLOW neuron: Low amplitude, and Low FREQuency
- smaller Schwan cells so there are more Action potentials within the sme space of an axon vs FAST
- FAST neuron: HIGH amplitude and High frequency
- Have BIGGER APs (cover more distance due to the LARGER Schwann cells on axon), so have to jump between them
Slow twitch action potential difference btw Fast twitch
Slow twitch are easier to activate: generating APs at a slower rate and slower max freq vs Fast twitch (MORE MYELINATED)
Ca role in muscle contraction
- Released from sarcoplasmic reticulum in order to INITIATE events of contraction
- 4 Ca binds to TROPONIN C to Change the CHARGE distribution: causes tropomyosin to move, EXPOSING MYOSIN binding site on the actin
To get a muscle to RELAX, what do you need to do to Ca?
- Take it away from the site of actin
- To contract the muscle, Ca needs to be FLOODED BACK IN
Myosin and actin binding
- Myosin ATP hydrolysis: causes conformational change allowing it to bind to ACTIN (needs to have tropomyosin removed by Ca and troponin C)
- Phosphate release from Myosin: cross-bridge formation occurs, and the myosin can use FORCE to PULL on the actin
- ADP released: once the myosin has fully rotated the ADP can be released
- ATP binding: as long as there is ATP available, ATP can bind and start the contraction cycle
Speed of contraction dictated by?
Myosin ATP-ase: there are 2, one makes ADP fall off myosin head faster than the other
Mitochondria difference in slow vs fast
HIGHER amt of mitochondria in SLOW muscles: higher capacity to make ATP via oxidative mechs.
Toxic end products
- 1. Heat: Enzyme reactions speed up, resulting in heat
- Dehydration causes more heat b/c there is DECREASED amt of heat transferred to H2O and away from the cell, therefore the cell heat incrases!
- Too much heat causes DECREASE in ability to create Action potentials, therefore cannot breath b/c cannot have APs in diaphragm
- 2. Radical production: Leakiness due to heat results in efficiency of ATP synthesis to DECREASE
- Radicals will attack UNSATurated fatty acids in phospho-lipid membranes