muscles and movement part 4 Flashcards
what are the three components of troponin
TnI- inhibitory
TnC- Ca bound
TnT- tropomyosin bound
what happens to the muscle in low/high calcium?
low calcium- troponin blocks binding sites and myosin cannot move or contract
high calcium- calcium binds to troponin moving it out of the way and myosin is able to sliding and contract
what are the differences between skeletal and cardiac muscle (EC coupling)
initial cause of depolarization
time of action potential
action potential propagation through sarcolemma
Ca storage being released
what are the two initial causes of depolarization
myogenic - beginning in the muscle - spontaneous - pacemaker cells neurogenic - beginning in the nerve - ACh activates receptors
what is tetanus?
when multiple muscle twitches occur close together and the muscle contraction is fused as 1
Transverse tubules (T-tubules)
invaginations of sarcolemma
enhance penetration of action potential into myocyte
more developed in larger faster twitching muscles
less developed in cardiac muscle
Sarcoplasmic reticulum
stores Ca bound to protein calsequestrin
terminal cisternae increases storage (less developed in cardiac muscle)
skeletal muscle EC coupling
depolarization induced Ca release
physical interaction between L-type Ca channel and Ryanodine receptor
cardiac EC coupling
Ca induced Ca release
Ca flux through L type Ca2 channel activates rynaodine receptor
DHPR receptor
dihydropyridine
L typed voltage gated Ca2 channel in cell membrane
RyR receptor
Ryanodine receptor
Ca2 channel in SR membrane
How is Ca regulated?
channels elevate cytosolic Ca
transporters remove Ca from the cytoplasm
Ca transporters in the cell membrane
Ca/ATP ase
Na/Ca exchanger
Ca transporters in SR membrane
Ca ATPase (SERCA)
what are the steps in relaxation?
repolarization of sarcolemma removing Ca from cytoplasm Ca dissociates from troponin tropomyosin blocks myosin binding sites myosin can not bind to actin
