locomotor system Flashcards
what activates voltage gated sodium channels
when the threshold is reached
what causes action potential
rapid activation and fluxes of ion currents
what causes depolarisation
upstroke of action potential
which ion triggers the contraction of myofilaments
calcium
what introduces calcium into the sarcoplasmic reticulum
sarcoplasmic reticululm calcium ATPase (SERCA)
what removes calcium from the cell
plasma membrane sodium calcium exchanger and the calcium ATPase
what binds to troponin C
cytoplasmic calcium ions
when is an action potential generated
if the depolarising ion, sodium, current of the plasma membrane is large enough
what does the action potential activate
voltage regulated l type calcium channel
describe contraction in smooth muscle
both voltage and receptor mediated influx of calcium may induce contraction
- calcium binds to calmoduin, and this activates myosin light chain kinase that phosphorylates myosin which leads to myosin binding to actin with subsequent induction of the power stroke
what is the difference between the contraction mechanisms of smooth and skeletal muscle
smooth - myosin light chain kinase
skeletal - troponin/tropomyosin complex
what removes calcium from the cell to stimulate relaxation
SERCA
NCX
PMCA
what is the resting membrane potential
-90mV
location of action potential generation in the heart
sino atrial node propagation
location of action potential generation in the voluntary skeletal muscle
motor unit, acetylcholine