Cell phys by Karius Flashcards
(23 cards)
2 major things used by cell to create ionic equilibrium
membrane selectively permeable
action of Na/K ATPase (creates conc. gradient, makes cell more -)
Na+/K+ ATPase pump
pumps 3 Na+ out
brings 2 K+ in
all ions we are concerned with haver higher conc. OUTside cell except
K+
the motor unit
alpha motorneuron and all the muscle it innervates
Ca++ sequestered in SR due to aciton of
Ca++ - Mg++ ATPase (pumps Ca++ into SR)
calsequestrin (protein that binds calcium within the SR) helps force the calcium to stay in place
located on t-tubule and undergoes conformational change in response to AP
DHP receptor
ryanodine receptor is
LIGAND gated
required for the myosin-actin interaciton to be broken
ATP
immediate source for ATP in muscle contraction
phosphorylcreatine
in isometric contraction
SAME LENGTH
cross-bridge cycling changes tension but not length
isotonic contraciton
SAME TENSION
muscle changes length rather than developing tension
even if trying to lift something tooheavy for us to lit, have some shortening that occurs due to?
series elastic component
includes - tendons, membranes surrounding the muscle, sarcomere that are not contracting
maximal tension is developed at sarcomere lengths of ?? why?
2-2.2 microns [ Lo, the resting length of the muscle]
- above it acitn and myosin unable to interact
- at sarcomere lengths less than 2.0 microns, actin filaments begin to overlap, preventing normal interaction
as muscles get shorter, tenson..
decreases for same reasons as in sarcomere
as muscles get longer, > L0
total tension generated by whole muscle starts to fall off, but then INCREASES (different from sarcomere)
- active tension falls off, eventually to 0
- passive tension created by stretching fibers now dominates
preload and postload
preload - if the muscle “feels” the load before contraction
afterload - if it “feels” it after contraction begins
if the resting muscle IS stretched by the load, it is a
PRELOAD
if resting muscle IS NOT stretched by the load, it is an
AFTERLOAD
when pushing against a wall, contraction is first.. then..
first isotonic (get some change in length as series elastic elements stretched) then isometric (can't move wall so no change in length but generating force so tension changing)
malignant hyperthermia DM
anesthetic agent activates Ca++ channel on SR (the ryanodine receptor) and allows calcium to leave the SR
muscle contraction occurs
- bypassing NS so no protective reflexes will cause relaxation (they work through motor neurons)
everything wrong with Sandy R.
hyperkalemic periodic paralysis
inactivaiton gate protein on Na+ channels in skeletal muscle only doesn’t work properly especially when K+ levels high - after bananas or exercising or when tissue cools)
paralysis in hyperkalemic periodic paralysis is because of
voltage-inactivation aka depolarization block
channels don’t “reset” because constant depolarization
JohnnY R with his muscle twitches but no weakness/ paralysis had
myotonia congenita
Cl- channel mutated
should be open at rest allowing for 80% of ion flow but mutated stays CLOSED at rest; no negative ion entering, cell, cause depolarization
or maybe allowing + ions ot enter;
either case muscle cell depolarizing spontaneously
