A&P 1 exam 3 (part 2)
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A&P 1 exam 3 (part 2)
anatomy physiology fall 2014 exam
Mechanism of Muscle Contraction Fall 2014
basic unit of contraction
what extends from z-line to z-line
involved in turning contraction on and off
what causes sarcomere to contract?
reaction of actin and myosin
repeated unit of thick and thin that gives you the striations
has actin and regulatory proteins
3 thin filaments?
shape of actin monomer?
yellow disk or circle where actin interacts with myosin
actin monomers patched together to form a string
use 2 of these strings to make thin filaments
with actin polymers, why is rotation important?
binding sites can face in all different directions
2 types of regulatory proteins?
sits on top of binding sites
found along tropomyosin and is a molecule that interacts with calcium ion
what happens if binding sites are blocked?
sarcomere cannot contract
2 shapes of troponin and tropomyosin?
either blocks or exposes binding sites
once binding sites are exposed what happens?
contraction is automatic
how to control contraction?
by controlling myosin access to binding sites
parts of myosin monomer?
stalk of myosin?
head of myosin monomer?
crossbridge of myosin monomer?
attachment of head to actin
high energy form?
cocked position of myosin
low energy form
rotator position of myosin
from high to end, myosin monomer: ___ rotates towards ___
heads face both directions
thick filaments grab thin on both sides and pull in
what happens during the resting state?
no myosin-actin building
tropomyosin blocking binding sites on actin
calcium is stored in sarcoplasmic recticulum
all myosin heads are in cocked position
initiation of contraction?
message relaying down?
during the resting state there is no?
stimulation is associated with?
during stimulation what happens?
neural action potential arrives at muscle fiber
during stimulation, the muscle fiber conducts
the action potential
during stimulation, the sarcoplasmic recticulum
releases calcium into the cell, then the calcium binds to tropomin
when exposing binding states you?
what happens when binding sites are exposed?
binding of calcium to troponin
binding of calcium to troponin cause a conformational change in troponin
____ rotates, thereby exposing myosin binding sites on action
myosin in its low energy state creates?
myosin in its high energy state is ?
once binding sites on action are exposed, myosin heads automatically bind to actin
letting go of actin and picking up ATP
release 1 phosphate, then back with ADP and actin
recock myosin head
the myosin head is recocked when
it lets go of actin and picks up ATP
only way to stop contraction?
block binding sites
uses active transport to pump calcium back in