A brief change in muscle cell voltage from negative to positive to negative. (normal is negative)
True or False: Muscle cell action potetial, travels along the suface of muscle cells very quickly, probably more thea 100 m/sec or about the speed of and Indy reacecar.
True.
Remember that skeletal and __________ muscle have a series of _________ _________ (T tubules) that help the action potential penetrate deep into the muscle ________.
cardiac, trasnvers tubules, fiber
From Action ptential to Calcium release
Muscle cell action potenial travels along muscle surface
Penetrates into the interior of the muscle cell at transvers tubules
Remember T tubules arein a triad with two sacs of sarcoplaspic reticulum
Sarcoplasmic reticulum releases calcium into the cytoplasm of the muscle cell
From Calcium Release to contraciton
Calcium released from SR them binds to troponin; this moves tropomyosin aside and exposes binding sites for myosin on the actin filament
True or False : The calcium released from the sarcoplasmic reticulum interacts with a special protien, found only in muscle cells
True.
When calcium binds to the protein called troponin...
...it changes shape, and pushes another specialized protien called tropomyosin
Tropomyosin
"moving muscle protein"
normally covers a myosin binding site ont e actin molecule
keeps myosin (which wants to bind actin) from being able to reach its binding site on actin.
When _________ is present, and troponin shoves topomyosin and topomyosin moves away from the _______ ______, myosin can grab _______.
calcium, binding site, actin
True or false : Stereograms don't work when projected on a screen.
true.see objective 14 p.446- 447
The cross-bridge cycle
6a. calcium binds to troponin; troponin choves tropomyosin; tropomyosin moves, exposing the myosin binding site on actin.
6b. Myosin brings a piggy backed molecule of ATP which is split to form ADP and the loose phosphate is released as myosin binds actin
6c. Power stroke: the shape of myosin changes; the head region flexes and moves the actin filament a tiny amount. this releases ADP and opens a site for ATP to bind again
6d. ATP binds, myosin release the actin filament, and the cycle can begin agian.
Rigor mortis
A dead person uses up their ATPin a matterof minutes ore hours depending on the temperature, and muscles are "locked" in position
Later, again cepending on temperature , cirobes break down muscle tissue to the point where muscle becomes loose again.
What happens if ATP is absent from the cross-bridge cycle?
Myosin remains permanently bound to actin, muscles cannot move
-miuscle stuck between step 5 and 1
Rigor motis results
Eventually , ensymes and microbes destroy muscle structure and corps becomes "loose" again.
Three terms used to describe muscle anatomy.
origin
insertion
action
Origin
the place where a muscle "begins," where it attaches to a relatively immoveable point
.-usually, this is proximal
Insertion
the place where a muscle "ends," where it attaches to a moveable part.
-usually, this is distal
Action
what the muscle does when it contracts.
Names of muscle function
prime mover (agonist)
antagonist
synergistfixator
Prime Mover (Agonist):
muscle that does most of the work in the action being discussed.
Antagonist:
oppose action of agonist
Synergist:
aid agonist in creating movement.
Fixator:
stabalizes the muscle origin.
Example: fixators in the shoulder girdle help to stop rotation of the shoulder joint during the motions of the triceps and biceps.
