Flashcards in Chapter 11: Muscular System Deck (123)
What separates the Schwann cells & the entire muscle cell from surrounding tissue?
What does the basal lamina contain?
acetylcholinesterase (AChE) to break down ACh after contraction causing relaxation
What helps hold the synaptic knob in place?
Schwann cells & basal lamina
electrical potential; a dif in electrical charge from one point to another
What is the resting membrane potential?How is it maintained?
about -90mV; Na-K pumps
What is happening in an unstimulated resting cell? (3)
-more anions on the inside of the plasma membrane
-plasma membrane is polarized
-excess Na (ECF) and excess K (ICF)
What else is inside the ICF?
proteins, nucleic acids, and phosphates (all which cant penetrate the membrane)
What is happening in a stimulated muscle fiber?
-ion gates open in the plasma membrane
-Na moves inside (down concentration gradient)
-cations override negative charge of ICF (depolarization)
-Na gates close/ K open
What turns the membrane back into its negative state?
loss of positive K ions (repolarization)
quick up & down
polarized(resting)-> depolarization-> repolarization
what type of paralysis is tetanus?
spastic paralysis caused by C. tetani
state in which the muscles are limp & cannot contract
type of food poisoning caused by neuromuscular toxin secreted by C. botulinum (prevent contraction)
What does the RMP shift to when Na is moved into the cell?
-90mV to +75mV
length tension relationship
amount of tension generated by a muscle & the force of contraction depends on how stretched/contracted it was before stimulated
What does the optimum resting length produce?
greatest force when muscle contracts
monitored by the nervous system that adjusts the length of the resting muscle & maintains a state of partial contraction
What does overly contraction cause?
crick in your neck
What does overly stretched cause?
actin filament have no myosin heads to attach to
hardening of muscles & stiffening of body beginning 3 to 4 hours after death
muscle relaxation requires _____, which is no longer produced after death
chart of the timing & strength of a muscle contraction
_____, subthreshold electrical stimulus cause ___ contraction
min voltage necessary to generate an action potential in the muscle fiber & produce contraction
quick cycle of contraction when stimulus is at threshold or higher
Twitches vary depending on?
-concentration of Ca in sarcoplasma
-how stretched the muscle was
-temp of muscle
If the pH of the sarcoplasma is lower than normal, what happens?
When stimulus intensity remains _____ twitch strength_____?
constant; vary with the stimulus frequency
10-20 stimuli per second produces what type of twitch? (staircase) describe
treppe; the muscle still recovers fully between twitches, but each twitch develops more tension than the one before