muscle ii Flashcards
3 steps to get from nerve impulse to muscle contraction
- transform nerve ap to muscle ap
- Excitation contraction coupling
- contraction cycle
neuromuscular joint
where the nerve and muscle meet
synapse
where communication occurs between somatic motor neuron and next cell (like muscle cell)
synaptic cleft
gap b/t motor neuron and muscle cell
neurotransmitter
- chemical released by one cell communicating with another
- acetylcholine (Ach) released via exocytosis from somatic neuron
- binds to muscle fiber
synaptic vesicles
-sacs suspended in synaptic end bulb containing molecules of Ach
motor end plate
- region of muscle cell membrane opposite synaptic end bulb
- has Ach receptors
What kind of channels are in the axon membrane of the somatic motor neuron?
voltage gated calcium channels
- open in response to electrical signal
- allow calcium influx into axon terminal
What signals the release of the synaptic vesicles from the axon terminal
influx of calcium
What kind of receptors are in the motor end plate?
Nicotine receptors = ligand gated antiporters
lets Na into the cell and K out of the cell
- More Na gets in than K gets out
- Net influx of Na = Depolarization
What is depolarization and what does it trigger?
- Depolarization = net influx of Na in response to Ach binding
- It triggers the opening of Na VOLTAGE gated channels
What even is the Muscle AP?
Sequential voltage gated channels that allow influx of Na
Acetylcholinesterase (AchE)
an enzyme that breaks down Ach rapidly after use
Absolute refractory period
membrane can’t respond to further stiumulus
Relative refractory period
membrane can only respond to bigger than usual stimulus
