Lecture 3 - Neuromuscular 1 Flashcards
major divisions of the nervous system
structures of the Neuron
describe resting membrane potential
- > -70mV
- > inside more negative than outside
- > Na channels are closed (want to enter but cant’t)
- > K channels are open
Depolarization vs Hyperpolarization
Depolarization
- > occurs when inside of cell becomes less negative (-70 to 0mV)
- > Na channels open
- > requires an impulse to arise and travel
Hyperpolarization
- > occurs when inside of cell becomes more negative after the impulse than initial readings (-70 to -90)
- > makes it difficult for another impulse to occur
graded potentials vs action potential
GP
- > will decide if signal will be passed along to the axon
- > can excite or inhibit a neuron
AP
- > GPs that pass the potential threshold triggering an AP that goes down the neuron and to the next cell
- > only excitatory
- > lasts around 1ms
inhibitory vs excitatory signals
inhibitory
- > K efflux (hyperpolarization)
excitatory
- > Na influx (depolarization)
all or none principle
an AP happens or it doesn’t, can’t have half and AP
threshold values
Na-K pump
absolute vs relative refractory periods
Absolute refractory period
- > during depol.
- > neuron unable to respond to another stimulus
- > Na channels already open, nothing else can come in
Relative refractory period
- > during repol.
- > neurons only respond to very strong stimulus
- > K channels open (Na closed but could open again)
how does the diameter of an axon influence the speed of an impulse
larger the diameter the faster the impulse
Myelin
speeds up propagation
- > fatty sheath around axon
- > non continuous
multiple sclerosis
degredation of myelin
synapse
gap/junction between neurons
- > AP must jump across
path of an impulse
neurotransmitters
chemicall messengers that carry electrical AP across synaptic cleft and mind to receptors on postsynaptic surfaces
- > stimulate GPs in postsynaptic neurons
neuron-muscle communication
neuromuscular junction
uses acetylcholine (ACh) as a neurotransmitter that excites the axon
- > ACh bind to receptor at motor end plate (specifically plasmalemma) and cause depolarization
categories of neurotransmitters
- Small molecules, rapid acting
2. neuropeptides, larger and slow acting
which neurotransmitters govern exercise
ACh and Norepinephrine (NE)
- > ACh stimulates skeletal muscle contractions and NE mediates sympathetic NS effects
PPARGC1gamma
peroxisome proliferator-activated receptor-gamma coactivator
- > released during exercise
- > increases the number vesicles
- > increases the number of receptors on cell, which increases the effect of ACh
- > exercise leads to inc. sensitivity to ACh
neuromuscular effects of HIIT vs END training
- > both have a similar improvement to VO2max
HIIT: increase in force production, motor unit firing, motor unit discharge rate
END: no changes
