Module 4 Flashcards
Which ion channels are required to conduct an AP?
Na+ and K+ voltage gated channels
Leak channels
Na+ voltage gated channels open ____. K+ voltage gated channels open ___.
Fast (Na)
Slow (K)
The rising phase is also known as ___. Which voltage gated channel opens?
Depolarization
Na+ voltage gated channels
The falling phase is also known as ___. Which voltage gated channel opens?
Repolarization
K+ voltage gated channels
During the after-hyperpolarization phase which channel is responsible for bringing the membrane potential back to -70mv?
Leak channels
What does the activation gate open in response to?
Depolarization
What does the inactivation state close in response to?
Depolarization
Contrast between absolute and relative refractory periods.
Absolute refractory period: a second AP cannot be generated
Relative refractory period: a second AP can be initiated but requires a larger than normal GP
Which channel is inactivated during the absolute refractory period?
Na+ channels
What is the purpose of a refractory period?
Ensuring the AP travels in one direction
Limit the frequency of firing
Prevent excitotoxicity
in terms of action potential, what does conduction mean?
Action potentials travelling over long distances without losing energy
what will repolarize the membrane?
Loss of K+
What are the two parameters that determine the velocity of conduction?
Diameter of the axon
Resistance of the axon membrane to leakage
Which of the following would we expect to have the highest velocity of conduction?
a) myelinated, small diameter, leaking axon
b) myelinated, large diameter, non-leaking axon
c) unmyelinated, small diameter, leaking axon
d) unmyelinated, larger diameter, non-leaking axon
b) myelinated, large diameter, non-leaking axon
The majority of synapses in the nervous system are ____ synapses.
Chemical
A chemical that is released, acts on a postsynaptic cell in close vicinity and causes a rapid response in the postsynaptic cell is a ____.
a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine
a) neurotransmitter
Where would we expect to find electrical synapses?
Few in the CNS
Cardiac muscle
Smooth muscle
A chemical that is released, acts on a postsynaptic cell in close vicinity and causes a slow response in the postsynaptic cell is a ____.
a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine
b) neuromodulator
Which neurocrine is secreted into the blood stream and acts on a target in the body?
a) neurotransmitter
b) neuromodulator
c) neurohormone
d) neurocrine
c) neurohormone
Which neurocrine receptor elicits a slower response but lasts longer and ligand binding leads to a g-protein mediated cellular response?
Metabotropic receptors
Which neurocrine receptor opens in a channel when ligand binding leads to a conformational change and mediates fast responses?
Ionotropic receptors
Large neurotransmitters are synthesized and packaged into vesicles at the ____, where as small neurotransmitters are synthesized and packaged at the ____.
Soma
Axon terminal
Neurotransmitters are released by which structure and which ion will induce release?
Vesicles
Calcium
What are the 3 ways neurotransmitter activity is terminated?
Returned to axon terminal for reuse
Enzyme inactivation
Diffusion
Which of the following would lead to increased neurotransmitter release?
a) increased firing of AP
b) decreased firing of AP
c) it doesnt matter, neurotransmitters are released when needed
d) none of the above
a) increased firing of AP
What is the idea of spatial summation?
summation of several subthreshold signals that results in an AP
What is the idea of synaptic inhibition?
one inhibitory postsynaptic potential sums with two excitatory postsynaptic potentials to prevent an AP
What is the idea of temporal summation?
two graded potentials from one presynaptic neuron occur close together in time
