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Citow - Physiology > Membrane Potentials and Action Potentials > Flashcards

Membrane Potentials and Action Potentials Flashcards

1
Q

What is the Nerst equation?

A

used to determine the electrical potential of a cell membrane in regards to one type of ion Nernst potential = 61 Log C intra/C extra

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2
Q

What is the resting membrane potential in large myelinated peripheral nerves and skeletal muscle?

A

-90 mV

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3
Q

The resting membrane potential is determined largely by which ion?

A

K+

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4
Q

What is the resting membrane potential in the soma of the neuron?

A

-65 mV

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5
Q

What is the resting memebrane potential in small nerve fibers and smooth muscle?

A

-55 mV

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6
Q

How is the resting membrane potential maintained?

A

leaky K+ channels (potassium is -94 mV and 100 times more permeable than sodium)

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7
Q

In the action potential pathway, what is the sequence for ion channel opening?

A
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8
Q

What is the mechanism of tetrodotoxin?

A

voltage gated Na+ channel blocker

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9
Q

What is the mechanism of Tetraethylammonium (TEA)?

A

voltage gated K+ channel blocker

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10
Q

What neurotransmitter and what ion are associated with presynaptic inhibition?

A

GABA and Cl-

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11
Q

In what synapses is ACh used as a neurotransmitter?

A
  • motor cortex
  • skeletal muscle
  • preganglionic autonomic nerves
  • postganglionic parasympathetic nerves
  • postganglionic sympathetic nerves for sweat glands
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12
Q

In what synapses is Norepi used as a neurotransmitter?

A
  • pontine locus ceruleus
  • postganglionic sympathetic nerve fibers
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13
Q

Is dopamine excitatory or inhibitory? In what synapses is Dopamine used as a neurotransmitter?

A

inhibitory

substantia nigra projections to the putamen and caudate

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14
Q

What is the rate limiting step in dopamine synthesis?

A

conversion of tyrosine to 3,4 DOPA by tyrosine hydroxylase

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15
Q

Is glycine excitatory or inhibitory? In what synapses is glycine used as a neurotransmitter?

A

inhibitory

spinal cord (Renshaw cells)

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16
Q

In what synapses is GABA used as a neurotransmitter?

A
  • cortex
  • basal ganglia
  • cerebellum (Purkinje Cells)
  • spinal cord
17
Q

Is glutamate excitatory or inhibitory? In what synapses is glutamate used as a neurotransmitter?

A

Excitatory

  • cortex
  • dentate gyrus of hippocampus
  • striatum
  • cerebellum (granular cells)
18
Q

Is serotonin excitatory or inhibitory? In what synapses is serotonin used as a neurotransmitter?

A

inhibitory

  • Median raphe nuclei that project to the hypothalamus and spinal cord (dorsal horns)
19
Q

What neurotransmitter serves as the precursor to melatonin?

A

Serotonin

20
Q

Where are nicotinic receptors located?

A
  • NMJ
  • preganglionic sympathetics and parasympathetics
21
Q

What are the subunits of the autonomic nicotinic receptor?

A

2 alpha, one beta, one gamma, and one delta

22
Q

Which subunit on the nicotinic autonomic receptor binds the ACh?

A

the alpha subunit

23
Q

What blocks the ACh binding receptor on the nicotinic autonomic receptor?

A

hexamethonium (not reversed by acetacholinesterase)

24
Q

What are the subunits of nicotinic receptors at the NMJ?

A

2 alpha subunits

25
Q

Where are muscarinic receptors located?

A
  • postganglionic parasympathetic
  • postganglionic sympathetics for sweat glands
26
Q

What intracellular messaging system is paired with muscarinic receptors?

A

G protein via second messahnger system

27
Q

Muscarinic receptors are blocked by what toxin?

A

pertussis toxin

28
Q

What messenger system is used by dopamine receptors?

A

cAMP second messenger

29
Q

What is the competitive antagonist of glycine receptors?

A

Strychnine

30
Q

Mutations in what receptor causes stiff person syndrome?

A

mutations in glycine receptor (loss of inhibition)

31
Q

GABA A receptors increase _______ permeability; GABA B receptors increase _______ conductance.

A

Cl-

K+

32
Q

What are the GABA A agonists? What is their function?

A

Barbituates (prolong duration of Cl - opening) and Benzodiazepines (increase frequency of Cl- opening)

33
Q

What are GABA B agonists?

A

Baclofen

34
Q

What toxin blocks GABA receptor activity? What is the clinical manifestation?

A

Picrotoxin

Causes seizure like activity

35
Q

NMDA receptors use what type of neurotransmitter?

A

Glutamate (requires glycine for coactivation)

36
Q

What blocks NMDA receptors?

A

Magnesium

37
Q

Kinesin mediates _________ and dynein mediates ________.

A

anterograde axonal transport

retrograde axonal transport

38
Q

Excitatory action potentials lead to _____ channels opening while inhibitory action potentials lead to _____ channels opening.

A

NA+

K+ and Cl-

39
Q

Action potentials start at the _______ due to ______.

A

Neuronal axon hillock

Higher concentrations of Na+ channels

Citow - Physiology (26 decks)

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