Wed - fitz - neural communication

Question 1

How many different types of channels are there?

Answer 1

Hundres

Question 2

4 types of ion channels

Answer 2

1 voltage gated
2 ligand gated (less specific)
3 mechanical (sensory receptors)
4 leak (don’t actually have gates)

Question 3

What type of inactivation is only present in some transmembrane channels?

Answer 3

Inactivation ball.

all gated channels can close; only some can inactivate

Question 4

Equilibrium (reversal) potential for
Cl
Ca
Na
K

Answer 4

Cl (-61)
Ca (+200)
Na (+60)
K (-88)

Question 5

The amplitude of a graded potential ______ with time, and _______ with distance

Answer 5

decreases, decreases

Question 6

Length constant applies to what types of potentials

Answer 6

Graded. (length until 37%)

Question 7

When do action potentials peak?

Answer 7

When the voltage-gated Na channels inactivate and voltage-gated K channels open. (between 0 and 40 mV)

Question 8

Two types of postsynaptic potentials

Answer 8

EPSP and IPSP

EPSP is the influx of cations into the cell

Question 9

What is meant by all or none?

Answer 9

once Vm reaches the AP threshold, the cell will depolarize in a manner that is independent of the initiating stimulus.

Does NOT mean that all action potentials are all the same size or shape, it doesn’t say anything about the amplitude at all.

Question 10

Why does the AP peak happen from 0 to 40 mV and not 60

Answer 10

because they are inactivated by the inactivation ball (this is sufficient enough to create the peak) THIS BEGINS REPOLARIZATION

plus chloride channels become more influential, and voltage gated K channels activate.

Question 11

Two things hyperkalemia can do to action potentials

Answer 11

slight depolarization can cause depolarizations in the membrane potential to be more likely, leads to innapropriate aciton potentials (arrhythmias).

can also prevent action potentials from occurring, leading to cardiac arrest.

Question 12

How do electrical synapses transfer their signals from cell to cell

Answer 12

through gap junctions made of connexin

Question 13

Lambert-eaton syndrome. Treatment?

Answer 13

rare, autoimmune destruction of voltage gated Ca channels at the ends of axons. Muscle contraction increases with repeated stimulation

K+ channel blocker diaminopyridine. (leaves Na channels open longer)

Question 14

Fast receptor activation name. slow?

Answer 14

Fast: ionotropic
slow: metabotropic

Question 15

Three actions for terminating the actions of neurotransmitter?

Answer 15

diffusion: amino acid neurotransmitters like glutamate and GABA

enzymatic degradation (ACh)

reuptake (monoamines)

Question 16

Function and chemical signal of these receptors

nicotinic
AMPA
NMDA
5HT3
GABA
clycine

Answer 16

nicotinic - ACH, skeletal muscle contraction, autonomic ganglia

AMPA - glutamate, most excitatory neurotransmission in brain

NMDA - glutamate - mediates long-term potentiation (learning, memory)

5HT3 - serotonin, nociception in gut, nausea and vomiting, appetite, sleep, happiness

GABA - GABA, inhibitory neurotransmission in brain, activating GABA receptor results in more Cl influx and hyperpolarization.

Glycine - glycine, inhibitory neurotransmission in spinal cord

Question 17

Effects of cocaine, amphetamine, tricyclic antidepressants?

effects of SSRIs?

Answer 17

block reuptake of all 3 monoamine neurotransmitters.

specific serotonin reuptake inhibitors block 5HT uptake

Question 18

Myasthenia gravis

Answer 18

autoimmune disease results from the generation of antibodies to the nACh receptor found in skeletal muscle. muscle contraction rapidly fatigues.

Question 19

Botulinum toxin

vs

tetanus

Answer 19

Both destroy components of the docking apparatus of vesicles.

Botulinum causes flaccid paralysis

Tetanus blocks release of inhibitory neurotransmitters.