Exam 2

Question 1

Proteins that form gap junctions

Answer 1

Connexins

Question 2

Gap junctions

Answer 2

Channels that allow direct communication between neighboring cells.

Question 3

How many connexins assemble to form a connexon.

Answer 3

6

Question 4

Electrical synapse

Answer 4

Direct conduction of electricity between two cells through gap junctions allowing for fast communication.

Question 5

Chemical synapse

Answer 5

Release of neurotransmitters into synaptic cleft which selectively activate receptors on the post synaptic cell surface resulting in change in the post synaptic cell

Question 6

What is the functional role of vesicles at the synapse?

Answer 6

Vesicles at the synapse play a role in release of neurotransmitters

Question 7

How is vesicle release at the synapse coordinated?

Answer 7

Depolarization, calcium entry, and SNARE proteins.

Question 8

Down regulation

Answer 8

Describes a decrease in the number of receptors on the surface of target cells –> this makes cells less sensitive to a hormone/NT

Question 9

If a change in PNa on a post synaptic neuron caused hyperpolarization, did PNa increase or decrease?

Answer 9

Hyperpolarization –> decrease

Question 10

What ion plays the most direct role in fusion of vesicles to presynaptic membrane and release of NT?

Answer 10

Calcium

Question 11

If mitochondria are carried from the cell body to synapse via fast axonal transport, what protein is most likely involved?

Answer 11

Kinesin

Question 12

A hyperpolarizing graded potential is…

Answer 12

inhibitory to the generation of an action potential

Question 13

Which ion gradient typically provides the energy for uptake of a neurotransmitter into vesicles in the presynaptic nerve terminal?

Answer 13

Hydrogen ion gradient

Question 14

Opiate drugs activate on which receptor

Answer 14

Metabotrophic receptors

Question 15

Do all metabrotropic receptors have the same effects?

Answer 15

No, they have different effects. May be depolarizing or hyperpolarizing.

Question 16

Naloxone is sometimes used to reverse heroin overdose because…

Answer 16

it is a receptor antagonist that attaches to opioid receptors w/o activating them. It binds w/ a higher affinity than heroin and prevents heroins attachment to the receptor.

Question 17

If overtime the sensitivity of a synapse has diminished due to repetitive stimulation what is the most likely reason?

Answer 17

The number of postsynaptic receptors is increased.

Question 18

A drug like cocaine slows the neurotransmitter dopamine from the synaptic cleft. Under normal conditions, what ion gradient provides the driving force for dopamine reuptake?

Answer 18

The sodium gradient across the presynaptic membrane

Question 19

Botox…

Answer 19

decreases fusion events

Question 20

cAMP increase leads to activation of…

Answer 20

protein kinase A

Question 21

Which subunit of heterotrimeric G protein is released when the receptor is activated?

Answer 21

Alpha

Question 22

What is a TEER?

Answer 22

Trans epithelial electrical resistance is an indicator of the tightness of the epithelium

Question 23

Aquaporins

Answer 23

Amphipathic integral membrane proteins that form water channels

Question 24

What is an estimate for the thickness (apical-basolateral dimension) of an enterocyte cell layer?

Answer 24

25-30 um

Question 25

The selective permeability of tight junctions is primarily influenced by…

Answer 25

claudin proteins associated with the tight junction complex