1st sem: Nerve and Synapse

Question 1

Distribution of Na+ channels in a neuron are greatest at the

Answer 1

nodes of Ranvier

Question 2

Contains channels formed by hemichannels called, “connexons” and morphological correlate of electrical synapses?

Answer 2

Gap junction

Question 3

it is a local hyperpolarization of the post synaptic membrane that can bring the neuron to its THRESHOLD POTENTIAL?

Answer 3

Excitatory post synaptic potential

Question 4

Can occur when the same synapse is activated multiple times in rapid succession because axons can fire action potentials at rates over 100Hz?

Answer 4

Temporal summation

Question 5

functional zone of a neuron that mainly involves AP generation?

Answer 5

ZONE II

Question 6

distinguishes excitatory chemical synapses in the brain

Answer 6

Temporal summation and spatial summation onto the post synaptic cell increase the likelihood that a post synaptic action potential will be evoked

Question 7

It controls pain and pleasure by blocking the neurotransmitter SUBSTANCE P which transmits pain impulses to the brain

Answer 7

ENDORPHIN

Question 8

membrane conductance at resting state is greater with

Answer 8

K (POTASSIUM)

Question 9

True about relative refractory period

Answer 9

The cell is able to fire a second AP but a stronger than normal stimulus intensity is required

Question 10

The minimum intensity of a stimulus capable of immediate generation AP is

Answer 10

Threshold stimulus intensity

Question 11

True regarding SALTATORY conduction

Answer 11

occurs in myelinated fibers
has slower velocity in COLD than in WARM
faster than non-saltatory conduction in nerve fibers with diameters around 10 micro meter

Question 12

It is directly proportional to conduction velocity of an impulse

Answer 12

nerve diameter
sodium conductance
myelination

Question 13

unmyelinated axons differ from myelinated axons in that they are

Answer 13

refractory for a longer period after excitation

Question 14

The RMP of a nerve axon is essential for signal generation. Instantaneous elimination of the _____ would most RAPIDLY bring RMP close to O mV?

Answer 14

high membrane permeability of K+

Question 15

Ion influx involved in neurotransmitter release in the pre-synaptic membrane

Answer 15

CALCIUM

Question 16

The nicotinic receptor at the motor end plate for acetylcholine is an example of an ion channel that is ______

Answer 16

ligand-gated channel

Question 17

TRUE of local potential

Answer 17

The amplitude of the response is proportional to the stimulus intensity

Question 18

Neuron C responds to stimulation of Neuron A with a propagated AP only when Neuron B (which terminates only on Neuron C) is also simultaneously stimulated. What is the likely situation?

Answer 18

Neuron B releases an excitatory NT

Question 19

Membrane depolarization in post synaptic terminal is due to

Answer 19

Sodium influx

Question 20

NOT true when volley of impulses travelling in a pre-synaptic neuron?

Answer 20

The generation of at least 1 AP in the post-synaptic neuron

Question 21

usual site where action potentials are generated because of its high concentration of necessary channels?

Answer 21

Axon hillock

Question 22

TRUE when a nerve cell membrane is depolarized by 5 mV

Answer 22

Its permeability to Na+ increases
Na+ ions move into the cell to causes further depolarization
Chloride ions move inwards down their electrochemical gradient

Question 23

Nerve fiber that is highly susceptible to conduction block by anesthesia

Answer 23

TYPE C

Question 24

It is coupled to a G protein that initiates second messenger cascades that can affect ion channels

Answer 24

METABOTROPIC RECEPTORS

Question 25

It would decrease conduction velocity of nerve fibers

Answer 25

decrease in fiber diameter

Question 26

what toxins inhibits the release of acetylcholine from alpha-motor neurons?

Answer 26

Botulinum toxin

Question 27

what cells in the CNS is primarily involved in the re-uptake of excitatory NT’s released by neurons?

Answer 27

Astroglial cell

Question 28

Transport of vesicles from the soma to the synaptic terminal requires all of the following

Answer 28

Metabolic energy
Ca++
Kinesin

Question 29

It refers to the process by which a neuron generates an AP as a result of its inputs?

Answer 29

Synaptic integration

Question 30

TRUE of an excitatory post synaptic potential

Answer 30

Increase in Na+ influx