Question 1 Synaptic vesicles discharge their contents by ex

Question 1 :

Synaptic vesicles discharge their contents by exocytosis at the

A

dendrite.

B

axon hillock.

C

nodes of Ranvier.

D

nucleus of the nerve cell.

E

presynaptic membrane.

Question 2 :

It is accurate to say that neural transmission across nearly all mammalian synaptic clefts is the result of

A

neural impulses involving the flow of K⁺ and Na⁺ across the cleft.

B

neural impulses traveling across the gap as electrical currents.

C

neural impulses causing the release of chemicals that diffuse across the cleft.

D

neural impulses traveling across the cleft in both directions.

E the calcium within the axons and dendrites of nerves adjacent to a synapse acting as the neurotransmitter.

Question 3  :

The exposed, unmyelinated gaps between glia on myelinated axons are also sites of voltage-gated Na⁺ channels.

True

False

Question 4 :

Action potentials are typically also characterized as graded potentials.

True

False

Question 5

Synaptic integration is most accurately described as

the summing of multiple excitatory or inhibitory influences in a postsynaptic neuron.

the fusing of presynaptic and postsynaptic membranes.

the binding of Ca²⁺ ions to secretory vesicles in presynaptic neurons.

the binding of secretory vesicles to the presynaptic neuron membrane.

the enzymatic degradation of neurotransmitters in the synaptic cleft.

A	dendrite.
B	axon hillock.
C	nodes of Ranvier.
D	nucleus of the nerve cell.
E	presynaptic membrane.

Solution

1. ANS: E. Presynaptic Membrane.

Explanation: Presynaptic Membrane is present in the nerve endings. In Presynaptic Membrane synaptic vesicles discharge their contents by exocytosis.

2. ANS: C. neural impulses causing the release of chemicals that diffuses across the cleft.

Explanation: Neural transmission across nearly all mammalian synaptic clefts is the result of neural impulses causing the release of chemicals that diffuses across the cleft.

3. ANS: True

Explanation:

Pharmacological studies on central and peripheral glia revealed the presence of voltage-gated Na channels with properties that are similar but not identical to those of neuronal Na channels

4. ANS: False.

Explanation:

Action potential characteristics:

   All or none response

   It propagates over entire cell

   Refractory period is present

   No stimulation is possible

    It is triggered by threshold

Graded potential characteristics:

Graded response is depends on stimulus.

It decreases with distance

Refractory period is absent

Stimulation is possible

It is triggered by threshold

5. ANS: B.The fusing of presynaptic and postsynaptic membranes.

Explanation:

Synaptic integration is described as how neurons are going to “add up” or \"summate\" input neurons which receive information from other neurons to generate the output with action potential or nerve impulse.

Pre and post synaptic membrane fusion in an electrical synapse is necessary to produce a low-resistance pathway for current from the presynaptic to the postsynaptic cell.