NP Midterm 2

Question 1

Gap junctions between cells is found in what type of synapses?

Answer 1

Electrical

Question 2

Where in the body are electrical synapses found?

Answer 2

Cardiac Muscle
Visceral Smooth Muscle
A few CNS synapses

Question 3

What type of synapse occurs across a space filled with interstitial fluid?

Answer 3

Chemical

Question 4

T or F

Chemical synapses are very fast and can travel in both directions through gap junctions?

Answer 4

False!

Electrical synapses are fast and use gap junctions

Question 5

What is a synaptic knob?

Answer 5

An axon ending having a presynaptic terminal

Question 6

How are synapses named?

Answer 6

First for the structure of the presynaptic neuron that contacts the post synaptic cell and secondly for the structure of the post synaptic cell that receives input.

Question 7

What are the most typical chemical synapse?

Answer 7

Axo-dendritic

Question 8

The most powerful excitatory chemical synapse is? Why is it the most powerful?

Answer 8

Axo-somatic
Local current flow experiences little resistance due to the large surface are of the cell body -> non decremental conduction.

Question 9

When is an axo-axonic synapse inhibitory?

Answer 9

When the synapse is on the axon hillock

Question 10

How can an axo-axonic veto excitatory effects of the axo-dendritic, and ado-somatic synapses?

Answer 10

By blocking or decreasing the frequency of action potentials generated by an EPSP on the soma

Question 11

When will an axo-axonic synapse exert presynaptic facilitation or inhibition?

Answer 11

When the synapse is onto the synaptic ending of the post synaptic cell.

Question 12

What type of synapse can only be electrical due to gap junctions?

Answer 12

Dendo-dendritic

Question 13

Name the variations in the Presynaptic Events of Synaptic Transmission.

Answer 13

• Regulation of Ca++ entry and the # of vesicles releasing NT
• # of Vesicles and NT available for release.

Question 14

What are the different mechanisms for changing the # of vesicles and NT available to be released?

Answer 14

Synthesis of NT
Inhibition of Synthesis of NT
Re-Uptake of NT
Inhibition of re-uptake
Destruction of NT by cytoplasmic enzymes
Depletion of vesicles = synaptic fatigue
Blockage of a NT release due to destruction of cytoskeleton

Question 15

Give an example of the inhibition of re-uptake of NT?

Answer 15

Mode of action of drugs like Prosac

Serotonin re-uptake inhibitor increases the effectiveness of the release of Serotonin

Question 16

Give an example of Destruction of NT by cytoplasmic enzymes:

Answer 16

Mono amino oxidases (MAO) enzymes oxidize the mono amines: Serotonin, Dopamine, and Norepi

Question 17

What do MAO inhibitors actually do?

Answer 17

They block the destruction of the monoamine NT’s inside the presynaptic cell and increase the availability of monoamines to be released.

Question 18

What enzyme will destroy Norepinephrine and Dopamine?

Answer 18

Catecholamine-O-methyl transferase COMT

Question 19

What enzyme converts Acetyl Choline to Acetate and Choline?

Answer 19

Acetyl Cholinesterase

Question 20

T or F

Drugs that inhibit COMT can decrease the effectiveness of the synapse

Answer 20

False

The drug will increase the effectiveness of the synapse because more will be available since it is not being destroyed.

Question 21

What are the variations in events in the synaptic cleft that will effect a synapse?

Answer 21

1. Enzymatic Destruction of Neurotransmitters by enzymes in the Synaptic Cleft
2. Presence of Antibodies against NT receptors

Question 22

When are Anti-acetyl Cholinesterase drugs used?

Answer 22

To increase the number of Ach molecules that reach the post synaptic cell membrane to compete with the Antibodies in the synaptic cleft.

Question 23

What are the ways in which Ca++ entry is regulated?

Answer 23

Frequency of AP
Presynaptic Inhibition
Presynaptic Facilitation
Increased Calcium in the presynaptic cell due to the release of Nitric Oxide by the post synaptic cell

Question 24

Describe the properties of receptors that are ion channels:

Answer 24

Open rapidly
Short Acting
Stay open for a brief time
Generally excitatory Na+ or Ca++ channels
Few sits for regulation of activity

Question 25

Give an example of when the Blockage of NT actions by molecules that bind to NT’s receptors discussed in class.

Answer 25

Curare the plant product binds to Nicotinic Acetyl Choline receptors on skeletal muscles -> paralysis

Question 26

Alpha and Beta Adrenergic blockers block the action of what monoamine?

Answer 26

Norepi

Question 27

Give an example of a receptor that is also an ion channel?

Answer 27

Nicotinic Acetyl Choline Receptor

Question 28

T or F

Nicotine binds to Ach receptors, closes the ion channel and remains bound also activating the Ach receptor

Answer 28

False

Nicotine binds to Ach receptors OPENS the ion channel and remains bound also INACTIVATING the Ach receptor.

Question 29

What remains open longer? G protein related channels or receptor ion channels?

Answer 29

G protein remain open or closed for longer periods of time - up to a number of seconds.

Question 30

Some neurotransmitters block the actions of other neurotransmitters how?

Answer 30

By working through receptors that cause the activation or inhibition of enzymes that block the mechanism of action of the other neurotransmitters.

Question 31

What do Phosphodiesterases do?

Answer 31

• They destroy second messenger molecules whose structure contains two phosphoesters.
• These enzymes are specific for either cyclic AMP or cyclic GMP.

Question 32

A NT that increases cyclic AMP - phosphodiesterase activity can diminish what mechanism?

Answer 32

The effectiveness of Norepi when it binds to Beta receptors and stimulates the production of cyclic AMP

Question 33

Give examples of phosphodiesterase inhibitors

Answer 33

Caffeine and Theophylline