NP Midterm 2 Flashcards
Gap junctions between cells is found in what type of synapses?
Electrical
Where in the body are electrical synapses found?
Cardiac Muscle
Visceral Smooth Muscle
A few CNS synapses
What type of synapse occurs across a space filled with interstitial fluid?
Chemical
T or F
Chemical synapses are very fast and can travel in both directions through gap junctions?
False!
Electrical synapses are fast and use gap junctions
What is a synaptic knob?
An axon ending having a presynaptic terminal
How are synapses named?
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.
What are the most typical chemical synapse?
Axo-dendritic
The most powerful excitatory chemical synapse is? Why is it the most powerful?
Axo-somatic
Local current flow experiences little resistance due to the large surface are of the cell body -> non decremental conduction.
When is an axo-axonic synapse inhibitory?
When the synapse is on the axon hillock
How can an axo-axonic veto excitatory effects of the axo-dendritic, and ado-somatic synapses?
By blocking or decreasing the frequency of action potentials generated by an EPSP on the soma
When will an axo-axonic synapse exert presynaptic facilitation or inhibition?
When the synapse is onto the synaptic ending of the post synaptic cell.
What type of synapse can only be electrical due to gap junctions?
Dendo-dendritic
Name the variations in the Presynaptic Events of Synaptic Transmission.
- Regulation of Ca++ entry and the # of vesicles releasing NT
- # of Vesicles and NT available for release.
What are the different mechanisms for changing the # of vesicles and NT available to be released?
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
Give an example of the inhibition of re-uptake of NT?
Mode of action of drugs like Prosac
Serotonin re-uptake inhibitor increases the effectiveness of the release of Serotonin
Give an example of Destruction of NT by cytoplasmic enzymes:
Mono amino oxidases (MAO) enzymes oxidize the mono amines: Serotonin, Dopamine, and Norepi
What do MAO inhibitors actually do?
They block the destruction of the monoamine NT’s inside the presynaptic cell and increase the availability of monoamines to be released.
What enzyme will destroy Norepinephrine and Dopamine?
Catecholamine-O-methyl transferase COMT
What enzyme converts Acetyl Choline to Acetate and Choline?
Acetyl Cholinesterase
T or F
Drugs that inhibit COMT can decrease the effectiveness of the synapse
False
The drug will increase the effectiveness of the synapse because more will be available since it is not being destroyed.
What are the variations in events in the synaptic cleft that will effect a synapse?
- Enzymatic Destruction of Neurotransmitters by enzymes in the Synaptic Cleft
- Presence of Antibodies against NT receptors
When are Anti-acetyl Cholinesterase drugs used?
To increase the number of Ach molecules that reach the post synaptic cell membrane to compete with the Antibodies in the synaptic cleft.
What are the ways in which Ca++ entry is regulated?
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
Describe the properties of receptors that are ion channels:
Open rapidly Short Acting Stay open for a brief time Generally excitatory Na+ or Ca++ channels Few sits for regulation of activity
