Npb_Synaptic Transmission

Front 1

Define Synapses.

Back 1

def. junction between two neurons, or between a neuron and a muscle or gland that enables one cell to electrically and/or biochemically influence another cell

Front 2

Define Synaptic Transmission.

Back 2

primary means of rapid inter-neuronal communication in the brain

Front 3

Features of Synaptic Transmission

Back 3

1. presynaptic cell
2. postsynaptic cells
3. postsynaptic targets

Front 4

Function of a Presynaptic Cell.

Back 4

initiates the (CHEMICAL) signal (VIA FUSION OF A NT-FILLED VESICLE WITH THE CELL MEMBRANE (EXOCYTOSIS))

Front 5

Function of a Postsynaptic (target)Cell

Back 5

receives the signal (THE NT IS RECIEVED BY RECEPTORS IN THE MEMBRANE OF THE POSTSYNAPTIC CELL)

Front 6

2 Types of Synaptic Junction

Back 6

1. Electrical Synapse
2. Chemical Synapse

Front 7

Define Electrical Synapse

Back 7

- def. a direct electrical connection between two cells, formed by a gap junction, that allows current to pass from one cell to another
- composed of multiple proteins called connexINS
- has no delay
- much less common than chemical synapses

Front 8

Define Chemical Synapses.

Back 8

- def. anatomical junction between two neurons, or between a neuron and a muscle or gland where a chemical neurotransmitter is released by the presynaptic neuron which diffuses across the synaptic cleft and binds to receptors on the postsynaptic neuron to exert a physiological response

Front 9

Mechanism of Presynaptic Release

Back 9

- neurotransmitter is concentrated into synaptic vesicles in the presynaptic terminal, and is released through exocytosis when the vesicles fuse with the plasma membrane

Front 10

Mechanism of Postsynaptic Response

Back 10

- referred to as a post-synaptic-potential (PSP)
- this response most commonly consists of a rapid and graded change in membrane potential in the postsynaptic neuron

Front 11

2 categories of PSPs

Back 11

1. EPSP(Excitatory Post
Synaptic Potentials)
2. IPSP (Inhibitory Post
Synaptic Potentials)

Front 12

Define EPSP.

Back 12

def. a depolarizing potential that tends to bring the cell towards threshold for generation of an action potential

Front 13

Define IPSP.

Back 13

def. a hyperpolarizing potential that tends to bring the cell away from threshold for generation of an action potential

Front 14

Means of Removing Transmitter

Back 14

- degradation by nz present in the synaptic cleft
- transported back into the presynaptic neuron by active transport
- diffuse out of the cleft

Front 15

Action of Drugs on Nervous System

Back 15

- either antagonistic or facilitory
- transmitter release - tetanus toxin degrades vesicle fusion
- transmitter uptake - Cocaine blocks the reuptake of Dopamine
- SSRIs (selective seratonin reuptake inhibitor)
- transmitter removal - many insecticides block the degradation of ACh
- EPSP - Curare blocks the postsynaptic action of ACh at the neuromuscular junction
- IPSP - Valium enhances the postsynaptic action of GABA
- 2nd messenger - Caffeine enhances the action of cAMP at adrenergic synapses

Front 16

Purpose of Synaptic Interaction and Neuronal Integration

Back 16

- to receive the thousands of synaptic input using only a simple mean of integration

Front 17

Define Convergence

Back 17

def. the synaptic input of many neurons on to one neuron

Front 18

Define Divergence.

Back 18

def. the synapic output of one neuron onto many neurons

Front 19

Define temporal summation.

Back 19

def. the additive effect of PSPs occuring close together in time

Front 20

Define spatial summation

Back 20

def. the additive effect of PSPs occuring together on nearby parts of the same cell

Front 21

Define presynaptic inhibition

Back 21

def. synaptic inhibition of a synaptic terminal causing a decrease in transmitter release