Neurons and the Process of Synaptic Transmission

Question 1

Order of neurons

Answer 1

Sensory ~> relay ~> motor

Question 2

Structure of sensory neuron

Answer 2

Long dentrites
Short axons
Unipolar
“Cell body in the middle”

Question 3

Unipolar

Answer 3

Only TRANSMITS information

Question 4

Function of sensory neuron

Answer 4

Afferent nerve cell
Carries sensory impulses from the sense organs (e.g skin) to the CNS (brain and spinal cord)

Question 5

Afferent

Answer 5

Towards CNS

Question 6

Efferent

Answer 6

Away from CNS

Question 7

Structure of relay neuron

Answer 7

Short dendrites
Short axons
Multipolar
Found in the brain / CNS

Question 8

Multipolar

Answer 8

SENDS and RECIEVES information from many sources

Question 9

Function of relay neuron

Answer 9

Relay neurons connect with other neurons (e.g sensory and motor)
Involved in analysis of the sensation and deciding how to respond to it
DECISION MAKING

Question 10

Structure of motor neuron

Answer 10

Short dendrites
Long axons
Multipolar

Question 11

Function of motor neuron

Answer 11

Efferent nerve cell
Transmits nerve impulses from the CNS to muscles or glands

Question 12

Synapse

Answer 12

Junction between the axon of one neurone and the dendrites of another.

Question 13

Synaptic transmission

Answer 13

The process of transmitting an electrical impulse from the presynaptic to the post synaptic neuron

Question 14

Ingredients for neurotransmitters:

Answer 14

Precursor chemicals

Question 15

Four processes of synaptic transmission:

Answer 15

1) Synthesis
2) Release
3) Receptor activation
4) Inactivation

Question 16

What occurs during synthesis:

Answer 16

Precursor chemicals are transported into the axon terminal in the presynaptic neurone
The precursor chemicals are used to produce neurotransmitters and are packaged into vesicles

Question 17

What occurs during release:

Answer 17

Neurotransmitters are released into the synapse

Question 18

What occurs during Receptor activation:

Answer 18

Neurotransmitters diffuse across the synapse and bind to specific receptors on the postsynaptic neurone

Question 19

What occurs during the process of Inactivation:

Answer 19

Neurotransmitters then unbind and either :
- go through re uptake into the presynaptic neuron via active transport
- is packaged back into vesicles
- it is broken down by enzymes in the synapse

Question 20

Where are neurotransmitters

Answer 20

Presynaptic neuron

Question 21

Diffusion

Answer 21

Movement of neurotransmitters from areas of high ~> low concentration

Pre to post synaptic membrane

Question 22

Explain the process of synaptic transmission {4}

Answer 22

~ electrical impulses reach the presynaptic terminal
~ electrical impulses trigger the release of neurotransmitters from synapse vesicles
~ neurotransmitters diffuse across the synaptic cleft
~ neurotransmitters bind to receptors on the postsynaptic membrane

Question 23

The two types of neurotransmitters:

Answer 23

Excitatory
Inhibitory

Question 24

What happens when an excitatory neurotransmitter binds to receptor site in the post synaptic neurone:

Answer 24

Produces excitatory post synaptic potential (EPSP)

Question 25

How is EPSP produced:

Answer 25

When an excitatory neurotransmitter binds to receptor site in the postsynaptic neurone

Question 26

EPSP

Answer 26

Makes postsynaptic neurone MORE likely to fire

Question 27

What happens when an inhibitory neurotransmitter binds to a receptor site in the postsynaptic neurone:

Answer 27

Produces inhibitory post synaptic potential (IPSP)

Question 28

How is IPSP produced:

Answer 28

When inhibitory neurotransmitter binds to the receptor site in the postsynaptic neurone

Question 29

IPSP

Answer 29

Makes postsynaptic neurone less likely to fire

Question 30

Fire

Answer 30

The speed of electrical impulse

Question 31

Sammation

Answer 31

When the postsynaptic neurone aggregates the overall amount of IPSP and EPSP to determine whether or not to fire

Question 32

What charge is it if the EPSP is greater than IPSP?

Answer 32

Overall positive charge in the post synaptic neurone

Question 33

Excitation (or depolarisation)

Answer 33

When the EPSP is greater than the IPSP so there is an overall positive charge in the postsynaptic neurone and is therefore more likely to fire

Question 34

The signals in a synapse can only travel

Answer 34

In one direction

Question 35

The synaptic bisected containing neurotransmitters are only released from:

Answer 35

Presynaptic neurone

Question 36

The receptors for neurotransmitters to bind with are only present on:

Answer 36

Post synaptic neurone

Question 37

Why can neurons only transmit information in one direction at a synapse?

Answer 37

~ The synaptic vesicles containing neurotransmitters are only released from the presynaptic neurone
~ neurotransmitters in the synapse travel via diffusion (high to low concentration) ~ so only pre to post synaptic membrane
~ the receptors for neurotransmitters to bind with are only present on the postsynaptic neuron and it is the binding which passes on the information

Question 38

Differences between neurotransmitters and hormones:

Answer 38

Neurotransmitters are produced within neurons and pass very quickly from one neurone to another nearby neurone ~ whereas
Hormones are secreted by glands and travel less quickly through the bloodstream to often quite distant target organs