Neurons, Synaptic Transmission and Neurotransmitters

Question 1

What is a Neuron?

Answer 1

A nerve cell. They allow communication by sending signals electrically and chemically.

Question 2

Cell body

Answer 2

Includes a nucleus containing genetic material of cell. Dendrites stick out which carry impulses from neurons to cell body.

Question 3

Axon

Answer 3

Carries impulses away from cell body down length of the neuron.

Question 4

Myelin Sheath

Answer 4

Protects axon and speeds up electrical transmission of the impulse.

Question 5

Terminal Buttons

Answer 5

Not physically connected but involved in communication across synapse.

Question 6

Sensory Neuron

Answer 6

Carry messages from sensory receptors along nerves in peripheral nervous system to CNS. Long dendrites and short axons.

Question 7

Motor Neurons

Answer 7

Carry messages from CNS along nerves in PNS to effectors in the body. Short dendrites, long axons.

Question 8

Relay Neurons

Answer 8

Connect sensory, motor together and also connect other relay neurons together.

Short dendrites and axons, only in CNS.

Question 9

Depolarisation

Answer 9

Rapid switch from negative to positive charge in neuron after a stimulus.
Creates an electrical impulse (action potential) that travels down axon to terminals .

Question 10

Action potential

Answer 10

Generated when depolarisation reaches a certain threshold, it is always the same intensity. Only happens when threshold is reached.

When AP reaches end of neuron it triggers release of synaptic vesicles.

Question 11

Synaptic Transmission

Answer 11

Neurons communicate through neural networks separated by synaptic cleft.

Signals in neurons travel electrically but between they are chemically across synapse.

Question 12

ST definition

Answer 12

A chemical process using biochemical substances called neurotransmitters.

Question 13

NT going across synapse

Answer 13

They fit into matching receptor sites on the postsynaptic neuron.

Different receptors for different neurotransmitters.

Chemical signal carried by NT is converted back into an electrical signal in postsynaptic neuron.

Question 14

Reuptake

Answer 14

NT molecules remaining in synapse are reabsorbed into presynaptic neuron, usually being broken down first.

Means they can be used again.

Question 15

Function of NT

Answer 15

Each NT has its own specific molecular structure and fits into a postsynaptic receptor.

They have specific functions like the Acetylcholine is found where motor neuron meets a muscle and when it releases the muscle will contract.

Question 16

Excitation

Answer 16

Postsynaptic neuron increasing its positive charge making it more likely to fire as a result of something like dopamine

Question 17

Inhibition

Answer 17

PSN is more negatively charged as a result of something like serotonin making it less likely to fire.

Question 18

Summation

Answer 18

PSN receives excitatory or inhibitory inputs from neural network.

Firing depends on summation of signals over time (temporal) or space (spatial).

Question 19

Excitatory and inhibitory summed

Answer 19

Summed if net effect on PSN becomes positively charged, depolarisation takes place and AP travels down dendrite towards cell body and along axon.