Nervous System - Micro Level

Question 1

What are the 6 structures of a neuron?

Answer 1

1. cell body
2. dendrites
3. axon
4. myelin sheath
5. nodes of ranvier
6. terminal buttons

Question 2

What is the cell body?

Answer 2

the cell body includes a nucleus, which contains all the genetics material of the cell

Question 3

What are dendrites?

Answer 3

branch like structures are called dendrites and they project from the cell body. They carry impulses from other neurons towards the cell body

Question 4

What is the axon?

Answer 4

the axon carries the impulses away from the cell body down the length of the neuron

Question 5

What is the myelin sheath?

Answer 5

the axon is covered in a layer of myelin sheath that protects the axon and speeds up the electrical impulse

Question 6

What are the nodes of ranvier?

Answer 6

the myelin sheath is segmented by gaps called nodes of ranvier. These speed up the transmission of the impulse by forcing it to ‘jump’ across gaps along the axon

Question 7

What are the terminal buttons?

Answer 7

at the end of an axon are axon terminal buttons that communicate with the next neuron in the chain across a synaptic gap by using neurotransmitters

Question 8

What are the three types of neurons?

Answer 8

sensory (unipolar) neurons
relay (multipolar) neurons
motor (multipolar) neurons

Question 9

What are sensory neurons?

Answer 9

they relay information from the sense organs and sensory receptors to the brain or other body structures

Question 10

What are relay neurons?

Answer 10

these relay information from one neuron to another. they are mainly between sensory and motor neuron

Question 11

What are motor neurons?

Answer 11

nerve all forming part of a pathway along which impulse pass from the brain or spinal cord to muscle or gland..

Question 12

What are the 7 steps in a synaptic transmission?

Answer 12

1. a dendrite picks up a message and then sends an impulse through the cell body and along the axon to the terminal button
2. the action potential now it needs to be transferred to another neuron by crossing the synaptic gap
3. at the end of the terminal button there are synaptic vesicles that contain and store NTs. these NTs convert the electrical impulse to a chemical message that is transferred to the next neuron
4. when the impulse reaches the synaptic vesicle, they release the NT that the crosses the synaptic gap
5. the NT diffuses across the synaptic gap, and binds to specialised receptors on the surface of the next cell
6. once the next cell is activated the receptor molecules produce either an excitatory effect or inhibitory effect at a post synaptic level
7. synaptic transmission is completed by a process called re-uptake. This is where the NT is taken back up by the pre-synaptic neuron

Question 13

What are neurotransmitters?

Answer 13

chemical messengers stored in the terminal button/synaptic knob. They are released into the synaptic cleft and diffused across it. they then fit into receptor sites on the post synaptic membrane

Question 14

What happens if neurotransmitters create excitation of the post synaptic ?

Answer 14

they increase its charge and make it more likely to fire. This rise in action potential will increase activity.

Question 15

What happens if neurotransmitters create inhibition of the post synaptic ?

Answer 15

they will create a negative charge and make other cells less likely to fire. This fall in the action potential will decrease activity

Question 16

What is the overall/net effect of excitatory and inhibitory neurotransmitters?

Answer 16

the influences of the two are summed together and if the overall effect on the post synaptic neuron in inhibitory, the neuron will less likely to ‘fire’ and vice versa

Question 17

What are two examples of excitatory neurotransmitters?

Answer 17

Glutamate

Acetylcholine

Question 18

What are two examples of inhibitory neurotransmitters?

Answer 18

Gamma-Aminobutyric Acid (GABA)

Glycine