biopsych - neurons/synaptic transmissions

Question 1

3 types of neurones

Answer 1

• motor
• relay
• sensory

Question 2

structure of neurones

Answer 2

• cell body includes a nucleus = contains genetic material of cell
• dendrites = carry nerve impulses towards cell body
• axon = carries impulses away from cell body
• axon covered in myelin sheath = protects axon & speeds up transmission of electric impulse
• myelin sheath segmented by nodes of Ranvier = speed up transmission of impulse by forcing it to ‘jump’
• terminal buttons at end of axon = communicate with next neurone across gap (synapse)

Question 3

describe the locations of the neurones

Answer 3

• motor neurones = cell body in CNS but have long axons which from part of PNS
• sensory neurones = outside of CNS, in clusters (ganglia)
• relay neurones = make up 97% of neurones & most found in brain/visual system

Question 4

when is the inside of a neurone negatively charged

Answer 4

neurone is in resting state

Question 5

when does the inside of a neurone become positively charged

Answer 5

• neuron activated by stimulus
• causes an action potential
• creates electrical impulse to travel down axon towards end of neuron

Question 6

neural networks

Answer 6

neurons communicate with each other in groups

Question 7

how are signals transmitted between/within neurones

Answer 7

between = chemically
within = electrically

Question 8

what happens when the electrical impulse reaches the presynaptic terminal

Answer 8

triggers release of neurotransmitter from synaptic vesicles

Question 9

what are neurotransmitters

Answer 9

chemicals which diffuse across synapse to next neurone

Question 10

what happens once the neurotransmitter has diffused across the synapse

Answer 10

• taken up by postsynaptic receptor site on dendrites of next neuron
• chemical message converted to electrical impulse

Question 11

direction of travel in neurones

Answer 11

one-way

Question 12

types of neurotransmitters

Answer 12

• excitatory
• inhibitory

Question 13

inhibition

Answer 13

eg. seretonin
causes inhibition in receiving neuron, resulting in neuron becoming more negatively charged & less likely to fire

Question 14

excitation

Answer 14

eg. adrenaline
causes excitation in post-synaptic neuron by increasing positive charge & making more likely to fire

Question 15

describe summation

Answer 15

• whether a postsynaptic neurone fires is decided by process of summation
• excitatory & inhibitory influences are summed = net effect of on postsynaptic neuron is inhibitory then neuron less likely to fire (net effect is excitatory, then more likely to fire)
• action potential of postsynaptic neuron is triggered if sum of excitatory/inhibitory signals reaches a threshold