PAPER 2 - BIOPSYCHOLOGY - neurons and synaptic transmission

Question 1

what are neurons?

Answer 1

nerve cells responsible for sending and receiving neurotransmitters

Question 2

what are the basic underlying structures of neurons?

Answer 2

dendrites
cell body
axon
presynaptic terminal

Question 3

what do dendrites do?

Answer 3

receive signals from other neurons or sensory receptors

Question 4

what does the cell body do?

Answer 4

control centre of the neuron

Question 5

what does the axon do?

Answer 5

conducts nerve impulses away from the cell body and towards other neurons

Question 6

what are the 3 types of neurons?

Answer 6

motor - multipolar
relay - multipolar
sensory - unipolar

Question 7

what are sensory neurons?

Answer 7

• have cell body with 2 stems either side
• carries sensory information from the body’s sensory receptors to the spinal cord & brain
• convert information from sensory receptors to neural impulses that travel to the brain and are translated into sensations
• allows for quick reflexes

Question 8

what are motor neurons?

Answer 8

• single axon, many dendrites HAS MYELIN SHEATH
• carries info from CNS to skeletal muscles/glands allowing control of movement & responses of internal systems
• located in CNS, their axons projected outside CNS and control muscles from synapses

Question 9

what are relay neurons?

Answer 9

• cell body surrounded entirely by dendrites
• lie between sensory input and motor output
• they are neurons within the CNS that interconnect different parts of the CNS
• pass messages within the CNS and allow sensory & motor neurons to cocmmunicate

Question 10

what are nerve impulses/action potential?

Answer 10

the electrical signal formed when information travels along the axon, away from cell body to axon terminal

Question 11

what is synaptic transmission?

Answer 11

the process where a nerve impulse passes across the synaptic gap/cleft from one neuron to another

Question 12

what is the synapse?

Answer 12

• small gap between neurons
• end of one dendrite / cell body of another where neurotransmitters are released, permitting nerve impulses transmitted between neurons
• includes end of presynaptic neuron and postsynaptic neuron

Question 13

what are neurotransmitters?

Answer 13

chemical substance that transmit nerve impulses across a synapse

Question 14

what is summation?

Answer 14

when multiple changes in voltage triggered by a neurotransmitter release, add up together

Question 15

when does summation occur?

Answer 15

• if multiple nerve impulses occur in the presynaptic neuron in close succession
• if multiple nerve impulses occur at synapses on the same postsynaptic neuron at the same time

Question 16

is the process of summation excitatory/inhibitory?

Answer 16

both - excitatory and inhibitory synaptic input on post synaptic neuron

Question 17

what is the process of synaptic transmission?

Answer 17

• transmission of nerve impulses across the synapse is chemical, takes less than a second
• synaptic vesicles containing neurotransmitters stored at end of axon
• as nerve impulse/action potential travels down axon terminal, vesicles release neurotransmitter molecules to synapse
• neurotransmitter molecules diffuse across gap to postsynaptic membrane of next neuron & bind to specialised receptors
• the whole process has either excitatory or inhibitory effects on postsynaptic neuron

Question 18

what happens after synaptic transmission?

Answer 18

neurotransmitter released back into synaptic space

Question 19

the neurotransmitter is cleared from synaptic cleft by which processes?

Answer 19

diffusion - some of the neurotransmitter drifts away
break-down - some of the neurotransmitter is broken down by enzymes
re-uptake - some of it is taken back up into the presynaptic neuron, repackages & stored for later release

Question 20

what are excitatory neurotransmitters?

Answer 20

• some neurotransmitters have excitatory effects on postsynaptic neuron (make it more likely to fire)
• excitatory synaptic connections increase neural activation in the CNS

Question 21

what does an excitatory neurotransmitter binding with a postsynaptic receptor cause?

Answer 21

• causes an electrical change in the cell membrane
• this results in an excitatory postsynaptic potential (EPSP) making post synaptic cell more likely to fire

Question 22

what are inhibitory neurotransmitters?

Answer 22

• some neurotransmitters have an inhibitory effect on the postsynaptic neuron (makes it less likely to fire)
• inhibitory synaptic connections decrease neural activation in the CNS

Question 23

what does an inhibitory neurotransmitter binding with a postsynaptic receptor result in?

Answer 23

results in inhibitory postsynaptic potential (IPSP) making the postsynaptic potential less likely to fire

Question 24

can a nerve cell receive excitatory or inhibitory influences?

Answer 24

a nerve cell can receive inhibitory or excitatory influences from several transmitters at the same time

Question 25

what is whether a neuron fires determined by?

Answer 25

determined by the sum of all excitatory and inhibitory synaptic input for the postsynaptic cell