Neurons and Synaptic Transmission

Question 1

what are the three neurons?

Answer 1

• sensory, relay and motor

Question 2

what is the sensory neuron?

Answer 2

• input
• sends sensory information(vision, touch and taste) from the peripheral nervous system to the central nervous system(brain)

Question 3

where are the sensory neurons located?

Answer 3

in the peripheral nervous system, in clusters known as ganglia

Question 4

what is the relay neuron?

Answer 4

connects sensory and motor neurons`
- connector

Question 5

what is the location of the relay neurons?

Answer 5

central nervous system (brain)

Question 6

what is the motor neuron?

Answer 6

sends messages via long axons from the brain to the muscles

Question 7

what is the location of the motor neurons?

Answer 7

• the cell bodies of motor neurons are in the CNS
• they have long axons which extend into the PNS

Question 8

where does electrical transmission take place?`

Answer 8

within neurons

Question 9

what is the process of electrical transmission?

Answer 9

• neuron in a resting state, inside of the cell is negatively charged
• neuron is activated by a stimulus
• the inside of the cell becomes positively charged
• causes an action potential
• the electrical impulse travels down the axon towards the end of the neuron

Question 10

where does synaptic transmission take place?

Answer 10

between neurons

Question 11

what is the process of synaptic transmission?

Answer 11

• electrical impulse reaches the end of the neuron (presynaptic terminal)
• it triggers the release of neurotransmitters (chemicals) from tiny sacs called synaptic vesicles
• the neurotransmitter diffuses across the synapse, and binds to the post-synpatic receptor site of the dendrite of the next neuron
• the chemical message is converted back into an electrical impulse

Question 12

what direction does synaptic transmission take place?

Answer 12

in one direction

Question 13

why does synaptic transmission take place in one direction?

Answer 13

neurotransmitters are released from the presynaptic neuron and received from the post-synaptic neuron
- neurotransmitters diffuse down a concentration gradient(high conc to low conc)

Question 14

what effect can neurotransmitters have?

Answer 14

neurotransmitters either have an excitatory or inhibitory effect on the next neuron

Question 15

what is meant by a neurotransmitter having an excitatory effect of the next neuron?

Answer 15

makes the next neuron positively charged and more likely to fire an impulse
- e.g. adrenaline

Question 16

what is meant by a neurotransmitter having an inhibitory effect of the next neuron?

Answer 16

makes the next neuron negatively charged and less likely to fire an impulse
- e.g. serotonin

Question 17

what is summation?

Answer 17

• the excitatory and inhibitory influences are summed
• if the net effect on the postsynaptic neuron is inhibitory = the neuron is less likely to fire
• if the net effect on the postsynaptic neuron is excitatory = the neuron is more likely to fire

Question 18

what is the structure of neurons?

Answer 18

• cell body includes a nucleus, which contains genetic material of the cell
• cell body has dendrites, carry nerve impulses from neighbouring neurons towards the cell body
• axon carries impulses away from the cell body
• axon is covered in a fatty layer of myelin sheath (protects the axon and speeds up electrical transmission of the impulse)
• myelin sheath is segmented by gape called nodes of ranvier
• at the end of acxons there are terminal buttons