Biopsych: Neurons and synaptic transmission

Question 1

What’s a neuron?

Answer 1

cells that are specialised to carry neural info throughout the body

Question 2

3 types of neuron?

Answer 2

sensory
relay
motor

Question 3

What does a sensory neuron do?

Answer 3

carries nerve impulses from sensory receptors – receptors for vision, touch and taste (which are found in the eyes, ears, tongue and skin) to the spinal cord and brain.
Sensory neurons convert information from sensory receptors to neural impulses.

When these impulses reach the brain they’re translated to sensations e.g., heat or pain so that the organism can act accordingly. Has long dendrites and short axons.

Question 4

What’s a reflex action + when do they occur?

Answer 4

not all sensory neurons travel as far as the brain with some terminating at the spinal cord which allows reflex actions to occur quickly without the delay of sending impulses to the brain.

Question 5

What does a relay neuron do + where’s it located?

Answer 5

located within the brain and spinal cord. Connects the sensory neurones to other relay or motor neurones. Has short dendrites and short axons.

Question 6

What does the motor neuron do?

Answer 6

Connects the CNS to effectors such as muscles and glands. Takes impulses from relay neurons to muscles around the body. Has short dendrites and long axons.

Question 7

what’s the cell body?

Answer 7

includes a nucleus which contains the genetic material of the cell

Question 8

What’s a dendrite?

Answer 8

branches carrying the nerve impulses from other neurons towards the cell body

Question 9

what’s an axon?

Answer 9

carries electrical impulses away from the cell body down the length of the neuron, covered with a fatty layer of myelin sheath which protects the axon.

Gaps in the axon are called nodes of Ranvier, which speeds up transmission.

Question 10

What’s synaptic transmissions?

Answer 10

The process by which a nerve impulse passes across the synaptic cleft from one neuron to another.

Question 11

What’s the 1st step of synaptic transmission?

Answer 11

Action potential (impulse) arrives at presynaptic membrane which causes the vesicles (containing neurotransmitter) to fuse with the presynaptic membrane.

Question 12

What’s the 2nd step of synaptic transmission?

Answer 12

Once the vesicle is fused to the pre-synaptic membrane releases their contents into the synaptic gap through exocytosis.

Question 13

What’s the 3rd step of synaptic transmission?

Answer 13

The neurotransmitter diffuses across the synaptic gap, down the concentration gradient. Then binds to complementary receptors on post-synaptic membrane.

Question 14

What’s the 4th step of synaptic transmission?

Answer 14

Receptors produce an excitatory or inhibitory effect resulting in action potential transmits along the post-synaptic neurone.

Question 15

What’s re-uptake?

Answer 15

when a neurotransmitter is taken up again by the pre-synaptic neurone. The speed of this determines how prolonged the effects will be.

Question 16

What’s an excitatory neurotransmitter?

Answer 16

increase the potential difference across the post-synaptic membrane, which increases the likelihood that an action potential will be generated. An example of an excitatory neurotransmitter is Dopamine.

Question 17

What’s an inhibitory neurotransmitter?

Answer 17

reduce the potential difference across the post-synaptic membrane, which decreases the likelihood that an action potential will be generated. An example of an Inhibitory neurotransmitter is Serotonin.

Question 18

What’s summation?

Answer 18

the calculation involving adding the excitatory and inhibitory synaptic input that indicates whether it was excitatory or inhibitory – determining of action potential is induced.