neurons and synaptic transmission

Question 1

what are neurones?

Answer 1

nerve cells that process and transmit messages through electrical and chemical signals

Question 2

describe the action of the sensory neurone

Answer 2

carry messages from the PNS or receptor site to the CNS

Question 3

describe the action of the relay neurone

Answer 3

connect the sensory neurones to the motor neurones and other relay neurones. In CNS

Question 4

describe the action of the motor neurone

Answer 4

connect the CNS to effectors such as muscles and glands

Question 5

describe the action potential of a neurone

Answer 5

when the neurone is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur. this creates an electrical impulse that travels down the axon towards the end of a neurone

Question 6

what is excitation within neurones?

Answer 6

when a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neurone. This INCREASES the likelihood that the postsynaptic neurone will pass on the electrical impulse

Question 7

what is inhibition within neurones?

Answer 7

when a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neurone. This DECREASES the likelihood that the postsynaptic neurone will pass on the electrical impulse

Question 8

how do neurones communicate with each other?

Answer 8

neural networks

Question 9

what is the gap between 2 neurones called?

Answer 9

a synapse

Question 10

what is a synapse?

Answer 10

a gap between 2 neurones

Question 11

how are signals WITHIN the neurones transmitted?

Answer 11

electrically

Question 12

how are signals BETWEEN neurones transmitted?

Answer 12

chemically

Question 13

what happens when the impulse reaches the end of the neurone?

Answer 13

neurotransmitters are released from tiny sacs called synaptic vesicles

Question 14

what is the end of the first neurone called?

Answer 14

presynaptic terminal

Question 15

explain synaptic transmission

Answer 15

The synapse is the gap between two neurones. The axon carries the electrical impulse to the presynaptic terminal. Here, the impulse is converted to a chemical impulse. Synaptic vesicles on the presynaptic terminal release neurotransmitters. These carry the impulse across the synapse. Once the neurotransmitter reach the post synaptic receptor site membrane, they bind to the receptor sites. Any that don’t bind experience re-uptake by the presynaptic terminal or are dissolved by enzymes. Then the impulse is taken electrically by the dendrites on the next neurone to begin the process again

Question 16

which part of the neurone takes the impulse TO the synapse?

Answer 16

axon

Question 17

which part of the neurone takes the impulse AWAY from the synapse?

Answer 17

dendrites

Question 18

in which direction can an impulse travel?

Answer 18

one way

Question 19

what is summation?

Answer 19

Summation is the addition of positive and negative post-synaptic potentials. A nerve cell can receive both positive and negative potentials simultaneously. These potentials are added and if the net effect on the postsynaptic neurone is inhibitory, the neurone will be less likely to fire, and if the net effect is excitatory, the neurone will be more likely to fire

Question 20

what is the role of dendrites?

Answer 20

carry nerve impulses from neighbouring neurones to the cell body

Question 21

what is the role of axons?

Answer 21

carries the impulse from the cell body down the neurone to the pre synaptic terminal

Question 22

what is the role of the myelin sheath?

Answer 22

protects the axon and speeds up the electrical transmission of the impulse

Question 23

what is the role of the nodes of ranvier?

Answer 23

speed up the transmission of the impulse by making it jump across the gaps on the axon. the gaps are the nodes

Question 24

Why can neurones only transmit info in one direction at a synapse?

Answer 24

The synaptic vesicles containing the neurotransmitter are only present on the presynaptic terminal. The receptors the neurotransmitter bind to are only present on the post synaptic neurone. The signal can only be passed on if it binds. Diffusion of the neurotransmitter mean they go from high to low concentration so can only travel one way