Neurons, Synaptic transmission and neurotransmitters

Question 1

What is a neuron?

Answer 1

The basic building block of the nervous system. Neurons are nerve cells that process and transmit messages through electrical and chemical signals.

Question 2

What are neurotransmitters?

Answer 2

Brain chemicals released from synaptic vesicles. Neurotransmitters relay signals from one neuron to another across a synapse. Neurotransmitters can be broadly divided into those that perform and excitatory function and those that perform an inhibitory function.

Question 3

What is synaptic transmission?

Answer 3

The process by which neighbouring neurons communicate with each other by sending chemical messages across a tiny gap (the synapse) that seperates neurons.

Question 4

What consists in the basic structure of a neuron?

Answer 4

-The cell body (soma)
-The axon
-Terminal buttons
-Dendrites
-Nucleus

Question 5

What is the role of the cell body?

Answer 5

-Includes the nucleus containing genetic material

Question 6

What is the role of the denrites?

Answer 6

These carry impulses from neighbouring neurons towards the cell body

Question 7

What is the role of the axon?

Answer 7

Is a tube like structure that carries the impulese away from the cell body down the length of the neuron

Question 8

What is the fatty layer (myelin sheath)?

Answer 8

Formed from special cells which wrap themselves around the axon
It both protects the axon and speeds up electrical transmission of the impulse.
Gaps in the myelin sheath- called the noded of ranvier- allow for this increase in speed by forcing the impulse to jump acrosee the gaps along the length of the axon.

Question 9

What are the roles of the terminal buttons?

Answer 9

These are not physically connected to the next neuron in the chain, but are involvede in communication across a gap known as the synapse.

Question 10

What are the 3 types of neurons?

Answer 10

-Sensory
-Motor
-Relay

Question 11

What is the role of a sensory neuron?

Answer 11

They carry messages from sensory receptors along nerves in the peripheral nervous system (PNS)to the central nervous system (CNS). They have long dendrites and short axons.

Question 12

What is the role of a motor neuron?

Answer 12

They carry messages from the CNS, along nerves in the PNS, to effectors in the body (e.g. muscles and glands). They have short dendrites and long axons.

Question 13

What is the role of the relay neuron?

Answer 13

They connect sensory and motor neurons together and also connect to other relay neurons. They have short dendrites and short axons and are only found in the CNS.

Question 14

When a neuron is in resting state, what charge is inside the cell?

Answer 14

Negative

Question 15

When a neuron is activated, what icharge is the inside of the cell?

Answer 15

Positive (for a split second)

Question 16

What is the rapid switch from negative and postive charge called in a cell?

Answer 16

Depolarisation.

Question 17

What does depolarisation create?

Answer 17

An electrical impulse (action potential AP)

Question 18

When is the AP generated?

Answer 18

Once depolarisation reaches a certain threshhold

Question 19

Does the instensity of AP depend on the stimulus?

Answer 19

No. It is always the same intensity regardless of the size of the stimulus

Question 20

How much can most myelinated neurons conduct?

Answer 20

Up to 500 action-potential a second

Question 21

Is synaptic transmission chemical or electrical?

Answer 21

chemical

Question 22

What are the biochemical substances used in synaptic transmission?

Answer 22

neurotransmitters

Question 23

Where are neurotransmitters released from?

Answer 23

Synaptic vesicles

Question 24

Where do the neurotransmitters go after crossing the synapse?

Answer 24

Receptors on the postsynaptic neuron

Question 25

What happens to the neurotransmitters that are in the postsynaptic neuron?

Answer 25

Converted back into an electrical signal - may fire another AP

Question 26

Where do the remaining neurotransmitters that are left in the synapse go?

Answer 26

They are reabsorbed into the presynaptic neuron (usually broken down first).

Question 27

What is the reabsorption of neurotransmitters called?

Answer 27

Reuptake

Question 28

What are the 2 types of neurotransmitters called?

Answer 28

Excitation and Inhibitation

Question 29

Why is seretonin an inhibitory neurotransmitter?

Answer 29

When in the postsynaptic neuron it makes the neuron more negative and less likely to fire

Question 30

Why is dopamine a excitation neurotransmitter?

Answer 30

When in the postsynaptic neuron- it increases the positive charge making it more likely to fire.

Question 31

What is the adding together of signals overtime called?

Answer 31

summation