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

Question 32

How may serotonin and dopamine affect aggression?

Answer 32

Low levels of serotonin and high levels of dopamine have been linked to aggression; psychologists believe that low levels of serotonin, known as the body’s natural ‘happy drug’, can lead to an increase in aggression levels. This is because serotonin is thought to inhibit our response to emotional stimuli that might otherwise lead to aggressive behaviour, so low levels of serotonin mean we will respond aggressively more ofte

Question 33

How is serotonin linked to the amgydala?

Answer 33

Serotonin is a neurotransmitter that has an important role in social decision-making by inhibiting aggressive social responses. Serotonin usually reduces aggression by preventing stimulation of the amygdala, a structure in the brain's limbic system. Stimulation of the amygdala increases aggressive behaviour but serotonin prevents stimulation, thereby reducing aggression.​ If there are low levels of serotonin in the brain, there is less inhibition of the amygdala. As a result it becomes more active when stimulated by external events, causing the person to act on their impulses and making aggression more likely. Therefore, low levels of serotonin have been associated with an increased susceptibility to impulsive and aggressive behaviour.

Question 34

How did Virkunen et al prove that serotonin has an effect on aggression?

Answer 34

They compared levels of serotonin breakdown product and the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders. The levels were significantly lower in the impulsive offenders, who also suffered from more sleep irregularities. Disturbance of sleep strongly implies some disruption of serotonin functioning.

Question 35

What evidence is that that increased levels of dopamine could cause aggression?

Answer 35

Increased dopamine levels can produce increased levels of aggressive behaviour. For example, the increased rates of aggressive behaviour found in the schizophrenic population are believed to be due to the raised levels of dopamine in the brain.

Question 36

How does Lavine support hte idea that an increase level of dopamine could cause aggresion?

Answer 36

Found that an increase in dopamine levels through the use of amphetamines was associated with an increase in aggressive behaviour, suggesting that higher levels of dopamine correlate with higher levels of aggression.

Question 37

How may there be a gender bias in serotnin research?

Answer 37

There may be a gender bias in this research. Although a link was found between low levels of serotonin and aggression, this was not evident for the female participants. This suggests that the role of serotonin in aggression may be different for female compared to males, and therefore there is a gender bias in human studies in this are