Biopsychology- Nervous and Synaptic Transmission

Question 1

what does neuron mean?

Answer 1

Basic building blacks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals.

Question 2

What is sensory neurons?

Answer 2

These carry messages from the PNS to the CNS. They have :

• long dendrites
• short axon

Question 3

What is relay neuron?

Answer 3

These connect the sensory neuron to motor or relay neurons. They have:

• short dendrites
• Short axons

Question 4

What is a motor neuron?

Answer 4

These connect the CNS to effectors such as muscles and . They have:

• short dendrites
• Long axon

Question 5

How man neurons are in the body?

Answer 5

There are 100 billion neurons 9nerve cell) in the human nervous system, 80% of which are located in the brain. By transmitting signals electrically and chemically these neurons provide the nervous system with its primary means of communication

Question 6

How many types of neurons are there

Answer 6

3 which are:

• Motor
• Relay
• Sensory

-LOOK AT IMAGES TO DIFFERENTIATE BETWEEN THEM

Question 7

What is the structure of a neuron?

Answer 7

Neuron vary in size form less than a millimetre to up to a metre long but all share the same basic structure.

Question 8

What is/ does the cell body do

Answer 8

The cell body includes a nucleus, which contains the genetic material of the cell. Branch like structures called dendrites protrude form the cell body.

Question 9

What does dendrites do?

Answer 9

These carry nerve impulses form neighbouring neurons towards the cell body.

Question 10

What is/ does the axon do?

Answer 10

The axon carries the impulses away from the cell body down the length of the neuron. The axon is covered in a fatty layer of myelin sheath that protects the axon and speeds up the electrical transmission of the impulse.

Question 11

What would happen if the myelin sheath was continuous?

Answer 11

If it was continuous this would have the reverse effect and slow down the electrical impulses.

Question 12

What is the node if Ranvier?

Answer 12

Myelin sheath is segmented by gaps - nodes of Ranvier. These speed up the transmission of the impulses by forcing it to jump across the gaps on the axon.

Question 13

What does the axon terminal do?

Answer 13

Its at the end of the axon. The terminal buttons communicate with the next neuron in the neuron across the gap - synapse.

Question 14

What happens during electrical transmission- firing of a neuron?

Answer 14

When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside. When a neuron 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 the neuron

Question 15

What is chemical transmission- synapse?

Answer 15

Neurons communicate with each other within groups known as neural networks. Each neuron us separated form the next by a tiny gap called the synapse. Signal’s within neurons are transmitted electrically, however signals between neurons are transmitted chemically across the synapse. When the electrical impulse reaches the end of the neuron (presynaptic terminal) it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.

Question 16

What are neurotransmitters?

Answer 16

they’re chemicals that diffuse across the synapse to the next neuron in the chain.

Question 17

What happens when the neurotransmitter crosses the gap?

Answer 17

Once the neurotransmitter crosses the gap, it is taken up by the postsynaptic receptor sites (the dendrites of the next neuron)
here, the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron

Question 18

What does each neurotransmitter have.

Answer 18

Several dozen types if neurotransmitter have been identified in the brain. Each neurotransmitter has its own specific molecular structure that fits perfectly into a post synaptic receptor site.(lock and key). Neurotransmitters also have specialist functions, for example, acetylcholine (ACh) is found at each point where a motor neuron meets a muscle and upon release they will cause muscles to contract

Question 19

What is excitation and inhibition?

Answer 19

Neurotransmitters have either excitory or inhibitory effects on the neighbouring neuron.
for instance, the neurotransmitter serotonin causes inhibition in the recieving neuron resulting in the neuron becoming more negatively charged and less likely to fire. In contrast, adrenaline causes excitation of the postsynaptic neuron by increasing it’s positive charge and making it more likely to fire

Question 20

What is summation?

Answer 20

The question of whether a postsynaptic neuron does fire is decided by the process of summation. The excitatory ad inhibitory influences are summed: if the net effect on the postsynaptic neuron is inhibitory then the postsynaptic neuron is less likely to fire: if the net effect is excitatory it is more likely to fire- and the inside of the post synaptic becomes positively charges. Once the electrical impulse is crated it travels down the neuron
Therefore, the action potential of the postsynaptic neuron is only triggers of the sum of the excitatory and inhibitory signals at any one time reaches the threshold.

Question 21

What the difference between excitation and inhibition?

Answer 21

Excitation increase the likelihood that the neuron will fire and pass on the electrical impulse.
-Inhibition DECREASES the likelihood that the neuron will fire and pass on the electrical impulse.