Neurons and Synaptic transmission

Question 1

Define neuron?

Answer 1

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

Question 2

Define sensory neurons?

Answer 2

These carry messages from the PNS to the CS. They have a long dendrite and a short axon.

Question 3

Define relay neurons?

Answer 3

These connect the sensory neurons to the motor neurons. they have a short dendrite and a short axons

Question 4

Define motor neurons?

Answer 4

These connect the CNS to affect things such as muscles and glands. They have short dendrites and long axons

Question 5

Where are neurotransmitters found?

Answer 5

There are a hundred billion neurotransmitters in the human NS - 80% of which are located in the brain

Question 6

What do neurons provide the nervous system with?

Answer 6

It’s primary means of communication by transmitting signals electrically and chemically

Question 7

What are the three types of neurons?

Answer 7

Sensory
Relay
Motor

Question 8

What is similar across neurons and whats the same?

Answer 8

Vary in size (from less than a mm up to a M)A=

Share the same basic structure

Question 9

What is the structure of a neuron like?

Answer 9

The cell body contains a nucleus which contains the genetic material of the cell
Branch like structures called dendrites protrude from the cell body

Question 10

What do dendrites do?

Answer 10

Carry nerve impulses from neighbouring neurons towards the cell body

Question 11

What do axons do?

Answer 11

Carries the impulses away from the cell body down the length of the new one

Question 12

What is the axon covered in?

Answer 12

A fatty layer of mileage sheets that protects the axon at speeds of electrical transmission of the imports

Question 13

What is electric transmission?

Answer 13

The firing of a neuron when you are on in a rested state the inside of the cell is negatively charged compared to the outside. When activated by a stimulus the inside of the cell becomes positively charged for a split second course of an action potential to occur. This creates an electrical impulse travels down the axon towards the end of a neuron

Question 14

How do neurone communicate?

Answer 14

Neurons communicate with eachother within groups known as neural networks. Each neuron is separate from the next. Neurons will send signals which are transmitted electrically , however signals between neurons transmit chemically across the synapse. When the electrical impulse reaches the end of the neuron it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.

Question 15

What are neurotransmitters?

Answer 15

The chemicals that are fired across the synapse to the next neuron in the chain.

Question 16

What happens once the neurotransmitter crosses the synapse?

Answer 16

It is taken up to the post-synaptic receptors site (the dendrites of the next neuron) where the chemical message is converted back into an electrical impulse and the process of transmission begins again in this new road

Question 17

How many types of neurotransmitter have been identified in the brain?

Answer 17

Several dozen types identified in the brain as well as in the spinal cord and some clamps

Question 18

In what ways are neurotransmitters specific?

Answer 18

Each neurotransmitter has its own specific molecular structure that fits perfectly into the post-synaptic receptor site (like lock and key)
They also have specialist functions e.g CH is found at each point where a new motor neuron … it will cause muscles to contract

Question 19

What two affects can neurotransmitters have on the neighbouring neurons give examples?

Answer 19

Inhibitory or exhibitory e.g serotonin causes inhibition resulting in the neuron becoming more negatively charged and less likely to fire. Adrenaline causes excitation of the post-synaptic neuron by increasing its positive charge and making it more likely to fire

Question 20

Define synaptic transmission?

Answer 20

The process by which neighbouring neurons communicate with eachother by sending chemical messages across the gap (the synapse) that separates them

Question 21

Define neurotransmitters?

Answer 21

Brain chemicals released from synaptic vesicles is what really signals across the synapse from one neuron to another. Neurotransmitters can be broadly divided inti those that perform an excitatory function and those that perform an inhibitory function

Question 22

Define excitation?

Answer 22

When a neurotransmitter such as adrenalin increases the positive charge of the post-synaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse

Question 23

Define inhibition?

Answer 23

When a neurotransmitter, such as serotonin increases the negative charge of the post-synaptic neuron. This decreases the likelihood that a neuron will fire and pass on an electrical impulse.

Question 24

Define a hormone?

Answer 24

Hormones are chemicals that are produced by endocrine glands such as the pituitary gland . In response to signals from the brain hormones are secreted directly into the bloodstream where they travel to their target cells and exert their influence by stimulating receptors on the surface of or inside cells. The presence of a hormone causes a physiological reaction in the cells altering its activity.

Question 25

Define a neurotransmitter (long)?

Answer 25

When a nerve impulse reaches the end of one neuron, a chemical called a neurotransmitter is released. It travels from one neuron to the next across a junction called a synapse. There are many different types of neurotransmitter, some of which trigger the receiving neuron to send an impulse and some stop it from doing so. Those neurotransmitters that trigger nerve impulses in the receiving neuron and stimulate the brain into action are called excitatory neurotransmitters. Those that inhibit nerve impulses in order to calm the brain and balance mood are called inhibitory transmitters.

Question 26

What would happen if the … was continuous?

Answer 26

It would have the reverse affect and slow down the electrical impulse

Question 27

What is the neuron segmented by?

Answer 27

Gaps called nodes of Ranvier - these speed up the transmission of impulse bisphosphonate by forcing it to jump across the gaps along the axon

Question 28

What happens at the end of the axon terminal?

Answer 28

Neurons communicate with the next neuron in the chain across the synapse.