The Nervous System

Question 1

What is the nervous system?

Answer 1

Transmits impulses from one part of the body to another using neurons
It consists of the central nervous system (CNS) and the peripheral nervous system (PNS)

Question 2

What is the central nervous system?

Answer 2

Consists of the brain and the spinal cord
Coordinates essential functions e.g breathing

Question 3

What are the 2 main functions of the CNS?

Answer 3

The control of behaviour
The regulation of the body’s physiological processes

Question 4

What’s the peripheral nervous system?

Answer 4

Sends information to the CNS from the outside world and transmits messages from the CNS to muscles and glands

Question 5

The PNS is subdivided into the _____________ and the _____________ nervous system

Answer 5

Autonomic nervous system
Somatic nervous system

Question 6

What is the function of the somatic nervous system?

Answer 6

Transmits information from receptor cells in the sense organs to the CNS
Receives information from the CNS that directs muscles to act
-has sensory and motor pathways

Question 7

What is the function of the autonomic nervous system?

Answer 7

Responsible for unconscious bodily functions
- has motor pathways

Question 8

The autonomic nervous system is divided into 2 systems called …

Answer 8

The sympathetic nervous system and the parasympathetic nervous system

Question 9

What does the sympathetic nervous system do?

Answer 9

Coordinates organs when in situations that need the individual to be aroused and expend energy
It signals our heart and lungs to work harder and our liver to release glucose
(Fight or flight)

Question 10

What does the parasympathetic nervous system do?

Answer 10

Coordinates our organs when we relax and conserve energy
Promotes digestion and slows our heart and breathing

Question 11

Define ‘neuron’

Answer 11

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

Question 12

Whats the function of dendrites?

Answer 12

Receive signals from other neutrons or from sensory receptor cells

Question 13

What is the axon?

Answer 13

A long slender fibre that carries nerve impulses in the form of an electrical signal (action potential)

Question 14

What is the function of the myelin sheath?

Answer 14

Insulates the axon so electrical impulses travel faster along the axon

Question 15

Whats the function of the axon terminals?

Answer 15

Connects the neuron to other neurons using synaptic transmission

Question 16

What does a motor neuron look like and what is its function?

Answer 16

It is the usual neuron that is shown
It carries impulses from the CNS to other areas of the body and triggers muscle movement by releasing neurotransmitters that bind to muscle receptors

Question 17

What does a relay neuron look like and what is it’s function?

Answer 17

Theres no myelin sheath and it has a very short axon
Unipolar neurons that are involved in analysing sensations and decision making in the brain

Question 18

What does a sensory neuron look like and what is it’s function?

Answer 18

The cell body is in the middle
Transmits nerve impulses from sensory receptors to the brain and spinal cord

Question 19

If the sensory impulses don’t reach the brain causing a sensation, what happens instead?

Answer 19

Some neurons terminate in the spinal cord which allows for reflex actions to occur quickly without the delay of sending impulses to the brain first

Question 20

Which two neurons are multipolar and why?

Answer 20

Motor and relay
- they send and receive impulses from many sources
Sensory is unipolar as it only sends impulses

Question 21

Define synaptic transmission

Answer 21

The process by which neighbouring neurons communicate with each other by sending chemical messages acrosss the synapse

Question 22

What’s a neurotransmitter?

Answer 22

Chemicals released from synaptic vesicles that relay signals across the synapse

Question 23

What is the process of synaptic transmission?

Answer 23

1. Information is passed down the axon as an electrical impulse known as action potential
2. Once the action potential reaches the axon terminal of the presynaptic cell, the impulse needs to be transferred
3. The action potential stimulates the release of neurotransmitters from the synaptic vesicles (which are at the end of the axon terminals)
4. The neurotransmitters carry the signal across the synaptic gap and bind to the receptor sites on the post synaptic cell
5. Stimulation of the post synaptic receptors by neurotransmitters produce excitatory or inhibitory effects on the cell membrane - excitatory neurotransmitters make the cell more likely to fire, inhibitory neurotransmitters make them less likely to fire
   - summation is the net effects of the excitatory and inhibitory potentials

Question 24

How is excitation and inhibition are involved in synaptic transmission?

Answer 24

Neurotransmitters can be excitatory or inhibitory
If the neurotransmitter is excitatory then the post synaptic neuron is more likely to fire an impulse
If the neurotransmitter is inhibitory then the post synaptic neuron is less likely to fire an impulse
The excitatory and inhibitory influences are ‘summed’ , if the net effect is inhibitory then the neuron is less likely to fire and if the net effect is excitatory the neuron is more likely to fire