5.2 Human Nervous System

Question 1

What is the function of the nervous system?

Answer 1

The nervous system allows the body to react to its surroundings and coordinate an appropriate response

Question 2

How does a stimulus lead to a response being carried out by the body?

Answer 2

● Stimulus is converted into an electrical impulse by the receptors.
● The electrical impulse passes along sensory neurones to the central nervous system (CNS).
● The CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector, which carries out the response.

Question 3

What sequence of events describes how the nervous system works?

Answer 3

Stimulus → receptor → coordinator → effector → response

Question 4

What is a reflex action?

Answer 4

A reflex action is an automatic and rapid response which does not involve any conscious input from the brain.

Question 5

Why are reflex actions important?

Answer 5

Reflex actions aid survival by preventing harm to the body.

Question 6

Describe how a reflex action occurs via a reflex arc

Answer 6

● The stimulus is detected by a receptor.
● An electrical impulse passes along a sensory neurone to the spinal cord (part of the CNS).
● At a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap and stimulates a new impulse which passes along the relay neurone.
● The same process occurs at a synapse between a relay neurone and a motor neurone.
● At the effector, an appropriate response is carried out.

Question 7

What is the difference between a reflex pathway and a conscious pathway?

Answer 7

Within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord/unconscious parts of the brain. In a conscious pathway, the coordination centre is in the conscious part of the brain.

Question 8

Why is the investigation and treatment of the brain difficult? (higher)

Answer 8

● Complex and delicate organ.
● Easily damaged and destroyed.
● Certain membranes prevent drugs from reaching the brain.
● The exact function of each part of the brain is not known.

Question 9

What methods are used by scientists to determine brain function? (higher)

Answer 9

● Studying patients with brain damage
● Electrical stimulation of the brain
● MRI scans