B10: The Human Nervous System

Question 1

What is homeostasis?

Answer 1

The regulation of the internal condition of the body to maintain optimum conditions for function in response to external changes.

Question 2

What are internal conditions which can be controlled?

Answer 2

• Water levels
• Blood glucose concentration
• Body temperature (37*C)

Question 3

What are the two Automatic Control Systems in the body?

Answer 3

• Nervous System

- Endocrine System

Question 4

What are the two main parts of the nervous system?

Answer 4

• The Central Nervous System (Brain and Spinal Cord)

- The Peripheral Nervous System (Nerves)

Question 5

What does the Nervous System respond to?

Answer 5

A stimulus/stimuli

Change in the environment

Question 6

How are stimuli detected?

Answer 6

Stimuli is picked up by receptors in our sense organs

Question 7

Name the five main sense organs and the stimuli they detect

Answer 7

Eyes - Light
Ears - Sound
Tongue - Chemicals (Taste)
Nose - Chemicals (Smell)
Skin - Touch, pressure, pain, temperature

Question 8

What are the three types of neurons and what do they do?

Answer 8

• Sensory neuron (sense organ to CNS) (converts stimuli to impulses)
• Relay neuron (transmits impulse to neuron from CNS)
• Motor neuron (relay neuron to effectors)

Question 9

What are the four parts of a neuron?

Answer 9

• Cell Body
• Axon
• Myelin Sheath
• Dendrites

Question 10

How is the neuron adapted for its purpose?

Answer 10

• The myelin sheath insulates the impulse and speeds up transmission
• The ends are highly branched to communicate with many different neurons

Question 11

Pathway of a nerve impulse (conscious action)

Answer 11

• A stimulus is detected by receptors in a sense organ e.g. the eyes
• The stimulus is converted to an electrical impulse by the receptor
• The electrical impulse travels along a sensory neuron to the brain (CNS)
• The brain decides the correct response that is required
• The electrical impulse is passed to a relay neuron in the brain
• The relay neuron passes the electrical impulse to a motor neuron
• The electrical impulse travels along the motor neuron to the effector
• The effector carries out the response

Question 12

What is a synapse?

Answer 12

A gap between neurons

Question 13

How does the synapse alter the function of the nervous system?

Answer 13

Electrical impulses can’t cross these gaps, so neurotransmitter chemicals are released across the gap.