B10 - Nervous System

Question 1

What is homeostasis

Answer 1

Homeostasis is the regulation of internal conditions in a cell or an organism to maintain optimum conditions for functions in response to internal or external conditions

Question 2

How is homeostasis controlled

Answer 2

The body has two automatic controls for homeostasis

• The nervous system(nervous response - controlled by electrical impulses travelling through nerve cells)
• The endocrine system(chemical response - controlled by hormones travelling through the bloodstream )

Question 3

What does the nervous system respond to

Answer 3

• The nervous system responds to stimuli
• Stimuli are changes in the environment of an organism or a cell (e.g touching a hot plate)
• Stimuli are picked up by receptors in our sense organs (eyes ,ears ,mouth,skin,nose)

Question 4

How does the nervous system respond to stimuli

Answer 4

• The nervous system transmits messages as electrical impulses
• These electrical impulses are sent down nerve cells called neurons

Question 5

What are the three different types of neuron

Answer 5

• Sensory neurons ( transmit electrical impulses to the CNS -the brain)
• Relay neurons (transmit electrical impulses to the motor neurons)
• Motor neurons (transmit electrical impulses to the effector -muscle or gland-)

Question 6

How is the nerve system divided up

Answer 6

The nerve system is dived into :

• The Central nerve system (brain,spinal cord)
• The peripheral nerve system (all other nerve cells)

Question 7

Describe the pathway of nerve impulses

Answer 7

Stimulus—>receptor(where stimuli are converted to an electrical impulse)—>sensory neuron—>CNS(brain)—>relay neuron—>motor neuron—>effector(muscle or gland)—>response

Question 8

How are impulses transferred over the synapse(gap between the two neurons)

Answer 8

1. Electrical impulses reach the end of the first neuron
2. This stimulates the release of neurotransmitter chemicals
3. The neurotransmitter chemicals diffuse across the synapse
4. The neurotransmitter chemicals bind to the receptors on the neuron
5. This binding stimulates the second neuron to to transmit an electrical impulse (with the same message as the first neuron) along its axon