8.1.3 - Nervous System: Response To A Stimulus

Question 1

Describe How The Nervous System Responds To A Stimulus
(3 Points)

Answer 1

~ Receptor cells detect the stimulus, causing an electrical impulse to be sent along the sensory neurone.

~ When the electrical impulse reaches the end of the neurone, neurotransmitters take information to the next neurone.

~ Once it reaches the CNS, it is processed and sent along motor neurones to effectors.

Question 2

What Is The Nerve Impulse Pathway?

Answer 2

Stimulus -> Receptor -> Sensory Neurone -> CNS -> Motor Neurone -> Effector

Question 3

What Determines The Diameter Of The Pupil?
(3 Points)

Answer 3

~ Circular muscles, that constrict the pupil.

~ Radial muscles, that dilate the pupil.

~ They work antagonistically.

Question 4

Describe How The Eye Responds To Bright Light
(5 Points)

Answer 4

~ Photoreceptors detect the bright light.

~ Impulse is passed along the sensory neurone.

~ CNS then processes the information.

~ Motor neurones carry the impulse to the effectors (Circular muscles).

~ Circular muscles in the iris contract to constrict the pupils.

Question 5

Why Do The Circular Muscles Constrict The Pupils, When In Contact With Bright Light?
(2 Points)

Answer 5

~ To limit the amount of light entering the eye.

~ Preventing damage to the retina.

Question 6

Describe How The Eye Responds To Dim Light
(5 Points)

Answer 6

~ Photoreceptors detect the dim light.

~ Impulse is passed along the sensory neurone.

~ CNS then processes the information.

~ Motor neurones carry the impulse to the effectors (Circular muscles).

~ Radial muscles in the iris contract to dilate the pupils.

Question 7

Why Do The Radial Muscles Dilate The Pupils, When In Contact With Dim Light?
(2 Points)

Answer 7

~ To maximise the amount of light entering the eye.

~ Improving vision.