Pupil dilation and contraction (7)

Question 1

What are receptors?

Answer 1

specific cells or proteins which detect one specific stimulus.

Question 2

What happens when a receptor is stimulated?

Answer 2

An action potential is produced.

Question 3

What is the state of a resting receptor?

Answer 3

Polarised

Question 4

What’s an effector? Give two examples.

Answer 4

A cell that brings about a response to a stimulus to produce an effect.

Muscle cells and cells found in glands eg, pancreas

Question 5

How do recptors and effectors communicate?

Answer 5

via the nervous system or the hormonal system

Question 6

What occurs to the pupil in the dark? Give the steps

Answer 6

1. Photoreceptors detect lack of light
2. Sensory neurones send this info to the CNS
3. CNS processes the info
4. Motor neurones send an impulse to an effector
5. The effector, in this case the radial muscles of the iris, are stimulated by the motor neurones
6. The radial muscles contract and the circular muscles relax in order to dilate the pupils

Question 7

What occurs to the pupil in bright light> Give the steps.

Answer 7

1. Photoreceptors detect bright light
2. Sensory neurones send this info to the CNS
3. CNS processes the info
4. Motor neurones send an impulse to an effector
5. The effector, in this case the radial muscles of the iris, are stimulated by the motor neurones
6. The circular muscles in the iris contact and the radial muscles relax in order to constrict the pupil.

Question 8

How do the muscles of the iris work?

Answer 8

Antagonistacally