3.6.1.2 Receptors

Question 1

What is the simple role of receptors?

Answer 1

• To respond to specific stimuli.

Question 2

What are the roles of baroreceptors, photoreceptors, chemoreceptors?

Answer 2

• Baroreceptors detect pressure.
• Photoreceptors detect light.
• Chemoreceptors detect chemicals.

Question 3

What is the Pacinian Corpuscle, what is it made up of?

Answer 3

• A type of baroreceptor found in the skin which detects pressure.
• Made up of sensory neurone endings wrapped in connective tissue called lamellae.

Question 4

How is a pacinian corpuscle activated?

Answer 4

1) Change in pressure causes lamellae to be deformed and press on sensory neurone endings.
2) Increase in pressure deforms the stretch mediate sodium ion channels.
3) Sodium ion channels open and doium ions diffuse in.
4) Depolarises the cell, creating a generator potential which forms an action potential if threshold is met.

Question 5

Why are rods highly sensitive to light?

Answer 5

• Many rods connect to 1 bipolar neurone, so many weak generator potentials combine to reach threshold and trigger an action potential.

Question 6

Why are cones not sensitive to light?

Answer 6

• 1 cone connects to each bipolar neurone so it takes more light to reach threshold and generate an action potential.