13.3 Sensory Receptors

Question 1

What is a sensory receptor?

Answer 1

specialised cell

which detects a stimulus.

Question 2

What are the 2 properties of sensory receptors?

Answer 2

1. SPECIFIC (only detect 1 type of stimulus)
2. TRANSDUCERS (convert 1 type of energy into another, e.g stimulus ⟶ nerve impulse)

Question 3

Outline the mechanism by which a sodium stretch-channel induces a generator potential:

Answer 3

1. Pressure causes axon membrane to stretch & sodium stretch-channels to open.
2. Sodium ions diffuse into axon, depolarising membrane.
3. Membrane reaches generator potential.

Question 4

What is the name of the type of sensory receptor detecting mechanical pressure in humans?

Answer 4

pacinian corpuscle

Question 5

Outline the mechanism by which the human body detects mechanical pressure:

Answer 5

1. Pressure applied >> pacinian corpuscle changes shape, membrane stretches
2. Sodium stretch-channels open.
3. Na⁺ diffuses ⟶ axon, depolarises membrane until generator potential reached.
4. @ generator potential, voltage-gated Na⁺ channels open.
5. Na⁺ influx causes further depolarisation >> action potential.
6. Action potential transmitted along neurones ⟶ CNS

Question 6

What is the function of a pacinian corpuscle?

Answer 6

To act as a transducer,

detecting mechanical pressure & converting it to an electrical impulse

Question 7

What is the general structure of a pacinian corpuscle?

Answer 7