5.3.1: Roles of Sensory Receptors

Question 1

Define pacinian corpuscle

Answer 1

A pressure sensor found in the skin.

Question 2

What are sensory receptors

Answer 2

specialised cells that detect changes in our surroundings. Most are energy transducers that convert one form of energy to another.

Question 3

When there is a stimulus, how does the sensory receptor respond?

Answer 3

By creating a signal in the form of electrical energy, this is called a nerve impulse.

Question 4

Stimulus: change in light intensity.

What are the sensory receptors and what is the energy change involved?

Answer 4

• Light sensitive cells (rods and cones) in the retina.

- Light to electrical.

Question 5

Stimulus: change in temperature

What are the sensory receptors and what is the energy change involved?

Answer 5

• Temperature receptors in skin and hypothalamus.

- Heat to electrical.

Question 6

Stimulus: change in pressure on the skin.

What are the sensory receptors and what is the energy change involved?

Answer 6

• Pacinian corpuscles in the skin.

- Movement to electrical .

Question 7

Stimulus: change in sound.

What are the sensory receptors and what is the energy change involved?

Answer 7

• Vibration receptors in the cochlea of the ear.

- Movement to electrical.

Question 8

Stimulus: movement

What are the sensory receptors and what is the energy change involved?

Answer 8

• Hair cells in inner ear.

- Movement to electrical.

Question 9

Stimulus: change in length of muscle

What are the sensory receptors and what is the energy change involved?

Answer 9

• Muscle spindles in skeletal muscles.

- Movement to electrical.

Question 10

Stimulus: chemicals in the air.

What are the sensory receptors and what is the energy change involved?

Answer 10

• Olfactory cells in the epithelium lining of the nose.

- These receptors detect an presence of a chemical and create an electrical nerve impulse.

Question 11

Stimulus: chemicals in food

What are the sensory receptors and what is the energy change involved?

Answer 11

• Chemical receptors in taste buds on tongue.

- These receptors detect an presence of a chemical and create an electrical nerve impulse.

Question 12

What is a Pacinian corpuscle?

Answer 12

A pressure sensor that detects a change in pressure in the skin.

Question 13

What does a Pacinian corpuscle look like?

Answer 13

Oval shaped structure consisting of a series on concentric rings of connected tissue wrapped around the end of a nerve cell.

Question 14

What happens to the Pacinian corpuscle when pressure on the skin changes?

Answer 14

Pressure deforms the rings of connective tissue and pushes against the nerve ending.

Question 15

Why do the corpuscles stop responding when pressure is constant?

Answer 15

The corpuscle is sensitive to only changes in pressure that deform the rings of consecutive tissue.

Question 16

What are sodium channels sensitive to and how does this allow them to create a generator potential?

Answer 16

• Small movements of the membrane, so when the membrane is deformed by the changing pressure, sodium channels open.
• This allows sodium ions to diffuse into the cell, producing a generator potential.

Question 17

How do sodium potassium pumps work?

Answer 17

They pump three sodium ions out for every two potassium ions they pump in.
When the channel proteins are all closed, the sodium/potassium pumps work to create a concentration gradient.

Question 18

Why can some potassium ions leak out of the cell?

Answer 18

Because the membrane is more permeable to potassium ions.

Question 19

What is the result of these ionic movements?

Answer 19

A potential gradient across the cell membrane. The cell is negatively charged inside compared with outside.

Question 20

What is the negative potential enhanced by?

Answer 20

The presence of negatively charged anions inside the cell.

Question 21

What is a generator potential?

Answer 21

The change in potential across a receptor membrane

Question 22

When is an action potential generated?

Answer 22

• Large enough stimulus is detected
• Opens enough sodium channels allowing enough sodium ions to enter the cell.
• Potential difference across the cell membrane changes significantly.
• Action potential created