Organisms Respond to Changes in their Internal and External Environments - Receptors, Pacinian Corpuscle

Question 1

What type of receptors are Pacinian corpuscles?

Answer 1

• Mechanoreceptors

- Detect mechanical stimuli e.g pressure and vibrations

Question 2

Where are Pacinian corpuscles found?

Answer 2

• In skin

Question 3

Do receptors respond to a variety of different stimuli?

Answer 3

• Receptors respond only to specific stimuli

Question 4

What type of potential is established after a receptor is stimulated?

Answer 4

• Generator potential

Question 5

How does the strength of a stimulus affect the generator potential produced?

Answer 5

• The bigger the stimulus, the bigger the generator potential
• Bigger stimuli excite the membranes more, causing a bigger movement of ions and therefore a bigger change in generator potential

Question 6

Describe the structure of Pacinian corpuscles

Answer 6

• Contain a sensory nerve ending

- Sensory nerve ending is wrapped in many layers of connective tissue called lamellae

Question 7

Explain what happens when a Pacinian corpuscle is stimulated

Answer 7

• Lamellae are deformed and press on sensory nerve ending
• This causes the sensory neurone’s cell membrane to stretch, deforming the stretch-mediated sodium ion channels
• Channels open and sodium ions diffuse into the cell, creating a generator potential

Question 8

What happens if a generator potential reaches a threshold?

Answer 8

• It triggers an action potential