Mammalian Sensory Receptors

Question 1

What do receptors detect?

Answer 1

A change in either internal or external environment

Question 2

Internal environment

Answer 2

Temperature or blood pressure

Question 3

External Environment

Answer 3

Spider

Question 4

What is each receptor specific to?

Answer 4

Only one stimulus

Question 5

What are receptors?

Answer 5

Are transducers which convert one form of energy into another form of energy

Question 6

Example One of Receptors

Answer 6

Photo receptors convert light energy to electrical energy

Question 7

Example Two of Receptors

Answer 7

Thermoreceptors convert light heat energy to electrical energy
-In hypothalamus (internal temp)
-In skin (external temp)

Question 8

Example Three of Receptors

Answer 8

Chemoreceptors convert chemical energy to electrical energy
-O2+CO2 in aorta/carotid artery
-Olfactory in nose
-Taste buds

Question 9

Example Four of Receptors

Answer 9

Mechanoreceptros convert movement/stretch/pressure into electrical energy
-e.g. Parcinian Corpuscle

Question 10

Diagram of Parcinian Corpuscles at rest/not being touched

Answer 10

See Notes

Question 11

First step of Parcinian Corpuscles at rest/not being touched

Answer 11

-Sodium potassium pumps, pump 3 NA+ out for every 1/2 K+ in.
-Cause the parcinian corpuscle to become more positive on outside/more negative on inside

Question 12

Second step of Parcinian Corpuscles at rest/not being touched

Answer 12

There are some non-gated potassium channels in the membrane so some potassium diffuses out by facilitated diffusion so it become even more positive on outside/negative on inside

Question 13

Third step of Parcinian Corpuscles at rest/not being touched

Answer 13

There are anions (positive ions) on inside so even more positive on outside and negative on inside

Question 14

What does this mean for the Parcinian Corpuscle being more positive on outside and negative on inside?

Answer 14

-Membrane is polarised
-PC has a resting potential of -70 mv

Question 15

Diagram of Parcinian Corpuscles being touched

Answer 15

See Notes

Question 16

What is the first part of when Parcinian Corpuscles are touched?

Answer 16

-Pressure is applied and causes connective tissue to stretch/deform to cause stretch-mediated channels to open so NA+ starts diffusing (facilitated) into sensory nerve ending and it become less negative on inside

Question 17

What happens as more pressure is applied?

Answer 17

More stretch mediated Na+ channel and more Na+ enter

Question 18

What is happening to the membrane?

Answer 18

Is depolarising and the amount of depolarising/Na+ entering is called the generator potential

Question 19

What happens is the generator potential reaches the threshold potential?

Answer 19

Causes the voltage gated Na+ channel to open too which causes a huge influx of Na+ into sensory nerve ending

Question 20

What is the second part of when Parcinian Corpuscles are touched?

Answer 20

When the Na+ floods in, the membrane fully depolarises and it reaches +40 mV on the inside causing an action potential in the sensory neuron

Question 21

What is all or none law?

Answer 21

An action potential either happens and ALWAYS gets to +40mV or inside or doesn’t happen at all