Sensory Receptors

Question 1

what is the role of sensory receptors?

Answer 1

convert stimulus into nerve impulse.

Question 2

what are the features of sensory receptors?

Answer 2

• specific to single type of stimulus.
• act as a transducer.

Question 3

what does a transducer do?

Answer 3

converts a stimulus into a nerve impulse (generator potential)

Question 4

what are the four main types of sensory receptors present in an animal?

Answer 4

• mechanoreceptor (pressure)
• chemoreceptor (chemicals)
• thermoreceptor (heat)
• photoreceptor (light)

Question 5

what are pacinian corpuscles?

Answer 5

specific sensory receptors which detect mechanical pressure.

Question 6

where are pacinian corpuscles located?

Answer 6

deep within skin - most abundant in the fingers and soles of the feet. also found within joints to allow to know which joints are changing direction

Question 7

what type of sodium channel does the neurone ending in the pacinian corpuscle have?

Answer 7

stretch-mediated sodium channel.

Question 8

how does a pacinian corpuscle convert mechanical pressure into a nervous impulse?

Answer 8

1. in its normal state, stretch mediated sodium ion channels in the sensory neurone’s membrane are too narrow to allow sodium ions to pass through. resting potential.
2. pressure is applied to PC, causing PC to change shape. membrane surrounding neurone changes shape.
3. when membrane stretches, sodium ion channels present widen. sodium ions can now diffuse into neurone.
4. influx of positive sodium ions changes potential of the membrane (depolarised). results in generator potential.
5. generator potential creates action potential that passes along sensory neurone.
6. action potential then transmitted along neurones to CNS.