Sensory Receptors & Sensory Coding

Question 1

Mention functions of sensory receptors

Answer 1

1. Detectors of stimuli
2. Transducers produce generator potential
3. Generators: generate action potential in affrent nerves
4. Inform CNS about changes in internal & external environment

Question 2

Mention properties of sensory receptors & corresponding law if present)

Answer 2

1. Specificity (Muller’s law)
2. Excitability (generator potential)
3. Dischange of impulse (Weber-Fechner’s law)
4. Adaptation

Question 3

State Weber-Fechner law

Answer 3

Generate potential in afferent neurons in a frequency proportional to log stimulus intesity

Question 4

Mechanism of receptor adaptation

Answer 4

1. Readjustment, as the fluid is redistributed & receptor potential is no longer elicited
2. Accomodation due to progressive inactivation of Na channels

Question 5

Describe mechanism of modality discrimination

Answer 5

Type of receptor stimulated
Pathway activated when stimulus is applied to receptor
“Labelled-line principle”

Question 6

…….helps CNS to localize a stimulus

Answer 6

Lateral inhibition

Question 7

Explain phantom limb phenomenon

Answer 7

It is explained by that the nerves remaining in the stump can form nodules called neuromas which can generate impulses to the brain interpreted as arising from the limb.

Question 8

Mention factors of discrimination of:
1. Intesity
2. Duration

Answer 8

1. Frequency of action potentials, number of receptors stimulated.
2. Ability of receptor to adapt slowly or rapidly

Question 9

Classify receptors acconding to adaptation with giving examples

Answer 9

Rapidly adapting, touch receotirs
Moderately adapting, thermoreceptors
Slowly adapting, pain receptors