2

Question 1

Receptors

Function

Answer 1

Specialized structures present at the peripheral end of afferent neurons & are sensitive to and can detect changes in environment.

Function: They respond to different types of stimuli
& transform them to electrical energy.

Question 2

Histological classification

Answer 2

A) Free nerve ending:
- More extensive in the skin.
- Receptors for pain, temperature & crude touch.
B) Expanded nerve ending :
Merkel’s : for fine touch. Numerous in lips & tips of einetown
fingers.

Question 3

Physiological classification (According to type of stimulus)

Answer 3

I. Mechanoreceptors

Question 4

Properties of the receptors:

Answer 4

1-Excitability of receptors.
2- Specificity of the receptors:
3-Weber-Fechner Law
(Compression function of the receptors).
4-Adaptation of the receptors.

Question 5

Excitability of the Receptors: Mechanisms of Receptor Potentials Receptors can be excited in one of several ways to cause receptor

Answer 5

1) Mechani cal deformation
(2) Application of a chemical
(3) Change of the temperature
(4) By electromagnetic radiation

Question 6

Specificity of the receptors:

Each type of the receptors is most sensitive to a ensure specific stimulus called the

This known as

Answer 6

Each type of the receptors is most sensitive to a ensure specific stimulus called the adequate stimulus.

This known as muler’s. law of specific nerve energy.

Response of the receptors to non specific stimuli can
occur when they have a very high intensity and the

Question 7

Weber-Fechner Law assassins
(Compression function of the receptors)

Answer 7

Weber-Fechner law states that the frequency of
action potential in the nerve is directly proportional to the logarithm of rate of increase
in intensity.

Question 8

decrease response in spite of constant
stimulation.

Answer 8

Adaptation of the receptors :

Question 9

Adaptation of the receptors
The receptors are classified into:

Answer 9

1- Rapidly adapting: as touch receptors
2- Slowly adapting receptors:
as Mechanoreceptors and Pain receptors
3-Moderately adapting receptors: as
Temperature receptors Smell receptors Taste receptors Pressure receptors

Question 10

Rapidly Adapting (……..) Receptors

Answer 10

Phasic
Detect rapid changing Stimuli or non
important stimuli (1) Receptors of the skin that detect touch
caused by clothes. (2) Receptors in muscles and joints that detect
rapid change in posture.

Question 11

Slowly Adapting (…….) Receptors

Answer 11

TONIC

Question 12

Mechanism of Adaptation

Answer 12

In photoreceptors:
adaptation by changing the concentration of the light sensitive pigment.

Mechanoreceptors:

4. Dissipation of energy to surrounding tissue.
5. Adaptation due to Vesico-Elastic properties of the
   Lamellae that surrounds the nerve ending.(new form of vacnames the receptors)
6. Adaptation by inactivation of Na+ channels in the nerve so membrane.
7. decreased sensitivity of 1st node of raniver