WORKING OF SENSORY RECEPTORS WITH SPECIAL REFERENCE TO SKIN

In the skin, there are at least 3 different types of sensory endings involved in touch stimulus reception. With skin, the receptors are concerned with at least five different senses: touch, pressure, heat, cold and pain.

1. Situated at the base of hairs, hair end organs receive touch stimulus.
2. Meissner's corpuscles (encapsulated endings) which lie in papillae which extend into the ridges of the fingertips. The corpuscle consists of spiral and much twisted endings, each of which ends in a knob. These are touch receptors. 
3. Pacinian corpuscles - situated quite deep in the body. These are also encapsulated neuron endings and receive deep pressure stimulus.Those located in limbs probably form a basis for vibration sense.

The sensation of touch, pressure, heat, cold and pain are detected by
modified sensory neurons having naked nerve endings.(touch and pain
receptors) or specialized cellular corpuscles (pressure, heat and cold
receptors.)

The intensity of stimuli received would either be transmitted in the form of repeated impulses or by more fibers carrying the impulse to the CNS.

The detection of vibrations of the ground by terrestrial vertebrates is probably achieved by receptors in the joints.

The relative abundance of various types of receptors differs greatly, e.g. pain receptors are nearly 27 times more abundant than cold receptors. The cold receptors are nearly 10 times more abundant than heat or temperature receptors. The receptors are not distributed evenly over the entire surface of the body, e.g. touch receptors are much more numerous in the finger tips than in the skin of the back, as might be expected in view of the normal functions of those two parts of the body. The stimulus received by the receptors in the skin, which are the endings of sensory neurons is passed to the motor neurons via inter or associative neurons, which are present in the brain and via spinal cord impulse is sent by the motor neurons to the effectors, which are muscles and glands.