1. M.G. COLLEGE ARMORI
DIST. GADCHIROLI
Class: B.Sc. II Sem III
Paper: I Unit: IV
Comparative Anatomy
Topic: Receptor Organs
By: Pro. S.B. Kumre
( Dept. Of Zoology )

2. • Sense organs are the specialized organs composed of sensory
neurons, which help us to perceive and respond to our
surroundings. There are five sense organs – eyes, ears, nose,
tongue, and skin.
• External receptors (exteroceptors): sense organs for touch,
smell, taste, sight and hearing.
• Internal receptors (interocepyors): these sense organs found in
the body which detect the temperature, pain, hunger, thirst,
fatigue and muscle position.
• Impulses transmitted from
• sensory fibres
receptors central nervous system

3. Cutaneous receptors
• cutaneous receptors found in dermis and epidermis.
• the entire body surface of aquatic vertebrates and the moist parts
of the skin of terrestrial vertebrates are sensitive to chemicals and
certain parts are sensitive to contact and temperature changes.
• The cutaneous receptors have free nerve endings and some
encapsulated nerve endings or tactile carpuscles.
• Tangoreceptors: sensitive to touch.
• Algesireceptors: sensitive to pain.
• Thermoreceptors: detect changes in temperature.
• Mechanoreceptors: sensitive to mechanical pressure or forces.
• Caloreceptors: sensitive to pressure and heat.
• Frigidoreceptors: sensitive to cold.
• Chemoreceptors:detect the presence of chemicals.

4. Cutaneous receptors

5. chemoreceptors
• Olfactory receptor, also called smell receptor.
• It consists of basal cells, supporting cells and neurosensory cells,
hair like structures called as sensory hairs ( cilia).
• Organs of taste : gustatoreceptors.
• Both these organs are stimulated by a chemical substances present
in solution. Water is the medium for dissolving substances in
aquatic animals. And mucus for land animals.
• Organ of jacobson or vomeronasal organ: sac like chamber
lying below the nasal cavities and above the buccal cavity.
• The organ is functions by smelling the recognition of food held in
mouth.
• In snakes and lizards the scent introduced into it by the tip of the
tongue.

6. Olfactory organs

7. Organ of Jacobson( vomeronasal organ)

8. Organs of taste ( Gustatoreceptors)