1. Receptors : Receptors are specialized cells, tissues or organs present in the body which receive different stimuli.
2. Types of receptors:
- Receptors are of two types, viz. exteroceptors and interoceptors.-
- Exteroceptors receive stimuli directly from the external environment. They are somatic in nature.
- Interoceptors are located inside the body and are visceral in nature. They respond to internal changes in the body.
- The various types of exteroceptors and interoceptors, their location and functions have been summarized in the table given below:
| Types of Exteroceptors |
Location |
Function |
| 1. Mechanoreceptors |
Touch corpuscles in skin |
Tangoreceptors Pressure Tactile receptors- Touch |
| 2. Thermoreceptors |
Skin |
Frigido receptors (cold) Heat receptors (warmth) |
| 3. Chemoreceptors |
Tongue, nasal mucosa |
Gustatoreceptors – Taste OlfactoreceptorsSmell |
| 4. Statoacoustic receptors |
Internal ear |
Cochlea – Hearing Semicircular canals-Balance and equilibrium |
| 5. Photoreceptors |
Retina of the eye |
Rods and cones interpret images Rods-black and white image. Sensitive to dim light. Cones – Coloured image. Sensitive to bright light. |
