Control and Co-ordination — BIOLOGY STD 12 Science — Question

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 Olfactoreceptors- Smell
  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.