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

1. Based on the location of their action : Thereflexes are divided into somatic reflexes and visceral reflexes.

• When effector is located in body structures such as skeletal muscles, it is called a somatic reflex.
• When the effector is located in the visceral organs such as glands or smooth muscles then it is called a visceral reflex.

2. Based on the basis of number of neurons : Reflexes are of two types, viz. monosynaptic reflexes and polysynaptic reflexes.

• Simple or monosynaptic reflexes are those in which one sensory and one motor neuron are involved in the reflex action.
• Polysynaptic or complex reflexes are those when more than two neurons are involved in the reflex action.

3. Based on inheritance and experience of learning : The reflexes are subdivided into unconditional or inborn and conditional or acquired.

• Unconditional or inborn reflexes are inborn or hereditary. They are permanent, never disappear and need no previous experience, e.g. blinking of eyes, suckling, swallowing, knee jerk, sneezing, coughing, etc.
• Conditional or acquired reflexes are acquired during life by experience or learning. They are based on individual learning or experience. These are not heritable, temporary and may disappear or reappear, e.g. driving, cycling, etc.