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Renin Angiotensin Mechanism.

Reflex Arc.

 

Reflex Arc:

  • Definition: It is a fast automatic unplanned sequence of actions occurring in response to a stimulus.

  • When the action is taken by the spinal cord the reflex is called “Spinal reflex”.

  • When the action is taken by the brain the reflex is called “cerebral reflex”.

  • As a result of action if there is a contraction of skeletal muscles the reflex is called “Somatic Reflex”.

  • As a result of action if there is a contraction of smooth muscles or glands get activated the reflex is called “Visceral Reflex”.

  • The path taken by impulses during the process of reflex is called “Reflex Arc” and is consists of,

  1. Sensory Receptor.

  2. Sensory Nerve.

  3. Integrating Center.

  4. Motor Neuron

  5. Effector Organ.

  1. Sensory Receptor:

  • The sensory receptors are present on dendrites of the sensory nerve.

  • On contact with stimulus a graded potential also called “receptor Potential” is generated which produces the nerve impulses.

  1. Sensory Nerve:

  • Sensory nerve carries this impulse to the spinal cord.

  1. Integrating Center:

  • One or more centers in CNS act as integrating centers.

  • Integrating center consists of a synapse between a sensory neuron and a motor neuron, connected by a connector neuron.

  1. Motor Neuron:

  • It carries nerve impulses of action from integrating center to effector organ.

  1. Effector Organ:

  • The organ which shows the action in response to the stimulus is called the effector organ.

  • Effector organs may be skeletal muscle, smooth muscle or a gland.

Commonly Asked Question:

  1. Write a short note on “Reflex Arc”.
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