Reflex Action: Types, Mechanism, Examples, And Diagram

Reflex Action: Types, Mechanism, Examples, And Diagram

Question 1. What are the nodes of Ranvier and the incisures of Schmidt–Lanterman?
Answer.

In myelinated nerve fibers, the myelin sheath is segmented. These segments are separated at regular intervals by nodes of Ranvier.

The incisures of Schmidt–Lanterman are oblique clefts in the myelin sheath and act as conduction channels for metabolites (nutrition) into depths of the myelin sheath and axon.

Question 2. Write a short note on reflex action.
Answer.

• A reflex action is an involuntary and almost instantaneous motor response of the body to sensory stimulus/stimuli, for example, when a pin is pricked in the hand, the pain impulses reach the spinal cord by sensory neurons.
• The spinal cord, then, through its motor neurons moves the muscles of the hand to keep it away from the pin. The complete pathway involved in this act constitutes the reflex action.

The reflex action is automatic and occurs independently of the higher centers of the brain. This reflex arc involved in reflex action consists of the following components:

• Receptor, for example, sensory nerve ending
• Sensory component (sensory neuron)
• Central component (spinal cord/brain)
• Motor component (motor neuron)
• Effector, for example, muscle