Question

1. A paper edge slices your left index finger and you immediately move your hand away but it takes a few moments before you are “aware” of the pain. Then, by lightly rubbing the area, the pain disappears.

A. Name and diagram the reflex pathwaythat allowed you to remove your hand.

B. Why was the “feeling of pain” delayed? Where would this information ultimately have been interpreted? Name the fiber type associated with the primary afferent involved, and name the somatosensensory pathway it would have taken to get to the ultimate processing area.

C. Explain why light rubbing removed the pain sensation.

Answer 1

A.

B. This pain is referred as somatic pain, the pain receptors (nociceptor) will detect the stimulus, senses danger and send an impulse to the brain and spinal cord through sensory neuron (afferent neuron), then an inter neuron. The spinal cord will transfer the signal to motor neuron (efferent neuron), which is then carried to the effector muscle. Then it starts contracting and moves away from the paper. Then feeling of pain can be observed. Here nociceptor will identify the danger first and then transmits the impulse to the brain, brain takes measures to move the hand away, then only we can feel sensation of pain. So feeling of pain delayed. Fear dominates the sensation of pain till we move the hand away.

Here nociceptors are the part of peripheral nervous system. The pain impulse pass along the peripheral nerves to the spinal cord.

Name the fiber type associated with the primary afferent involved: Nociceptive fibers

somatosensory pathway: Voluntary mechanism, Reflex arc

Where would this information ultimately have been interpreted: Brain’s thalamus

c. When we rub the area affected, it activates the pleasure nerve fibers which lies under skin, so it masks the sensation of pain from other nerves.