Question

A person touches something hot, and their hand immediately pulls away. How does the sensory-somatic nervous system react by reflex to this situation?

(a) Sensory neurons in the hand detect the heat and send a signal to the brain. The brain then sends a signal back to the hand to pull away.
(b) Sensory neurons in the hand detect the heat and send a signal to the spinal cord. The spinal cord then sends a signal back to the hand to pull away.
(c) Sensory neurons in the hand detect the heat and send a signal to the brain and the spinal cord. The brain and spinal cord then work together to send a signal back to the hand to pull away.
(d) Sensory neurons in the hand detect the heat and send a signal directly to the muscles in the hand to pull away.

Answer 1

The sensory-somatic nervous system responds sensory neurons send a signal to the spinal cord. The correct answer is option (b).

Step-by-step explanation:

When a person touches something hot and their hand immediately pulls away, the sensory-somatic nervous system reacts by reflex in a specific way. Sensory neurons in the hand detect the heat and send a signal through the sensory fiber to the spinal cord. Within the spinal cord, the signal is transmitted to a motor neuron without the involvement of the brain.

The motor neuron then sends a signal back to the muscles in the hand, specifically the biceps brachii, leading to a contraction that pulls the hand away. This process forms a reflex arc which enables a quick withdrawal response, crucial for protection from injury.

Therefore, the correct response to the student's question is (b) Sensory neurons in the hand detect the heat and send a signal to the spinal cord. The spinal cord then triggers the hand to pull away. This automatic action is a protective reflex that occurs without the direct involvement of the brain and is designed to prevent tissue damage from harmful stimuli.