The reflex that pulls your hand away when you prick your finger on a sharp object relies on a neuronal circuit with two synapses in the spinal cord. Draw a simple diagram of the brain indicating where pain would eventually be perceived.

Verified step by step guidance

1. Start by drawing a simple outline of the human brain. You can represent it with a basic oval shape to indicate the general structure.
2. Identify the location of the spinal cord in relation to the brain. The spinal cord is a long, thin, tubular structure that extends from the brainstem down the back.
3. Indicate the pathway of the sensory neurons that carry the pain signal from the finger to the spinal cord. These neurons enter the spinal cord through the dorsal root.
4. Show the interneurons within the spinal cord that process the pain signal and initiate the reflex action. These interneurons connect the sensory neurons to motor neurons, which trigger the reflex to pull the hand away.
5. Finally, illustrate the pathway from the spinal cord to the brain where the pain is perceived. The signal travels up the spinal cord to the thalamus and then to the somatosensory cortex in the brain, where the sensation of pain is processed.

Key Concepts

Reflex Arc

A reflex arc is a neural pathway that controls a reflex action. It involves sensory neurons that detect stimuli, interneurons in the spinal cord that process the information, and motor neurons that trigger a response. This mechanism allows for rapid reactions without involving the brain, ensuring quick withdrawal from harmful stimuli.

Synapse

A synapse is a junction between two neurons where electrical or chemical signals are transmitted. In the reflex arc, synapses in the spinal cord facilitate communication between sensory neurons and interneurons, and between interneurons and motor neurons, enabling the reflex action to occur swiftly.

Pain Perception in the Brain

Pain perception occurs in the brain, specifically in areas like the thalamus and somatosensory cortex. While reflex actions are processed in the spinal cord, the brain eventually receives signals that allow for the conscious perception of pain, enabling further assessment and response to the injury.