DRAW IT 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. (a) Using a circle to represent a cross section of the spinal cord, draw the circuit. Label the types of neurons, the direction of information flow in each, and the locations of synapses.

Verified step by step guidance

1. Step 1: Draw a circle to represent a cross-section of the spinal cord. This circle will serve as the base for illustrating the neuronal circuit involved in the reflex action.
2. Step 2: Inside the circle, draw two types of neurons: sensory neurons and motor neurons. Sensory neurons carry information from the sensory receptors (in this case, the skin of the finger) to the spinal cord, and motor neurons carry commands from the spinal cord to the muscles.
3. Step 3: Indicate the direction of information flow. Draw an arrow from the sensory neuron entering the spinal cord to the location where it forms the first synapse with an interneuron inside the spinal cord.
4. Step 4: From the interneuron, draw another arrow showing the information flow to the motor neuron, indicating the second synapse. This demonstrates how the signal is transmitted within the spinal cord to initiate the reflex.
5. Step 5: Label the synapses as 'Synapse 1' and 'Synapse 2' respectively, and clearly mark the sensory neuron, interneuron, and motor neuron. This labeling helps in understanding the flow of information and the types of neurons involved in the reflex action.

Key Concepts

Reflex Arc

A reflex arc is a neural pathway that controls a reflex action. It typically involves a sensory neuron that detects a stimulus, an interneuron in the spinal cord, and a motor neuron that triggers a response. This circuit allows for rapid responses to stimuli without the need for conscious brain involvement, ensuring quick reactions to potentially harmful situations.

Types of Neurons

There are three main types of neurons involved in reflex actions: sensory neurons, interneurons, and motor neurons. Sensory neurons transmit signals from sensory receptors to the spinal cord, interneurons process the information and connect sensory and motor pathways, while motor neurons carry signals from the spinal cord to muscles, resulting in movement. Understanding these roles is crucial for mapping the reflex circuit.

Synapses

Synapses are the junctions where neurons communicate with each other. In the context of a reflex arc, there are typically two synapses: one between the sensory neuron and the interneuron, and another between the interneuron and the motor neuron. These synaptic connections facilitate the transmission of electrical signals, allowing for the rapid processing and response to stimuli.