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Describe a simple reflex arc in terms of: receptor, sensory neurone, relay neurone, motor neurone and effector
Describe a simple reflex arc in terms of: receptor, sensory neurone, relay neurone, motor neurone and effector
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A simple reflex arc is a neural pathway that mediates a reflex action, allowing for rapid responses to stimuli without the need for conscious thought. It consists of several key components: the receptor, sensory neuron, relay neuron, motor neuron, and effector. Here’s a detailed description of each component:
1. Receptor
- Function: The receptor is the first component of the reflex arc and is responsible for detecting a specific stimulus (e.g., heat, pressure, or pain).
- Location: Receptors are located in sensory organs or tissues (such as skin, muscles, or internal organs).
- Example: In a withdrawal reflex, pain receptors in the skin detect a sharp object.
2. Sensory Neuron
- Function: The sensory neuron transmits the electrical impulse generated by the receptor to the central nervous system (CNS).
- Structure: Sensory neurons typically have a long dendrite that carries signals from the receptor to the cell body and a short axon that extends into the spinal cord.
- Example: In response to the detected stimulus, the sensory neuron carries the impulse towards the spinal cord.
3. Relay Neuron (Interneuron)
- Function: The relay neuron processes the incoming signal from the sensory neuron and connects it to the appropriate motor neuron.
- Location: Relay neurons are located within the CNS (specifically in the spinal cord or brain).
- Example: In a reflex arc, an interneuron may receive input from multiple sensory neurons and transmit it to one or more motor neurons.
4. Motor Neuron
- Function: The motor neuron carries impulses away from the CNS to effectors (muscles or glands) that will execute a response.
- Structure: Motor neurons typically have a long axon that extends from the spinal cord to the target muscle or gland.
- Example: In response to signals from relay neurons, motor neurons activate muscles to contract.
5. Effector
- Function: The effector is any muscle or gland that responds to the motor neuron’s signal, resulting in a physical action or change in function.
- Example: In a withdrawal reflex, muscles in the arm contract to pull away from a painful stimulus.
Summary of Reflex Arc Pathway
- Stimulus (e.g., touching something hot) activates a receptor.
- The sensory neuron transmits an impulse to the spinal cord.
- The impulse is relayed through a relay neuron in the spinal cord.
- The motor neuron transmits signals from the spinal cord to an effector.
- The effector (e.g., muscle) responds by contracting or performing an action (e.g., pulling away from heat).
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