Reflex Arc Flashcards
How does a reflex response differ from a voluntary response?
Does not have to involve the brain as a coordinator
What are reflex responses?
They are involuntary/automatic, meaning they happen without consciously deciding
What is the purpose of a reflex response?
To protect the body from potential damage (like touching a hot surface)
What does the ‘reflex arc’ refer to?
The sequence of neurons that the impulse passes through in order to trigger the reflex response
What is the reflex arc sequence?
Stimulus → Receptor → Sensory Neurone → Relay Neurone (CNS) → Motor Neurone → Effector → Response
What are the three types of neurons transmitting the impulse in one direction?
Sensory Neurone, Relay Neurone and Motor Neurone
What is an effector?
Something that carries out the response, like a muscle/gland
How has the sensory neuron adapted to its functionality?
It is long, with a cell body containing the nucleus in the middle of the axon
How has the relay neuron adapted to its functionality?
It is short and highly branched, this is important for its role in the CNS
How has the motor neuron adapted to its functionality?
The cell body is at the top of the cell, where the impulse moves opposite it. Electrical impulse is insulated by myelin sheath (Schwann cells) where the impulse ‘jumps’ from one node to another.
What do all three cells have in common?
Highly branched dendrites to connect to other neurons
Describe the Reflex Arc of stepping on a sharp pin.
The pin’s pressure stimulates receptors on the sole of the foot, triggering an electrical impulse in the sensory neuron, which travels to the spinal cord (CNS). The impulse crosses a synapse to a relay neuron, then to a motor neuron via another synapse. Simultaneously, a signal is sent to the brain for awareness. The motor neuron transmits the impulse to the leg muscle (effector), causing it to contract and move away from the pin.
