This assignment will give you practice drawing neuron pathways as they travel th
ID: 97582 • Letter: T
Question
This assignment will give you practice drawing neuron pathways as they travel through the spinal cord.
Part 1 - Using the template attached, draw the 3 pathways/reflexes identified below. You may submit them as 3 separate drawings if you choose. When making your drawings, pay close attention to where you are placing your axons and your synapses (Hint: Remember the roles of white matter and gray matter as well as anterior, posterior, and lateral horns). Label your pathways 1-3.
An incoming sensory signal destined for the cerebral cortex of the brain
An outgoing motor command to the skeletal muscles of the lower limb
A polysynaptic, contralateral, spinal reflex arc
Part 2 - Answer the following questions:
What is the role of the stretch reflex?
Why is the stretch reflex arc faster than the withdrawal reflex arc?
Explanation / Answer
Part 2
What is the role of the stretch reflex?
The stretch reflex is a muscle contraction which is seen to be produced in response to stretching happening within the muscle. Stretch reflex is considered as a monosynaptic reflex, its main function is providing automatic regulation of skeletal muscle length in the provided situation. These reflexes are known to be quick and automatic and are mediated by the spinal cord.
Functions of the Stretch Reflex
It helps in the production and modulation of muscle tone
It protects our muscles from tearing
Plays role in posture, as this stretch reflex will quickly counter the stretch in the spinal, hip and leg muscles caused due to slightly lean.
Why is the stretch reflex arc faster than the withdrawal reflex arc?
Stretch reflex arc is faster than the withdrawal reflex arc, because the stretch reflex arc is a mono synaptic, at the same time when you consider the withdrawal reflex, it is a poly synaptic one.
Being a monsynaptic reflex (simplest reflex arc), it involves one sensoty and one motor neuron aand it is fast due to only one synapse.
Where as withdrawal reflex as polysynaptic reflexes, it involves one interneuron, one sensory neuron, and one motor neuron and it has a longer delay between stimulus and response, and is due to increased number of synapses and will produce complex reflexes. In aaditon to this, the afferent fibers which are smaller in their diameter will have slow conduting making them slower.
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