Put these parts of a reflex arc in the order in which the impulse passes through them…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Put these parts of a reflex arc in the order in which the impulse passes through them.
(1) Effector (a muscle) (2) Dorsal nerve root (3) Receptor (4) Efferent neuron (5) Afferent neuron (6) Synapse in the spinal cord
- Write the order of the numbers.
- Which neuron is in contact with the effector?
- Which root does the afferent neuron use?
Need a reminder? The key ideaShow
A reflex is an involuntary response that needs a part of the CNS. The reflex arc has at least one afferent neuron, which enters the CNS by a dorsal root, and one efferent neuron, which goes to the effector. Time equals distance divided by speed, and each chemical synapse adds about . A body falling from rest covers .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Receptor (3), afferent neuron (5), dorsal nerve root (2), synapse in the spinal cord (6), efferent neuron (4), effector (1). The order is 3, 5, 2, 6, 4, 1.
Step 2. (b) The efferent neuron.
Step 3. (c) The dorsal root.
Answer: (a) 3, 5, 2, 6, 4, 1; (b) efferent; (c) dorsal.
Watch out. The afferent neuron enters by the dorsal root. The efferent neuron leaves by the ventral root.
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