Question 1

What are the five main parts of a reflex arc?

Accepted Answer

A reflex arc contains a receptor, a sensory or afferent neuron, a spinal cord centre with a synapse or interneuron, a motor or efferent neuron, and an effector. In this example, the effector is the biceps muscle.

Question 2

Why is the dorsal root ganglion important?

Accepted Answer

The dorsal root ganglion contains the cell body of the sensory neuron. Its peripheral process carries the impulse from the receptor, while its central process enters the spinal cord through the dorsal root.

Question 3

Where does reflex integration take place in the spinal cord?

Accepted Answer

Integration takes place in the butterfly-shaped grey matter. The white matter lies outside it and carries ascending and descending tracts, not the main reflex synapse.

Question 4

How do sympathetic and parasympathetic pathways differ?

Accepted Answer

Both are two-neuron efferent chains with a preganglionic neuron, a ganglion and a postganglionic neuron. Sympathetic ganglia are near the spinal cord in the paravertebral chain, whereas parasympathetic ganglia are near or within the visceral organ.

Question 5

Does a reflex arc mean no information reaches the brain?

Accepted Answer

No. The reflex response can be organized without conscious processing in the brain, but sensory information may also ascend through pathways to the brain. The important distinction is automatic spinal processing versus conscious perception.

Reflex Arc & Visceral Nervous System — From Receptor to Effector

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