Grey matter is composed of?

Appeared in: HPSSC Staff Nurse - 2021

Explanation

Grey matter is primarily composed of the cell bodies of neurons, which are also known as nerve cells.
In addition to neuronal cell bodies, grey matter contains dendrites, unmyelinated axons, glial cells (such as astrocytes and oligodendrocytes), and a rich network of capillaries.
This composition makes grey matter the primary site for information processing, synaptic activity, and neural computation in the central nervous system.

Option A: Ependymal cells are specialized glial cells that line the fluid-filled ventricles of the brain and the central canal of the spinal cord; they do not constitute the main tissue of grey matter.
Option C: Nerve fibres, particularly myelinated ones, are the main component of white matter, not grey matter. White matter's function is to transmit signals over distances.
Option D: Nissl granules are structures (rough endoplasmic reticulum) found inside the neuron's cell body. They are a component of a nerve cell, not the tissue itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Composition of grey matter in the central nervous system as background academic context rather than a clinical decision trigger.
Understanding the difference between grey and white matter is fundamental for interpreting neuroimaging like MRI and CT scans to locate pathologies such as strokes, tumors, or demyelinating diseases.
Diseases that primarily affect grey matter, like Alzheimer's disease, lead to cognitive decline because the processing centers (neuron cell bodies) are damaged.
Diseases affecting white matter, such as Multiple Sclerosis, disrupt communication pathways, leading to motor, sensory, and coordination problems.

How to Approach the Question

First, identify the core concept of the question, which is the composition of 'grey matter'.
Recall the basic structural organization of the central nervous system and the two main types of tissue: grey and white matter.
Differentiate between the primary components of each. Grey matter is for processing and contains cell bodies. White matter is for transmission and contains myelinated axons (fibres).
Evaluate each option based on this understanding:
Ependymal cells are for lining ventricles.
Nerve cells (specifically their bodies) are the main component of grey matter.

Concept Tested & Keywords

QPWXhfO_33Va7ZKKXXODIh

E6 Anatomy Applied Ashalatha 4e pp. 403-405, 405-407

E6 Anatomy Grays 43e Vol 1 Part 1 p. 72-74

Practise the full HPSSC Staff Nurse - 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.