KPSC Staff Nurse - 2021
Applied Physiology
Easy
Which of the following forms the myelin sheath in the central nervous system?
Appeared in: KPSC Staff Nurse - 2021
Explanation
- Oligodendrocytes are a type of neuroglia found specifically in the Central Nervous System (CNS), which consists of the brain and spinal cord.
- Their primary function is to produce myelin, a fatty substance that wraps around nerve axons to form an insulating layer known as the myelin sheath.
- This myelination is crucial for saltatory conduction, a process that dramatically increases the speed of nerve impulse transmission.
- A single oligodendrocyte extends its processes to myelinate multiple segments of several different axons simultaneously.
Why Other Options Were Wrong
- Option A: Astrocytes are the most numerous glial cells in the CNS, but their main roles are providing structural support to neurons, forming the blood-brain barrier, and regulating the chemical environment of the brain. They do not produce myelin.
- Option B: Microglia are the resident immune cells of the CNS. They act as phagocytes, removing cellular debris, waste products, and pathogens. They are not involved in myelination.
- Option D: Schwann cells are responsible for forming the myelin sheath, but they do so in the Peripheral Nervous System (PNS), not the Central Nervous System (CNS).
Related Visual
Clinical Relevance
- Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cellular components of the nervous system and myelination as background academic context rather than a clinical decision trigger.
- Damage to oligodendrocytes and the subsequent loss of CNS myelin is the hallmark of Multiple Sclerosis (MS), a chronic autoimmune disease. Nursing care focuses on managing symptoms like fatigue, weakness, and visual disturbances, and preventing complications like falls.
- Damage to Schwann cells and PNS myelin occurs in Guillain-Barré Syndrome (GBS). Nurses must closely monitor respiratory status (vital capacity) due to the risk of respiratory muscle paralysis and be prepared for mechanical ventilation.
- What if? If the question had asked about myelination in the nerves of the arm (part of the PNS), the correct answer would be Schwann cells, as they are responsible for myelination outside of the brain and spinal cord.
How to Approach the Question
- First, identify the key terms in the question: 'myelin sheath' and 'central nervous system (CNS)'.
- This is a factual recall question that requires knowledge of the specific functions of different neuroglial cells.
- Recall the four main types of glial cells and their primary roles.
- Differentiate between myelination in the CNS and the Peripheral Nervous System (PNS).
- Associate Oligodendrocytes with the CNS and Schwann cells with the PNS.
- Eliminate Astrocytes and Microglia as their functions (support, blood-brain barrier, immunity) are not related to myelination.
Concept Tested & Keywords
- Concept Tested: Cellular components of the nervous system and myelination
- Stem keywords: myelin sheath, central nervous system, CNS
- Lead-in keywords: Which
Question ID
Q_bP1WM81P0bI2WcAQf4iy
Reference Book
E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 185-187
E6 Anatomy Applied Ashalatha 4e p. 405-407
E6 Physiology Ganong 27e Vol 1 Part 1 p. 115-117
Practise the full KPSC Staff Nurse - 2021
Attempt every question from this paper in a timed mock, then review the full solution for each one.
More Nervous System Questions
- The junction at which an impulse travels from one neuron to another is called:
- One function of parasympathetic nervous system is:
- What is the normal Intracranial pressure?
- Lumbar puncture for adults is done at:
- In healthy adults, the normal plantar flexion causes a:
- Which are the main functions of the hypoglossal nerve?
- Which is mainly responsible for fight (or) flight reactions?
- Nervous tissue is made of \ \ \ \ that receive and conduct impulses
- Which cortical area is responsible for the formulation of speech?
- Which part of the brain is affected in spatial disorientation?
More KPSC Staff Nurse - 2021 Questions
- Which cranial nerve innervates the lateral rectus muscle of the eye?
- Which of the following cells secrete pulmonary surfactant?
- Which of the following photoreceptors helps in "bright light vision"?
- Bacilli are the term used for
- As per the psychosocial development theory of Erikson, identity and role confusion are associated with?
- Ability to see beyond outward behavior and sense accurately inner experience of another at a given point is?
- Ivan Pavlov is associated with?
- Perception without stimuli is?
- Behavioral pattern of everyday life which unconsciously arises within a group is?
- Government of India announced year of empowerment of women in the year?