A gland that disappears in the adult but is active during childhood is

UPPSC 2017

Applied Anatomy

Easy

Appeared in: UPPSC 2017

Explanation

The thymus is a primary lymphoid organ, not a classic endocrine gland, but it's essential for the development and maturation of T-lymphocytes (T-cells), a cornerstone of adaptive immunity.
It is largest and most active during neonatal life and childhood, playing a critical role in building a person's immune system.
After puberty, the thymus undergoes a natural process of shrinking called involution.
During involution, the functional thymic tissue is gradually replaced by adipose (fat) tissue, and its T-cell production significantly decreases, although it never disappears completely.

Option A: The hypothalamus is a crucial part of the brain that links the nervous system to the endocrine system. It controls body temperature, hunger, thirst, and circadian rhythms, functions that are essential throughout a person's entire life.
Option B: The parathyroid glands secrete parathyroid hormone (PTH) to regulate blood calcium and phosphorus levels. This function is vital for nerve function, muscle contraction, and bone health, and it continues throughout life.
Option C: The adrenal cortex produces life-sustaining steroid hormones, including glucocorticoids (like cortisol), mineralocorticoids (like aldosterone), and androgens. These hormones are necessary for metabolism, blood pressure regulation, and stress response throughout life.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Lifespan and function of endocrine and lymphoid organs as background academic context rather than a clinical decision trigger.
The thymus's central role in immunity means that congenital problems, such as in DiGeorge syndrome where the thymus is underdeveloped or absent, lead to severe immunodeficiency and high susceptibility to infections.
The age-related decline in thymic function, known as immunosenescence, is a key reason why older adults have a weaker immune response. This makes them more vulnerable to new infections (like influenza or pneumonia) and have a reduced response to vaccinations.
What if? If the question asked about a gland whose fetal zone involutes rapidly after birth, the correct answer would be the Adrenal Cortex. The large fetal zone is prominent during fetal life but shrinks dramatically after the baby is born.

How to Approach the Question

This is a factual recall question testing your knowledge of the endocrine and lymphoid systems.
First, analyze the question's keywords: 'gland', 'disappears in adult', and 'active during childhood'.
Next, systematically review the function of each option.
Recall that the Hypothalamus, Parathyroid, and Adrenal glands perform vital functions (homeostasis, calcium regulation, steroid production) that are necessary throughout a person's entire life. This allows you to eliminate these three options.
Remember that the Thymus is primarily an immune organ that is most important for developing T-cells during childhood.
Conclude that the Thymus is the only gland listed that significantly reduces in size and function after puberty, fitting the question's description.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 28-48

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 1074-1076

E6 Histology Inderbir 11e p. 144-146