Oxytocin is secreted by?

AIIMS Bhuvneshwar NO- 2018

Applied Anatomy

Easy

Appeared in: AIIMS Bhuvneshwar NO- 2018

Explanation

Oxytocin is synthesized in the hypothalamus, specifically in the paraventricular and supraoptic nuclei.
It is then transported down axons to the posterior pituitary gland (neurohypophysis) for storage.
The posterior pituitary does not produce hormones itself but releases oxytocin and antidiuretic hormone (ADH) into the bloodstream upon receiving nerve signals from the hypothalamus.

Option A: The adrenal cortex is part of the adrenal gland and is responsible for producing steroid hormones (corticosteroids) like cortisol and aldosterone, not peptide hormones like oxytocin.
Option B: The anterior pituitary (adenohypophysis) is a true endocrine gland that synthesizes and secretes its own hormones, including GH, TSH, ACTH, FSH, LH, and prolactin. It does not secrete oxytocin.
Option C: The adrenal medulla is the inner part of the adrenal gland that secretes catecholamines (epinephrine and norepinephrine) as part of the sympathetic nervous system's 'fight-or-flight' response.

Visual 1: Diagram: A clear illustration of the hypothalamus and pituitary gland, showing the neuronal connection to the posterior lobe and the portal system to the anterior lobe. This visual helps differentiate how the hypothalamus controls each part.
Visual 2: Flowchart: A simple flowchart depicting the synthesis, transport, and release of oxytocin, starting from the hypothalamic nuclei, moving through the hypothalamo-hypophyseal tract, and ending with secretion from the posterior pituitary.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Endocrine System: Hormone Secretion as background academic context rather than a clinical decision trigger.
A synthetic version of oxytocin (Pitocin) is one of the most common drugs used in obstetrics to induce or augment labor and to control postpartum hemorrhage by causing uterine contractions.
Nurses administering oxytocin must meticulously monitor uterine activity (frequency, duration, and strength of contractions) and fetal heart rate to prevent complications like uterine tachysystole (excessive contractions), which can lead to fetal distress or uterine rupture.
What if? If a patient receiving an oxytocin infusion develops signs of water intoxication (e.g., headache, confusion, hyponatremia), the nurse's priority is to stop the infusion immediately and notify the provider. This is because oxytocin has a weak antidiuretic effect similar to ADH, especially at high doses.

How to Approach the Question

First, identify the core of the question, which is asking for the site of oxytocin secretion.
Recall the major glands of the endocrine system and the primary hormones they produce.
Differentiate between the anterior and posterior pituitary. A key memorization point is that the posterior pituitary is more like a storage and release site for the hypothalamus, while the anterior pituitary is a manufacturing plant.
Evaluate each option: The adrenal glands produce steroids and catecholamines. The anterior pituitary produces its own set of six key hormones. The posterior pituitary releases oxytocin and ADH.
Based on this knowledge, select the posterior pituitary as the correct site of secretion.

Concept Tested & Keywords

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