Which hormone is responsible for the secretion of milk after parturition?

Appeared in: OSSSC Nursing Officer-2023

Explanation

Prolactin is the key hormone responsible for lactogenesis, which is the process of milk synthesis and secretion.
It is produced by the anterior pituitary gland.
During pregnancy, high levels of estrogen and progesterone block the milk-producing effect of prolactin on the breasts.
After parturition (childbirth), the levels of estrogen and progesterone fall dramatically, which 'unblocks' the action of prolactin, allowing it to stimulate the alveolar cells in the breast to produce milk.

Option A: ICSH (Interstitial Cell Stimulating Hormone) is the term for Luteinizing Hormone (LH) in males. Its function is to stimulate testosterone production and it plays no role in lactation.
Option C: ACTH (Adrenocorticotropic Hormone) stimulates the adrenal glands to produce cortisol, a stress hormone. It is not the primary hormone for milk secretion.
Option D: Oxytocin is responsible for the milk 'ejection' or 'let-down' reflex, which moves milk from the alveoli into the ducts. It does not stimulate the 'secretion' or production of milk.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal control of lactation as background academic context rather than a clinical decision trigger.
Understanding the difference between prolactin and oxytocin is crucial for nurses counseling new mothers on breastfeeding.
Issues with milk supply are related to prolactin, while problems with milk 'let-down' (e.g., due to stress or pain) are related to oxytocin inhibition.
Nurses can educate mothers that relaxation and comfort can facilitate the oxytocin reflex, while frequent and effective emptying of the breast stimulates prolactin and increases milk production.

How to Approach the Question

First, identify the core of the question: it asks about the hormone for 'secretion' of milk after parturition.
Recognize that 'secretion' in this context means the production or synthesis of milk.
Analyze the options. Prolactin and Oxytocin are both related to lactation and are the most plausible choices.
Recall or deduce the specific function of each hormone. Prolactin is for 'production', while Oxytocin is for 'ejection' or 'let-down'.
Match the keyword 'secretion' with the function of Prolactin.
Eliminate the other options: ICSH is related to male reproduction, and ACTH is related to the adrenal glands and stress response.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 69-71

E6 Obstetrics Williams p. 48-68

E6 Gynecology Williams p. 365-430

Practise the full OSSSC Nursing Officer-2023

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