Posterior Pituitary Hormones: Oxytocin and Vasopressin (ADH)
Biology · Chemical Coordination and Integration · NEET
The posterior pituitary (neurohypophysis) releases two hormones: oxytocin and vasopressin (ADH). Both are actually made in the hypothalamus and only stored here. Memory hook: "O for uterus and milk Out, V for water reabsorption" — Oxytocin pushes things out, Vasopressin holds water in.
Oxytocin and vasopressin (ADH) are made in the hypothalamus, carried down axons, and stored/released by the posterior pituitary. Oxytocin acts on the uterus and mammary glands; vasopressin acts on the kidney to conserve water.
Your doubts, answered
Are oxytocin and vasopressin made in the posterior pituitary?
No. This is the most tested point. Both hormones are synthesised in the hypothalamus. They travel down nerve fibres (axons) to the posterior pituitary, which only stores and releases them. So the posterior pituitary is a storage and release site, not a factory.
What is the exact action of oxytocin?
Oxytocin acts on smooth muscles. In females it causes strong contraction of the uterus during childbirth and milk ejection (release) from the mammary glands. Note: oxytocin does not make milk (that is prolactin) — it only ejects the already-made milk.
Why is vasopressin also called ADH?
Vasopressin acts mainly on the kidney. It stimulates reabsorption of water and electrolytes by the distal tubules, so less water is lost in urine. Because it works against diuresis (urine loss), it is called the Anti-Diuretic Hormone (ADH). Vasopressin and ADH are the same hormone.
What happens if ADH is low? What is diabetes insipidus?
If ADH synthesis or release is impaired, the kidney cannot conserve water. The person loses large amounts of water in urine and becomes dehydrated. This condition is called diabetes insipidus. It has nothing to do with blood sugar — do not confuse it with diabetes mellitus (insulin problem).
Is the posterior pituitary the same as the neurohypophysis?
Yes. The posterior pituitary = neurohypophysis = pars nervosa. The anterior pituitary = adenohypophysis = pars distalis. NEET often uses these alternate names in matching questions, so memorise both labels.
⚠️ The NEET trap ✗ Oxytocin and vasopressin are synthesised by the posterior pituitary gland. ✓ They are synthesised by the hypothalamus and only stored and released by the posterior pituitary. 🧠 NTA loves the word 'synthesised'. Posterior pituitary STORES and RELEASES; hypothalamus MAKES. If the option says the posterior pituitary makes these hormones, it is wrong.
Real NEET questions
NEET 2019
Which of the following hormones is responsible for both the milk ejection reflex and the foetal ejection reflex?
A · Estrogen
B · Prolactin
C · Oxytocin ✓
D · Relaxin
Solution: Oxytocin acts on smooth muscles. In females it causes vigorous contraction of the uterus at childbirth (foetal ejection reflex) and milk ejection from the mammary glands (milk ejection reflex). One hormone does both, so the answer is oxytocin. Prolactin only makes milk, it does not eject it.
NEET 2025
Which of the following hormones released from the pituitary is actually synthesized in the hypothalamus?
A · Follicle-stimulating hormone (FSH)
B · Adrenocorticotropic hormone (ACTH)
C · Luteinizing hormone (LH)
D · Anti-diuretic hormone (ADH) ✓
Solution: ADH (vasopressin) and oxytocin are released from the posterior pituitary but are actually made in the hypothalamus and transported down axons. FSH, LH and ACTH are made by the anterior pituitary itself. So the pituitary-released hormone made in the hypothalamus is ADH.
NEET 2026
Match List-I with List-II. A. Excess growth hormone; B. Luteinizing hormone; C. Vasopressin; D. Oxytocin vs I. Reabsorption of water and electrolytes in kidney; II. Contraction of uterus during child birth; III. Acromegaly; IV. Ovulation.
A · A-III, B-IV, C-II, D-I
B · A-III, B-IV, C-I, D-II ✓
C · A-II, B-IV, C-I, D-III
D · A-IV, B-III, C-I, D-II
Solution: Vasopressin (ADH) causes reabsorption of water and electrolytes in the kidney (C-I). Oxytocin causes contraction of the uterus during childbirth (D-II). Excess growth hormone in adults gives acromegaly (A-III) and LH triggers ovulation (B-IV). So A-III, B-IV, C-I, D-II.
Solved Chemical Coordination and Integration NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. Prolactin (from the anterior pituitary) makes milk. Oxytocin only ejects the already-made milk from the mammary gland. This exact swap is a common NEET trap.
Is diabetes insipidus the same as diabetes mellitus?
No. Diabetes insipidus is caused by lack of ADH and involves excess water loss in urine. Diabetes mellitus is caused by insulin problems and involves high blood sugar. Only the word 'diabetes' is shared.
Which gland stores oxytocin and vasopressin?
The posterior pituitary (neurohypophysis / pars nervosa) stores and releases them, but the hypothalamus makes them.
Does vasopressin affect blood pressure?
For NEET, focus on its main kidney action: water and electrolyte reabsorption in the distal tubule, reducing urine loss (anti-diuretic action). Its name 'vasopressin' hints at raising blood pressure, but NCERT stresses the ADH role.
What are the other names for the posterior pituitary?
Neurohypophysis and pars nervosa. The anterior pituitary is called adenohypophysis or pars distalis. NEET uses these names in matching questions.
