---
title: "Posterior Pituitary | Anatomy and Physiology II"
description: "Posterior pituitary is the pituitary lobe that stores and releases hypothalamic hormones, especially oxytocin and vasopressin, in Anatomy and Physiology II."
canonical: "https://fiveable.me/anatomy-physiology-ii/key-terms/posterior-pituitary"
type: "key-term"
subject: "Anatomy and Physiology II"
unit: "Unit 14"
---

# Posterior Pituitary | Anatomy and Physiology II

## Definition

The posterior pituitary, or neurohypophysis, is the back lobe of the pituitary gland that stores and releases oxytocin and vasopressin made by the hypothalamus. In Anatomy and Physiology II, it shows how the nervous and endocrine systems work together.

## What It Is

The posterior pituitary is the back part of the pituitary gland that does not make its own hormones. Instead, it stores and releases hormones that are produced in the hypothalamus, mainly oxytocin and vasopressin, also called antidiuretic hormone or ADH.

That setup is what makes the posterior pituitary different from the anterior pituitary. The anterior lobe acts more like a true gland, while the posterior lobe works more like a release site for hormones that were made in the brain. In Anatomy and Physiology II, this is a classic example of neuroendocrine integration, where nerve tissue and hormone control are linked.

Here is the path those hormones follow. Specialized neurons in the hypothalamus synthesize oxytocin and vasopressin, then send them down long axons to the posterior pituitary. They travel with carrier proteins called neurophysins, are stored in axon terminals, and wait there until nerve impulses trigger release into the bloodstream. So when a signal comes in, the posterior pituitary acts fast, turning a nervous system signal into hormonal output.

That fast release matters because the body uses these hormones for immediate control. Oxytocin stimulates uterine contractions during childbirth and causes milk ejection during breastfeeding. Vasopressin helps the kidneys conserve water and also supports blood pressure by constricting blood vessels when needed.

A common misconception is that the posterior pituitary is a gland that manufactures hormones the way the anterior pituitary does. In reality, its job is closer to a storage and dispatch center. The hormones are hypothalamic in origin, but the posterior pituitary is the structure that gets them into circulation at the right time.

## Why It Matters

Posterior pituitary is one of the clearest examples of how Anatomy and Physiology II connects structure to function. If you know where oxytocin and vasopressin are made, stored, and released, you can explain a lot of homeostasis content without memorizing random facts.

It also helps you separate the two pituitary lobes, which shows up a lot in diagrams, labeling questions, and hormone matching. If you mix up the posterior and anterior pituitary, you can lose track of which hormones come from the hypothalamus and which come from the pituitary itself.

This term also gives you a way to trace a body response from cause to effect. For example, dehydration increases vasopressin release, which changes kidney water reabsorption and helps stabilize blood volume. Labor contractions or nipple stimulation can increase oxytocin release, which strengthens uterine contractions or triggers milk letdown.

If you can explain the posterior pituitary clearly, you are usually in good shape for the broader neuroendocrine integration unit because it shows how the nervous system can control an endocrine response quickly and precisely.

## Connections

### Hypothalamus

The hypothalamus makes the hormones that the posterior pituitary stores and releases. It is the control center that links neural signals to endocrine output, so if you are tracing the pathway, the hypothalamus comes first and the posterior pituitary comes after. That relationship is what makes this structure a neuroendocrine bridge.

### Oxytocin

Oxytocin is one of the two main hormones released from the posterior pituitary. You usually see it connected to childbirth and milk ejection, but in this course it also comes up as a clean example of hypothalamic control through the posterior lobe. When a question asks where oxytocin is released, the posterior pituitary is the structure you name.

### Vasopressin

Vasopressin, or ADH, is the other major posterior pituitary hormone. It is tied to water balance, kidney function, and blood pressure regulation, so it often appears in homeostasis questions. When body water drops, vasopressin release helps the kidneys reabsorb more water and conserve fluid.

### [Anterior pituitary](/anatomy-physiology-ii/key-terms/anterior-pituitary)

The anterior pituitary is easy to confuse with the posterior pituitary because both are part of the same gland, but they work very differently. The anterior pituitary synthesizes and secretes its own hormones in response to hypothalamic signals, while the posterior pituitary stores and releases hypothalamic hormones. That difference shows up often in comparisons and labeling tasks.

## On the AP Exam

A diagram label, matching question, or short-answer item will usually ask you to identify the posterior pituitary as the lobe that releases hypothalamic hormones rather than making its own. You may need to trace the route of oxytocin or vasopressin from the hypothalamus down axons to the posterior lobe and into the blood. In lab images, look for the back lobe of the pituitary and connect it to neuroendocrine control. If a question describes dehydration, milk letdown, or labor contractions, you should be able to choose the hormone and explain why the posterior pituitary is involved. On tests and quizzes, the common trap is mixing it up with the anterior pituitary, so name both the hormone source and the release site clearly.

## posterior pituitary vs anterior pituitary

These are the two lobes of the pituitary gland, but they do opposite jobs. The posterior pituitary stores and releases hormones made in the hypothalamus, while the anterior pituitary makes and secretes its own hormones in response to hypothalamic releasing hormones through the portal system. If a question asks about oxytocin or vasopressin, think posterior pituitary. If it asks about hormones like ACTH or growth hormone, think anterior pituitary.

## Key Takeaways

- The posterior pituitary does not make its own hormones, it stores and releases hormones made by the hypothalamus.
- Oxytocin and vasopressin are the two main hormones linked to the posterior pituitary in Anatomy and Physiology II.
- This structure is a direct example of neuroendocrine integration because nerve signals trigger hormone release.
- The posterior pituitary matters for childbirth, breastfeeding, water balance, and blood pressure control.
- If you can separate the posterior pituitary from the anterior pituitary, you can answer a lot of hormone and anatomy questions correctly.

## FAQs

### What is posterior pituitary in Anatomy and Physiology II?

The posterior pituitary is the back lobe of the pituitary gland that releases hormones made in the hypothalamus. It is the release site for oxytocin and vasopressin, so it connects the nervous system to endocrine control. In class, you will usually see it in hormone pathways and pituitary labeling questions.

### Does the posterior pituitary make hormones?

No. The posterior pituitary does not synthesize hormones the way the anterior pituitary does. Hypothalamic neurons make oxytocin and vasopressin, then transport them down axons to be stored and released from the posterior lobe.

### What hormones are released by the posterior pituitary?

The two major hormones are oxytocin and vasopressin, also called antidiuretic hormone or ADH. Oxytocin is tied to labor contractions and milk ejection, while vasopressin helps the body conserve water and support blood pressure.

### How is the posterior pituitary different from the anterior pituitary?

The posterior pituitary releases hormones made in the hypothalamus, while the anterior pituitary makes and secretes its own hormones. That difference is a common source of confusion in A&P II. If you remember release versus production, the two lobes are much easier to tell apart.

## Related Study Guides

- [14.1 Neuroendocrine Integration](/anatomy-physiology-ii/unit-14/neuroendocrine-integration/study-guide/kUeIzrwZEbnimUZB)

## About This Document

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