What Is the Pituitary Gland?
The pituitary gland is a pea-sized endocrine gland at the base of the brain that controls many of the body's other hormone glands. It has two distinct lobes — anterior and posterior — with different tissue types, origins, and hormones.
The pituitary gland is the body's 'master gland': its anterior lobe makes and releases six hormones under hypothalamic control, while its posterior lobe stores and releases two hormones made by the hypothalamus itself.
- •Glandular tissue
- •Makes 6 hormones: GH, TSH, ACTH, FSH, LH, Prolactin
- •Controlled by hypothalamic releasing hormones
- •Connected by hypophyseal portal blood vessels
- •Neural tissue (axon terminals)
- •Stores & releases ADH and oxytocin
- •Hormones made in the hypothalamus
- •Connected by nerve fibers, not blood vessels
Step-by-step worked examples
A patient has low blood volume and feels very thirsty. Which pituitary hormone helps retain water, and where is it released from?
Low blood volume is sensed by hypothalamic osmoreceptors Hypothalamus produces ADH (antidiuretic hormone) ADH travels down the axon to the posterior pituitary Posterior pituitary releases ADH into the blood, causing the kidneys to reabsorb water
A child has slow growth and a doctor suspects a growth hormone deficiency. Which pituitary lobe and cell type are likely affected?
Growth hormone (GH) is made and secreted by the anterior pituitary Somatotroph cells in the anterior lobe produce GH GH release depends on hypothalamic GHRH via the portal system If GHRH signaling or somatotrophs fail, GH output drops and growth slows
During breastfeeding, a baby suckling triggers milk release within seconds. Which hormone and pathway explain this quick reflex?
Suckling stimulates sensory nerves in the nipple The signal reaches the hypothalamus, triggering oxytocin release Oxytocin is stored in posterior pituitary axon terminals Posterior pituitary releases oxytocin instantly into blood, contracting milk ducts (let-down reflex)
Flashcards
Quick quiz
Q1.Which hormone is released by the posterior pituitary?
Q2.The anterior pituitary is connected to the hypothalamus by…
Q3.Which of these is NOT an anterior pituitary hormone?
Q4.Tissue-wise, the posterior pituitary is best described as…
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Common mistakes
The pituitary makes all of its own hormones. — Correct: The posterior pituitary only stores and releases hormones made by the hypothalamus.
Anterior and posterior pituitary have the same tissue type. — Correct: Anterior is glandular tissue; posterior is neural tissue — they develop from different embryonic origins.
ADH and oxytocin are anterior pituitary hormones. — Correct: They are posterior pituitary hormones, synthesized in the hypothalamus.
The hypothalamus and pituitary are unrelated organs. — Correct: The hypothalamus directly controls both pituitary lobes via blood vessels (anterior) and nerve axons (posterior).
FAQ
What is the pituitary gland?
It's a pea-sized endocrine gland at the base of the brain, often called the 'master gland' because it regulates other hormone glands.
What is the difference between anterior and posterior pituitary?
The anterior pituitary makes 6 hormones itself; the posterior pituitary only stores and releases 2 hormones made by the hypothalamus.
What hormones does the anterior pituitary produce?
GH, TSH, ACTH, FSH, LH, and prolactin.
How is the pituitary gland connected to the brain?
Via the infundibulum (pituitary stalk), with blood vessels serving the anterior lobe and nerve fibers serving the posterior lobe.