The hypothalamus and pituitary gland (video) | Khan Academy
The hypothalamus makes up the lower region of the diencephalon and lies just above the brain stem. The pituitary gland (hypophysis) is attached to the bottom. The hormones of the pituitary gland help regulate the functions of other endocrine glands. The pituitary gland has two parts—the anterior lobe. The pituitary gland, also known as the hypophysis, is a roundish organ that lies from the Visible Human Project, shows these anatomical relationships in the.
The anterior lobe releases hormones upon receiving releasing or inhibiting hormones from the hypothalamus. These hypothalamic hormones tell the anterior lobe whether to release more of a specific hormone or stop production of the hormone.
ACTH stimulates the adrenal glands to produce hormones. FSH works with LH to ensure normal functioning of the ovaries and testes.
GH is essential in early years to maintaining a healthy body composition and for growth in children. In adults, it aids healthy bone and muscle mass and affects fat distribution.
LH works with FSH to ensure normal functioning of the ovaries and testes. Prolactin stimulates breast milk production.Hypothalamus and Pituitary Gland Functions, Animation
TSH stimulates the thyroid gland to produce hormones. The posterior lobe contains the ends of nerve cells coming from the hypothalamus. A branch of the hypophyseal artery ramifies into a capillary bed in the lower hypothalamus, and hypothalmic hormones destined for the anterior pituitary are secreted into that capillary blood.
Functional Anatomy of the Hypothalamus and Pituitary Gland
Blood from those capillaries drains into hypothalamic-hypophyseal portal veins. Portal veins are defined as veins between two capillary beds; the hypothalamic-hypophyseal portal veins branch again into another series of capillaries within the anterior pituitary. Capillaries within the anterior pituitary, which carry hormones secreted by that gland, coalesce into veins that drain into the systemic venous blood.
Those veins also collect capillary blood from the posterior pituitary gland. This pattern of vascular connections is presented diagramatically below.
What is the pituitary gland? | The Pituitary Foundation
Note also the hypothalamic-hypophyseal portal vessels in the image of a real pituitary gland seen above. The utility of this unconventional vascular system is that minute quantities of hypothalamic hormones are carried in a concentrated form directly to their target cells in the anterior pituitary, and are not diluted out in the systemic circulation. And then last but not least, we have prolactin inhibitory factor, PIF. And prolactin inhibitory factor is a little bit different, because it's constantly being released.
And when it stops being released, that's when the pituitary gland is signaled to release prolactin, and prolactin is a hormone involved in milk production in moms.
An Overview of the Pituitary Gland
And so some of the anterior pituitary hormones go down and directly stimulate other endocrine glands, like FSH and LH, but some of the anterior pituitary glands directly affect parts of the body, like growth hormone and prolactin.
Let me get a different color for this.
- What is the pituitary gland?
- The hypothalamus and pituitary gland
- The Hypothalamus and Pituitary Glands
And the tropic hormones are hormones that stimulate other endocrine glands. PEG hormones are the direct hormones, and they include prolactin and growth hormone.
And the E is for endorphins, which I haven't included in this list because the anterior pituitary does release endorphins, but so do a lot of other parts of the body. So E is for endorphins, but the PEG hormones are direct hormones. And direct hormones stimulate a part of the body directly.
So growth hormone directly stimulates the bones and the muscles, and prolactin directly stimulates lactation. And so the hypothalamus signals the anterior pituitary's release of its hormones through the hypophyseal portal system, or this little capillary bed.
And then the hypothalamus also communicates with the posterior pituitary, and it does that through stimulation of nerves which run down that pituitary stalk right here. And the hypothalamus sends a signal down those nerves to the posterior pituitary and causes the posterior pituitary to release a couple hormones, too.
And I want to make a point, because the posterior pituitary releases these hormones, but they're actually made in the hypothalamus and stored in the posterior pituitary. And the two major hormones are ADH and oxytocin.