the pituitary gland & hypothalamus gland

7/28/2019 The Pituitary Gland & Hypothalamus Gland

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Important autonomic nervous system andendocrine center of the brain locatedinferior to the thalamus.

It controls the pituitary gland.

Emotions as well as stress come from here.

2 kinds of hormones secreted by the

hypothalamus: Releasing hormone : stimulates release of

hormones

Inhibiting hormones : inhibits release of hormones


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A small pea-sized gland.

Rests in a depression of the sphenoid

bone inferior to the hypothalamus of thebrain (sella turcica)

Located posterior to the optic chiasma

and Is connected to the hypothalamusby a stalk called infundibulum.


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Divided into 2 parts: Anterior : made up of epithelial cells derived

from the embryonic oral cavity.

Posterior : extension of the brain and is madeup of neurons.

It is called the master gland because it

controls the functions of other glands. Secretes hormones that influence

growth, kidney function, birth and milkproduction.


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Secretions from the anterior pituitary arecontrolled by hormones that pass

through the hypothalamic-pituitaryportal system from the hypothalamus.

Hormones secreted from the posteriorpituitary are controlled by the actionpotentials carried by axons that passfrom the hypothalamus to the posteriorpituitary.


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Growth Hormone (GH)

Stimulates the growth of bones, muscles, and

other organs by increasing protein synthesis. Resists protein breakdown during periods of

food deprivation and favors fat breakdown.

Secretion of GH is controlled by 2 hormones

from the hypothalamus: Releasing hormone (stimulates release of GH)

Inhibiting hormone (inhibits release of GH)


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GH secretion increases during periods offasting & exercise.

Aside from GH, genetics, nutrition, and sexhormones influence growth.

Part of the effect of growth hormone isinfluenced by a group of protein chemical

signals called insulin-like growth factors (IGFs)or somatomedins.


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Thyroid-stimulating hormone (TSH)

Binds to the membrane-bound receptors on

cells of the thyroid gland and cause the cellsto secrete thyroid hormone.

When there is too much TSH, thyroid glandsenlarge & secretes too much thyroid

hormone. (Vice versa) The rate of TSH secretion is increased by a

releasing hormone from the hypothalamus.


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Adrenocorticotropic hormone (ACTH)

Binds to the membrane-bound receptors on

cells in the cortex of the adrenal glands. ACTH increases the secretion of a hormone

from the adrenal cortex called cortisol orhydrocortisone.

ACTH is required to keep the adrenal cortexfrom degenerating.


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ACTH binds to melanocytes which increasesskin pigmentation. In accordance to this, toomuch ACTH will result to darkening of the

skin.

The rate of ACTH secretion is increased by areleasing hormone from the hypothalamus.

the pituitary gland & hypothalamus gland

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