Pituitary

half inch in diameter, sits at base of brain

The hypothalamus and pituitary gland are connected by the ___________?

They are connected by the infundibulum (pituitary stalk).

What an awesome name

During embryotic development, what tissues form the anterior and posterior pituitary.

The anterior pituitary is comprised of tissue from the primative oral cavity known at Rathke's Pouch.

The posterior pituitary is comprised of an extention of the hypothalamus.

Anterior Pit.= Adenohypophysis

(Greek for Gland-under-growth)

Posterior Pit.= Neurohypophysis 

(greek for brain-under-growth, since it is an extension of the brain)

adenohypophysis = anterior pituitary 

1.  Pars distalis (Anterior lobe)

2.  Pars Tuberalis (sides of pit. stalk)

3.  Pars intermedia

neurohypophysis = posterior pituitary

1.  Infundibular stem

2.  Infundibular process (posterior lobe)

All of the hormones produced by the hypothalamus and pituitary, except one, are from this class of hormones.

1. Name the class of hormone

2. What is the exception?

1.  Peptide hormones

2.  dopamine (catecholamine!)

Signal transduction through cell membrane receptors:

1.  G proteins

2.  second messengers

3.  protein kinases

neurohypophysis = posterior pituitary 

1.  Supraoptic

2.  Paraventricular

Since these nuclei are large, they are sometimes referred to as magnocellular neurons

1.  median eminence

2.  long portal veins

3.  Hypothalamic Pituitary Portal System (HPPS)

Corticotropin-releasing hormone

-released from the hypothalamus

-stimulates secretion of Adrenocorticotropic hormone (ACTH)

Thyrotropin-Releasing hormone (TRH)

-released from the hypothalamus

-Stimulates Thyroid stimulating Hormone secretion from the anterior pituitary.

Gonadotropin-Releasing Hormone (GnRH)

-released from the hypothalamus

-Stimulates Leutenizing and Folicle Stimulating Hormones (LH and FSH) release from anterior pituitary.

Somatostatin (SRIF)

-released from the hypothalamus

-Inhibits Growth Hormone (GH) and Thyroid stimulating hormone (TSH) secretion from the anterior pituitary.

Growth Hormone Releasing Hormone

-released from the hypothalamus

-Stimulates Growth Hormone Release from anterior pituitary.

Prolactin-Releasing factor (PRF)

-released from the hypothalamus

-Stimulates prolactin secretion from anterior pituitary.

dopamine = prolactin inhibitory hormone

-released from the hypothalamus

-Inhibits prolactin secretion

Name the targets for the following hormones from the anterior pituitary:

1.  TSH

2.  ACTH

3.  Prolactin

4. FSH

5.  LH

6. GH

1.  Thyroid stimulating hormone- THYROID

2.  Adrentocorticotropic hormone (ACTH) -Adrenal Cortex

3.  Prolactin- Breast

4.  FSH- Follicle Stimulating Hormone-Ovaries

5.  Leutenizing Hormone-Testes

6.  Growth Hormone- Various Tissues

Adrenocorticotropic hormone (corticotropin)

Function:  Stimulates steroidogenesis and the secretion of glucocorticoids, mineralcorticoids, and androgenic steroids from adrenal cortex.  (Remember--Sweet, Salty, Sexy)

Hypothalamus (CRH)--Ant. pit (ACTH)--adrenal cortex (G,M,A)

Glucocorticoids inhibit ACTH (negative feedback)

Stress and AVP/ADH incresses ACTH secretion

Thryroid Stimulating Hormone

Function:  Stimulates iodide uptake, hormonogenesis, and release of thyroid hormones.

Hypothalamus (TRH)-->Ant. Pit. (TSH)-->Thryroid (T3 and T4)

Growth Hormone (Human Growth Hormone!)

Function:  primarily in promotion of linear growth.

Inhibited by somatostatin (Buzzkillington)

Hypothalamus (GHRH)-->Ant. Pit. (GH)-->Various tissues

1.  Increase a.a. uptake

2.  Increase Protein synthesis

3.  decrease glucose uptake

MAKE MUSCLES BIGGER! hGH!

1.  Increase in protein synthesis

2.  Increase in RNA synthesis

3.  Increase in gluconeogenesis

4.  Increase in somatomedin production

-FYI Somatotrophin=Growth Hormone

Somatotrophin

(Somatotropin is synthetic and abb. rhGH)

1. Decrease glucose uptake

2.  Increase Lipolysis

DECREASE ADIPOSITY

Luteinizing Hormone

Follicle Stimulating Hormone

Both also known as gonadotropin

Function:  regulate gonadal function by promoting sex steroid production and gametogenesis.

Hypothalamus (GnRH)-->Ant. Pit. (LH & FSH)-->gonads

Prolactin aka lactotropin

Function:  acts to induce and maintain lactation, decreases reproductive function and suppresses sex drive.

Hypothalamus (PRF, TRH)-->Ant. Pit. (PRL)-->Breast Tissue

1.  Prolactinoma

2.  Adenoma

Secreting FSH, LH, TSH, or ACTH

3.  Growth Hormone Problem

Gigantism, Dwarfism, Acromegaly

Prolactin

Women:  galactorrhea, lack of perior, no libido

men:  infertility, headache, vision changes

headache

impaired vision

gonadal hypofunction

FSH is secreted a lot more than LH

Depends!

a.  GH is secreted during childhood and adolescence then the condition would be GIGANTISM.

OR

b.  If the growth plates have already fused and the GH is secreted during adulthood then ACROMEGALY.

Synthesized in the hypothalamus

secreted via the neuroendocrine cells

Oxytocin is a hormone produced by the posterior pituitary.

Function:  When the nipple is stimulated, myoepithelial cells contract to produce lactation.  Also works in uterine smooth muscle contraction (also has stretch receptor function in cervix)

Antidiuretic hormone and arginine vasopressin

Stimulators:  decrease in blood volume and catecholamines, angiotensin II, and ANP.

Function:  Released during dehydration, conserves water, decreases urine

In other words: increases water permeability of the luminal membrane of the collecting duct epithelium-->increases renal water reabsorption

Characterized by severe thirst and excretion of massive ammount of dilute urine.

Caused by deficiency in Antidiuretic Hormone or argenine vasopressin.

Can be caused by tumor in hypothalamus or trauma to region

FYI:  Diabetes means "To pass through" and insipidous means "without taste".  Means you pee a lot but it doesn't taste sweet like diabetes mellitus.  Doctors actually used to taste the pee to detect glucose (mellitus means honey)...gross and awesome. BOOYAH