Endocrine System and Hormonal Control: Hypothalamic pituitary

endocrine axis

Vibuntita Chankitisakul, D.V.M., Ph.D.

Hypothalamus

Region of the lower brain Receives information from nerves throughout the body

and brain Initiates endocrine signals appropriate to the

environmental conditions Regulates the Pituitary Gland

Pituitary Gland

Located at the base of the hypothalamus

Two lobes: anterior and posterior; numerous functions

The posterior pituitary stores and secretes hormones that are

made in the hypothalamus

The anterior pituitary makes and releases

hormones under regulation of the

hypothalamus

Contains axon from neurons

in the hypothalamus

Posterior Pituitary Gland

Posterior Pituitary Gland

Posterior pituitary hormone function

Two hormones Three internal organs

Antidiuretic hormone (ADH) or Vasopressin - Stimulates kidneys

to conserve water - Increase blood

pressure

Oxytocin -triggers mammary glands to express milk -triggers uterine contractions

Consists of glandular

tissue

Anterior Pituitary Gland

Cells that produce anterior pituitary

hormones

Anterior Pituitary Gland

A specific hormone affects a specific cell type of ant.

Pituitary cell.

Cell types Chromophils Hormones

Somatotrophs Acidophils Growth hormone(GH)

Lactotrophs Acidophil Prolactin(PRL)

Corticotrophs Basophil adenocorticotropic- hormone(ACTH)

Gonadotrophs Basophil Follicle stimulating hormone

(FSH) and luteinizing hormone (LH)

Thyrotrophs Basophil Thyroid stimulating hormone (TSH)

Five hormones Many internal organs

Tropic hormones

Tropic and non-tropic hormone

• Tropic hormones are hormones that have other

endocrine glands as their target. Most are produced and secreted by the ant.pituitary gl.

• Non-tropic hormones are those that act directly on targeted tissues or cells to induce effects.

Tropic hormones mean??

Tropic hormones and the glands they control

hypothalamus

Releasing hormone

Inhibiting hormone

Pituitary gland

somatostatin

PIFs, dopamine

HYPOTHALAMIC-PITUITARY-ENDOCRINE AXIS

Hormones of the hypothalamus

Thyrotropin-releasing hormone (TRH)

Gonadotropin-releasing hormone (GnRH)

Growth hormone-releasing hormone

(GHRH)

Corticotropin-releasing hormone (CRH)

Somatostatin Dopamine

Hypothalamic-Pituitary-Endocrine axis

1. Hypothalamic-pituitary-breast axis

2. Hypothalamic-pituitary-growth hormone-somatotroph axis

3. Hypothalamic-pituitary-gonadal axis

4. Hypothalamic-pituitary-adrenal axis

5. Hypothalamic-pituitary-thyroid axis

Thyrotropin-releasing hormone (TRH)

Gonadotropin-releasing hormone (GnRH)

Growth hormone-releasing hormone

(GHRH)

Corticotropin-releasing hormone (CRH)

Somatostatin Dopamine

1. Hypothalamic-pituitary-breast axis

Regulation of prolactin secretion

TRH = thyrotropin-releasing hormone

Regulation of prolactin secretion

Physiological effects of prolactin

Thyrotropin-releasing hormone (TRH)

Gonadotropin-releasing hormone (GnRH)

Growth hormone-releasing hormone

(GHRH)

Corticotropin-releasing hormone (CRH)

Somatostatin Dopamine

2. Hypothalamic-pituitary-growth hormone-somatotroph axis

Regulation of growth hormone (somatotropin )

Bone and tissue growth and

nutrient metabolism.

GHRH Tropic effect

Regulation of growth

hormone

Sm= Somatomedin C or Insulin-like growth factor I (IGF-I)

Effects of GH: Bone and tissue growth

and nutrient metabolism.

Negative feedback

= inhibiting factor = negative feedback

Summarize (again)!!

inhibit

Let’s read some articles in class and make the discussion!!

Hypothalamic-pituitary-adrenal axis

Hypothalamic-pituitary-gonadal axis Hypothalamic-pituitary-thyroid axis