ANATOMY OF

THE PITUITARY GLAND

Who suffer (s) from pituitary disturbances?1) Soldier # 12) Soldier # 23) Soldier # 34) Soldiers # 1 & 3

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OBJECTIVESAt the end of the lecture, students should be able to:

Describe the position of the pituitary gland. List the structures related to the pituitary

gland. Differentiate between the lobes of the gland. Describe the blood supply of pituitary gland &

the hypophyseal portal system.

§ Introduction

1. The “master gland”— controls three other endocrine glands

2. Better to think of the pituitary gland as the relay center—

3. Its function covers both endocrine target glands and nonendocrine target glands

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PITUITARY GLAND(HYPOPHYSIS CEREBRI)

It is a small oval structure of 1 cm in diameter.It doubles its size during pregnancy.

PITUITARY GLAND(POSITION)

It lies in the hypophyseal fossa of the body of sphenoid bone, between optic chiasma (anteriorly) & mamillary bodies (posteriorly).

Mamillary bodyOptic chiasma

Body of sphenoid

PITUITARY GLAND(POSITION)

It lies in the middle cranial fossa It is well protected in sella turcica of body of sphenoid

Sella turcica

PITUITARY GLAND(POSITION)

A fold of dura mater (Diaphragma sellae) covers the pituitary gland & has an opening for passage of infundibulum (pituitary stalk) connecting the gland to hypothalamus.

Infundibulum

PITUITARY GLANDX-RAY SKULL: LATERAL

VIEWSAGITTAL SECTION OF HEAD &

NECK

Hypophyseal fossa

Sphenoidal air sinus

Pituitarygland

IMPORTANT RELATIONS

SUPERIOR: Diaphragma sellaeINFERIOR: Sphenoidal air sinusesLATERAL: Cavernous sinuses

Hypothalamus and pituitarygland

SUBDIVISIONS OF PITUITARY GLAND

The gland is subdivided into:

1) Anterior lobe (adenohypophysis): true gland, secretes hormones

2) Posterior lobe (neurohypophysis): connected to hypothalamus through hypothalamo-hypophyseal tract, stores hormones secreted by hypothalamic nuclei

Hypothalamo-hypophyseal tract

§ Pituitary Gland (Hypophysis) Suspended from hypothalamus by stalk (infundibulum)

Location and size housed in sella turcica of sphenoid bone 1.3 cm diameter

Adenohypophysis (________ pituitary) arises from hypophyseal (Rathke’s) pouch

(outgrowth of pharynx); Fig. 2.1 and x Neurohypophysis (________ pituitary)

arises from brain; Magnocellular neurons– supraoptic and

paraventricular nuclei; Nerve endings?

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BLOOD SUPPLY OF PITUITARY GLAND

ARTERIES: Superior & inferior hypophyseal arteries (branches of internal carotid artery)

VEINS: hypophyseal veins drain into cavernous sinuses.

Cavernous sinuses

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ARTERIES OF PITUITARY GLAND

The inferior hypophyseal: supplies posterior lobe of pituitary gland.The superior hypophyseal: supplies infundibulum & forms a capillary network from which vessels pass downward & form sinusoids into the anterior lobe of pituitary gland (hypophyseal portal system).

a hypothalamo-hypophseal portal vessel

Infundibulum

ANTERIOR LOBE OF PITUITARY

Hormone-releasing & inhibiting factors produced by hypothalamus use hypophyseal portal system of vessels to reach the anterior lobe of pituitary gland

Hypophyseal portalsystem

Anterior pituitary Anterior pituitary: connected to the

hypothalamus by hypothalmoanterior pituitary portal vessels.

The anterior pituitary produces six peptide hormones: prolactin, growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH).

1. FSH (follicle stimulating hormone) 2. LH (luteinizing hormone)The above two are called gonadotropins3. TSH (thyroid stimulating hormone,

thyrotropin)4. ACTH (adrenocorticotropic hormone)5. GH (growth hormone; somatotropin or

somatotropic hormone) 6. PRL (prolactin) Tropic (trophic) hormones-- target

other endocrine glands to release their own hormones;

§ Hormones secreted by anterior pituitary

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Too Much Growth Hormone

GIGANTISM IN CHILDREN skeletal growth; may

grow up to 8 ft. tall and > 300 lbs

ACROMEGALY IN ADULTS enlarged feet/hands,

thickening of bones, prognathism, HTN, wt. gain, H/A, visual disturbances, diabetes mellitus, enlargement of the heart and liver

What assessment findings would the nurse document?

S & S Anterior Pituitary HYPOfunctioning GH FSH/LH Prolactin ACTH TSH

§ Glycoprotein hormone family– TSH, FSH, LH

1. TSH– to stimulate the secretion of thyroid hormone

2. FSH & LH– important for the function of the testes and the ovaries

FSH– growth of ovarian follicles and formation of sperm

LH (in women)– induce ovulation and the formation of the corpus luteum; stimulate the ovarian production of estrogen and progesterone

LH (in men)– stimulates the production of Testosterone; what cells?

Regulation of gonadotropin secretion

Prolactin Stimulates breast development and

lactogenesis May be involved in development of

Leydig cells in pre-pubertal males Immunomodulatory effects– stimulates T

cell functions Prolactin receptors in thymus

POSTERIOR LOBE OF PITUITARY

Axons of supraoptic & paraventricular cells of hypothalamus send their secretion (neurosecretion) to posterior lobe of pituitary gland through hypothalamo-hypophyseal tract

Hypothalamo-hypophyseal tract

§ The Posterior Pituitary

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OT (oxytocin) and ADH produced in hypothalamus transported by hypothalamo-

hypophyseal tract to posterior lobe (stores/releases hormones)

§ Posterior Pituitary Hormones

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Hormone Actions: Posterior Lobe

ADH (Antidiuretic Hormone) Target organ/tissue-- ?

water retention, reduce urine also functions as neurotransmitter

Oxytocin labor contractions, lactation (milk

ejection) possible role in

sperm transport . . . emotional bonding

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1. 3.

2.

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3 hormonal families of the anterior lobe: Table 2.1 (ALL proteins)

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