2. OBJECTIVES
At 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.
3. § 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
2-3
6. PITUITARY GLAND
(POSITION)
It lies in the hypophyseal fossa of the body of
sphenoid bone, between optic chiasma (anteriorly) &
mamillary bodies (posteriorly).
Mamillary body
Optic chiasma
Body of sphenoi
8. 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
9. PITUITARY GLAND
X-RAY SKULL: LATERAL VIEW
SAGITTAL SECTION OF HEAD &
NECK
Hypophyseal fossa
Sphenoidal air sinus
Pituitary
gland
12. 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
13. § 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?
17-13
14. BLOOD SUPPLY OF PITUITARY
GLAND
ARTERIES: Superior & inferior hypophyseal arteries (branches
of internal carotid artery)
VEINS: hypophyseal veins drain into cavernous sinuses.
Cavernous sinuses
16. 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
17. 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 portal
system
18. 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).
19. 1. FSH (follicle stimulating hormone)
2. LH (luteinizing hormone)
The above two are called gonadotropins
3. 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
21. 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
24. S & S Anterior Pituitary
HYPOfunctioning
GH
FSH/LH
Prolactin
ACTH
TSH
25. § 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?
27. 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
28. 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
30. OT (oxytocin) and ADH
produced in hypothalamus
transported by hypothalamo-
hypophyseal tract to posterior lobe
(stores/releases hormones)
§ Posterior Pituitary Hormones
2-30
31. 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
2-31