Hypothalamus Posterior Pituitary Connection atf

Posterior Pituitary Connection
ENDOCRINE PHYSIOLOGY: Note #2.
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2. POSTERIOR PITUITARY CONNECTION
Endocrinology | Hypothalamus: Posterior Pituitary Connection
Medical Editor: Ilia-Presiyan Georgiev
OUTLINE
I) ANATOMY
II) TYPES OF CONNECTION
III) SUPRAOPTIC NUCLEUS (SON)
IV) PARAVENTRICULAR NUCLEUS (PVN)
V) APPENDIX
VI) REVIEW QUESTIONS
VII) REFRENCES
I) ANATOMY
(1) Hypothalamus
Several gray matter nuclei – supraoptic nucleus (SON),
paraventricular nucleus (PVN), arcuate nucleus (AN),
preoptic nucleus (PON), etc
Situated anterior and a little bit inferior to the thalamus
o Nucleus - a group of cell bodies in the central nervous
system collectively joined together in a specific area which
is unmyelinated and forming gray matter
o Tract – a bundle of axons grouped together in the central
nervous system
(2) Infundibulum
The connection between the hypothalamus and the
hypophysis
(3) Pituitary gland (Hypophysis)
Anterior pituitary gland (Adenohypophysis)
o Made of glandular cuboidal epithelial tissue
o Originates form pharyngeal mucosa - Rathke’s
pouch
Posterior pituitary gland (Neurohypophysis)
o Made of neural tissue - pituicytes (glial cells)
o Considered a part of the brain and not a separate
type of endocrine gland.
Figure 1 Location of the hypothalamus and pituitary gland.
II) TYPES OF CONNECTION
Tract – neural connection
o between the hypothalamus and the neurohypophysis
(hypothalamic hypophyseal tract)
Figure 2 Hypothalamic hypophyseal tract.
Portal system – connection of two capillary beds by a
portal vein
o between the hypothalamus and the adenohypophysis
(hypothalamic hypophyseal portal system)
Figure 3 Hypothalamic hypophyseal portal system.
III) SUPRAOPTIC NUCLEUS (SON)
Secretes antidiuretic hormone (ADH)
o A.k.a. vasopressin
After it’s created it is transported down the axons
o In synaptic vesicles
o By specific motor proteins
The vesicles need certain stimuli to release the ADH
o ↓ blood volume → ↓ blood pressure
o ↑ plasma osmolality
o Pain
Osmolality refers to the concentration solutes and water inside
the plasma
o High plasma osmolality - ↓ water, ↑ solutes
o Low plasma osmolality - ↑ water, ↓solutes
Inhibitors of the ADH secretion
o ↑ blood volume
o ↓ plasma osmolality
o Alcohol
Last edited: 9/29/2021

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ENDOCRINE PHYSIOLOGY: Note #2.
Posterior Pituitary Connection
Figure 4 Function of the supraoptic nucleus.
(1) Osmoreceptors
Subfornical organ and organum vasculosum of the
laminae terminalis
Register the plasma osmolality
o High osmolality stimulates the receptors
IV) PARAVENTRICULAR NUCLEUS (PVN)
There are two PVN
(1) Secretes Oxytocin
After oxytocin is created it is transported down the axons
in synaptic vesicles by specific motor proteins
The vesicles need certain stimuli to release the oxytocin
o Birthing process
o Suckling by the baby on the mother’s mammary
glands.
 There are specific receptors in the areola
o Male ejaculation
Figure 5 Function of the paraventricular nuclei.
V) APPENDIX
Products
Stimuli
Inhibitors
Supraoptic nucleus Antidiuretic hormone
↓ blood pressure
↑ plasma osmolality
Pain
↑ blood volume
↓ plasma osmolality
Alcohol
Paraventricular nucleus Oxytocin
Birthing process
Suckling by the baby
Male ejaculation

Posterior Pituitary Connection
ENDOCRINE PHYSIOLOGY: Note #2.
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VI) REVIEW QUESTIONS
What structure connects the hypothalamus with the
pituitary gland?
a. Neurohypophysis
b. Infundibulum
c. Adenohypophysis
d. Rathke’s pouch
How many components has the pituitary gland?
a. 3
b. 4
c. 2
d. 1
What do we call a group of cell bodies collectively
joined together in a specific unmyelinated are, forming
gray matter?
a. A tract
b. Axons
c. A nucleus
d. Vesicles
Which nucleus produces ADH?
a. Supraoptic
b. Subthalamic
c. Paraventricular
d. Arcuate
What is the other name of ADH?
a. Oxytocin
b. Renin
c. Angiotensin
d. Vasopressin
Which stimuli activate the release of ADH?
a. ↓ blood volume, ↓ blood pressure, ↓ plasma
osmolality
b. ↑ blood volume, ↑ blood pressure, ↓ plasma
osmolality
c. ↓ blood volume, ↑ blood pressure, ↑ plasma
osmolality
d. ↓ blood volume, ↓ blood pressure, ↑ plasma
osmolality
Which are the inhibitors of the ADH?
a. Pain, ↑ blood pressure, ↓ plasma osmolality
b. Pain, ↓ blood pressure, ↑ plasma osmolality
c. Alcohol, ↓ blood pressure, ↓ plasma osmolality
d. Alcohol, ↑ blood pressure, ↓ plasma osmolality
Which nucleus produces Oxytocin?
a. Paraventricular
b. Subthalamic
c. Supraoptic
d. Arcuate
Specific receptors that can stimulate the release of
oxytocin are located in?
a. Subfornical organ
b. Areola
c. Adenohypophysis
d. Organum vasculosum of lamina terminalis
Which stimuli activates the release of Oxytocin?
a. Birthing process, male ejaculation, suckling by the baby
b. ↑ blood pressure, male ejaculation, suckling by the baby
c. ↑ blood pressure, birthing process, ↓ plasma
osmolality
d. ↑ blood pressure, suckling by the baby, ↑ plasma
osmolality
CHECK YOUR ANSWERS
VII) REFRENCES
● Le T, Bhushan V, Sochat M, Chavda Y, Zureick A. First Aid for
the USMLE Step 1 2018. New York, NY: McGraw-Hill Medical; 2017
● Marieb EN, Hoehn K. Anatomy & Physiology. Hoboken, NJ:
Pearson; 2020.
● Boron WF, Boulpaep EL. Medical Physiology.; 2017.
● Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL,
Loscalzo J. Harrison's Principles of Internal Medicine, Twentieth
Edition (Vol.1 & Vol.2). McGraw-Hill Education / Medical; 2018
● Hall JE, Hall ME. Guyton and Hall Textbook of Medical
Physiology. Philadelphia, PA: Elsevier; 2021.