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Lecture 1

PHGY 210 Lecture Notes - Lecture 1: Posterior Pituitary, Neurohormone, Pituitary Stalk

Course Code
PHGY 210
Ann Wechsler

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Phgy 210
January 5, 2015
Endocrinology Lecture 1
Coordination of physiological processes
o In a living organism there must be coordination of number of physiological activities taking place
simultaneously such as movement, respiration, circulation, digestion, excretion and metabolism
o The central nervous system and the endocrine system represent the two major means by which
these functions are coordinated
Long distance communication
o Communication between cells that are not in contact is achieved through a number of chemical
substances, which are secreted by releasing cells and interact with specific receptors on distant
target cells
o Signalling through these receptors leads to a specific physiological effect
Endocrine Signalling
Involves hormone secretion into the blood by an endocrine gland
The hormone is transported by the blood to a distant target site
Neuroendocrine signalling
Release of a hormone by a neuronal cell cells from the hypothalamus and the posterior pituitary
Paracrine signalling between one cell and an adjacent cell
Autocrine signalling between a cell and itself
Communication by hormones (or neurohormones) can involve six steps
1) Synthesis of the hormone by endocrine cells (or neurons in case of neurohormone)
2) Release of the hormone by the endocrine cells (or the neurohormones by the neurons)
3) Transport of the hormone or neurohormone to the target site by the blood stream
4) Detection of the hormone or neurohormone by a specific receptor protein on the target cells
5) A change in cellular metabolism triggered by the hormone-receptor interactions
6) Removal of the hormone, which often terminates the cellular response
Hypothalamic-Pituitary Signalling
Via blood vessels of the pituitary stalk
Hypothalamic-hypophyseal portal system from the hypothalamus to the adenohypophysis
(anterior pituitary)
Hypothalamic neurohormones either activate or inhibit activity of one of the six types of hormone-
producing cells in the anterior pituitary
Called either releasing hormones (releasing factors) or inhibiting hormones (inhibiting factors)
Classes of Hormones Based on Structure
Glycoproteins are proteins that are glycosylated after the peptide has been synthesized
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