1070 MSNBIO 2070 September 12 2016 Control 2 Functions of Hormones Hormones act on their target cells in one of three basic ways Control the rate of enzymatic reactions Control transport of molecules across cell membranes ID: 426908
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Slide1
Control 2
September 9, 2019Slide2
Functions of Hormones
Hormones act on their target cells in one of three basic ways:
Control the rate of enzymatic reactions
Control transport of molecules across cell membranes
Control gene expression and synthesisSlide3
Types of Hormones
Peptides
Amino Acids
SteroidsSlide4Slide5
Divisions of Pituitary
Anterior pituitary
(also called adenohypophysis)
True glandular tissue
Posterior pituitary
(also called neurohypophysis)
Extension of brainSlide6
Hypothalamic-Hypophyseal
Portal SystemSlide7
Tropic Hormones — Control the Release of Other Hormones
Anterior Pituitary Hormones are Tropic Hormones
End Products Regulate Tropic Hormone Secretion
Short Loop Feedback
Long Loop Feedback
Ultra Short Loop FeedbackSlide8
Anterior Pituitary Hormones
No
Known
Tropic
RoleSlide9
Proopiomelanocortin(POMC)
POMC is cleaved within a vesicle to form ACTH,
β
-Endorphin,
γ
LPH
, and 16K fragmentSlide10
Hypophysiotropic Hormones: Control Anterior Pituitary Secretions
Others likely exist, but have not been discovered because of their low concentrations in bloodSlide11
What happens if feedback mechanisms are dysfunctional?
Tumors can produce large amounts of hormones without feedback regulation
Autoimmune diseases can damage receptors on hormone-secreting cells, so they no longer respond to tropic hormones
Intracellular signal transduction pathways can become aberrantly altered, thereby affecting how hormone-producing cells respond to tropic hormones.Slide12
Posterior Pituitary Hormones
Arginine Vasopressin
Named as such because the first vasopressin discovered was from pig; this hormone has a lysine instead of arginine as residue 8
Produces vasoconstriction when present in high concentrations (hence the name)
Affects water reabsorption in kidney at lower concentrations, hence the secondary name: antidiuretic hormone
Oxytocin
Triggers uterine contractions during birthing
Triggers milk release from mammary glands during suckling
May have roles in cardiovascular control and renal function (men and women who are not of child-bearing age also synthesize oxytocin)Slide13
Posterior Pituitary Hormones
Posterior pituitary hormones are synthesized by neurons in the
paraventricular
and
supraoptic
nuclei of the hypothalamus
These hormones are released like neurotransmitters when the neurons fire
The release of the hormones is dependent on the number of neurons that fire and the rate and duration of their firingSlide14
Examples of Some Hormones
Hormone
Where Produced
Effect
Stimu-lation
Inhi-bition
LH
Anterior Pituitary
Stimulates Leydig cells of testis to synthesize & release testosterone; stimulates estrogen & progesterone secretion by corpus luteum; stimulates ovulation
GnRH from Hypo-thalamus
Testos-terone
, estrogen,
proges-terone
,
Inhibin
Testos-terone
Leydig
Cells of Testis (mainly)
Production & maintenance of male sexual characteristics
LH from anterior pituitary
None
Erythro-poietin
Tubular epithelial cells of Kidney
Stimulation of red blood cell production by bone marrow
Hypoxia of tubular epithelial cells
None
Aldos-terone
Adrenal cortex
Promotes reabsorption of Na
+
and excretion of K
+
by tubular epithelial cells of kidney
Increased K
+
in plasma, Angiotensin II
Increased Na+ in plasma
Gastrin
G cells of stomach
Stimulates acid secretion by stomach
Peptides and amino acids in stomach; enteric nervous system
Somato
-statin and low pH in stomach
Insulin
Islets of Langer-
hans
Enhances glucose transport by many tissues; increases glucose metabolism and storage
High plasma glucose levels, hormone GIP,
parasym
-pathetic activity
Sympa-thetic
activity
Epin-ephrine
Adrenal medulla
Many effects mediated by binding to
β
-receptors
Sympathetic nervous system influences on Adrenal medulla
NoneSlide15