PHGY 210 Lecture Notes - Lecture 2: Thyroid Dysgenesis, Fetus, Diiodotyrosine
Jan 6, 2017
Feedback Control of Hormone Secretion
-hormone secretion is precisely regulated by feedback mechanisms
-excess of hormone, or excess hormonal activity, leads to diminution of hormone secretion
-conversely, deficiency of hormone leads to increase in hormone secretion
-Ca++ acts in negative feedback loop to regulate plasma calcium levels
Hormonal Feedback Mechanisms
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-CRH: corticotopin releasing hormone
-ACTH: adrenocorticotropic hormone
-cortisol (glucocorticoid)
Endocrine Glands and their Secretions
1. Anatomic Location
2. Hormones Secreted
3. Chemical Nature of Hormones
4. Effects
5. Mechanism of Action
6. Control of Release
7. Problems
8. Treatment
Pituitary Gland
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-anatomy: two distinctly different tissues
-adenohypophysis
-a.k.a. anterior pituitary, or pars distalis
-neurohypophysis
-a.k.a. posterior pituitary, or pars nervosa
-histologically:
-anterior pituitary is endocrine tissue
-posterior pituitary is neural tissue
-surrounded by bone
Signaling b/w Hypothalamus and Pituitary
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Document Summary
Hormone secretion is precisely regulated by feedback mechanisms. Excess of hormone, or excess hormonal activity, leads to diminution of hormone secretion. Conversely, deficiency of hormone leads to increase in hormone secretion. Ca++ acts in negative feedback loop to regulate plasma calcium levels. Endocrine glands and their secretions: anatomic location, hormones secreted, chemical nature of hormones, effects, mechanism of action, control of release, problems, treatment. Back in evolution there was a gene duplication event. Oxytocin and vasopressin synthesized in two hypothalamic nuclei. Whose axons run down pituitary stalk and terminate in posterior pituitary close to capillary blood vessels. Prohormones processed in secretory granules during axonal transport. Uterus extremely sensitive to oxytocin at end of pregnancy. Dilation of uterine cervix by fetal head causes release of oxytocin. Uterine contraction, which assists expulsion of fetus and then placenta. In lactating mother: response to stimulus of suckling. Oxytocin causes milk filled ducts to contract and squeeze milk out.
