Endocrine #1 Flashcards
What hormones are released by the hypothalamus relating to growth?
Growth hormone regulating hormone (GHRH)
Somatostatin (SST)
What effect does GH secretion have on GHRH secretion?
GH is a negative regulator of GHRH secretion
Insulin-like Growth Factor 1 (ILGF-1)
Produced in the liver in response to GH
Negative regulator of GH
Positive stimulator of SST release
JAK-STAT kinase activity
A receptor associated JAK kinase activity mediates the effect of GH
Growth Hormone Physiology
Complex effects on growth and metabolism
Many effects are mediated through IGF-1
Growth Hormone Theraputics
Treatment in children with short stature
Treatment of severe catabolic states (ie AIDS)
Anti-aging (benefits are controversial)
GH antagonists are used to treat acromegaly
Where is Follicle Stimulating Hormone (FSH) released from?
Anterior Pituitary
Where is Leutinizing hormone (LH) released from?
Anterior Pituitary
Where is Human Chorionic Gonadotropin (hCG) released from?
Placenta
FSH and LH receptors are what?
G protein coupled receptors linked to Gas
What is FSH release related to in women?
Ovarian follicle development
What is FSH and LH release related to in women?
Ovarian steroidogenesis
What is LH release related to during the follicular stage of the menstrual cycle?
Androgen production
What is FSH release related to during the follicular stage of the menstrual cycle?
Conversion of androgens to estrogens
What is LH release related to during the luteal stage of the menstrual cycle?
Estrogen and progesterone production (if pregnancy does not occur)
What is hCG release related to during the luteal stage of the menstrual cycle?
Estrogen and progesterone production if pregnancy occurs
The coordinated pattern of FSH and LH secretion during the menstrual cycle required for what?
Follicle development, ovulation, and pregnancy
What is FSH responsible for in men?
Spermatogensis
What is LH responsible for in men?
Testosterone produciton
FSH, LH, hCG theraputics
Used to induce ovulation that is secondary to hypogonadotrpic hypogonadism, polycystic ovary syndrome, obesity, and others
Complex protocols require close monitoring
Expensive
Used to treat male infertility in cases not treatable with androgen alone
What hormones are released from the posterior pituitary?
Oxytocin
Vasopressin (aka ADH)
What is the net effect of the release of vasopressin?
Vasoconstriction - increasing arterial blood pressure
Renal fluid reabsorption - increasing blood volume and arterial pressure
What are the different receptors for vasopressin?
V1
V2
V1 vasopressin receptors
G-protein coupled receptors
On vascular smooth muscle - mediates vasoconstriction
Linked to Gaq
Activation contracts vascular smooth muscle
V2 vasopressin receptors
G-protein coupled receptors
On kidney tubules
Mediate water retention
Linked to Gas
Clinical uses of vasopressin
Treatment of diabetes insipidous
Treatment of certain types of bleeding problems
Treatment of nocturnal enuresis (bed wetting)
Clinical uses of vasopressin antagonists
Used to treat hyponatremia (low Na in the blood)
Very complex - almost counter-intuitive
Limit water retention
Oxytocin
Works through G-protein coupled receptors (Gaq)
Induces contraction of uterine smooth muscle
Eliciys mile ejection in lactating women
“the love hormone” - because of its role in sexual arousal
Oxytocin Physiology
Low dose - Increase frequency and force of contractions
High dose - Sustained contractions
Oxytocin Theraputics
Induce labor - if early vaginal delivery required or labor problems
Atosiban - antagonist (of both vasopressin and oxytocin), used to halt premature labor
Metabolic effects of thyroid hormone
Calorogenic effect - induces tolerance to cold and avaliability of ATP
Carbohydrate metabolism - increased glucose absorption from gut, glycogenolysis, gluconeogensis, and glucose oxidation
Lipid metabolism - lipogenesis in adipocytes, in coordination with blood glucose levels
What is the significance of thyroid hormone and development
Effect on growth as manifested in growing children - TH stimulates GH secretion and promotes GH effects
Important in promoting growth and development of the brain during fetal and postnatal life - deficiency can lead to mental retardation
Goiter
Enlargment of the thyroid gland
What are causes of a goiter?
Iodine deficiency (leading cause but rare in N America) Autoimmune disease where antibodies attack thyroid
Treatment of a goiter
Not necessary unless the goiter is large enough and has symptoms (often no symptoms)
Surgery is rarely used and is reserved for cases that cause difficulty of swallowing or breathing
Treatment for under-active thyroid
Synthetic thyroid hormone
T3, T4, or a combination of the two of them
Treatment for over-active thyroid
Anti-thyroid drugs
Thioamides
Anion inhibitors
Iodide
Which form of Thyroid hormone is dominant?
T4 is most abundant in plasma
T3 is the most active
Thioamides
Block thyroid hormone synthesis
Anion inhibitors
Block I- transport into the the thyroid
Iodide
High concentrations inhibit transport and inhibit hormone biosynthesis
