Hypothalamic-Adrenal-Pituitary, Thyroid Hormones Flashcards Preview

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Flashcards in Hypothalamic-Adrenal-Pituitary, Thyroid Hormones Deck (50)
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what are the 6 main hormones made in the anterior pituitary (adenohypophysis)?

TSH, ACTH, FSH, LH, GH, and prolactin


what does TSH target and where made?

Thyroid stimulating hormone; made in anterior pituitary, targets the thyroid


what promotes the production of TSH?

thyrotropin releasing hormone produced in hypothalamus


what two main hormones are produced in the posterior pituitary (neurohypophysis)?

oxytocin, and ADH (antidiuretic hormone aka vasopressin)


what controls secretion of hormones from the pituitary?

releasing or inhibiting hormones made in the hypothalamus


what hormones are produced in the hypothalamus that affect the pituitary?

CRH - corticotropin releasing hormone; TRH- thyrotropin releasing hormone; GH-releasing hormone; somatostatin (GH inhibitor); Gn-RH (gonadotropin releasing) and PRL-inhibiting factor which is actually dopamine


what is the function of LH?

luteinizing hormone in females: induces ovulation and ovarian secretion of estrogen and progesterone males: stims testes to produce androgens


function of FSH

females: promotes egg development and secretion of estrogen males: supports sperm production, stims secretion of testosterone


function of TSH

stims thyroid to produce T3/T4


what will be the relative concentrations of TSH, T3 and T4 in primary vs secondary hypothyroidism?

primary: increased TSH, decreased T3 and 4 secondary: all 3 decreased


what is primary vs secondary hypothyroidism?

primary means the issue is with the thyroid gland itself which could be due to loss of function, infiltrative disease or due to defects in hormone synthesis secondary means the issue stems from either the pituitary (TSH deficiency) or hypothalamus (TRH def)


what is the most frequent cause of primary hypothyroidism in developed countries vs worldwide?

In developed nations it is Hashimoto's (nongoitrous), often associated with antithyroid antibodies Worldwide it is iodine deficiency (causes goiter)


what are the relative levels of TSH, T3 and 4 in hypERthyroidism?

increased T3 and T4, decreased TSH


what is the most common cause of hyperthyroidism in the U.S. (give name and simple etiology); what can be other causes?

Grave's disease: development of circulating IgG against TSH receptors on the thyroid, causing overproduction of T3 and T4 due to the negative feedback Cam also be due to toxic multinodular goiter (Plummer's) or adenoma on thryoid


what is another term used in place of hyperthyroidism and it smeaning

thyrotoxicosis, defines the hypermetabolic state induced by increased amounts of circulating T3 &4


what is the function of ACTH

adrenocorticotropic hormone, made in the ant pit, stimulates the adrenal cortex to secrete glucocorticoids, esp cortisol


In Addison's disease, what will be circulating in increased amounts and why?

increased circulating ACTH bc of a lack of cortisol to act as the negative feedback stimulus


among the glycoprotein hormones of the ant pit, how are the hormones structured and what is distinctive between them?

they are of two peptide chains with carbohydrate moieties. The alpha subunits are similar, but the B subunits distinguish them from each other


what is another term for TSH and what does it promote the thyroid gland to do?

thyrotropin; promotes growth and uptake of iodine and stims secretion of the thyroid hormones


what are alternative terms for ADH, where is it formed and stored?

arginine vasopressin or just vasopressin; formed in neurons of the hypothalamus and stored in the posterior pituitary (neurohypophysis)


what does ADH/vasopressin do to: capillaries/arterioles intestinal muscles kidney tubules

1. stims contraction of capillary and arteriole muscle to raise blood pressure 2. promotes contraction of GI muscles to cause peristalsis 3. causes reabsorption of free water to concentrate urine and dilute blood serum


what regulates ADH secretion, PRIMARILY? secondarily? other?

plasma osmolarity; baroreceptors that respond to changes in blood volume; many other stimuli can cause ADH release: pain, stress, sleep, exercise, chemi agents like angiotensin II, catecholamines


where is oxytocin made and stored?

hypothalamus, stored in post pit


on what part of the kidney does ADH act ?

the distal convoluted tubules to increase water reabsorption


what disorder is associated with ADH excess and lack?

excess: SIADH lack of: diabetes insipidus


what is the effect of diabetes insipidus on electrolyte levels? SIADH?

It concentrates them bc too much fluid is lost, so hypernatremia; too much fluid retained without electrolyes, so in SIADH, hyponatremia


where are human steroid hormones synthesized primarily, and from what precursor substance?

in the adrenals and gonads; from cholesterol acquired from circulating LDL or it can also be synthesized intracellularly


where are steroids metabolized and how excreted?

in the liver, and to a lesser extent in kidney and GI tract; they are conjugated with glucuronic or sulfuric acids to be excretes as water-soluble metabolites in the urine


what are three major categories of steroids synthesized in adrenals?

glucocorticoids (think cortisol), mineralocorticoids (think aldosterone) and adrenal androgens plus progesterone and estrogen (obv also made in gonads)


major actions of cortisol the primary glucocorticoid include:

affects all macronutrient metabolism including raising blood glucose and release of FFAs OR lipogenesis have antiinflammatory properties, thus are used therapeutically