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What hormones are released by the posterior pituitary?
Antidiuretic hormone (ADH) - also known as vasopressin and oxytocin
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What is the function of ADH?
- Controls water homeostasis by affecting the permeability of the collecting tubules of the kidney and enhancing water resorption, making urine more concentrated and the blood more dilute
- Raises blood pressure by stimulating musculature of arterioles and capillaries
- Affects uterine contraction
- Promotes intestinal muscle contraction
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What causes an increase level of ADH?
- Syndrome of inappropriate ADH secretion (SIADH) - no known stimulus for the release
- Small cell carcinoma of the lung
- CNS disease
- Pulmonary disease
- Side effect of certain drugs
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What clinical conditions results in decreased levels of ADH?
- Polyuria
- Diabetes insipidus
- Polydipsia
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What is the function of oxytocin?
- Stimulates uterine contractions during childbirth
- Causes the ejection of breast milk
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Name the 3 layers of the Adrenal cortex
- Zona glomerulosa (outermost)
- Zona fasciculata (2nd layer)
- Zona reticularis (3rd layer)
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What does the zona glomerulosa secrete?
- Mineralocorticoids
- (Aldosterone is the major one)
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What does the zona fasciculata secrete?
- Glucocorticoids
- (Cortisol is the major one)
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What does the zona reticularis secrete?
- Sex hormones
- (principally the androgens)
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What is the inner portion of the adrenal gland?
Adrenal medulla
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What does the adrenal medulla produce?
- Amine hormones
- (epinephrine and norepinephrine)
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What are collectively known as catecholamines?
- Epinephrine
- Norepinephrine
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What secretes the steroid hormones?
Adrenal glands
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Name the 3 groups of steroid hormones
- Mineralocorticoids
- Glucocorticoids
- Androgens
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What regulates salt balance?
Mineralcorticoids
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What assists with carbohydrate metabolism?
Glucocorticoids
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What is required for sexual function?
Androgens
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What controls the retention of Na, Cl, and H2O, the excretion of K and H, and the amount of fluid in the body?
Aldosterone
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What is aldosterone production controlled by?
Renin-angiotensin system of the kidneys
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What is produced when there is a decrease in blood pressure or blood volume?
Renin
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What is a protein that acts on angiotensinogen to produce angiotensin I?
Renin
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What stimulates the secretion of aldosterone and is a potent vasoconstrictor?
Angiotensin II
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What is the function of aldosterone?
- Increase salt
- Water conservation
- Overall effect is vasoconstriction
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What is the reference range of aldosterone?
- Adult supine: 3-16 ng/dL
- Adult upright: 7-30 ng/dL
- Levels are higher in the morning
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What is the clinical significance of hyperaldosteronism?
- Primary hyperaldosteronism: adrenal disease (Conn syndrome)
- Secondary hyperaldosteronism: Renin-angiotensin system disorder, malignant hypertension, or renin-secreting renal tumor
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What is the clinical significance of hypoaldosteronism?
- Atrophy of the adrenal glands
- Addison disease
- Congenital deficiency of 21-hydroxylase enzyme
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What condition:
Pigmemtation of the skin
Muscle weakness
Weight loss
Decreased blood pressure
Nausea
Diarrhea
Atrophy of adrenal glands
Depressed production of aldosterone and glucocorticoid
Addison disease
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Name the physiological effects of cortisol
- Anti-insulin effects on carbs that result in increased blood glucose levels
- Increased gluconeogenesis
- Increased lipolysis
- Increased protein catabolism
- Decreased protein synthesis
- Decreased antibody formation
- Suppressed inflammatory response
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How is cortisol regulated?
- Hypothalamus secretes corticotropin-releasing hormone
- Anterior pituitary secretes adrenocorticotropic hormone
- Low levels of plasma cortisol promote ACTH release
- High levels of plasma cortisol inhibit ACTH
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What is the reference range of total cortisol?
- 8 AM: 5-23 micro-gram/dL
- 4 PM: 3-16 micro-gram/dL
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What is the clinical significance of hypercortisolism?
- Primary hypercortisolism: adrenal adenoma or carcinoma, exogenous administration of cortisol, Cushing syndrome
- Secondary hypercortisolism: excessive production of ACTH due to pituitary tumor, ectopic production of ACTH by nonendocrine tumor, Cushing disease
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What is the clinical significance of hypocortisolism?
- Primary hypocortisolism: atrophy of adrenal gland, autoimmune disease, tuberculosis, prolonged high-dosage cortisol therapy
- Secondary hypocortisolism: pituitary hypofunction
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Name the inner portion of the adrenal gland
Adrenal medulla
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How are catecholamines synthesized?
Synthesized from tyrosine by chromaffin cells of the adrenal medulla, brain, and sympathetic neurons
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Name the hormones that are included in catecholamines
- Epinephrine
- Norepinephrine
- Dopamine
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What hormone mobilizes energy stores by converting glycogen to glucose, which allows the voluntary muscles to have greater work output?
Epinephrine
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What hormone functions as a neurotransmitter affecting the vascular smooth muscle and heart and released primarily by the potganglionic sympathetic nerves?
Norepinephrine
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What hormone functions as a neurotransmitter in the brain affecting the vascular system?
Dopamine
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What are epinephrine and norepinephrine metabolized into and what is the final product?
- Metabolized into metanephrine and normetanephrine
- Final end product vanillylmandelic acid (VMA)
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What are increased levels of epinephrine and norepinephrine associated with?
Pheochromocytoma
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What is a malignant tumor of the adrenal medulla that occurs in children?
Neuroblastoma
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What does the neuroblastoma tumor produce?
Produces epinephrine, norepinephrine, and dopamine
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What is the end product of dopamine metabolism?
Homovanillic acid (HVA)
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What clinical condition is characterized by:
Increased HVA urinary excretion
Increased VMA urinary excretion
Neuroblastoma
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