Hormones COPY

Question 1

aldosterone

Answer 1

• secreted by adrenal cortex when sodium in ECF is low
• triggers nephrons to reabsorb sodium and water
• promotes kidneys to excrete potassium
• effect: decreased serum potassium, increased serum sodium, increased blood pressure

Question 2

antidiuretic hormone (ADH)

Answer 2

• AKA vasopressin
• released by posterior pituitary in response to increased serum osmolarity (especially sodium)
• increases nephron reabsorption of water
• effect: dilutes serum osmolarity and increases blood pressure

Question 3

natriuretic peptides (NPs)

Answer 3

• atrial natriuretic peptide (ANP) is secreted by atria of heart
• brain natriuretic peptide (BNP) is secreted by ventricles of heart
• secreted in response to increased blood pressure & volume (baroception)
• bind to nephrons to decrease resorption of sodium and water
• effect: increase urine output, decrease blood volume & osmolarity, decrease blood pressure

Question 4

renin-angiotensin-aldosterone system (RAAS)

Answer 4

• kidneys detect low blood pressure, blood volume, blood osmolarity (sodium), blood oxygen level
• any event that puts perfusion at risk (see above) triggers kidneys to release renin
• renin activates angiotensinogen into angiotensin I
• angiotensin I is activated by angiotensin converting enzyme (ACE) into angiotensin II
• angiotensisin II causes rapid constriction of arteries and veins (increasing peripheral resistance and decreasing venous reservoir), stimulates aldosterone secretion (triggers nephrons to resorb water and sodium, promotes kidneys to excrete potassium), constricts afferent arterioles in nephrons (decreasing GFR and urine formation, increasing water and sodium resorption)
• effect: increased blood pressure and volume