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functions of urinary system
- nitrogenous wastes
- toxins
- drugs
- regulate aspects of homeostasis (water balance, acid base balance, blood pressure, vit D activation)
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osmolarity
overall water balance (water and sold content in the body remain constant)
-
osmolarity of extra cellular fluid
equals osmolarity of intracelllular fluid
-
regulation of osmolarity is achieved by
balancing intake and excretion of sodium with that of water
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electrolyte
any chemical compound that produces ions when dissolved in water
help maintain acid base balance and water balance
-
acid-base balance
- kidneys monitor and regulate levels of hydrogen ions and bicarbonate ions in the blood to control blood pH
- H+ byproduct of dietary protein metabolism and accumulates in blood over time
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blood pressure
- the stregnth of blood pushing against sides of blood vessels
- kidneys monitor blood pressure
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when blood pressure is too low
kidneys produce renin, a hormone which restricts blood vessels and produces concentrated urine (allowing more water to remain in the blood)
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red blood cell production
erythropoietin aka EPO
- EPO = hormone produced by kidneys to stimulate the production of red blood cells
- if blood doesn't have enough oxygen, EPo released
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activation of vitamin D
- kidneys play role in turning vitamin D into active form Calciferol
- helps balance calcium and phosphorus levels by controlling the absorption of these minerals
- Parathyroid hormones (PTH) regulates calcium homeostasis and bone
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location of kidneys
- T12 to L3
- against dorsal body wall
- right lower than left
- adrenal gland on top of kidney
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organs of urinary system
- kidneys
- ureters
- urinary bladder
- urethra
-
regions of kidney
- renal cortex - (90% of blood flow) and all glomeruli found here
- renal medulla - inside of cortex
- renal pelvis - inner collecting tube, turns into ureter
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kidney structures
- medullary pyraminds
- renal columns
- calyces (cup shaped funnel urine)
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nephrons
- functional unit
- form urine
- glomerulus
- renal tubule
-
1 million nephrons
each kidney
-
glomerular filtrate rate
- one way to measure remaining kidney function
- process where kidneys filter blood, removing excess wastes in fluid
- 120ml/min
glomerulus is primary site for filtration
-
bowman's space
filtrate
- where glomerular filtrate collects
- filtrate = H2O, glucose, salts, and urea
-
review
- blood comes to kidney from renal artery
- transferred to afferent arteriole
- filtrated in glomerulus
- filtered carried out by efferent arteriole
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reabsorption
2/3 nutrient reabsorption takes place in the proximal convoluted tubule
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loop of henle/descending loops
- water reabsorbed passively (passive transport)
- descending loop is impermeable to Na
-
ascending loop
- reabsorbed via active transport (Na, K, Cl)
- secretion (and reabsorption) of NA and Cl is controlled by aldosterone
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collecting ducts
principle cells
- reabsorb Na and H2O
- secrete K
-
creatinine
chemical waste product in the blood that passes through the kidneys to be filtered and eliminated in urine
-
water balance
antidiuretic hormone ADH
regulates the osmotic pressure of body fluids by causing the kidneys to increase water reabsorption in the collecting ducts
makes collecting ducts more permeable to water
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osmoreceptors
- in hypothalamus
- detect changes in osmotic pressure
- dehydration causes osmotic pressure to increase
- cells are called sensors
-
hypothalamus
- sends message to pituitary gland
- relsease ADH
- hypothalamus acts as co ordinating center
- PT gland is effector/regulator
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dehydrated
- lowers osmotic pressure
- more concentrated urine
-
over hydration
- osmoticreceptors detect changes in osmotic pressure
- causes osmotic pressure to decrease
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UTI
more common in women because of shorter urethra
-
kidney stones
- dehydration is major risk for kidney stones
- 80% kidney stones are calcium based
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calcitriol
stimulates small intestines for protein synthesis
-
detrusor muscles
overactive bladder
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