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128 Cards in this Set
- Front
- Back
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What is the osmolarity if blood in mOsm/kg of water?
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290
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The kidneys can regulate blood volume and blood pressure through the regulation of what ion?
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Na+
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What is normal blood pH? How do the kidneys regulate blood pH?
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Normal pH = 7.4. Kidneys involved in secretion of H+ and conservation of bicarbonate ions (HCO3), and important buffer of H+
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What amino acids can the kidneys utilize for gluconeogenesis?
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glutamine
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What hormones are released by the kidneys?
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Calcitrol, Erythropoetin, Renin, Renalase
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Which hormone increases blood levels of Ca++ and phosphate and is also the active form of Vitamin D ?
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Calcitrol
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A decrease in partial pressure of oxygen (hypoxia) stimulates the release of what hormone from the kidneys which stimulates maturation of RBCs?
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Erythropoetin
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Renin is released from what cells in the kidney and what is it's function?
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released from granular cells of the juxtaglomerular apparatus and it functions in regulating BP
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What is the function of Renalase?
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Renalase is an amine oxide that breaks down catecholamines. It is important to breakdown catecholamines in order to prevent high blood pressure since EPI and NE increase high blood pressure.
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Insufficiency of Erythropoetin due to renal disease can lead to what disease?
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Anemia
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What enters/exits at the renal hilus?
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Ureters, blood and lymphatic vessels, nerves
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What is the functional unit of the kidneys in which urine is formed?
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Nephrons
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Urine formed in the nephrons drains into the....
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Papillary ducts --> minor calyx ---> major calyx ---> Renal Pelvis ---> Ureter ---> Urinary Bladder.
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What are kidney stones?
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percipitations of calcium, phosphate, oxalate, or urate, that can obstruct flow of urine at renal papilla or at any point downward
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Blood filtration occurs in which part of the nephron?
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In the renal corpuscle which consists of the glomerulus and the glomerular (Bowman's) capsule.
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Reabsorption and secretion occur in which part of the nephron?
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In the renal tubule
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At what point does the tubular fluid become urine?
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When papillary ducts drain through the papilla into the minor calyces.
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Which type of nephron is characterized by a SHORT loop of Henle reaching into outer medulla, NO THIN ASCENDING LIMB, and a glomerulus in the outer cortex?
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Superficial (cortical ) nephrons (85% of nephrons)
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Which type of nephron is characterized by LONG Loop of Henle reaching into inner medulla, a thick AND thin ascending limb, and a glomerulus in the DEEP cortical regions?
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Juxtaglomedullary nephrons (15% of nephrons)
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Which type of nephron is important in conditions of water deficiency (dehydration) due to it's ability to better reabsorb and retain water?
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Juxtamedullary nephrons.
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What enters/exits at the renal hilus?
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Ureters, blood and lymphatic vessels, nerves
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What is the functional unit of the kidneys in which urine is formed?
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Nephrons
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Urine formed in the nephrons drains into the....
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Papillary ducts --> minor calyx ---> major calyx ---> Renal Pelvis ---> Ureter ---> Urinary Bladder.
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What are kidney stones?
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percipitations of calcium, phosphate, oxalate, or urate, that can obstruct flow of urine at renal papilla or at any point downward
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Blood filtration occurs in which part of the nephron?
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In the renal corpuscle which consists of the glomerulus and the glomerular (Bowman's) capsule.
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Reabsorption and secretion occur in which part of the nephron?
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In the renal tubule
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At what point does the tubular fluid become urine?
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When papillary ducts drain through the papilla into the minor calyces.
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Which type of nephron is characterized by a SHORT loop of Henle reaching into outer medulla, NO THIN ASCENDING LIMB, and a glomerulus in the outer cortex?
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Superficial (cortical ) nephrons (85% of nephrons)
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Which type of nephron is characterized by LONG Loop of Henle reaching into inner medulla, a thick AND thin ascending limb, and a glomerulus in the DEEP cortical regions?
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Juxtaglomedullary nephrons (15% of nephrons)
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Which type of nephron is important in conditions of water deficiency (dehydration) due to it's ability to better reabsorb and retain water?
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Juxtamedullary nephrons.
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Substances and fluid REABSORBED (not absorbed) across and between the tubular epithelial cells are returned to the..
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peritubullar capillaries and vasa recta
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The process of removing substances such as waste, drugs, and excess ions from the peritubular capillaries and the vasa recta and transporting them across the tubular epithelial cells is termed what?
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tubular SECRETION
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Where is the portal system seen in the kidneys?
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The portal system in the kidneys is the 2 capillary networks in series made up of the glomerulus capillaries and the peritubular capillaries.
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The amount of substance excreted can be determined by what equation?
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Amount Excreted = Amount filtered - amount reabsorbed + amount secreted
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The space between the peritubular capillaries and the renal tubules is called what?
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interstitial space
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What substances make up transcellular fluids (1-3% of body weight)?
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CSF, Aqueous Humor, secretions of the digestive glands, sweat, synovial fluids, renal tubular fluid, urine.
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What is the 20, 40, 60 rule?
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20% of body weight = ECF volume
40 % of body weight = ICF volume 60 % of body weight = Total Body Water |
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What makes up 3/4 of ECF?
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Interstitial fluid - ultrafiltrate of plasma
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what makes up 1/4 of ECF?
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Plasma - aqueous component of blood.
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Between muscles, skeleton, organs, and adipose, which contains the greatest % of water, which contains the least?
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Muscles contains the greatest % of water (76%) and Adipose the least (10%)
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What factors determine total body weight?
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1. Amount of body fat - greater amount of fat, lower TBW because fat only contians 10% water
2. Age - TBW decreases as age increases due to increase in amount of fat. 3. gender - women have less TBW than men. (again because MORE FAT) |
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What is the main positive ion in plasma? interstitial fluid? intracellular fluid?
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plasma - Na+
interstitial fluid - Na+ Intracellular fluid - K + |
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What is the main negative ion in plasma? interstitial fluid? intracellular fluid?
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plasma - Cl - (also HPO4-2)
interstitial fluid - Cl - (also HPO4-2) Intracellular fluid - HPO4-2, SO4-2 |
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In which fluid compartment is the greatest concentration of protein anions and Mg+ found?
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Intracellular fluid
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Which fluid compartment contains calcium?
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Extracellular fluid
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Concentration of what substance is equal between plasma, interstitial fluid, and intracellular fluid?
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H2CO3
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What percentage of water is filtered each day? excreted? reabsorbed?
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180 L of water is filtered each day, 99% is reabsorbed, and 1.8 in excreted
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What percentage of glucose is reabsorbed?
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100 %
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What is the filtration factor?
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filtration factor is the amount of plasma that passes through the glomerulus that is filtered. It is approximately 20 %
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What % of the filtration factor is excreted?
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<1 % is excreted from the 20% filtered because 19% is reabsorbed
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Which type of ANS innervation controls the kidneys?
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only sympathetic!
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What are podocytes?
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Podocytes are specialized epithelial cells with numerous pedicles that cover glomerular capillaries (visceral layer)
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Where are mesangial cells located?
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located between the capillaries of the glomerulus
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What forms the Juxtaglomerular Apparatus?
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The MACULA DENSA cells of the THICK ASCENDING Loop of Henle contact the GRANULAR cells of the AFFERENT arteriole
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What is the function of the Macula Densa Cells in the thick ascending Loop of Henle ?
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The cells are specialized tubular epithelial cells that monitor flow and NACL content of tubular fluid and regulate glomerular filtration rate and renin secretion
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What is the function of the Granular cells in afferent arterioles?
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Specialized smooth muscle cells that produce and secrete renin
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What layers make up the glomerular filtration barrier?
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1. Fenestrated capillaries - have pores
2. basement membrane - containts negatively charged glycoproteins that act like a coarse sieve 3. Podocytes - form filtration slits |
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What factors determine filterability of substances?
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1. molecular radius - (>42 angstrom not filtered)
2. molecular charge - for molecules between 20-42 angstrom. note: ALL LOW MOLECULAR WEIGHT SUBSTANCES GO THROUGH (<20) REGARDLESS OF CHARGE |
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What prevents proteins from being filtered through the glomerulus capillaries?
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Large molecular radius and negative charge of basal lamina restrict filtration of most plasma proteins.
ex. Serum albumin and hemoglobin are not absorbed |
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What is the function of mesangial cells?
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Mesangial cells are immunoreactive transformed smooth muscle cells that can contract in response to circulating vasoactive substances, impending blood flow and filtration in the glomerulus. When they contract, flow is slowed. Mesangial cells also function in phagocytosis and proliferation in response to antigens.
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What is glomerulonephritis?
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a complex of glomerular capillary diseases with mostly immunological underlying mechanisms (deposition of various antigens within the barrier)
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How does diabetes mellitus lead to chronic renal failure?
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Diabetic neuropathy begins with increased glomerular filtration --> proteinuria --> changes in basement membrane and podocytes --> mesangial cells proliferate and compress glomerular capillaries --> perfusion is impeded --> filtration falls leading to renal insufficiency.
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Hematuria, Inflammation, and moderate proteinuria are characteristic of nephRItic or nephROtic syndrome?
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nephRItic syndrome
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Profound proteinuria, hypoalbuminemia, and edema are characteristic of nephRItic or nephrOtic syndrome?
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nephROtic syndrome
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How does proteunuria lead to edema?
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Loss of proteins with urine lead to a decrease in oncotic pressure of blood vessels --> fluid shifts from plasma into interstitial fluid --> Edema and Decreased plasma Volume.
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Accumulation of wastes, creatine, and BUN in plasma are indicators of what?
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indicate renal insufficiency progressing into renal failure.
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Which two forces oppose filtration in the glomerulus?
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Hydrostatic pressure in Bowman's space
Oncotic pressure in glomerular capillary |
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Which is the only force that favors filtration in the glomerulus?
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hydrostatic pressure in glomerular capillary
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How is NFP (net filtration pressure) determined?
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Hydrostatic pressure in glomerular capillary - hydrostatic pressure in bowman's space - oncotic pressure in glomerular capillary = NFP
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What is GFR (Glomerular Filtration Rate) and how is it determined?
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GFR is volume of filtered fluid per unit of time. It is determined by..
GFR = Kf (filtration coefficient) x NFP |
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How does NFP change along the length of the capillary? Why does it change?
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NFP decreases along the length of the capillary because oncotic pressure of capillary increases due to increase concentration of proteins. At a certain point NFP becomes 0 and filtration stops.
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Where does the greatest drop in blood pressure occur in renal vascular segments?
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occurs at the afferent and efferent arterioles
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What is the force underlying reabsorption of water in the peritubular cappillaries?
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increase of oncotic pressure (due to increase of proteins - i.e lipoproteins)
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What happens to RBF and GFR if afferent arteriole is constricted?
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RBF decreases, GFR decreases
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What happens to RBF and GFR if efferent arteriole is constricted?
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RBF decreases, GFR increases
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What is the effect of sympathetic innervation or norepinephrine on GFR and RBF? How is it activated?
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Symp. Innervation or Norepi cause vasoconstriction via alpha-1 adrenergic receptor --> DECREASE of RBF and GFR.
It is activated by reduction in arterial pressure (decrease in ECF volume) via baroreceptors |
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What is the effect of angiotensin II ?
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Constricts arterioles and decreases RBF and GFR.
note: It is released in response to changes in ECF volume |
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What is the effect of ANP and what causes it's release ?
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ANP is released from atrial muscle cells in response to blood volmume. It dilates afferent arterioles and INCREASES RBF and GFR
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What is the effect of ADH?
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ADH in high concentrations causes vasoconstriction to decrease RBF and GFR
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What is the effect of high doses of dopamine? low doses?
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low doses of dopamine cause vasodilation --> increased renal blood flow, GFR, sodium secretion, and urine flow.
intermediate doses of dopamine stimulate the beta 1- adrenoreceptors improving myocardial contractility at intermediate rates of infusion. High doses of dopamine activate alpha-adreno receptors and cause vasoconstriction, reversing renal dilation and natriuresis |
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What is the function of autoregulation in the kidneys?
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Renal autoregulation prevents changes of atrial blood pressure from producing large changes in glomerular filtration rate. If BP decreases, blood vessels upstream to glomerulus (afferent) dilate. If BP increases, they constrict.
note: very low blood pressure (like due to hemorrhage, will be regulated by sympathetic innervation taking over |
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What three factors does GFR depend on?
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1. total surface area available for filtration
2. filtration barrier permeability 3. NFP |
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What is a high plasma creating (>1.3) an indicator of?
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suggest low GFR and impaired kidney function
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How many ml of filtrate per minute must be delivered to Bowman's capsule to effectively clear any given substance through the nephrons?
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120 ml
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What is azotemia?
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elevated level of urea
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What is a high BUN (blood urea nitrogen) indicate?
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indicates renal insufficiency
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Why is insulin a good measure of GFR?
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because it is only filtered, it is not reabsorbed or secreted
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What formula determines excretion rate?
What formula determines filtered load? |
excretion = Urinary flow x Urine concentration of subtance
filtered load = GFR x plasma concentration of substance |
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What is the function of the Na-K ATPase pump in the basolateral membrane of tubular epithelial cells?
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It draws NA+ from lumen, it is a key factor in tubular transepithelial transport of sodium and other substances
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How is sodium transported across apical membrane?
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Glucose/Na co-transport (same direction)
Na/Amino acid - same direction Na/phosphate, lactate, or citrate - same direction Na/H+ Antiport - DIFFERENT direction |
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Water passage is primarily what mode of transport across kidney epithelial cells?
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Water passage is primarily transcellular and involves specialized water channels - aquaporins
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In which part of the tubules does most of HCO3 reabsorption and H+ Secretion take place?
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In the proximal tubule
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Bicarbonate reabsorption involves chemical reactions catalyzed by what?
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Carbonic Anhydrase
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What substances are dissolved in water and reabsorbed by solvent drag?
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Ca2+, Mg2+, K+, Urea
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What effect does Acetazolamide (Glaucoma medication) have on reabsorbtion.
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suppresses bicarbonate reabsorption and induces adverse effects such as acidosis
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What is Faconi syndrome?
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impaired reabsorption in proximal tubules = waste of phosphate, amino acids, bicarbonate, glucose and uric acid
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What is the mechanism of action of diuretics?
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All diuretics elevate solute concentration of filtrate resulting in water retention inside tubular lumen with subsequent increased excetion
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What is the mechanism of action of Thiazide and loop diuretics?
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inhibit reabsorption of ions through the apical membrane causing retention of ions and water in tubular lumen.
note: major side effect - hypokalemia |
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What is the mechanism of potassium sparing diuretics?
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inhibit reabsorption of Na but also inhibit potassium secretion in the distal tubule
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What are the functions of ADH and where do they take place?
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ADH functions to retain water. Increases water permeability in late distal tubule and collecting duct. Increases urea permeability in inner medullary collecting duct. Increases Na reabsorption in thick ascending limb of loop on Henle
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Where is ADH synthesized and released?
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Synthesized by mainly neurons of the supraoptic necluei of hypothalamus and released from the axonal endings into general circulation at the posterior lobe of the pituitary.
note: production is stimulated by hypothalamis osmoreceptors |
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Increase in plasma osmolality that causes release of ADH is detected where?
Decrease in ECF volume or blood pressure (hypovolemia; hypotension; hemorrhage) that causes release of ADH is detected where? |
increase in plasma osmolality is detected in osmoreceptors in hypothalamus
decrease in ECF volume or blood pressure is detected in arteries (carotid sinus and arch) |
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What factors increase ADH secretion?
decrease? |
increase: Angiotensin II, stress and heat, nicotine and estrogen, pain, nausea, vomiting
-decrease: ANP, hypervolemia, ethanol |
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What does desmopressin treat?
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It is a synthetic analog of ADH used to treat central diabetis insipidus (not nephrogenic)
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What is nephrogenic diabetis insipidus? what are it's symptoms?
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decreased renal response to ADH (abnormal vasopressin receptors or aquaporins)
Symptoms: high or normal ADH is plasma water loss large volume of dilute urine constant thirst hypovolemic shock if cut in water supply |
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What is SIADH? Causes? Consequences?
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Syndrome of Inapproptiate ADH secretion is abnormal high ADH release resulting from lung disease, CNS disease, or drug interaction.
major consequences: hypertension - increased ECF volume low plasma osmolatiry hyponatremia - low plasma NA level high urine osmolality - Na secretion with urine increases despite low serum NA |
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What is the function of Angiotensin II?
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-increase aldosterone secretion
-increase NA reabsorption - Constrict afferent and efferent arterioles to decrease GFR and NA filtered load - increase ADH secretion |
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What is the function of Aldosterone?
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increase NA reabsorption and
increase potassium secretion in late distal tubule and collecting duct |
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What is the function of ANP?
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increase water and NA excretion by:
- decrease release of renin and aldosterone -decrease release of ADH -decrease NA reabsorption -dilate afferent arteriole and constricts efferent arteriole to increase GFR and NA filtered load. |
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What is positive Na balance vs. negative Na balance?
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Positive Na balance is when Na excretion is less than its intake (gain sodium)
Negative Na balance is when Na excretion is greater than its intake (loose sodium) |
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What can be a consequence of positive Na balance?
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ECF volume expansion = increase blood volume and blood pressure rises and edema develops.
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What are consequences of negative Na balance?
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decrease in ECF volume contraction = blood volume and blood pressure drop.
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In what areas of the nephron does Na reabsorption occur and what regulates is?
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In proximal tubule 67% regulated by angiotensin II
In thick ascending limb 25 % and regulated by ADH in distal 5% and collecting duct 3% regulated by aldosterone |
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What factors stimulate secretion of renin?
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1. decrease in the renal perfusion (stenosis of renal artery)
2. increased sympathetic nervous activity 3. decrease in Na concentration and/or tubular flow at the macula densa |
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What are the physiological actions of Angiotensin II?
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1. stimulate secretion of aldosterone from adrenal cortex to increase NaCl reabsorption in distal nephron
2. vasocostrictior - to increase blood pressure and decrease GFR to decrease Na+ load (less excreted) 3. directly increase Na+ reabsorbption in proximal tubule 4. increase ADH secretion and thirst note: all bind to AT1 receptor. |
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What is the main function of Aldosterone?
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increases sodium (reabsorbed)/potassium(secreted) exchange across the principle cells and increases H secretion
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How does Amilouride help retain K in blood?
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K+ sparing diuretics reduce secretion of K+ by inhibiting Na transport (either by blocking Na/K pu,p activity or by blocking apical sodium channel
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What is the difference between a volatile and non volatile acid?
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volatile means that it has the potential to generate H+ after hydration with H2O. non volatile means that acid is not derived from it (lactic acid)
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The ratio of what two substances determine pH?
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ratio of concentration of bicarbonate to CO2.
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How do the kidneys function to regulate pH? How do the lungs function to regulate pH?
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lung can independently regulate CO2
kidney can independently regulare HCO3 |
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Which is the most important physiological buffer?
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carbonic acid - bicarbonate
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which is the most important urinary buffer?
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phosphate: NaH2PO4
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what cause respiratory acid-base disorders?
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disturbances in arterial Pco2
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What compensates for respiratory acid-base problems? what compensates for metabolic acid-base problems?
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respiratory - renal mechanisms
metabolic - both respiratory and renal |
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What happens in respiratory acidosis?
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in respiratory acidosis, PaCO2 exceeds 45 mm hg.
Co2 increases cause ph decrease. To compensate the kidneys increase bicarbonate reabsorption which increases H secretion Can be caused by any kind of pulmonary insufficiency (copd, lung edema, anesthetics, morphin) |
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What happens in respiratory alkalosis?
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PaCO2 falls below 35
can be caused by high altitude. fever, anxiety, heat exposure. to compensate, the kidneys decrease HCO3 reabsorbtion, which causes decrease in H+ secretion |
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What causes metabolic acidosis?
alkalosis? |
metabolic acidosis is caused by a decrease in bicarbonate to less than 22 mEq/L
metabolic alkalosis is caused by an increase in bicarbonate that exceeds 28 mEg/L |
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what is the compensatory mechanism for metabolic acidosis?
metabolic alkalosis? |
acidosis: lungs get rid of CO2
alkalosis: stop breathing...kinda. |
