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102 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the process called where molecules can enter the filtrate by transport across the walls of the nephron tubules?
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Secretion
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Pg. 281
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What is the term used to describe the kidney’s use of the mechanisms of filtration and secretion to “clear” molecules from the blood?
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Renal Plasma Clearance
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Pg. 283
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Through which ways do the kidneys help maintain the homeostasis of the concentration of particular solutes in the blood plasma?
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Filtration
Secretion and Reabsorption |
Pg. 283
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What is the primary function of the kidneys?
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It is to maintain homeostasis of the blood volume and the plasma concentrations of particular molecules and ions.
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Pg. 283
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___________ is the waste left over as the kidneys perform the function of maintaining the homeostasis of the blood volume and the plasma concentrations of particular molecules and ions.
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Urine
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Pg. 283
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__________________ is the measure of the kidney’s ability to remove, or clear, particular molecules from the blood plasma.
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Renal Plasma Clearance
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Pg. 283
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True or False. Molecules smaller than proteins in the plasma are easily “filtered.”
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True. Molecules smaller than proteins in the plasma are easily “filtered,” this means that they easily enter the glomerular filtrate.
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Pg. 283
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What is the average amount value for the Glomerular Filtration Rate (GFR)?
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120 ml/min
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Pg. 283
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___________ decreases the renal plasma clearance of a molecule.
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Reabsorption
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Pg. 283
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A molecule that is filtered, but then reabsorbed, will have a renal plasma clearance ____than the GFR.
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Less
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Pg. 283
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When will a molecule’s renal plasma clearance be zero?
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If the molecule is completely reabsorbed
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Pg. 283
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What action is the opposite of reabsorption?
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Secretion
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Pg. 284
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What occurs in the action of secretion by the kidneys?
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The transport of a molecule or ion from the peritubular blood, across the wall of the tubule, and into the fluid within the nephron.
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Pg. 284
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How is secretion like filtration?
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It removes molecules from the blood plasma and adds them to the urine.
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Pg. 284
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How will the renal plasma clearance value of molecules that are both filtered and secreted be compared to the Glomerular Filtration Rate (GFR) value?
Why is this the case? |
Molecules that are both filtered and secreted have a renal plasma clearance greater than the GFR.
Because more than only the molecules filtered are cleared from the blood. |
Pg. 284
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Where are transporter proteins located that secrete a large number of foreign molecules (such as antibiotics) that may have entered the blood for various reasons, thus allowing the kidneys to eliminate them at a rapid rate?
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The Proximal Convoluted Tubules
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Pg. 284
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What renal plasma clearance values do molecules such as Glucose and Amino Acids have compared to the Glomerular Filtration Rate (GFR) value?
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They have a renal plasma clearance less than the GFR.
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Pg. 284
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Why does Glucose and Amino Acids have a renal plasma clearance less than the GFR?
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Because they are filtered and reabsorbed
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Pg. 284
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What renal plasma clearance values do molecules such as penicillin and foreign molecules have compared to the Glomerular Filtration Rate (GFR) value?
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They have a renal plasma clearance greater than the GFR.
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Pg. 284
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Why does penicillin and foreign molecules have a renal plasma clearance greater than the GFR?
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Because they are filtered and secreted
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Pg. 284
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What renal plasma clearance values do molecules that are filtered but neither reabsorbed nor secreted have compared to the Glomerular Filtration Rate (GFR) value?
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They have a renal plasma clearance equal to the GFR
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Pg. 284
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What does the metabolic breakdown of creatine phosphate produce?
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Creatinine
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Pg. 284
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What is the name of the test that measures Blood and Urine creatinine levels in patients with kidney disease to assess the ability of their kidneys to clear creatinine from the blood?
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Creatinine Clearance Test
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Pg. 284
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What is the name of the polysaccharide of fructose that enters the glomerular filtrate but is neither reabsorbed nor secreted?
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Inulin
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Pg. 284
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What renal plasma clearance value does Inulin have compared to the Glomerular Filtration Rate (GFR) value?
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It is equal to the GFR
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Pg. 284
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Why is the concentration of Inulin reduced in the blood going back to the general circulation?
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Because the amount that was contained in the filtered blood was eliminated in the urine
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Pg. 284
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True or False. Glucose is filtered but normally completely reabsorbed.
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True
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Pg. 284
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Why are Glucose and Amino Acids not usually present in urine even though they are easily filtered out of the glomeruli?
What does this indicate about their renal clearance? |
Because they are normally completely reabsorbed across the walls of the proximal convoluted tubules back into the blood.
Their renal clearance is zero. |
Pg. 284-285
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True or False. Carrier-Mediated Transport is affected by the concept and property of Saturation..
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True
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Pg. 285
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What is the term used to describe when all of the carrier proteins are occupied and the rate of transport will not increase?
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Transport Maximum
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Pg. 285
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What is the average transport maximum for glucose in the nephrons?
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375 mg per minute
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Pg. 285
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What is the GFR of Glucose?
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120 ml/min
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Pg. 285
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Why do the tubules normally receive 120 mg per minute of glucose?
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Because the GFR of glucose is 120 ml/min and the normal fasting glucose concentration is 1mg/ml.
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Pg. 285
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How much would the blood glucose concentration have to increase to saturate all of the carriers and exceed the transport maximum?
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More than three times the normal fasting level
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Pg. 285
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What is the term used for the plasma glucose concentration that must be reached for glucose to first appear in the urine?
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Plasma Renal Threshold
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Pg. 285
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What are the average values for the Plasma Renal Threshold for Glucose?
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180-200 mg of glucose per 100 ml of blood
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Pg. 285
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What is the term used to describe an abnormally high fasting blood glucose concentration?
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Hyperglycemia
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Pg. 285
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What is the term of the condition when glucose appears in the urine?
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Glycosuria
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Pg. 285
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True or False. Hyperglycemia will cause glycosuria.
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True
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Pg. 285
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True or False. Glycosuria results when the plasma glucose concentration is greater than the plasma renal threshold for glucose.
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True
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Pg. 285
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How does excess glucose in the urine beyond the Plasma Renal Threshold affect the osmolarity of the filtrate in the Nephron?
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It abnormally increases the osmolarity of the filtrate in the Nephron
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Pg. 285
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How does the abnormal increase in the osmolarity of the filtrate in the Nephron caused by excess glucose in the urine beyond the Plasma Renal Threshold affect the reabsorption of water?
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It reduces the normal reabsorption of water that occurs as a secondary consequence to the active transport of sodium.
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Pg. 285
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What occurs as a consequence of excess glucose in the urine?
What is the name of this specific consequence? |
Osmotic Diuresis
Polyuria |
Pg. 285
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Why do medications often combine penicillin with another molecule that binds to the same carrier proteins in the tubules?
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Because this results in competition that decreases the rate of penicillin secretion and which reduces its elimination in the urine.
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Pg. 285
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What is the name of a good competitor for the same carrier proteins used in penicillin?
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Probenecid
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Pg. 285
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What is the name of foreign but harmless molecule that can be infused into the blood to measure Total Renal Blood Flow?
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Para-Aminohippuric Acid (PAH)
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Pg. 286
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Why can PAH be used to measure Total Renal Blood Flow?
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Because PAH is completely eliminated from the blood that enters the kidneys and whatever isn’t filtered out of the glomeruli is removed from the peritubular capillaries by secretion across the tubule wall. Since all the blood going to the kidneys is cleared of PAH, the renal plasma clearance of PAH is equal the total renal flow.
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Pg. 286
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What is the average ml/min of the renal plasma clearance of PAH or the total renal flow?
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625 ml/min
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Pg. 286
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What does comparing the Glomerular Filtration Rate (GFR) value to the total renal flow value indicate?
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It indicates that about 20% of the blood entering the kidneys is filtered out of the glomeruli
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Pg. 286
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Where does the remaining percentage of blood that is not filtered out of the glomeruli pass?
What is a consequence of this action? |
The remaining 80% of the renal blood flow passes into the efferent arterioles and peritubular capillaries.
It can only be cleared of molecules that are secreted |
Pg. 286
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How do the kidneys help maintain homeostasis of the plasma concentrations of many ions (electrolytes) when their plasma concentration increases and when their plasma concentration decreases?
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By excreting them in the urine when their plasma concentration increases
and By retaining them in the blood when their plasma concentration decreases |
Pg. 286
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By what general mechanism do the kidneys regulate the concentration of blood bicarbonate (the major buffer in the plasma)?
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By excretion and retention
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Pg. 286
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How are the kidneys responsible for the metabolic component of acid-base balance?
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By regulating the blood bicarbonate and excreting H+ in the urine
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Pg. 286
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What are some of the other plasma electrolytes (ions) concentrations besides bicarbonate ions that the kidneys regulate?
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Sodium
Potassium Chloride Calcium Phosphate |
Pg. 286
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What is a consequence of plasma electrolytes (ions) ability to be easily filtered or (enter the glomerular filtrate), and or also be secreted into the tubules?
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This allows the ions to be excreted in the urine when their blood concentrations increase or they can be reabsorbed to varying degrees, depending on its concentration in the blood
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Pg. 286
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The degree to which the renal tubules ______or______ an ion is adjusted to maintain homeostasis of the ion concentration in the blood plasma.
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Secrete
Reabsorb |
Pg. 286
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How is the adjustment of the degree to which the renal tubules secrete and absorb ions accomplished?
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It occurs in response to particular hormones that act on the Nephron
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Pg. 286
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What hormone regulates how the nephron handles the calcium and phosphate ions?
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Parathyroid Hormone (PTH)
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Pg. 286
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What corticosteroid secreted by the adrenal cortex regulates how the nephron handles Na+, K+, and H+?
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Aldosterone
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Pg. 286
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Why is Aldosterone classified as a mineralocorticoid?
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Because it is a corticosteroid that regulates “Mineral” (ion) balance.
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Pg. 286
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What type of action does Aldosterone stimulate with regards to Na+?
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It stimulates Na+ reabsorption
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Pg. 286
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What type of action does Aldosterone stimulate with regards to K+?
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It stimulates K+ secretion
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Pg. 286
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Where is the vast majority of the Na+ that enters the filtrate reabsorbed?
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About 90% of the Na+ that enters the filtrate is reabsorbed across the walls of the proximal tubules and ascending limbs of the loops
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Pg. 286
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How much of the original percent of Na+ enters the distal convoluted tubules and collecting ducts?
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10%
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Pg. 286
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True or False. Without Aldosterone, most of the remainder approximately 8% of the original amount filtered will not be reabsorbed in the later regions of the nephron.
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False. Without Aldosterone, most of the remainder approximately 8% of the original amount filtered will be reabsorbed in the later regions of the nephron. Which leaves 2% of the filtered Na+ to be excreted in the urine, which is still a rather large amount (averaging 30g/day)
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Pg. 286 -287
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What structure(s) does Aldosterone stimulate to reabsorb remaining Na+?
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The last part of the distal convoluted tubule and Cortical Collecting Duct
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Pg. 287
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What is the Cortical Collecting Duct?
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It is the portion of the collecting duct located in the Renal Cortex
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Pg. 287
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What will occur under maximum aldosterone stimulation?
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All of the Na+ will be reabsorbed so that none is excreted in the urine
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Pg. 287
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What is the reabsorption of Na+ accompanied by?
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Cl- and Water Retention
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Pg. 287
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What important regulation does the aldosterone stimulation of salt and water retention accomplish?
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Regulation of the Total Blood Volume and thus Blood Pressure
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Pg. 287
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Where is the majority of the K+ that enters the glomerular filtrate is also absorbed?
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About 90% is absorbed across the walls of the Proximal Convoluted Tubules
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Pg. 287
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True or False. Reabsorption of 90% of the K+ that enters the Glomerular Filtrate across the walls of the Proximal Convoluted Tubules is constant and unregulated and thus leaves very little K+ in the filtrate to be excreted in the urine.
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True
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Pg. 287
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What is the only way additional K+ can be excreted in the urine after almost all of it has been reabsorbed?
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For it to be secreted into the tubules later
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Pg. 287
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What does Aldosterone stimulate the secretion of K+ into?
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It stimulates the secretion of K+ into the late Distal Convoluted Tubule and Cortical Collecting Duct
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Pg. 287
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What type of homeostatic mechanism is manifested by the adrenal cortex being stimulated to secrete Aldosterone as a consequence of a rise in the plasma concentration of K+?
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Negative Feedback Loop
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Pg. 287
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Should levels of Aldosterone secretion increase or decrease if there is a decrease in plasma Na+ concentration?
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Increase
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Pg. 287
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What will occur to Blood Volume and Pressure if a person has an inadequate diet of Na+ (as salt)?
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The Blood Volume and Pressure will fall
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Pg. 287
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What is the name of the structure that is located where the afferent arteriole contacts the last portion of the ascending limb of the loop of Henle?
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The Juxtaglomerular Apparatus
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Pg. 287
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What structure is stimulated when there is a fall in Blood Volume and Pressure?
What is secreted when this structure is stimulated? |
The Juxtaglomerular Apparatus
The enzyme Renin |
Pg. 287
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What function does the enzyme Renin have?
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It catalyzes the conversion of the plasma protein Angiotensin into Angiotensin I
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Pg. 287
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What happens to the inactive Angiotensin I as it circulates in the blood?
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It is converted by Angiotensin Converting Enzyme (ACE) into Angiotensin II
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Pg. 287
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What is the overall effects of Angiotensin II?
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It raises Blood Volume and Pressure
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Pg. 287
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How does Angiotensin II affect the arterioles and the Adrenal Cortex?
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It acts on arterioles to cause vasoconstriction
and It stimulates the Adrenal Cortex to secrete Aldosterone |
Pg. 287
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What is created as a result of the reabsorption of Na+ across the walls of the late Distal Convoluted Tubule and Cortical Collecting Duct?
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An electrical attraction for K+ or H+ to be secreted
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Pg. 288
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What happens as a consequence of Acidosis (increased plasma H+ concentration)?
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K+ secretion is reduced because of the increased secretion of H+
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Pg. 288
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What happens as a consequence alkalosis (lowered plasma H+ concentration)?
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K+ secretion is increased because of the reduced secretion of H+
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Pg. 288
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What is Hyperkalemia?
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High Plasma K+ concentration
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Pg. 288
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With regards to ions, what can Hyperkalemia cause?
Why does this occur? |
It can cause an increase in the Blood concentrations of H+ and Acidosis
Because there is an increased K+ secretion and a reduced secretion of H+ into the tubular fluid |
Pg. 288
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What produces Metabolic Acidosis?
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An excess of H+ derived from nonvolatile acids such as Lactic Acid and Ketone Bodies relative to Bicarbonate
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Pg. 288
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What produces Metabolic Alkalosis?
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A deficiency of H+ relative to bicarbonate
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Pg. 288
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What must the kidneys normally reabsorb to prevent Metabolic Acidosis?
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The kidneys must normally reabsorb all of the bicarbonate in the glomerular filtrate
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Pg. 288
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True or False. Tubular reabsorption of bircarbonate is occurs directly and not indirectly.
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False. The tubules can’t reabsorb bicarbonate directly, and so the reabsorption is indirect.
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Pg. 288
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What is formed when bicarbonate combines with H+ in the tubular fluid?
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Carbonic Acid is fromed
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Pg. 288
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What is the name of the enzyme in the plasma membrane of microvilli facing the lumen of the proximal convoluted tubule?
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Carbonic Anhydrase
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Pg. 288
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What product(s) does Carbonic Anhydrase convert bicarbonate into in the tubular fluid?
What happens to these products? |
It converts it into CO2 and H2O
They diffuse out of the tubular fluid and into the epithelial cytoplasm. |
Pg. 288
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What happens to the CO2 and Water once it is inside the epithelial cells?
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Carbonic Anhydrase catalyzes the conversion of CO2 and Water into Carbonic Acid
Carbonic Acid then dissociates to form Bicarbonate and H+ |
Pg. 288
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What happens to the Bicarbonate and H+ when once Carbonic Acid has dissociated in the cytoplasm of tubular epithelial cells?
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The H+ can be secreted back into the tubular fluid, while bicarbonate enters the plasma
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Pg. 288
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What nonvolatile acids does bicarbonate buffer in the plasma?
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Ketone Bodies and Lactic Acid
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Pg. 288
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True or False. Noraml urine is usually Basic.
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False. Normal urine is typically slightly acidic or neutral
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Pg. 288
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What is the pH of urine normally?
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7.35-7.45
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Pg. 288
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True or False. The pH of urine is usually lower than arterial blood.
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True
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Pg. 288
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True or False. Arterial pH varies just like Urine pH.
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False. The arterial pH is kept constant while the urine pH varies, depending on the body’s production of the nonvolatile acids and on the acidity of foods and drinks.
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Pg. 289
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