Renal Physiology Flashcards
When measuring glomerular filtration rate:
The result matches the clearance of the marker if it behaves ideally
True
When measuring glomerular filtration rate:
A single plasma creatinine concentration provides an accurate value
False
When measuring glomerular filtration rate:
Renal blood flow must be measured or calculated
False
When measuring glomerular filtration rate:
Tubular reabsorption of the marker will lead to an erroneously low GFR
True
When measuring glomerular filtration rate:
Glomerular filtration fraction must be measured or calculated
False
Transport processes in the kidney include:
Tubular Secretion of NH3
True
Transport processes in the kidney include:
Reabsorption of 60g glucose per day
True
Transport processes in the kidney include:
Excretion of bicarbonate ions buffered by phosphate
False
Transport processes in the kidney include:
Glomerular fiktration of all molecules under 5nm diameter
True
Transport processes in the kidney include:
Chloride reabsorption by co-transport with Na in the PCT
False
The kidneys:
Have a large arteriovenous oxygen difference
False
The kidneys:
Produce around 180L filtrate a day in a healthy adult
True
The kidneys:
Have no autonomic nervous innervation
False
The kidneys:
Receive around 25% of the cardiac output
True
The kidneys:
Play an important role in Vitamin D synthesis
True
Antidiuretic Hormone:
Decreases the volume of urine passed
True
Antidiuretic Hormone:
Decreases the osmolality of plasma
True
Antidiuretic Hormone:
Increases water reabsorption in the PCT
False
Antidiuretic Hormone:
Acts via DNA transcription
False
Antidiuretic Hormone:
Causes Vasoconstriction
True
Sodium reabsorption in the kidney:
Is the main objective of the countercurrent mechanism
False
Sodium reabsorption in the kidney:
Is the major energy consuming activity of the kidney
True
Sodium reabsorption in the kidney:
Occurs predominantly in the proximal convoluted tubule
True
Sodium reabsorption in the kidney:
Is linked to H+ extrusion in the distal tubule
False
Sodium reabsorption in the kidney:
Is important for glucose reabsorption
True
In the proximal tubule of the nephron:
95% of filtered potassium is reabsorbed
False
In the proximal tubule of the nephron:
90% of filtered water is reabsorbed
False
In the proximal tubule of the nephron:
Sodium is actively reabsorbed
True
In the proximal tubule of the nephron:
Bicarbonate is secreted
False
In the proximal tubule of the nephron:
50% of ammonia is reabsorbed
False
Concerning water handling by the kidneys:
Water is actively transported out of the proximal tubule
False
Concerning water handling by the kidneys:
35% of the filtered water is reabsorbed
False
Concerning water handling by the kidneys:
Water reabsorption in the loop of henle is mainly in the ascending limb
False
Concerning water handling by the kidneys:
Nearly 90% of filtered water is reabsorbed by the kidney
False
Concerning water handling by the kidneys:
Antidiuretic hormone increases the permeability of the proximal tubule to water
False
Potassium:
Concentration in the plasma is a good reflection of total body potassium
False
Potassium:
concentration in the plasma rises in metabolic acidosis
True
Potassium:
excretion increases in hypovolaemia
True
Potassium:
enters cells in the presences of insulin
True
Potassium:
Excretion is promoted by aldosterone
True
The ideal substance for determining glomerular filtration rate:
Is 100% bound to plasma proteins
False
The ideal substance for determining glomerular filtration rate:
Is freely filtered from the plasma
True
The ideal substance for determining glomerular filtration rate:
Is entirely reabsorbed in the tubule
False
The ideal substance for determining glomerular filtration rate:
Is actively secreted by tubules
False
The ideal substance for determining glomerular filtration rate:
Has a molecular weight greater than 69,000
False
Regarding tubular reabsorption of glucose:
The tubular transport maximum for glucose is around 2 mmol/min
True
Regarding tubular reabsorption of glucose:
An increase in GFR increases the risk of glycosuria
True
Regarding tubular reabsorption of glucose:
If the plasma concentration is <8 mmol/L, all will normally be reabsorbed
True
Regarding tubular reabsorption of glucose:
Most reabsorption is via the para-cellular route in the PCT
False
Regarding tubular reabsorption of glucose:
Reabsorption is by co-transport with sodium
True
The following have higher intracellular than extracellular concentration:
Phosphate
True
The following have higher intracellular than extracellular concentration:
Magnesium
True
The following have higher intracellular than extracellular concentration:
Potassium
True
The following have higher intracellular than extracellular concentration:
Calcium
False
The following have higher intracellular than extracellular concentration:
Bicarbonate
False
Anti-diuretic hormone:
Determines whether the majority of water is reabsorbed by the nephron or excreted
False
Anti-diuretic hormone:
Secretion is inhibited by alcohol
True
Anti-diuretic hormone:
Is a steroid
False
Anti-diuretic hormone:
Is synthesized in the posterior pituitary
False
Anti-diuretic hormone:
increases arterial blood pressure
True
Renal autoregulation:
Is effective up to MAP of 200 mmHg
False
Renal autoregulation:
Has a contribution directly from the autonomic nervous system
False
Renal autoregulation:
Involves simultaneous constriction of both afferent and efferent arterioles
False
Renal autoregulation:
Maintains a constant renal artery pressure despite changes in blood flow
False
Renal autoregulation:
Increases glomerular filtration fraction in the presence of hypovolaemia
True
Regarding sodium transport in the kidney:
The main active process occurs on the luminal side of tubular cells
False
Regarding sodium transport in the kidney:
Reabsorption in the loop of henle occurs with potssium and chloride
True
Regarding sodium transport in the kidney:
The majority of reabsorption is regulated by aldosterone
False
Regarding sodium transport in the kidney:
Approximately 1.5kg of salt is reabsorbed by the kidney per day
True
Regarding sodium transport in the kidney:
final sodium excretion is determined by the principle cell
True
Regarding glomerular filtration:
Glomerular capillary hydrostatic pressure is lower than that of most capillary beds
False
Regarding glomerular filtration:
Colloid osmotic pressure in bowmans capsule is almost zero
True
Regarding glomerular filtration:
Colloid osmotic pressure drops alone the lenght of the glomerular capillary
False
Regarding glomerular filtration:
20% of renal plasma flow is filtered into bowmans capsule
True
Regarding glomerular filtration:
Anions are more readily filtered than cations
False
Primary active transport is used in the reabsorption of:
Sodium
True
Primary active transport is used in the reabsorption of:
Chloride
False
Primary active transport is used in the reabsorption of:
Glucose
False
Primary active transport is used in the reabsorption of:
Bicarbonate
False
Primary active transport is used in the reabsorption of:
Water
False
Aldosterone:
Acts partially on the distal convoluted tubule
True
Aldosterone:
Acts via tyrosine kinase linked receptors
False
Aldosterone:
decreases the osmolarity of urine
False
Aldosterone:
increases potassium excretion
True
Aldosterone:
Release is triggered by angiotensin II
True
In the loop of henle:
Fluid entering is it approximately isotonic with plasma
True
In the loop of henle:
The ascending limb is impermeable to water
True
In the loop of henle:
The thin ascending limb is primary responsible for the reabsorption of sodium
False
In the loop of henle:
Only 15% of the loops pass deeply into the medulla
True
In the loop of henle:
The osmolarity of tubular fluid increases to a maximum of 1200 mOsmol/L
True
Angiotensin II:
Decreases aldosterone release
False
Angiotensin II:
Decreases osmoreceptor firing
False
Angiotensin II:
Causes vasoconstriction
True
Angiotensin II:
Causes a decrease in renin secretion
True
Angiotensin II:
Has a half life of a few seconds
False
The following are involved in renal autoregulation:
Aldosterone
True
The following are involved in renal autoregulation:
Aldosterone
False
The following are involved in renal autoregulation:
Bradykinin
False
The following are involved in renal autoregulation:
Prostaglandin E2
True
The following are involved in renal autoregulation:
Vasopressin
False
Primary Active transport in the renal tubules:
Are involved in the movement of 3 potassium ions into the cell
False. The sodium potassium ATPase pump on the basolateral membrane of the tubular cell pumps 3 sodium ions into the interstitial fluid and 2 potassium ions into the tubular cell.
Primary Active transport in the renal tubules:
Occurs independently of carrier proteins
False. The sodium potassium ATPase pump is located on the basolateral membrane of the tubular cell.
Primary Active transport in the renal tubules:
Produces a net positive gradient outside the cell
True. This is due to the fact that the sodium potassium ATPase pump on the basolateral membrane of the tubular cell pumps 3 sodium ions into the interstitial fluid and 2 potassium ions into the tubular cell.
Primary Active transport in the renal tubules:
Provides gradients for other processes
True. After the sodium ions have been pumped out of the tubular cell by the sodium potassium ATPase pump, other sodium ions move from the luminal fluid into the tubular cell down the gradient created. This releases energy which is used in the process of secondary active transport.
Primary Active transport in the renal tubules:
Involves cleavage of ATP
True. ATPase is important in this energy consuming process.
The functions of the kidney include:
Regulation of body fluid buffer stores
True. The buffering functions of the kidney are essential in acid base balance. The bicarbonate and ammonia systems are most important.
The functions of the kidney include:
Temperature regulation
False. Temperature regulation is not a major function of the kidneys.
The functions of the kidney include:
The production of angiotensin converting enzyme
False. Angiotensin converting enzyme is produced mainly by the endothelial cells of the lungs.
The functions of the kidney include:
Regulation of arterial pressure
True. This occurs via several mechanisms.
The functions of the kidney include:
Glucose synthesis
True. Gluconeogenesis is a function of the kidney.
Consider the following statements regarding transport across renal tubular cell membranes:
Transcellular transport is not important
False. Transcellular transport is important. Import on one side of the cells is combined with export on the opposite side.
Consider the following statements regarding transport across renal tubular cell membranes:
Paracellular transport occurs only across tight junctions
False. Paracellular transport occurs through both tight junctions and intercellular spaces.
Consider the following statements regarding transport across renal tubular cell membranes:
Paracellular transport occurs via active transport
False. Paracellular transport occurs via diffusion and not active transport.
Consider the following statements regarding transport across renal tubular cell membranes:
Paracellular transport is driven by osmotic gradients
True. Paracellular transport is driven by osmotic, concentration and electrical gradients.
Consider the following statements regarding transport across renal tubular cell membranes:
Electrical gradients are not utilized in paracellular transport processes
False. Paracellular transport is driven by osmotic, concentration and electrical gradients.
Consider the following statements regarding diffusion across a semi permeable membrane:
Rate of diffusion is not dependent on the concentration gradient across the membrane
False. Fick’s law states that rate of diffusion across a membrane is proportional to the concentration gradient across that membrane.
Consider the following statements regarding diffusion across a semi permeable membrane:
Graham’s Law states that the rate of diffusion is proportional to the molecular weight of the substance
False. Graham’s law states that the rate of diffusion across a membrane is inversely proportional to the square root of the molecular weight of the substance.
Consider the following statements regarding diffusion across a semi permeable membrane:
The surface area of the membrane is important
True. Rate of diffusion is proportional to the available area of the membrane.
Consider the following statements regarding diffusion across a semi permeable membrane:
Uncharged weak acids or bases diffuse more readily
True. The cell membrane is more soluble for example, to NH3 than NH4 +.
Consider the following statements regarding diffusion across a semi permeable membrane:
The diffusion of weak acids and bases does not depend on pH
False. The pH of a solution determines whether or not substances are charged. Uncharged weak acids or bases diffuse more readily across membranes.
The functions of the kidney include:
Production of 1,25 dihydroxy-cholecalciferol
True. One of the roles of the kidney is in the process of hydroxylation of Vitamin D3.The kidney produce 1-alpha-hydroxylase which acts on 25-hydroxycholecalciferol to produce 1,25-dihydroxy-cholecalciferol (calcitriol). Calcitriol promotes calcium reabsorption from the intestine and kidneys, and is important in bone mineralisation.
The functions of the kidney include:
Temperature regulation
False. Temperature regulation is not a major function of the kidney.
The functions of the kidney include:
Erythropoietin production
True. Erythropoietin is a glycoprotein produced by capillary endothelial cells. It acts as a cytokine for erythrocyte precursors in the bone marrow.
The functions of the kidney include:
Glycogenolysis
False. Gluconeogensis occurs in the kidneys, not glycogenolysis.
The functions of the kidney include:
Prostaglandin secretion
True. Prostaglandins are secreted by the kidneys.
Primary active transport in the renal tubules:
Is involved in sodium transport into the cell
False. 3 sodium ions are pumped outward for 2 potassium ions inward.
Primary active transport in the renal tubules:
Involves a carrier protein which imparts energy to the transported substances
True. In primary active transport the imparted energy allows the substance to be moved against its electrochemical gradeint.
Primary active transport in the renal tubules:
Involves the activation of ATPase
True. When 2 potassium and 3 sodium ions bind to the carrier protein, the ATPase function of the protein is activated.
Primary active transport in the renal tubules:
Provides gradients for secondary active transport
True. Gradients are set up via the Na/K ATPase pump to allow the reabsorption of sodium ions via secondary active transport.
Primary active transport in the renal tubules:
Establishes a net negative voltage inside the cell
True. 3 sodium ions are pumped outward for 2 potassium ions inward.
Sodium:
Reabsorption is greatest in the proximal convoluted tubule
True. Approximately 65% of filtered sodium is reabsorbed in the proximal convoluted tubule.
Sodium:
Reabsorption is dependent on the GFR
True
Sodium:
Reabsorption is decreased by aldosterone
False. Aldosterone increases the permeability of the luminal membrane to potassium and sodium. It also activates basolateral sodium-potassium-ATPase pumps.
Sodium:
Is pumped into the tubular cell by the Na+/K+ ATPase pump
False. Three sodium ions are pumped out of the tubular cell by the sodium potassium ATPase pump.
Sodium:
Is important in glucose reabsorption
True. Glucose reabsorption occurs by co-transport with sodium into the tubular cell, again utilising the gradient produced by the Na+/K+ ATPase pump. Glucose then diffuses into the peritubular interstitium.
Consider the following statements regarding glucose reabsorption:
The tubular transport maximum for glucose is 380 mg/min
True. There is a tubular transport maximum for glucose, and it is 380 mg/min.
Consider the following statements regarding glucose reabsorption:
Glucose will appear in the urine at a renal threshold of 110 mmol/l
False. The renal threshold for glucose is 11 mmol/l.
Consider the following statements regarding glucose reabsorption:
Glucose is reabsorbed by counter transport with sodium
False. Glucose is co transported with sodium.
Consider the following statements regarding glucose reabsorption:
Glucose is usually reabsorbed in the distal convoluted tubule
False. Glucose reabsorption is in the proximal convoluted tubule.
Consider the following statements regarding glucose reabsorption:
Glucose is completely reabsorbed providing the plasma concentration is normal
True. As described in the tutorial, glucose has a tubular transport maximum that is not exceeded at normal plasma glucose concentrations.
Consider the following statements regarding reabsorption of substances by the kidney:Most filtered bicarbonate is excreted by the kidneys
False. Bicarbonate is mainly reabsorbed. This reabsorption is essential in maintaining acid base balance, as large amounts of bicarbonate are filtered.
Consider the following statements regarding reabsorption of substances by the kidney:
Bicarbonate reabsorption occurs mainly in the Loop of Henle
False. 80% occurs in the PCT.
Consider the following statements regarding reabsorption of substances by the kidney:
The ammonia buffer system is quantitatively the most important
True. Less important systems include the phosphate buffer system, and then the urate and citrate systems.
Consider the following statements regarding reabsorption of substances by the kidney:
Potassium is 60-70% absorbed in the proximal convoluted tubule
True. The majority of the potassium is absorbed in the PCT.
Consider the following statements regarding reabsorption of substances by the kidney:
Aldosterone is important in potassium reabsorption
False. The action of aldosterone is to increase reabsorption of sodium and the excretion of potassium.
Consider the following statements regarding the proximal convoluted tubule (PCT):
Water is reabsorbed here due to the action of aldosterone
False. Water is reabsorbed by diffusion.
Consider the following statements regarding the proximal convoluted tubule (PCT):
All of glucose is reabsorbed here in normal circumstances
True. All of glucose is reabsorbed as long as the tubular transport maximum is not reached.
Consider the following statements regarding the proximal convoluted tubule (PCT):
15% of water is reabsorbed
False. 60–70% of water is reabsorbed in PCT.
Consider the following statements regarding the proximal convoluted tubule (PCT):
Bicarbonate is excreted
False. Bicarbonate is mainly reabsorbed here. Hydrogen ions are secreted.
Consider the following statements regarding the proximal convoluted tubule (PCT):
Morphine is secreted here
True. Morphine is one of the cations secreted into the PCT
Consider the following statements regarding renin:
Release is from juxtaglomerular cells
True. Renin is released from juxtaglomerular cells in the wall of the afferent arteriole.
Consider the following statements regarding renin:
Release is controlled by macula densa, detecting a low sodium flux
True. Less filtrate reaches the macula densa and sodium concentration is reduced. This is detected by the macula densa cells and an increase in renin secretion is triggered.
Consider the following statements regarding renin:
Release is increased by antidiuretic hormone
False. Renin release is decreased by antidiuretic hormone, which acts to conserve water.
Consider the following statements regarding renin:
Release is increased by hypotension
True. Renin is released in response to the low cardiovascular pressures which occur in hypotension.
Consider the following statements regarding renin:
Release is inhibited by beta blockers
True. Renin release is increased in response to beta-1 receptor stimulation.
Consider the following statements regarding aldosterone:
Production is increased by sodium chloride ingestion
False. Sodium chloride ingestion increase plasma osmolality and will decrease aldosterone production. One of the main roles of aldosterone is sodium reabsorption.
Consider the following statements regarding aldosterone:
Trauma leading to hypovolaemia will result in an increase in aldosterone release
True. Hypovolaemia causes renin release, and thus angiotensin II release. Angiotensin causes aldosterone release, with the ultimate effect of increasing sodium and water reabsorption.
Consider the following statements regarding aldosterone:
Reduces the sodium content of sweat
True. Aldosterone increases sodium reabsorption from the gut, sweat and saliva.
Consider the following statements regarding aldosterone:
Production increases urinary potassium excretion
True. Aldosterone causes the production of potassium channels in the luminal membrane of the cortical collecting duct. Potassium is lost through these.
Consider the following statements regarding aldosterone:
Increases urinary sodium concentration
False. Aldosterone is the main determinant of sodium reabsorption.
Consider the following statements about the role of angiotensin II:
It decreases aldosterone release
False. Angiotensin II increases aldosterone release.
Consider the following statements about the role of angiotensin II:
It decreases osmoreceptor firing
False. Thirst is stimulated due to increased osmoreceptor activation
Consider the following statements about the role of angiotensin II:
It causes vasoconstriction
True. This is one of its main roles.
Consider the following statements about the role of angiotensin II:
It causes a decrease in renin secretion
True. Angiotensin II causes a decrease in renin secretion as a part of the negative feedback system.
Consider the following statements about the role of angiotensin II:
It has a half life of a few seconds
False. Has a half life of a few minutes.
Consider the following statements about ANP:
It causes vasodilatation
True. ANP is a potent vasodilator.
Consider the following statements about ANP:
It impairs renal blood flow
False. It improves renal blood flow.
Consider the following statements about ANP:
It is released from the coronary sinus
False. It is released from the atrial myocytes.
Consider the following statements about ANP:
It is released in response to atrial relaxation
False. Is released in response to atrial stretch.
Consider the following statements about ANP:
It increases the filtration coefficient
True. This action, combined with afferent arteriolar dilation and efferent arteriolar vasoconstriction increases the net filtration pressure.
When measuring GFR:
Renal blood flow must be measured or estimated
False. Renal blood flow is not part of the equation for measuring GFR.
When measuring GFR:
An indicator substance must not undergo reabsorption following tubular excretion
True. If it is to be used for accurate assessment of GFR, these properties are important.
When measuring GFR:
The result matches clearance of the indicator if it is renally inert
True. An indicator should not be renally altered if it is to accurately reflect GFR.
When measuring GFR:
One would expect 180 L/day to be filtered
True. This is the quoted normal figure.
When measuring GFR:
Use of sodium as an indicator would lead to a falsely high GFR
False. Sodium is reabsorbed and therefore the urine concentration would be decreased. This would result in an underestimate of GFR.
Consider the following statements about clearance:
Clearance of a substance equals renal excretion divided by the plasma concentration
True.
Consider the following statements about clearance:
Clearance of PAH estimates renal plasma flow
True. Para-aminohippuric acid (PAH) is 90% cleared by the kidneys from the plasma. PAH clearance is therefore used to estimate renal plasma flow.
Consider the following statements about clearance:
Clearance of inulin is less than that of glucose
False. Inulin is almost completely cleared. Its rate of excretion is very close to its filtration rate. Glucose is reabsorbed up to its transport maximum.
Consider the following statements about clearance:
Clearance of free water is greater than that of inulin
False. A majority of filtered water is reabsorbed by the renal tubules.
Consider the following statements about clearance:
Clearance of an actively reabsorbed substance must exceed that of inulin
False. If a substance is actively reabsorbed, its clearance will be below that of inulin.
