Primary FRCA Course Renal Physiology Exam Prep Questions Flashcards
When measuring glomerular filtration rate:
The result matches the clearance of the marker if it behaves ideally
True. An ideal marker is cleared by glomerular filtration only, so its clearance equals GFR
When measuring glomerular filtration rate:
A single plasma creatinine concentration provides an accurate value
False. A single plasma creatinine value enables only an approximate GFR to be estimated
When measuring glomerular filtration rate:
Renal blood flow must be measured or calculated
False. Neither renal blood flow nor glomerular filtration fraction needs to be known to measure GFR
When measuring glomerular filtration rate:
Glomerular filtration fraction must be measured or calculated
False. Neither renal blood flow nor glomerular filtration fraction needs to be known to measure GFR
When measuring glomerular filtration rate:
Tubular reabsorption of the marker will lead to an erroneously low GFR
True. Tubular reabsorption means that not all of the filtered marker is found in the urine, thus underestimating GFR
Transport processes in the kidney include:
Tubular secretion of NH3
True. Ammonia secretion is a vital part of tubular buffering of excreted acid
Transport processes in the kidney include:
Reabsorption of 160 g glucose per day
True. A GFR of 180 L/day contains 900 mmol of glucose (Mol Wt 180) = approximately 160 g
Transport processes in the kidney include:
Excretion of bicarbonate ions buffered by phosphate
False. Bicarbonate is extensively reabsorbed, in the form of CO2. H+ ions are buffered by phosphate.
Transport processes in the kidney include:
Glomerular filtration of all molecules under 5 nm diameter
True. Virtually all molecules under 5 nm are filtered regardless of charge. Overlapping podocytes means that the cut off is around 8nm (~55-60,000 Da).
Transport processes in the kidney include:
Chloride reabsorption by co-transport with Na+ in the PCT
False. Chloride is reabsorbed in the PCT passively down its concentration gradient via the para-cellular route
The kidneys:
Have a large arteriovenous oxygen difference
False. The kidneys do use a lot of active processes and therefore oxygen, however their overall blood flow is so high that oxygen extraction ratio is only around 0.07.
The kidneys:
Produce around 180 L filtrate a day in a healthy adult
True. 120 mL/min equates to ~180 L/day
The kidneys:
Have no autonomic nervous innervation
False. Sympathetic innervation (B1 receptors) of the JGA contributes to renin release.
The kidneys:
Receive around 25% of the cardiac output
True. Renal blood flow is approximately 1.2 L/min
The kidneys:
Play an important role in vitamin D synthesis
True. The final hydroxylation of vitamin D occurs in the kidney
Antidiuretic hormone (ADH):
Decreases the volume of urine passed
True. By promoting water reabsorption from the CD, a fall in both urine volume and plasma osmolarity will result
Antidiuretic hormone (ADH):
Decreases the osmolarity of plasma
True. By promoting water reabsorption from the CD, a fall in both urine volume and plasma osmolarity will result.
Antidiuretic hormone (ADH):
Increases water reabsorption in the proximal convoluted tubule
False. ADH works solely in the CD in the kidney
Antidiuretic hormone (ADH):
Acts via DNA transcription
False. ADH is a peptide and acts on cell surface GPC receptors and leads to build up of cAMP.
Antidiuretic hormone (ADH):
Causes vasoconstriction
True. ADH, aka vasopressin, is a potent vasoconstrictor
Sodium reabsorption in the kidney:
Is the main objective of the countercurrent multiplier
False. The main objective of the countercurrent system is to generate a hyperosmolar environment in the renal medulla
Sodium reabsorption in the kidney:
Is the major energy consuming activity of the kidney
True. It is the main leader of reabsorption, requiring energy via the Na+/K+ pump
Sodium reabsorption in the kidney:
Occurs predominantly in the proximal convoluted tubule
True. Approximately 2/3 reabsorbed in the PCT
Sodium reabsorption in the kidney:
Is linked to H+ extrusion in the distal tubule
False. Na+ reabsorption/H+ extrusion occurs in the proximal tubule.
Sodium reabsorption in the kidney:
Is important for glucose reabsorption
True. The Na+/glucose symporter is the main method for glucose reabsorption.
In the proximal tubule of the nephron:
95% of filtered potassium is reabsorbed
False. Approximately 2/3 of the filtered K+ and water are reabsorbed in the PCT
In the proximal tubule of the nephron:
90% of filtered water is reabsorbed
False. Approximately 2/3 of the filtered K+ and water are reabsorbed in the PCT
In the proximal tubule of the nephron:
Sodium is actively reabsorbed
True. Na+ reabsorption is an active process
In the proximal tubule of the nephron:
Bicarbonate is secreted
False. Bicarbonate is extensively reabsorbed in the PCT
In the proximal tubule of the nephron:
50% of ammonia is reabsorbed
False. Ammonia is one of the important buffering systems in tubular fluid
Concerning water handling by the kidneys:
Water is actively transported out of the proximal tubule
False. Water reabsorption is passive, following Na+
Concerning water handling by the kidneys:
35% of the filtered water is reabsorbed in the proximal tubule
False. Approximately 2/3 of the filtered water is reabsorbed in the PCT
Concerning water handling by the kidneys:
Water reabsorption in the Loop of Henle is mainly in the ascending limb
False. The ascending limb of the LoH is impermeable to water
Concerning water handling by the kidneys:
Nearly 90% of filtered water is reabsorbed by the kidney
False. Over 99% of filtered water is reabsorbed in the nephron
Concerning water handling by the kidneys:
Antidiuretic hormone increases the permeability of the proximal tubule to water
False. ADH acts in the collecting duct not the PCT
Potassium:
Concentration in the plasma is a good reflection of total body potassium
False. The majority of the body’s K+ is intracellular
Potassium:
Concentration in the plasma rises in metabolic acidosis
True. In acidosis, H+ excretion is in exchange for K+ reabsorption
Potassium:
Excretion increases in hypovolaemia
True. In hypovolaemia, aldosterone increases Na+ reabsorption is in exchange for K+ excretion
Potassium:
Enters cells in the presence of insulin
True. Insulin promotes uptake of K+ into cells
Potassium:
Excretion is promoted by aldosterone
True. In hypovolaemia, aldosterone increases Na+ reabsorption is in exchange for K+ excretion
The ideal substance for determining glomerular filtration rate:
Is 100% bound to plasma proteins
False. Protein-bound substances will not be filtered.
The ideal substance for determining glomerular filtration rate has to be freely filtered (i.e. not protein-bound and has a low molecular weight), not reabsorbed or secreted by the tubules, non-toxic, and is not metabolised. Inulin, a polymer of fructose with a molecular weight of 5,200 meets these criteria.
The ideal substance for determining glomerular filtration rate:
Is freely filtered from the plasma
True.
The ideal substance for determining glomerular filtration rate has to be freely filtered (i.e. not protein-bound and has a low molecular weight), not reabsorbed or secreted by the tubules, non-toxic, and is not metabolised. Inulin, a polymer of fructose with a molecular weight of 5,200 meets these criteria.
The ideal substance for determining glomerular filtration rate:
Is entirely reabsorbed in the tubule
True.
The ideal substance for determining glomerular filtration rate has to be freely filtered (i.e. not protein-bound and has a low molecular weight), not reabsorbed or secreted by the tubules, non-toxic, and is not metabolised. Inulin, a polymer of fructose with a molecular weight of 5,200 meets these criteria.
The ideal substance for determining glomerular filtration rate:
Is actively secreted by tubules
True.
The ideal substance for determining glomerular filtration rate has to be freely filtered (i.e. not protein-bound and has a low molecular weight), not reabsorbed or secreted by the tubules, non-toxic, and is not metabolised. Inulin, a polymer of fructose with a molecular weight of 5,200 meets these criteria.
The ideal substance for determining glomerular filtration rate:
Has a molecular weight greater than 69,000
False.
The ideal substance for determining glomerular filtration rate has to be freely filtered (i.e. not protein-bound and has a low molecular weight), not reabsorbed or secreted by the tubules, non-toxic, and is not metabolised. Inulin, a polymer of fructose with a molecular weight of 5,200 meets these criteria.
Regarding tubular reabsorption of glucose:
The tubular transport maximum for glucose is around 2 mmol/minute
True. Tmax for glucose is between 1.5-2.0 mmol/minute
Regarding tubular reabsorption of glucose:
An increase in GFR increases the risk of glycosuria
True. Glucose delivery to the PCT is determined by the concentration and the GFR. At a concentration of 8 mmol/L and a GFR of 125 mL/min, the delivery rate of glucose is 1 mmol/minute
Regarding tubular reabsorption of glucose:
If the plasma concentration is <8 mmol/L, all will normally be reabsorbed
True. Glucose delivery to the PCT is determined by the concentration and the GFR. At a concentration of 8 mmol/L and a GFR of 125 mL/min, the delivery rate of glucose is 1 mmol/minute. This is easily reabsorbed by the PCT.
Regarding tubular reabsorption of glucose:
Most reabsorption is via the para-cellular route in the PCT
False. Glucose is reabsorbed through the PCT cells via a symporter with sodium
Regarding tubular reabsorption of glucose:
Reabsorption is by co-transport with sodium
True.
The following have a higher intracellular than extracellular concentration:
Phosphate
True. Phosphate is the main intracellular anion
The following have a higher intracellular than extracellular concentration:
Magnesium
True. Concentration inside cells is 2.5x that outside
The following have a higher intracellular than extracellular concentration:
Potassium
True. Potassium is the main intracellular cation
The following have a higher intracellular than extracellular concentration:
Calcium
False. The intracellular Ca2+ concentration is virtually zero
The following have a higher intracellular than extracellular concentration:
Bicarbonate
False. The intracellular environment is slightly acidic compared to extracellular
Anti-Diuretic Hormone:
Determines whether the majority of water is reabsorbed by the nephron or excreted
False. The majority of filtered water is reabsorbed in the PCT independently of ADH
Anti-Diuretic Hormone:
Secretion is inhibited by alcohol
True. Alcohol leads to a diuresis because of this
Anti-Diuretic Hormone:
Is a steroid
False. ADH is a peptide
Anti-Diuretic Hormone:
Is synthesized in the posterior pituitary
False. ADH is synthesized in the hypothalamus and stored in the posterior pituitary
Anti-Diuretic Hormone:
Increases arterial blood pressure
True. ADH (aka vasopressin) is a powerful vasoconstrictor
Renal autoregulation:
Is effective up to a mean arterial pressure of 200 mmHg
False. It is effective up to around a MAP of 160 mmHg
Renal autoregulation:
Has a contribution directly from the autonomic nervous system
False. The only contribution is via angiotensin II
Renal autoregulation:
Involves simultaneous constriction of both afferent and efferent arterioles
False. Contributions come from afferent dilatation and efferent constriction
Renal autoregulation:
Maintains a constant renal artery pressure despite changes in blood flow
False. It maintains a constant flow despite changes in pressure
Renal autoregulation:
Increases glomerular filtration fraction in the presence of hypovolaemia
True. An increase in filtration fraction maintains GFR.
Regarding sodium transport in the kidney:
The main active process occurs on the luminal side of tubular cells
False. The main active process is the Na+/K+ pump on the basal side of the cell
Regarding sodium transport in the kidney:
Reabsorption in the Loop of Henle occurs with potassium and chloride
True. This occurs in the thick ascending limb via the NKCC
Regarding sodium transport in the kidney:
The majority of reabsorption is regulated by aldosterone
False. Approximately 65% of reabsorption takes place in the PCT independent of aldosterone
Regarding sodium transport in the kidney:
Approximately 1.5 kg of salt is reabsorbed by the kidney per day
True. A GFR of 180 L per day equates to 1.5 kg of salt - 99.5% is reabsorbed
Regarding sodium transport in the kidney:
Final sodium excretion
True. The principal cell in the DCT is the site of action of aldosterone
Regarding glomerular filtration:
Glomerular capillary hydrostatic pressure is lower than that of most capillary beds.
False. The hydrostatic pressure is far higher than ‘standard’, at 55 mmHg.
Regarding glomerular filtration:
Colloid osmotic pressure in Bowman’s capule is almost zero
True. There should be almost no protein in the filtrate
Regarding glomerular filtration:
Colloid osmotic pressure drops along the length of the glomerular capillary
False. Because water is lost and protein is not, the COP rises in the glomerular capillary
Regarding glomerular filtration:
20% of renal plasma flow is filtered into Bowman’s capsule
True. Normal filtration fraction is 15-20%
Regarding glomerular filtration:
Anions are more readily filtered than cations
False. The negative charge on the filtration channels favour passage of cations
Primary active transport is used in the reabsorption of:
Sodium
True. The Na+/K+ pump on the basal side of the tubular cell is a primary active transport system that drives Na+ reabsorption by keeping the intracellular concentration low
Primary active transport is used in the reabsorption of:
Chloride
False. Chloride is, for the most part, reabsorbed passively, down the concentration gradient established as water is removed from the tubular fluid; mostly this occurs by the para-cellular route. It is also re-absorbed as part of the NKCC co-transporter in the ascending limb of the loop of Henle, however this is secondary (not primary) active transport.
Primary active transport is used in the reabsorption of:
Glucose
False. Glucose is reabsorbed by secondary active transport, via a symporter with Na+
Primary active transport is used in the reabsorption of:
Bicarbonate
False. Bicarbonate is reabsorbed passively in the form of CO2
Primary active transport is used in the reabsorption of:
Water
False. Water is reabsorbed passively driven by the osmotic pressure gradient generated
Aldosterone
Acts primarily on the distal convoluted tubule
True. It acts on the principal cell in the DCT
Aldosterone
Acts via tyrosine kinase linked receptors
False. It is a steroid and so works intracellularly
Aldosterone
Decreases the osmolarity of urine
False. Urine osmolarity is determined by ADH
Aldosterone
Increases potassium excretion
True. The Na+ reabsorption stimulated by aldosterone is linked to K+ excretion
Aldosterone
Release is triggered by angiotensin II
True. Angiotensin II is the greatest stimulus for aldosterone release
In the loop of Henle:
Fluid entering it is approximately isotonic with plasma
True. Fluid entering has an osmolarity of around 300 mOsmol/L
In the loop of Henle:
The ascending limb is impermeable to water
True. This enables the tubular fluid delivered to the DCT to be hypo-osmolar
In the loop of Henle:
The thin ascending limb is primarily responsible for the reabsorption of sodium
False. The thick ascending limb is where sodium reabsorption occurs
In the loop of Henle:
Only 15% of the loops pass deeply into the medulla
True. Only around 15% of the loops are long in humans
In the loop of Henle:
The osmolarity of tubular fluid increases to a maximum of 1200 mOsmol/L
True. In the tip of the LoH the osmolarity has increased approximately 4 fold
Angiotensin II:
Decreases aldosterone release
False. It increases aldosterone release.
Angiotensin II:
Decreases osmoreceptor firing
False. It does not influence osmolarity
Angiotensin II:
Causes vasoconstriction
True. It is a powerful vasoconstrictor
Angiotensin II:
Causes a decrease in renin secretion
True. It exerts negative feedback to inhibit further renin release
Angiotensin II:
Has a half-life of a few seconds
False. Its half-life in the circulation is less than 30 seconds
The following are involved in renal autoregulation:
Adenosine
True. Adenosine is an inhibitory influence in renal autoregulation, being produced when hydration/perfusion are good to limit renal blood flow/glomerular filtration
The following are involved in renal autoregulation:
Aldosterone
False. Adenosine, prostaglandin E2 and angiotensin II are involved in autoregulation in the kidney.
The following are involved in renal autoregulation:
Bradykinin
False. Adenosine, prostaglandin E2 and angiotensin II are involved in autoregulation in the kidney.
The following are involved in renal autoregulation:
Prostaglandin E2
True. PEGE2 dilates the afferent arteriole to maintain renal blood flow when perfusion pressure falls.
The following are involved in renal autoregulation:
Vasopressin
False. Adenosine, prostaglandin E2 and angiotensin II are involved in autoregulation in the kidney.
