Glomerular Filtration Rate (GFR)
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Questions and Answers

Which of the following factors would directly decrease the Glomerular Filtration Rate (GFR)?

  • Afferent arteriolar vasodilation
  • Mesangial cell relaxation
  • Efferent arteriolar vasoconstriction
  • Afferent arteriolar vasoconstriction (correct)

An ideal substance for measuring GFR would be significantly metabolized by the kidneys.

False (B)

What effect does Angiotensin II (AII) typically have on the afferent and efferent arterioles, and how does this impact Renal Blood Flow (RBF)?

Angiotensin II causes vasoconstriction of both afferent and efferent arterioles, leading to a decrease in RBF.

In GFR measurement, __________ is considered the 'gold standard' exogenous substance due to its properties of being freely filtered and neither secreted nor reabsorbed.

<p>Inulin</p> Signup and view all the answers

Why is creatinine clearance a more convenient method for estimating GFR compared to inulin clearance?

<p>Creatinine is endogenously produced and maintains a relatively constant plasma concentration. (B)</p> Signup and view all the answers

Which of the following scenarios would directly lead to a decrease in GFR due to changes in glomerular capillary dynamics?

<p>Decreased glomerular capillary hydrostatic pressure (C)</p> Signup and view all the answers

Intrinsic autoregulatory factors maintain a constant GFR regardless of changes in blood pressure outside the range of 70-175 mmHg.

<p>False (B)</p> Signup and view all the answers

What percentage of filtered sodium and water is typically reabsorbed by the proximal convoluted tubule (PCT)?

<p>65%</p> Signup and view all the answers

Increased activity of the Sympathetic Nervous System (SNS) and the Renin-Angiotensin-Aldosterone System (RAAS) typically leads to constriction of both the ______ and efferent arterioles, reducing GFR.

<p>afferent</p> Signup and view all the answers

Match the hormone with its primary effect on renal sodium reabsorption:

<p>Aldosterone = Increases sodium reabsorption in the distal convoluted tubule and collecting duct ADH = Afferent arteriolar constriction and mesangial cell contraction ANP = Inhibits afferent arteriolar dilation and mesangial cell relaxation</p> Signup and view all the answers

What is the primary mechanism by which increased GFR leads to increased sodium and water reabsorption in the proximal convoluted tubule (PCT)?

<p>Increased oncotic pressure in peritubular capillaries (C)</p> Signup and view all the answers

Glomerulotubular balance ensures that a constant amount of sodium and water is excreted, regardless of changes in GFR.

<p>False (B)</p> Signup and view all the answers

Name two extrinsic factors that, when decreased, lead to a decrease in GFR.

<p>Sodium concentration and ECFV (Extracellular Fluid Volume)</p> Signup and view all the answers

Aldosterone stimulates sodium reabsorption by inducing the production of the basolateral ______ pump in tubular cells.

<p>Na+/K+ ATPase</p> Signup and view all the answers

Which of the following best describes the effect of decreased ECFV on peritubular capillary dynamics and subsequent sodium reabsorption?

<p>Decreased hydrostatic pressure and increased oncotic pressure, leading to increased Na+ reabsorption (A)</p> Signup and view all the answers

Which of the following transporters is responsible for sodium reabsorption in the thick ascending limb (TAL) of the loop of Henle?

<p>Na+-K+-2Cl- cotransporter (NKCCT) (C)</p> Signup and view all the answers

The majority of chloride reabsorption in the tubular system occurs via active transport independently of sodium.

<p>False (B)</p> Signup and view all the answers

What percentage of filtered sodium is typically reabsorbed in the proximal convoluted tubule (PCT)?

<p>65%</p> Signup and view all the answers

In the late distal convoluted tubule and collecting duct, sodium reabsorption is primarily regulated by the hormone ________.

<p>aldosterone</p> Signup and view all the answers

Match the tubular segment with the primary mechanism of sodium reabsorption:

<p>Proximal Convoluted Tubule (PCT) = Na+/H+ exchanger (NHE-3) Thick Ascending Limb (TAL) = Na+-K+-2Cl- cotransporter (NKCCT) Early Distal Convoluted Tubule (DCT) = Na+/Cl- cotransporter Late DCT and Collecting Duct = ENaC (Epithelial Sodium Channel)</p> Signup and view all the answers

Which of the following factors is the MOST important determinant of extracellular fluid volume (ECFV)?

<p>Sodium content (D)</p> Signup and view all the answers

Glomerulotubular balance is the primary mechanism for long-term regulation of sodium excretion compared to GFR autoregulation.

<p>True (A)</p> Signup and view all the answers

Besides the kidneys, list two other routes of sodium loss from the body.

<p>sweat and feces</p> Signup and view all the answers

Low pressure baroreceptors, located in the atria and great vessels, sense changes in ________ which ultimately influences sodium regulation.

<p>blood volume</p> Signup and view all the answers

In type B intercalated cells of the collecting duct, chloride is reabsorbed via which mechanism?

<p>HCO3-/Cl- exchanger (D)</p> Signup and view all the answers

The thin descending limb of the loop of Henle actively reabsorbs chloride.

<p>False (B)</p> Signup and view all the answers

Explain how sodium reabsorption plays a vital role in tubular transport.

<p>Sodium reabsorption plays a vital role in the tubular transport of other substances, including water, electrolytes such as potassium, chloride, bicarbonate, and phosphate, as well as substances like amino acids, glucose, and lactate. Additionally, it facilitates the secretion of organic substances and H+.</p> Signup and view all the answers

Within the tubular system, the majority of chloride reabsorption involves _ly active transport coupled to sodium reabsorption.

<p>secondarily</p> Signup and view all the answers

A patient presents with hypotension and hyponatremia. Which of the following compensatory mechanisms is MOST likely to occur in the kidneys to restore blood pressure and sodium balance?

<p>Decreased GFR and increased sodium reabsorption in the proximal tubule (D)</p> Signup and view all the answers

Increased activity of the Na+/K+-ATPase on the basolateral membrane of renal tubular cells primarily facilitates sodium secretion into the tubular lumen.

<p>False (B)</p> Signup and view all the answers

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In the scenario of acute afferent arteriolar vasoconstriction leading to a decreased glomerular filtration rate (GFR), which compensatory mechanism would most precisely modulate efferent arteriolar tone to maintain GFR, considering the interplay between hydrostatic and oncotic pressures?

<p>Preferential efferent arteriolar constriction via angiotensin II (AII) to elevate $P_{GC}$ while minimizing the reduction in renal blood flow (RBF). (C)</p> Signup and view all the answers

The gold standard for GFR measurement, inulin clearance, is clinically impractical for routine assessment primarily due to its inherent toxicity and significant impact on renal function.

<p>False (B)</p> Signup and view all the answers

Describe the theoretical impact on calculated creatinine clearance if an individual with consistently normal renal function begins a high-protein diet, assuming no change in muscle mass or renal handling of creatinine.

<p>Creatinine clearance may be artifactually increased due to increased creatinine production from the high-protein diet, leading to elevated plasma and urine creatinine concentrations.</p> Signup and view all the answers

The measurement of renal plasma flow (RPF) using para-aminohippuric acid (PAH) relies on the principle that PAH is nearly completely ______ by the kidneys in a single pass, allowing its clearance rate to approximate RPF.

<p>extracted</p> Signup and view all the answers

Match each substance with its primary limitation for accurately measuring GFR in clinical settings:

<p>Inulin = Requires continuous intravenous infusion and timed urine collections, inconvenient for routine use. Creatinine = Overestimation of GFR due to tubular secretion, varies with muscle mass, and is affected by diet. Radioactive tracers (e.g., 51Cr-EDTA) = Potential radiation exposure and specialized equipment needed, safety concerns. Cystatin C = Affected by factors other than GFR, such as thyroid dysfunction and inflammation.</p> Signup and view all the answers

In the context of intrinsic autoregulation impacting glomerular filtration rate (GFR), which scenario would most likely override the tubuloglomerular feedback and myogenic mechanism, leading to a significant alteration in GFR and filtered sodium?

<p>A substantial drop in MAP from 110 mmHg to 65 mmHg, activating potent baroreceptor reflexes. (D)</p> Signup and view all the answers

A decrease in extracellular fluid volume (ECFV) primarily increases glomerular capillary hydrostatic pressure, thereby elevating GFR and sodium filtration.

<p>False (B)</p> Signup and view all the answers

Detail the neurohormonal mechanisms initiated by baroreceptor reflexes in response to a reduction in extracellular fluid volume (ECFV) and how these mechanisms synergistically modulate glomerular filtration rate (GFR).

<p>Baroreceptor activation due to decreased ECFV stimulates the sympathetic nervous system (SNS) and the renin-angiotensin-aldosterone system (RAAS), increasing afferent and efferent arteriolar constriction and mesangial cell contraction. Simultaneously, antidiuretic hormone (ADH) release is augmented which further constricts afferent arterioles and stimulates mesangial cell contraction, while atrial natriuretic peptide (ANP) secretion is suppressed, removing its vasodilatory influences. The combined effect of these mechanisms reduces GFR.</p> Signup and view all the answers

Glomerulotubular balance maintains that the proximal convoluted tubule (PCT) reabsorbs a ______ proportion of glomerular filtrate, minimizing the impact of GFR changes on sodium and water excretion.

<p>constant</p> Signup and view all the answers

Match the following physiological changes with their effect on sodium and water reabsorption in the peritubular capillaries:

<p>Increased peritubular capillary oncotic pressure = Increased sodium and water reabsorption Decreased peritubular capillary hydrostatic pressure = Increased sodium and water reabsorption Increased extracellular fluid volume (ECFV) = Increased peritubular capillary hydrostatic pressure which decreases sodium and water reabsorption Decreased mean arterial pressure (MAP) = Decreased peritubular capillary hydrostatic pressure, which increases sodium and water reabsorption</p> Signup and view all the answers

Which of the following scenarios would result in the most significant increase in sodium reabsorption by the distal convoluted tubule (DCT) and principal cells of the collecting duct (CCD)?

<p>Selective impairment of the mineralocorticoid receptor, diminishing aldosterone's genomic effects. (B)</p> Signup and view all the answers

The effect of aldosterone on renal sodium reabsorption primarily involves direct modulation of existing ion channels within the distal nephron, without significantly influencing new protein synthesis.

<p>False (B)</p> Signup and view all the answers

Describe the glomerulotubular balance mechanism and clarify its significance in maintaining stable sodium and water balance despite fluctuations in glomerular filtration rate (GFR).

<p>Glomerulotubular balance is the mechanism whereby the proximal tubule adjusts its reabsorption rates in response to changes in GFR, ensuring a constant proportion of filtered sodium and water is reabsorbed. The balance leads to increased oncotic pressure in the peritubular capillaries. This maintains stable sodium and water balance independent of GFR fluctuations.</p> Signup and view all the answers

Reduced extracellular fluid volume (ECFV) leads to a decrease in mean arterial pressure (MAP), which subsequently results in a decreased ______ pressure and increased ______ pressure of the peritubular capillaries and, consequently, enhanced sodium and water reabsorption from the tubular interstitium.

<p>hydrostatic, oncotic</p> Signup and view all the answers

In a patient experiencing hypovolemic shock and a subsequent decrease in mean arterial pressure (MAP), which hormonal response is most important for maintaining sodium balance by increasing sodium reabsorption in the distal nephron?

<p>Decreased secretion of atrial natriuretic peptide (ANP), leading to reduced inhibition of sodium reabsorption. (C)</p> Signup and view all the answers

In a scenario of sustained hypovolemia triggering the renin-angiotensin-aldosterone system (RAAS), which of the following compensatory mechanisms would exert the least direct influence on restoring effective circulating volume via modulation of renal sodium handling?

<p>Suppression of afferent arteriolar tone, leading to increased glomerular capillary hydrostatic pressure and a resultant elevation in GFR (B)</p> Signup and view all the answers

Considering the established glomerulotubular balance, a moderate reduction in GFR, absent any other compensatory mechanisms, would predictably lead to a proportional decrease in absolute sodium reabsorption, thereby maintaining a constant fractional excretion of sodium.

<p>False (B)</p> Signup and view all the answers

A patient presents with Bartter's syndrome, specifically a loss-of-function mutation in the Na+-K+-2Cl- cotransporter (NKCC2) in the thick ascending limb. Describe the anticipated compensatory adaptations in downstream nephron segments (early DCT and collecting duct) with regard to sodium and water handling, and detail one hormonal alteration that contributes significantly to these adaptations.

<p>In Bartter's syndrome, reduced Na+ reabsorption in the TAL leads to increased Na+ delivery to the DCT and collecting duct. Compensatory mechanisms include: (1) increased Na+ reabsorption via the Na+-Cl- cotransporter in the early DCT, (2) enhanced ENaC-mediated Na+ reabsorption in the collecting duct, and (3) increased aldosterone secretion due to volume depletion. The increased aldosterone enhances ENaC activity, further promoting Na+ retention.</p> Signup and view all the answers

In the context of metabolic alkalosis with concurrent hypochloremia, the paradoxical aciduria observed stems from increased bicarbonate reabsorption in the proximal tubule. This is primarily driven by enhanced activity of the __________ exchanger in the luminal membrane, consequent to intracellular __________ depletion.

<p>Na+/H+, chloride</p> Signup and view all the answers

Match the following diuretics with their primary site of action within the nephron:

<p>Furosemide = Thick Ascending Limb of Henle (TAL) Hydrochlorothiazide = Distal Convoluted Tubule (DCT) Amiloride = Collecting Duct Acetazolamide = Proximal Convoluted Tubule (PCT)</p> Signup and view all the answers

A patient exhibiting hyperkalemia secondary to acute kidney injury (AKI) also demonstrates a urine anion gap of +30 mEq/L. Given this information, which of the following mechanisms is least likely to contribute to the observed hyperkalemia?

<p>Enhanced activity of apical H+-ATPase in type A intercalated cells of the collecting duct, leading to increased distal bicarbonate excretion (D)</p> Signup and view all the answers

In a state of chronic hyperaldosteronism, the resultant increased sodium reabsorption in the collecting duct invariably leads to a sustained expansion of extracellular fluid volume (ECFV) and a corresponding elevation in mean arterial pressure (MAP), without any potential for adaptation or escape mechanisms.

<p>False (B)</p> Signup and view all the answers

Explain the counter-regulatory mechanisms that prevent unchecked sodium retention in response to prolonged activation of the renin-angiotensin-aldosterone system (RAAS). Detail the specific hormonal and intrarenal factors involved.

<p>Counter-regulatory mechanisms involve pressure natriuresis (increased sodium excretion due to elevated renal perfusion pressure), downregulation of ENaC expression in the collecting duct, and increased release of atrial natriuretic peptide (ANP) from the heart in response to volume expansion. Intrarenal factors include altered intrarenal hemodynamics and changes in local prostaglandin and nitric oxide production.</p> Signup and view all the answers

The fractional excretion of sodium (FENa) is classically used to differentiate between prerenal and intrinsic renal causes of acute kidney injury (AKI). However, in patients with diuretic use, FENa may be unreliable. In these cases, fractional excretion of __________ (FEurea) may provide a more accurate assessment of underlying renal function.

<p>urea</p> Signup and view all the answers

Match the following conditions with their expected effect on the filtered load of sodium:

<p>Severe Hypotension = Decreased Nephrotic Syndrome = Variable (May be increased due to proteinuria affecting tubular function or decreased due to volume depletion) Administration of a Vasoconstrictor Affecting the Afferent Arteriole = Decreased Increased Plasma Sodium Concentration (Hypernatremia) = Increased</p> Signup and view all the answers

A researcher is investigating the effects of a novel natriuretic peptide structurally distinct from ANP, BNP, and CNP. This peptide selectively targets guanylyl cyclase-C (GC-C) receptors expressed in the inner medullary collecting duct. What primary effect on renal sodium handling would be anticipated following administration of this novel peptide, assuming all other compensatory mechanisms remain constant?

<p>Decreased sodium reabsorption in the collecting duct, accompanied by increased water excretion (B)</p> Signup and view all the answers

The clearance of para-aminohippuric acid (PAH) provides an accurate estimate of renal plasma flow (RPF) under all physiological conditions, irrespective of variations in PAH secretion or extraction efficiency.

<p>False (B)</p> Signup and view all the answers

Describe the technical and physiological limitations of using inulin clearance as the gold-standard method for measuring glomerular filtration rate (GFR) in a large-scale clinical study.

<p>Technical limitations include the requirement for continuous intravenous infusion, meticulous urine collections, and complex laboratory assays. Physiological limitations involve potential for inulin to alter tubular flow and create inaccurate GFR values. Plus, inulin needs to be administered intravenously and requires special lab assays.</p> Signup and view all the answers

In the context of estimating GFR using creatinine, the MDRD (Modification of Diet in Renal Disease) equation incorporates several patient-specific variables. However, it notably assumes a constant value for body surface area (BSA), typically set at 1.73 m². This assumption can lead to significant inaccuracies in individuals with extreme variations in __________ , such as morbidly obese or severely underweight patients.

<p>body size</p> Signup and view all the answers

Match given scenarios or conditions with the factor of GFR determinant that primarily contributes to the change:

<p>Administration of an ACE inhibitor = Reduced efferent arteriolar resistance Severe dehydration = Decreased renal plasma flow Increased plasma protein oncotic pressure = Decreased net ultrafiltration pressure Ureteral obstruction = Increased Bowman's capsule hydrostatic pressure</p> Signup and view all the answers

Flashcards

RBF and GFR Regulation

Reduced GFR due to afferent arteriolar vasoconstriction, mesangial contraction and increased protein concentration in glomerular capillaries, offset by increased hydrostatic pressure in glomerular capillaries caused by efferent arteriolar vasoconstriction.

Renin-Angiotensin System Effect

Stimulation of renin secretion occurs via β1 receptors on JG cells leading to increased Angiotensin II (AII) production and subsequently afferent and efferent arteriolar vasoconstriction resulting in reduced renal blood flow (RBF) and glomerular filtration rate (GFR).

Ideal GFR Measurement Substance

GFR is determined by measuring the renal clearance of a substance that is freely filtered, not secreted/reabsorbed, not metabolized/stored, doesn't affect renal function, not excreted extrarenally, non-toxic and easily measurable.

Inulin Use in Measuring CFR

Inulin, a fructose polymer (5.2 kDa), is the gold standard for measuring GFR because it meets all the criteria of an ideal substance, although it is inconvenient to use.

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Creatinine Clearance

Creatinine, a breakdown product of creatine phosphate, is convenient for GFR measurement since it's produced at a constant rate, but less accurate than Inulin.

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Na+/H+ Exchanger

Exchanges Na+ for H+ in the tubular system, aiding in Na+ reabsorption.

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Paracellular Na+ Reabsorption

Some Na+ is reabsorbed alongside water and solutes due to osmotic gradients or charge differences.

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Importance of Na+ Reabsorption

Na+ reabsorption is key for water, electrolyte, amino acid, glucose, and lactate reabsorption, AND secretion of organic substances and H+.

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PCT Na+ Reabsorption

65% of filtered Na+ is reabsorbed in the PCT via transporters (like SGLT) and the Na+/H+ exchanger.

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PCT Intercellular Junctions

Not very tight, allowing passive reabsorption of Na+ with water and Cl-.

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TAL Na+ Reabsorption

25% of filtered Na+ is reabsorbed via the NKCCT co-transporter and Na+/H+ exchanger.

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Early DCT Na+ Reabsorption

Reabsorbs Na+ via the Na+-Cl- co-transporter and Na+ channel, accounting for 5% of filtered Na+.

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Late DCT/Collecting Duct Na+ Reabsorption

Reabsorbs Na+ via ENaC channels, regulated by aldosterone.

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Overview of Renal Cl- Handling

Glomerulus filters a lot of it, but most (99.2%) is reabsorbed.

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Tubular Cl- Reabsorption

Occurs in all segments EXCEPT the thin descending limb of the loop of Henle.

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Mechanisms of Renal Cl- Handling

Mainly coupled to Na+ reabsorption via the transcellular route. Minority: solvent drag or negatively charged lumen.

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PCT Cl- Reabsorption

Absorbs Cl- passively via paracellular route due to solvent drag.

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TAL Cl- Reabsorption

25% reabsorbed via NKCCT, along with Na+.

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DCT and CCD Cl- Reabsorption

In the DCT, Cl- is reabsorbed via the Na+/Cl- co-transporter and passively. In the CCD, it's reabsorbed by HCO3-/Cl- exchanger.

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Importance of Na+ Regulation

ECF Na+ content determines ECFV, which influences plasma volume and hydrostatic pressure.

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Intrinsic Autoregulation of GFR

Intrinsic mechanisms (tubuloglomerular feedback and myogenic mechanism) help maintain a stable GFR despite MAP changes, but baroreceptor reflexes can override this.

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Direct Renal Effects of Low Na+

Low sodium or ECFV decreases GFR by reducing glomerular capillary hydrostatic pressure and increasing oncotic pressure.

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Indirect Renal Effects of Low Na+

Low sodium or ECFV triggers baroreceptor reflexes, increasing SNS, RAAS, ADH, and decreasing ANP, all leading to reduced GFR.

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Glomerulotubular Balance

The PCT reabsorbs a constant proportion of filtrate (65% of Na+ and H2O), minimizing GFR changes on excretion.

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Mechanism of Glomerulotubular Balance

Increased GFR leads to higher oncotic pressure in peritubular capillaries, favoring reabsorption from the tubules.

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Renal Interstitial Hydrostatic Pressure Effect

Low ECFV decreases hydrostatic and increases oncotic pressure in peritubular capillaries, promoting Na+ and H2O reabsorption.

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Aldosterone Secretion Triggers

Aldosterone, a steroid hormone from the adrenal cortex, is secreted in response to Angiotensin II, ACTH and high [K+].

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Action of Aldosterone

Aldosterone increases Na+ reabsorption in the DCT and collecting duct by increasing Na+/K+ ATPase and ENaC channels

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Importance of Aldosterone

Because ~2% of filtered Na+ can be reabsorbed, aldosterone is the most important regulator of Na+ reabsorption.

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Increased SNS and RAAS activity

Increases in SNS and RAAS activity causes afferent and efferent arteriolar constriction and mesangial cell contraction

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Decreased GFR Factors

Vasoconstriction of afferent arterioles, contraction of mesangial cells, and increased oncotic pressure in glomerular capillaries all contribute to a decreased in GFR

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Efferent Arteriole Effect on GFR

Efferent arteriolar vasoconstriction increases hydrostatic pressure in glomerular capillaries, helping to maintain GFR

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Renin Secretion Stimulation

Stimulation of renin secretion occurs through β1 receptors on JG cells, which leads to increased Angiotensin II (AII) production.

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GFR Measurement Criteria

Ideal substances are freely filtered, not secreted/reabsorbed by tubules, not metabolized/stored in the kidney, do not impact the renal function or get excreted extrarenally, and are nontoxic and easy to measure.

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Inulin Use in GFR Measurement

Inulin, a fructose polymer, is the gold standard for measuring GFR, but its use requires continuous IV infusion until steady state plasma levels are reached.

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Na+ Reabsorption Role

Na+ reabsorption drives H2O and electrolyte reabsorption, and secretion of organic substances and H+.

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Na+ Co-transporters

It's reabsorbed with glucose, amino acids, phosphates, and lactate in the PCT.

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Leaky Intercellular Junctions

Not very 'tight', allowing passive Na+ reabsorption in the PCT and TAL.

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Late DCT/Collecting Duct

Reabsorbs Na+ via ENaC channels in principal cells; regulated by aldosterone.

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Filtered vs. Excreted Cl-

Most (99.2%) of filtered Cl- is reabsorbed by the tubules.

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Tubular Cl- Reabsorption Location

All EXCEPT the thin descending limb of LoH

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ECFV Determinants

Volume of ECF is determined by osmotically active solutes, primarily Na+ and Cl-.

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Baroreceptor Reflex Feedback

Monitors changes in hydrostatic pressure to maintain a regular MAP.

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Baroreceptor Locations

Low-pressure (atria), High-pressure (aortic arch), Intra-renal (JGA).

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Daily Na+ Loss

Most lost through the kidneys; less through sweat and feces.

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Renal Na+ Regulation

GFR and tubular reabsorption.

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Na+ Excretion Equation

Na+ excretion = Na+ filtered – Na+ reabsorbed.

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GFR Autoregulation

Intrinsic mechanisms (tubuloglomerular feedback and myogenic mechanism) help maintain stable GFR, but can be overridden by baroreceptor reflexes (BRR).

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Direct Renal Effect

Decreased Na+ or ECFV reduces GFR by decreasing glomerular capillary hydrostatic pressure and increasing oncotic pressure.

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Indirect Renal Effects

Decreased Na+ or ECFV activates baroreceptor reflexes, leading to increased SNS, RAAS, ADH, and decreased ANP, reducing GFR.

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Glomerulotubular Balance Function

The PCT reabsorbs a constant proportion (65%) of filtered Na+ and H2O, minimizing the impact of GFR changes on excretion.

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Glomerulotubular Balance Mechanism

Increased GFR leads to higher oncotic pressure in peritubular capillaries, favouring tubular reabsorption.

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Renal Interstitial Pressure Influence

Low ECFV decreases hydrostatic and increases oncotic pressure in peritubular capillaries, promoting Na+ and H2O reabsorption.

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What Triggers Aldosterone Release?

Steroid hormone from adrenal cortex secreted in response to Angiotensin II, ACTH, and high plasma [K+].

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How Does Aldosterone Work?

Increases Na+ reabsorption by DCT and collecting duct by increasing Na+/K+ ATPase and ENaC channels.

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Why Aldosterone is Important

Aldosterone is the MOST important regulator of Na+ reabsorption, because ~2% of filtered Na+ can be reabsorbed.

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SNS and RAAS Activity Effect

Causes afferent and efferent arteriolar constriction and mesangial cell contraction, reducing GFR.

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Study Notes

Control of Renal Na⁺ Handling

  • Excretion of Na ⁺regulation depends on glomerular and tubular resoption
  • Note control is important for renal handling of Na* and is more important than GFR (Glomerulotubular) because GFR is heavily Auoregulation

Renal Control is:

  • Internic = 1- autorefulatory factor - MAP has a minor effects
  • Extrisnic Factors = body Na, decreases GGR due to glomeilar cap hydro

Renal Regulation By tubular Reabsoprtion

  • Glomerulotubular - balances . if less water means less pressure and vica versa

Reanl intersial is where the presue is lowe and high tonicity from water Horemnal - Aldestrone hormone

  • sterird horizone - increases Na
  • ATpase is ddtugulated to regulate - and controls Na and potassium

Anti-Diuretic Horizone

  • peptive harmone produced from SON and PVN to to control
  • plasm osmaity by Detect by osmoreceptors in the Hypopthualsu
  • low presuure B recoptiros - less sense
  • ALL - Nauseua Vomiting- ADH will create a increase at a 1 Cation to contort V1 receptor - with 1, smooth muscle - causes vaso dialiation V2 receptor - Creates CA=pm PKA which create water permebalit to peritublular capillaries

Antril Naturetric Harmone

  • Peptide hormone produced to contort of atril pressure . ATN receport = Gc activity RENal effect
  • Increase of sodium by CD
  • inhibition of renin

SNS - Symethietic Nervous System

Increase in rBF due to constrictory of arteries

REal Handling of Glucose-

  • glomeilurs filters the glucose so can get to plasma the the proximal convoluted tubules -Sodium handles the transpotr as reabsoprtio of sodium

renal thrshold for glucose

  • Reagets when TMM gets too over wheled

Sodium handling and circiulation in the reinal system+

  • Rebasorbstion is reabsorbed by tubuallies pt
  • Na 1 from sodium in take equals water

Chloride handling in real system

  • anddsoium is reabsotrbed through tube
  • transclellar is couples to sodium to reabsorb
  • passivly or thourg solvent drag through tube"""

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Description

This quiz covers factors affecting Glomerular Filtration Rate (GFR), the role of Angiotensin II, and ideal substances for GFR measurement. Key concepts include the impact on afferent and efferent arterioles and the convenience of creatinine clearance. It also touches on the properties of inulin.

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