Human Kidney Function and Urine Regulation M 3.4

<p>The plasma urea concentration increases, as less urea is filtered from the blood and excreted in urine. (C)</p> Signup and view all the answers

<p>The tight junctions between cells in these segments impede urea diffusion. (B)</p> Signup and view all the answers

<p>Passive diffusion of urea down its concentration gradient. (A)</p> Signup and view all the answers

<p>Urine urea concentration decreases due to reduced time for urea reabsorption. (B)</p> Signup and view all the answers

<p>UT-A2 facilitates the diffusion of urea from the thin loop of Henle into the interstitial fluid, contributing to urea secretion. (C)</p> Signup and view all the answers

<p>It increases. (B)</p> Signup and view all the answers

<p>Ascending loop of Henle (B)</p> Signup and view all the answers

<p>Continued solute reabsorption from the distal segments of the tubules, while reducing water reabsorption (D)</p> Signup and view all the answers

<p>Hypoosmotic to plasma (A)</p> Signup and view all the answers

<p>ADH makes the urine more concentrated. (B)</p> Signup and view all the answers

<p>Sodium, potassium, and chloride are actively reabsorbed. (D)</p> Signup and view all the answers

<p>The kidneys regulate the amount of fluid loss through urine production. (B)</p> Signup and view all the answers

<p>1200 to 1400 milliosmoles per liter (D)</p> Signup and view all the answers

<p>The surrounding medullary interstitium osmolarity (C)</p> Signup and view all the answers

<p>Urea diffuses out of the tubular lumen into the interstitium, increasing its concentration. (B)</p> Signup and view all the answers

<p>Sodium concentration is directly proportional to extracellular fluid osmolarity. (B)</p> Signup and view all the answers

<p>The kidneys have a limited ability to concentrate urine, and a certain amount of urine must be excreted to eliminate solutes. (D)</p> Signup and view all the answers

<p>Urea readily permeates most cell membranes, minimizing its osmotic effect. (D)</p> Signup and view all the answers

<p>It becomes more dilute due to continued solute reabsorption and decreased water reabsorption. (B)</p> Signup and view all the answers

<p>The active reabsorption of sodium in the proximal tubule (D)</p> Signup and view all the answers

<p>The concentration of sodium ions in the extracellular fluid and its associated anions (B)</p> Signup and view all the answers

<p>It becomes more dilute as sodium is actively transported out. (A)</p> Signup and view all the answers

<p>The presence or absence of antidiuretic hormone (ADH). (A)</p> Signup and view all the answers

<p>They facilitate the diffusion of urea out of the tubule and into the interstitial fluid. (C)</p> Signup and view all the answers

<p>It increases the osmolarity by promoting water reabsorption. (A)</p> Signup and view all the answers

<p>Urea contributes to the concentration gradient in the medulla, promoting water reabsorption. (C)</p> Signup and view all the answers

<p>It is reabsorbed into the peritubular capillaries. (A)</p> Signup and view all the answers

<p>Urea reabsorption is independent of ADH levels. (A)</p> Signup and view all the answers

<p>To regulate the concentration of sodium and osmolarity of extracellular fluid (C)</p> Signup and view all the answers

<p>They shrink and send nerve signals to the super optic nuclei (B)</p> Signup and view all the answers

<p>Increased blood pressure and blood volume (D)</p> Signup and view all the answers

<p>Super optic and paraventricular nuclei of the hypothalamus (B)</p> Signup and view all the answers

<p>By stimulating the production of more aquaporins (D)</p> Signup and view all the answers

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

<p>Cranial nerves (D)</p> Signup and view all the answers

<p>The osmo receptor system operates through hormonal mechanisms, while the thirst mechanism operates through behavioral mechanisms. (C)</p> Signup and view all the answers

<p>Changes in plasma osmolarity (A)</p> Signup and view all the answers

<p>10% (C)</p> Signup and view all the answers

<p>Increased arterial pressure (C)</p> Signup and view all the answers

<p>To regulate fluid intake (A)</p> Signup and view all the answers

<p>Angiotensin II acts on regions outside the blood-brain barrier to stimulate thirst. (C)</p> Signup and view all the answers

<p>2.0 mOsm/L (D)</p> Signup and view all the answers

<p>To excrete excess solutes. (B)</p> Signup and view all the answers

<p>Thirst and ADH release are stimulated by the same factors, but act independently. (C)</p> Signup and view all the answers

Filtrate that has the same osmotic pressure as its surrounding environment.

Part of the nephron where water is reabsorbed by osmosis.

Region of the kidney with higher osmolarity than the filtrate.

Section of nephron that reabsorbs sodium, potassium, and chloride, but is impermeable to water.

Process where reduced water reabsorption leads to urine with lower concentration of solutes.

Part of nephron where additional sodium chloride is reabsorbed and water impermeability occurs.

Antidiuretic hormone that regulates water reabsorption, concentrating urine.

The ability of kidneys to produce highly concentrated urine, 1200-1400 mOsm/L.

Urea cannot pass through certain kidney tubules, leading to increased concentration.

Antidiuretic hormone (ADH) increases water reabsorption in kidneys.

A process in the kidneys establishing osmolarity in the medullary interstitium.

These ducts have urea transporters that allow urea to diffuse out, raising interstitial osmolarity.

The kidneys can excrete highly concentrated or dilute urine based on solute needs.

The minimum urine volume required for excreting daily solutes, e.g., 2.5L for 600 million osmotic solutes.

Osmolarity affects the distribution of fluids; typically stable within 2-3%.

Sodium concentration in extracellular fluid is tightly controlled, ranging 104-145 MQ/L.

The segment of the nephron where tubular fluid is further diluted and sodium is actively transported out.

Antidiuretic hormone that regulates water reabsorption in the kidneys.

Tubular segment with variable water reabsorption depending on ADH presence.

Inner part of the kidney where osmolarity is maintained for urine concentration.

Concentration of solutes in a solution, important in urine formation.

The process where urea is passively reabsorbed from the tubular fluid into interstitial fluid.

Proteins that facilitate the diffusion of urea from the tubular fluid into renal interstitium.

Urine with high concentration due to significant water reabsorption and urea levels.

ADH (antidiuretic hormone) levels are highly sensitive to changes in plasma osmolarity.

The measure of solute concentration in blood plasma; affects ADH release significantly.

The body's system that regulates intake of fluids based on osmolarity and other factors.

Sensory cells that detect changes in plasma osmolarity and trigger ADH release.

Dehydration increases plasma osmolarity, stimulating ADH and thirst for fluid intake.

A hormone that stimulates thirst and increases blood pressure, acting outside the blood-brain barrier.

The osmotic receptor feedback system reduces fluid loss during dehydration.

The slight increase (2 mOsm/L) in osmolarity that activates the thirst response.

Regulates sodium concentration and osmolarity in extracellular fluid.

Hormone released to increase water reabsorption in kidneys.

Synthesizes ADH and regulates thirst and osmolarity.

Increases water permeability and reabsorbs water when ADH is present.

Water channels inserted in renal tubules to increase water reabsorption.

Process involves balancing water and solute concentrations in the body.

Stimuli that regulate ADH secretion in response to blood pressure changes.

Reabsorption of urea occurs in the thick limb, distal tubule, and cortical collecting duct with limited amounts due to low permeability.

UT A1 and UTA transporters facilitate urea diffusion into the medulla, increasing osmotic pressure to aid water reabsorption.

High urine flow decreases urine concentration and interstitial osmotic gradient, increasing urea excretion.

Healthy individuals excrete 20-60% of filtered urea, influenced by urine flow, hydration, and plasma urea concentration.

In renal disease, decreased GFR leads to higher plasma urea concentration and greater urea filtration and excretion.

In the proximal tubule, 40-50% of filtered urea is reabsorbed despite high concentration in the tubular fluid.

The thin loop of Henle secretes urea into tubular fluid, aided by the UT A2 transporter in combination with other transporters.

Renal medullary blood flow is low (less than 5% of total) and facilitated by the vasa recta as a counter current exchanger.