Renal tubules, Reabsorption and Secretion Flashcards by Geno Sadaya

The proximal tubule cells have: cilia, microvilli, stereocillia?

Microvilli

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Which two major proteins are responsible for the proximal tubules’ reabsorption of 65% of the ultrafiltrate?

Na/K-ATPase pumps and AQP-1

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The NA/K-ATPase pump reabsorbs which component of the ultrafiltrate?

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Active transport of Na is followed by passive transport of which ion to maintain electrochemical neutrality?

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The accumulation of which compound in the lateral intercellular spaces creates an osmotic gradient that draws water from the lumen into the intercellular compartment?

NaCl

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Which protein channel allows water to leave the proximal tubule?

AQP-1

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Amino acid and glucose transport out of the proximal convoluted tubule depends on the active transport of which ion?

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In the first half of the proximal tubule, Na is reabsorbed primarily with which molecule?

Bicarbonate

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In the second half of the proximal tubule, Na is reabsorbed with which ion?

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Any Na that enters the cells across the apical membrane leaves the cell and enters the blood via which transport protein?

Na-K ATPase

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Reabsorption of glucose and other organic solutes across the basolateral membrane of the the first part of the proximal tubule is by (active/passive) transport.

Passive

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In the first part of the proximal tubule, which is reabsorbed more: Cl or water?

Water

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Reabsorption of NaHCO3 in the first part of the proximal tubule establishes a transtubular osmotic gradient for the passive reabsorption of which substance?

Water

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Na and Cl are absorbed via both paracellular pathway and transcellular pathway in which part of the proximal tubule: first or second part?

Second

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Why is Na reabsorbed primarily with Cl and not with other organic molecules in the second part of the proximal tubule?

Because the transport mechanisms in the second part are unlike the first and the second part contains very little glucose and amino acids but very high concentration of Cl that exceeds that of the first half

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In the second part of the proximal tubule, Cl is reabsorbed across the basolateral membrane via which transporter?

K-Cl symporter

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Why can NaCl be reabsorbed via the paracellular route in the second half of the proximal tubule?

Because the rise in the Cl concentration in the tubular fluid in the first part of the proximal tubule creates a Cl gradient that favors diffusion of Cl from the tubular lumen across the tight junctions into the intracellular space.

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A drug that inhibits Na+ reabsorption results to lower \_\_\_\_\_\_\_\_\_\_ reabsorption.
A. Amino acid
B. H+
C. Creatinine
D. Organic acid or base

AAs are cotransported with sodium. Organic acids and bases are secreted. Creatinine is not reabsorbed. Hydrogen ion is secreted via an antiport mechanism.

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An important mechanism in reabsorbing amino acids and organic molecules in the proximal tubule is:
A. facilitated diffusion
B. endocytosis
C. second active transport
D. simple diffusion

Amino acids and organic molecules are reabsorbed with sodium in a cotransport mechanism. The transport is driven by the Na/K ATPase pump in the basolateral surface.

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95% of the molecules is reabsorbed in the proximal tubule except:
A. bicarbonate
B. sodium
C. urea
D. water

Urea is only 50% reabsorbed in the PCT.

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Which of the following statements is true regarding PCT reabsorption?
A. It replies on the osmotic gradient created by the Na-K pump
B. It is dependent on ADH
C. It is independent of Na.

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Where are drugs and foreign substances such as creatinine secreted?
A. Proximal tubule
B. Loop of Henle
C. Distal tubule
D. collecting duct

Most drugs and foreign substance are secreted along the proximal convoluted tubule.

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Reabsorbed electrolytes from PCT go back to circulation through 
A. vasa recta
B. arcuate arteries
C. peritubular capillaries
D. arcuate veins
E. all of the above

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A 30-year old male was found unconscious in a highway, probably a victim of hit and run. He was brought to the emergency room of the Philippine General Hospital and was found to have a systolic BP if 70 mmHg and feeble pulses. He was noted to be probably in shock. How will this affect Na reabsorption in the PCT?

A. Decreased Na reabsorption due to increased sympathetic nerve activity
B. Increased Na absorption secondary to increased renin-angiotensin-aldosterone system
C. Increased Na reabsorption secondary to increased renal interstitium
D. All except B
E. All except C

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``` The Brush Border Microvilli in the apical membrane is a distinct characteristic of: A. glomerulus B. bowman's capsule C. PCT D. DCT ```

Proximal tubule a. N-K 2 cl transporter b. facilitated diffusion for glucose reabsorption c. Na-H antiport d. Basolateral Na-K Antiport

Sodium transport across the proximal tubule occurs by all of the following mechanism except: a. sodium transport with chloride b. cotransport with glucose, amino acids, and phosphates c. Na-H exchanger d. Na-K-2Cl transporter

The (descending/ascending) thin limb of Henle's loop absorbs water.

Descending

The ascending thin limb of Henle's loop absorbs (water/NaCl)

NaCl

Water is absorbed in the loop of Henle via which protein channels?

AQP1

The bulk of magnesium reabsorption occurs in the A. Proximal tubule B. Distal convoluted tubule C. Thick ascending limb of loop of Henle D. Collecting tubule

These control mechanisms are activated seconds after change in blood pressure except A. RAAS B. baroreceptor C. chemoreceptor D. CNS ischemic response

Which part of the nephron has lowest [Na+] in filtrate? a. collecting duct b. thick limbs of Loop of Henli c. thin limbs of Loop of Henli d. glomerulus

True about LOH a. has water-permeable descending loop and water-impermeable ascending loop b. acted upon by aldosterone and ADH c. determine osmotic gradient... d. removes all blood components from filtered urine e. AOTA

The renal threshold for glucose is the A. maximum concentration of glucose the glomerulus can filter B. minimum concentration of glucose the glomerulus can filter C. plasma concentration of glucose above which will appear in the urine D. plasma concentration of glucose below which will appear in the urine

C By definition, the renal threshold for glucose is the plasma concentration of which any concentration of glucose above the said threshold will appear in the urine.

Reabsorption of NA and Cl in the DCT and CD is directly affected by A. angiotensin II B. ADH C. aldostesrone D. ANP

C ANP causes the kidneys to excrete more water through excretion of Na. ADH increases the permeability of water along the apical membrane of the collecting ducts by activating aquaporin-2 channels. The presence of Angiotensin II will cause the release of aldosterone. It is aldosterone which can cause Na and Cl reabsorption in the DCT and CD of the kidneys.

Which of the following will increase ADH stimulation? A. intake of 10 bottles of beer B. intake of food rich in salt C. intake of 2 liters of water before ultrasound

Which of the following is true? A. ADH1 affects intercalated cells of the proximal tubule. B. ADH attached to the apical membrane receptors leads to CAMP activation, leading to the formation of water channels C. Aquaporin-2 water channels insert into the apical membrane of the collecting duct, which render the segment water permeable D. AOTA

C ADH, once secreted by the posterior pituitary, enters the bloodstream and gets transported to the kidneys, where it increases the permeability of the distal tubules, cortical collecting tubules and medullary collecting ducts to water. ADH binds with specific receptors, with increases the formation of CAMP and protein kinases. These, in turn, causes Aquaporin-2 to move towards the luminal side of the cell membranes, fusing with it to form water channels that facilitate rapid movement of water through diffusion. Answer is C, since ADH only affects the distal tubules and collecting ducts and it requires both CAMP and protein kinases to stimulate movement of Aquaporin-2 water channels. (Guyton)

Release of renin by granular cells of d JGA is stimulated by: A. increase ECF volume B. increase sympathetic activity C. increase stretch of afferent arteriole D. increase NA and Cl sensed by macula densa

B Renin secretion is stimulated by 1) perfusion pressure 2) sympathetic activity 3) NaCl delivery to macula densa.

``` Site of local RAA system? A. Brain B. Adrenal gland C. Vascular endothelium D. Aorta ```

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In the collecting tubule A. Entry of K+ into the cell across the basolateral membrane occurs via Na+-K+ ATPase. B. Secretion of K+ into tubular lumen in intercalated cells. C. K+ movement across apical membrane is via Na+-K+ antiport. D. Secretion of K+ occurs against an electrochemical gradient.

Which is an abnormal finding in urinalysis? a. specific gravity of 1.020 b. protein c. amorphous crystal d. pH 6.0

Magnesium is involved in many biochemical processes in the body. What are the sites of Mg2+ reabsorption? A. PT & Thick Ascending Limb B. Thick & Thin Loop C. CD & PT D. PCT & DT

Which of the following is NOT a necessary component of the countercurrent mechanism? A. Straight segment of the proximal tubule B. Loop of Henle C. Vasa recta D. Collecting tubule

Characteristics of the renal medullary interstitium: A. Osmolarity is highest at the junction of the cortex and medulla B. Medullary osmolarity is contributed to by both NaCl & urea C. Decreased medullary blood flow decreases medullary osmolarity D. All of the above

What happens to the small amount of albumin that is filtered into the tubular lumen a. It is excreted unchanged b. It is reabsorbed via channels in the proximal tubule and is reterurned to systemic circulation via peritubular capillaries c. It is taken up via endocytosis and is broken down by lysozyme inside the cell. Amino acids are then reabsorbed d. Filtered proteinases break down albumin in the lumen, amino acids are reabsorbed.

Which of the following is false a. Fluid in int. contains hyperosmotic NaCl b. H2O reabsorbed in last segment of DCT c. Urea enters DLH at slower rate than efflux of NaCl d. Osmotically abstracts H2O from ALH

. Major ICF cation a. Na+ b. K+ c. H+ d. Ca2+

The glucose plasma concentration at which urine starts testing positive for glucose a. Tm b. Renal threshold for glucose c. Absorptive threshold d. Splay

In the renal medulla, to maintain osmotic gradient, which of the following is true? A. the descending loop of Henle is selectively permeable to water B. counter current flow of the urine is opposite the renal blood flow C. only 20% of renal blood flow through medulla D. the thick ascending limb of loop of Henle actively transports salt and water E. all of the above

Which of the following is true for the collecting duct? A. There are 2 cell types: principal cell and dark staining intercalated cell. B. It is lined mostly by intercalated cells that regulate sodium reabsorption. C. It has aquaporin 3 responsible for urea reabsorption due to solvent drag. D. It is affected by SIADH, which presents inappropriately low vasopressin levels, causing water retention.

80 year old woman found in her bed unconscious with an empty bottle of salicylic acid on the nearby table. Obviously a victim of accidental salicylate poisoning, she was brought to the ER. If you were the intern who initially saw the victim, you would treat her with sodium bicarbonate Your objective in doing the above intervention is to A. increase the amount of salicylic acid (ASA) which is lipid soluble B. increase the amount of the anionic form (ASA-) of salicylic acid

What differentiates the distal tubule from the proximal convoluted tubule? A. presence of Na-K ATPase pump at the basolateral membrane B. Ca reabsorption at this site is enhanced by the the parathyroid hormone C. reabsorbed Na diffuses to the peritubular capillaries D. presence of brush border at the luminal side

Water reabsorption from interstitial space to peritubular capillaries is by A. interstitial hydrostatic pressure B. interstitial oncotic pressure C. peritubular capillary hydrostatic pressure D. peritubular oncotic pressure

``` In the absence of ADH, at the same level of the medulla, which has more concentrated tubular fluid? A. descending loop of henle B. ascending loop of henle C. medullary interstitium D. collecting tubule ```

``` Which of the following will stimulate renin release? A. aldosterone B. antidiuretic hormone C. increased salt intake D. increased sympathetic activity ```

In kidney failure, edema is secondary to A. Increased capillary hydrostatic pressure B. Decreased plasma oncotic pressure C. Increased capillary permeability D. Lymphatic obstruction

Reabsorption of water in the proximal entrain the absorption of especially which solutes by solvent drag_

K and Ca

Which ion primarily influences reabsorption in the proximal tubule?

Proteins are taken in the proximal tubule cells by which process?

Endocytosis

What is mostly absorbed in the thin descending limb?

Water

NaCl reabsorption in the thin ascending limb happens via which mechanism?

Passive absorption

Solute reabsoprtion in the thick ascending limb is linked to which protein transporter?

Na-K ATPase

Na-K ATPase maintains (high/low) intracellular Na which provides favorable chemical gradient for the movement of Na from tubular fluid into the cell.

Low

The 1Na-1K-2Cl is found in which part of the loop of Henle?

Thick ascending limb

Tubular fluid in the thick ascending limb is more (negative/positive) than blood.

Positive

Increased NaCl transport by the thick ascending limb (increases/decreases) the magnitude of positive voltage in the lumen.

Increases

Which is known as the "diluting segment" of the loop of Henle?

The ascending limb

The last segment of the distal tubule has which two types of cells?

Intercalated cells and principal cells

Which distal tubule cells reabsorb NaCl, water and secrete K?

Principal cells

Which distal tubule cells reabsorb K via an H-K-ATPase?

Intercalated cells

Which distal tubule cells secrete H or HCO3?

Intercalated cells

Reabsorption of Na and K in principal cells both depend on which transport portein?

Na-K-ATPase

Reabsorption of Na generates a (positive/negative) luminal voltage across the late distal tubule and collecting duct for the reabsorption of which ion?

Which part of the distal tubule is permeable to water?

Late distal and the collecting duct

Which aquaporins are present in the apical membrane of late distal tubule cells?

AQP2

Which aquaporins are present in the basolateral membrane of the late distal tubule cells?

AQP3 and AQP4

Which hormone does the distal tubule need to absorb a vast amount of water?

ADH

K is secreted by the principal cell via which two steps?

1. K enters the principal cell via the Na-K ATPase in the basolateral membrane. 2. K diffuses down its concentration gradient through the K channels in the apical membrane.

``` All are functions of the kidney except A. Excretion of metabolic wastes B. Synthesis of glucose using amino acids during fasting C. Regulation of electrolyte balance D. Secretion of ADH ```

In the proximal convuluted tubule, penicillin is a. Actively secreted into tubule b. Actively reabsorbed from tubule c. Passively reabsorbed from tubule d. Metabolized by tubule cells

Ammonia excreted in urine comes mainly from the metabolism of: a. Glycine b. Glutamine c. Leucine d. Alanine

Protein X, a cationic molecule, has a MW of 86,000 daltons. You expect Protein X to be A. present in urine B. reabsorbed in the proximal tubule C. repelled by the capillary endothelium D. blocked by the glomerular filtration membrane

Which is not characteristic of proximal tubule cell? A. simple cuboidal B. clear cytoplasm C. brush borders D. basolateral interdigitations

You want to enhance the excretion of inulin. Which of the following will you give? A. concentration albumin B. loop diuretic C. low dose angiotensin D. dextran

79. Order from lowest to highest the plasma clearance of the following substances. (Na+, glucose, inulin, creatinine) A.glucose, Na+, inulin, creatinine B. Na+, glucose, creatinine, inulin C. inulin, Na+, glucose, creatinine D. Na+, inulin, creatinine, glucose

80. Which of the following provides the driving force for solute transport along nephron segments of the kidney? A. the basolateral Na+-K+-ATPase pump B. the apical Na+K+2Cl- carrier C. the basolateral GLUT2 transporter D. the apical Na+-H+ antiporter

81. Along the entire length of the proximal tubule, the TF/P ratio is lowest for A. chloride B. glucose C. sodium D. phosphate

82. Sodium is reabsorbed in the apical membrane of the proximal tubule cotransported with all of the following except A. glucose B. amino acids C. phosphate D. hydrogen

Water reabsorption in the proximal tubule A. occurs exclusively via the tight junctions B. is driven by the transtubular osmotic gradient created by solute reabsorption C. is independent of solute reabsorption D. is ADH independent

Which is true with regard to glucose reabsorption in the kidney? A. occurs by facilitated diffusion across the apical membrane of the proximal tubule B. basolateral transport is sodium dependent C. renal threshold is the plasma glucose concentration at which glucose will start to appear in the urine D. involves high affinity low capacity carriers in the S1 and S2 segment

Which is true of the NaK2Cl cotransporter? A. inhibited by furosemide B. mutations cause classic Barter's syndrome C. affinity for sodium and potassium is very high D. all of the above

Gary, 24 year old male weighing 60 kgs. Was referred to you for clearance prior to overseas employment. He was noted to be hypertensive, slightly pale with proteinuria by dipstick method and sulphosalicylic method. Creatinine was 4.0 mg. 24 hour urine collection showed a urine volume of 1000 ml, protein of 4.5 gms. And urine creatinine of 120 mg/dl. How would you check for the adequacy of urine collection? A. urine output should be greater than 1000 ml in 24 hours B. Gary should have a 24 hour creatinine excretion of at least 1200 mg C. The protein-creatinine ratio should be greater than 2 D. All of the above findings should be present.

Gary, 24 year old male weighing 60 kgs. Was referred to you for clearance prior to overseas employment. He was noted to be hypertensive, slightly pale with proteinuria by dipstick method and sulphosalicylic method. Creatinine was 4.0 mg. 24 hour urine collection showed a urine volume of 1000 ml, protein of 4.5 gms. And urine creatinine of 120 mg/dl. The computed creatinine clearance of Gary by 24 hour urine collection is A. 10 ml/min B. 20 ml/min C. 30 ml/min D. 40 ml/min

Gary, 24 year old male weighing 60 kgs. Was referred to you for clearance prior to overseas employment. He was noted to be hypertensive, slightly pale with proteinuria by dipstick method and sulphosalicylic method. Creatinine was 4.0 mg. 24 hour urine collection showed a urine volume of 1000 ml, protein of 4.5 gms. And urine creatinine of 120 mg/dl. If Maria, a 30 year old, weighing 60kgs has the same laboratory results as Gary's, what will be creatinine clearance by Cockroft and Gault? A. 15 ml/min B. 20 C. 25 D. 35

The following are components of urinary acidification. Identify the sites where these processes are observed. Na+ movement out of the cell via the Na+ K+ ATPase A. for proximal tubule B. for distal tubule C. for both D. for neither

The following are components of urinary acidification. Identify the sites where these processes are observed. Na+ H+ exchange A. for proximal tubule B. for distal tubule C. for both D. for neither Na+ H+ exchange

The following are components of urinary acidification. Identify the sites where these processes are observed. Na+ entry through channels A. for proximal tubule B. for distal tubule C. for both D. for neither

The following are components of urinary acidification. Identify the sites where these processes are observed. Aldosterone mediated processes A. for proximal tubule B. for distal tubule C. for both D. for neither

The following are components of urinary acidification. Identify the sites where these processes are observed. HCO3+ Cl- exchanger A. for proximal tubule B. for distal tubule C. for both D. for neither

``` transport of sodium facilitated by aldosterone A. proximal tubular cell B. loop of Henle C. distal tubular cell D. collecting duct cell ```

ADH dependent water reabsorption A. proximal tubular cell B. loop of Henle C. distal tubular cell D. collecting duct cell

glucose reabsorption A. proximal tubular cell B. loop of Henle C. distal tubular cell D. collecting duct cell

diffusion of water A. proximal tubular cell B. loop of Henle C. distal tubular cell D. collecting duct cell

Match the nephron segment with a function it is closely associated with. countercurrent exchanger ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Match the nephron segment with a function it is closely associated with. site of organic anion and cation secretion ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Match the nephron segment with a function it is closely associated with. reabsorbs 60 to 70% of filtered NaCl and water ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Match the nephron segment with a function it is closely associated with. site of final urine osmolality modification ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Match the nephron segment with a function it is closely associated with. site of NaK2Cl transport ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Match the nephron segment with a function it is closely associated with. reabsorbs 15%of filtered water ``` A. proximal tubule B. descending limb of loop of Henle C. ascending limb of loop of Henle D. vasa recta E. collecting tubule ```

Renal tubules, Reabsorption and Secretion Flashcards

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