Renal tubules, Reabsorption and Secretion Flashcards
The proximal tubule cells have: cilia, microvilli, stereocillia?
Microvilli
Which two major proteins are responsible for the proximal tubules’ reabsorption of 65% of the ultrafiltrate?
Na/K-ATPase pumps and AQP-1
The NA/K-ATPase pump reabsorbs which component of the ultrafiltrate?
Na
Active transport of Na is followed by passive transport of which ion to maintain electrochemical neutrality?
Cl
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
Which protein channel allows water to leave the proximal tubule?
AQP-1
Amino acid and glucose transport out of the proximal convoluted tubule depends on the active transport of which ion?
Na
In the first half of the proximal tubule, Na is reabsorbed primarily with which molecule?
Bicarbonate
In the second half of the proximal tubule, Na is reabsorbed with which ion?
Cl
Any Na that enters the cells across the apical membrane leaves the cell and enters the blood via which transport protein?
Na-K ATPase
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
In the first part of the proximal tubule, which is reabsorbed more: Cl or water?
Water
Reabsorption of NaHCO3 in the first part of the proximal tubule establishes a transtubular osmotic gradient for the passive reabsorption of which substance?
Water
Na and Cl are absorbed via both paracellular pathway and transcellular pathway in which part of the proximal tubule: first or second part?
Second
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
In the second part of the proximal tubule, Cl is reabsorbed across the basolateral membrane via which transporter?
K-Cl symporter
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.
A drug that inhibits Na+ reabsorption results to lower \_\_\_\_\_\_\_\_\_\_ reabsorption. A. Amino acid B. H+ C. Creatinine D. Organic acid or base
A
AAs are cotransported with sodium. Organic acids and bases are secreted. Creatinine is not reabsorbed. Hydrogen ion is secreted via an antiport mechanism.
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
C
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.
95% of the molecules is reabsorbed in the proximal tubule except: A. bicarbonate B. sodium C. urea D. water
C
Urea is only 50% reabsorbed in the PCT.
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.
A
Where are drugs and foreign substances such as creatinine secreted? A. Proximal tubule B. Loop of Henle C. Distal tubule D. collecting duct
A
Most drugs and foreign substance are secreted along the proximal convoluted tubule.
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
C
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
C
The Brush Border Microvilli in the apical membrane is a distinct characteristic of: A. glomerulus B. bowman's capsule C. PCT D. DCT
C
Proximal tubule
a. N-K 2 cl transporter
b. facilitated diffusion for glucose reabsorption
c. Na-H antiport
d. Basolateral Na-K Antiport
C
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
D
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
C
These control mechanisms are activated seconds after change in blood pressure except
A. RAAS B. baroreceptor C. chemoreceptor D. CNS ischemic response
A
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
B
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
A
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
B
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
)
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.
A
Which is an abnormal finding in urinalysis?
a. specific gravity of 1.020
b. protein
c. amorphous crystal
d. pH 6.0
B
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
A
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
A