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