Muscular System: Tubular Reabsorption and Secretion
1. REABSORPTION is the movement of water and valuable solutes from the filtrate in the renal
tubules into the blood. In which part of the renal tubule does this take place? In which part
of the renal tubules do most of it take place?
2. SECRETION is the movement of selected solutes from the blood of the peritubular capillaries
into the renal tubule for excretion.
3. What is the purpose of reabsorption in the kidney tubule?
THE PURPOSE OF REABSORPTION IS TO ALLOW THE BODY TO RECLAIM WATER
AND VALUABLE SOLUTES (GLUCOSE, AMINO ACIDS, IONS ETC.) FROM THE FILTRATE
AND KEEP THEM FROM BEING EXCRETED.
4. Name 2 pathways whereby water and solutes can be reabsorbed from the lumen of the renal
tubule to the blood of the peritubular capillaries. Which pathway is the most commonly used?
A. TRANSCELLULAR PATHWAY - MOST COMMONLY USED
B. PARACELLULAR PATHWAY
5. How does the Na-K pump affect the reabsorption of sodium and water in the renal tubule?
THE Na-K PUMP ACTIVELY TRANSPORT SODIUM FROM THE LUMEN OF THE RENAL
TUBULE TRANSCELLULARLY INTO THE INTERSTITIAL FLUID. THIS INCREASES THE
OSMOLARITY OF THE INTERSTITIAL FLUID AND DRAWS WATER FROM THE RENAL
TUBULE INTO THE INTERSTITIAL FLUID BY OSMOSIS. THE BULK FLOW OF THE WATER
SWEEPS SODIUM AND OTHER SOLUTES INTO THE PERITUBULAR CAPILLARIES.
6. Consuming a salty meal would increase/decrease water reabsorption from the filtrate.
INCREASE
7. How does sodium reabsorption by the proximal tubule drive the reabsorption of other solutes
such as glucose?
THE Na-K PUMP ACTIVELY TRANSPORTS SODIUM FROM THE TUBULAR CELL INTO
THE INTERSTITIAL FLUID. THIS LOWERS THE CONCENTRATION OF SODIUM IN THE
TUBULAR CELL AND CAUSES ADDITIONAL SODIUM TO USE FACILITATED DIFFUSION TO
MOVE INTO THE TUBULAR CELL FROM THE FILTRATE.
8. Explain the concept of transport maximum in your own words.
1. REABSORPTION is the movement of water and valuable solutes from the filtrate in the renal
tubules into the blood. In which part of the renal tubule does this take place? In which part
of the renal tubules do most of it take place?
2. SECRETION is the movement of selected solutes from the blood of the peritubular capillaries
into the renal tubule for excretion.
3. What is the purpose of reabsorption in the kidney tubule?
THE PURPOSE OF REABSORPTION IS TO ALLOW THE BODY TO RECLAIM WATER
AND VALUABLE SOLUTES (GLUCOSE, AMINO ACIDS, IONS ETC.) FROM THE FILTRATE
AND KEEP THEM FROM BEING EXCRETED.
4. Name 2 pathways whereby water and solutes can be reabsorbed from the lumen of the renal
tubule to the blood of the peritubular capillaries. Which pathway is the most commonly used?
A. TRANSCELLULAR PATHWAY - MOST COMMONLY USED
B. PARACELLULAR PATHWAY
5. How does the Na-K pump affect the reabsorption of sodium and water in the renal tubule?
THE Na-K PUMP ACTIVELY TRANSPORT SODIUM FROM THE LUMEN OF THE RENAL
TUBULE TRANSCELLULARLY INTO THE INTERSTITIAL FLUID. THIS INCREASES THE
OSMOLARITY OF THE INTERSTITIAL FLUID AND DRAWS WATER FROM THE RENAL
TUBULE INTO THE INTERSTITIAL FLUID BY OSMOSIS. THE BULK FLOW OF THE WATER
SWEEPS SODIUM AND OTHER SOLUTES INTO THE PERITUBULAR CAPILLARIES.
6. Consuming a salty meal would increase/decrease water reabsorption from the filtrate.
INCREASE
7. How does sodium reabsorption by the proximal tubule drive the reabsorption of other solutes
such as glucose?
THE Na-K PUMP ACTIVELY TRANSPORTS SODIUM FROM THE TUBULAR CELL INTO
THE INTERSTITIAL FLUID. THIS LOWERS THE CONCENTRATION OF SODIUM IN THE
TUBULAR CELL AND CAUSES ADDITIONAL SODIUM TO USE FACILITATED DIFFUSION TO
MOVE INTO THE TUBULAR CELL FROM THE FILTRATE.
8. Explain the concept of transport maximum in your own words.
