Module 5.8: Sodium-Dependent Reabsorption of Other Solutes Flashcards
The reabsorption of _____\_is important for the reabsorption of numerous other solutes, both by _____\_ and _____\_ mechanisms.
The reabsorption of sodium (Na+) is important for the reabsorption of numerous other solutes, both by active and passive mechanisms.
Provide an example of an active mechanism in which Sodium Reabsorption is used for the reabsorption of other solute?
Protein-mediated transport of solute coupled to the movement of Na+ down its electrochemical gradient
- Under normal conditions, how much glucose is reabsorbed?
- Where does reabsorption occur in the nephron?
Fill in the blanks for how glucose is reabsorbed:
- _______dependent secondary active transport proteins provide the mechanism for the reabsorption of glucose.
- In the apical membrane,______________\_concentrate glucose inside the _____ ____\_ cells, using the _________\_gradient, and then glucose moves across the basolateral membrane, using a ___________________\_.
- In the proximal tubule Na+-dependent secondary active transport proteins provide the mechanism for the reabsorption of glucose.
- Normally, all of the glucose that is filtered is reabsorbed and no glucose is excreted in the urine.
- _Na+-_dependent secondary active transport proteins provide the mechanism for the reabsorption of glucose.
- In the apical membrane, Na+-glucose transport proteins concentrate glucose inside the tubule epithelial cells, using the Na+ electrochemical gradient, and then glucose moves across the basolateral membrane, using a facilitated diffusion carrier protein.
Explain the image of Glucose reabsorption:
Glucose is transported across the apical membrane of ________\_by cotransport with _____\_ through a ______________ ______\_.
Glucose then moves across the ______\_membrane of tubule epithelial cells using a _______ ____________________\_.
Explain the image of Glucose reabsorption:
Glucose is transported across the apical membrane of tubule epithelial cells by cotransport with sodium (Na+) through a secondary active transport protein.
Glucose then moves across the basolateral membrane of tubule epithelial cells using a facilitated diffusion carrier protein.
Glucose, like any other permeant transported by a transport protein, has a ______________\_
Glucose, like any other permeant transported by a transport protein, has a maximum rate of transport.
The transport maximum is achieved when _____________________ ____________________\_.
The transport maximum is achieved when the transport proteins are saturated and operating at their maximum speed.
The concentration of glucose (in the filtrate) that causes the transport maximum to be reached is called the _______, concentrations above which glucose will be excreted in the urine
The concentration of glucose (in the filtrate) that causes the transport maximum to be reached is called the renal threshold concentrations above which glucose will be excreted in the urine
Define Renal Threshold
the concentration level up to which a substance (as glucose) in the blood is prevented from passing through the kidneys into the urine
Max concentration of a substance can be reabsorbed - once reached the substance is removed in the urine
The diagram outlines the renal handling of glucose:
Glucose filtration, reabsorption, and excretion in urine are graphed as a function of plasma glucose concentration. The excretion rate is calculated as the _____________________. The GFR used is 125 mL/min.
The diagram outlines the renal handling of glucose:
Glucose filtration, reabsorption, and excretion in urine are graphed as a function of plasma glucose concentration. The excretion rate is calculated as the difference between the filtration and reabsorption rates. The GFR used is 125 mL/min.
Why doesn’t Na+ have a transport maximum?
Because when all of the carriers are saturated, Aldosterone just stimulates the synthesis of more Na+K+ pumps
How is Na+ reabsorption linked to Chloride (Cl-) reabsorption?
Unlike most solutes, Cl- is reabsorbed by moving through the _____ __\_of the ___________\_
The active transport of Na+ creates an electrochemical gradient down which Cl- passively moves
Unlike most solutes, Cl- is reabsorbed by moving through the tight junctions of the proximal tubules
How is the active reabsorption of Na+ linked to the reabsorption of water?
Water is reabsorbed _____\_down its _____\_ gradient, which is primarily established by the active transport of Na+ and the accompanying solutes.
Water flows through _____\_ (water channels) in the epithelial cell membranes.
Approximately 80% of the water is reabsorbed in the ______ _____\_in an _____\_ manner, and the remainder (approximately 20%) is reabsorbed by _____\_mechanisms in the ______ _____\_.
Water is reabsorbed passively down its osmotic gradient, which is primarily established by the active transport of Na+ and the accompanying solutes.
Water flows through aquaporins (water channels) in the epithelial cell membranes.
Approximately 80% of the water is reabsorbed in the proximal tubules in an unregulated manner, and the remainder (approximately 20%) is reabsorbed by regulated mechanisms in the collecting ducts.
In the proximal tubule, the reabsorption of water establishes a concentration gradient favouring the reabsorption of ____\_.
In the proximal tubule, the reabsorption of water establishes a concentration gradient favouring the reabsorption of urea.
Urea ________\_across the epithelial cell membrane, but due to limited permeability, only about ___% of the urea is actually reabsorbed, with the remainder being _____\_.
Urea freely diffuses across the epithelial cell membrane, but due to limited permeability, only about 50% of the urea is actually reabsorbed, with the remainder being excreted.
Explain the image: Reabsorption of chloride (Cl-), water (H2O), and urea:
(1) Chloride (Cl-) is reabsorbed by moving through tight junctions linking the _______\_.
(2) Water (H2O) is reabsorbed _______\_through _______\_ down its _______\_gradient, which exists primarily due to the active transport of _______\_ and _______\_.
(3) Urea is reabsorbed _______\_by _______\_ across the tubule epithelial cell membrane.
(1) Chloride (Cl-) is reabsorbed by moving through tight junctions linking the proximal tubules.
(2) Water (H2O) is reabsorbed passively through aquaporins down its osmotic gradient, which exists primarily due to the active transport of sodium (Na+) and solutes.
(3) Urea is reabsorbed passively by diffusion across the tubule epithelial cell membrane.
