Tubular Transport of NaCl and Water Flashcards
Carnivore urine is more _________ than herbivore urine.
acidic
Normal GFR is ___________.
125 ml/min
What four parts of homeostasis does the kidney control?
pH
Electrolytes
Osmolarity
Fluid volume
The tubules are lined with polarized cells. Which side is the apical surface facing?
The lumen
Differentiate transcellular and paracellular transport.
Transcellular means passing through the cell–that is, through both the apical and basolateral membranes–and paracellular means passing between cells.
The kidney is second only to the ________ in terms of oxygen needed per gram of tissue.
heart
Which side of the tubular epithelium is the Na/K pump on?
The basolateral
The sodium-potassium pump drives the gradient into the cells, which pulls ____________ along co-transporters.
chloride ions, glucose, and amino acids
In what section of the tubule are glucose and amino acids resorbed?
100% in the proximal convoluted tubule for both
The proximal convoluted tubule is responsible for ____________.
bulk resorption of water, ions, and macromolecules
What acid-base functions take place in the proximal convoluted tubule?
H+ secretion and HCO3- absorption
The ____________ is impermeable to water.
thick ascending loop of Henle
The thick ascending loop of Henle ________ the urine.
dilutes, by absorbing Na, K, and Cl in a lumen that is impermeable to water; also, Mg and Ca get pulled along in paracellular transport
Where do thiazides work?
The distal convoluted tubule
In what section of the tubule are magnesium and calcium reabsorbed?
The distal convoluted tubule and the thick ascending limb
What force drives re-entry of ions into the peritubular capillaries?
Oncotic pressure of the interstitial area (where the tubules send material) drives ions and fluid into the capillaries.
Why is the peritubular capillary oncotic pressure so high?
Because the large proteins and cells remain unfiltered, so the blood is relatively concentrated
How much sodium is filtered and reabsorbed by the kidneys each day?
1,500 g
What three properties does the collecting duct fine tune?
Potassium
Water
Acid/base balance
Organic anions are secreted in the ____________.
proximal tubule
The collecting duct has two types of cells. What are they and what do they do?
Principal cells: secrete K and reabsorb Na; fine tune water
Intercalated cells: acid/base balance
What cells does vasopressin act on?
Principal
What does vasopressin do?
It stimulates the release of aquaporins in principal cells of the collecting duct, thereby inducing reabsorption of water.
Regardless of filtered load, the proximal tubule still absorbs ___________.
65% of the NaCl and water
Macula densa cells are part of the ____________.
ascending limb of the loop of Henle
The macula densa cells secrete paracrine signals in response to __________.
changes in distal-tubule flow; with decreased NaCl they stimulate renin release (from JGA) that induces efferent-arteriole vasoonstriction
