the min amount of water needed to excrete the normal metabolic by-products and maintain homeostasis
Because the medulla becomes more _______ the deeper you go, the juxtamedullary nephrons contribute more to creating _________ urine.
Function of the glomerulus.
sieve- water and dissolved solutes leave capillary and enter bowman's space
Function of the proximal tubule.
bulk reabsorption of Na+, Cl-, glucose, calsium, AAs, and water
Function of the descending thin limb of the loop of henle.
Function of the ascending thick limb of the loop of henle.
Function of the distal tubule.
diluting segment, fine-tunes acid-base balance and potassium balance
Function of the collecting duct.
final determination of urine concentration via aquaporins and ADH
Reabsorption that involves entering the tubular epithelial cell from the luminal side and then exiting via the basolateral side.
Reabsorption that involves solutes moving between the cells leaky tight junctions, such as in the proximal tubule.
Reabsorption is driven by...
energy-consuming pumps and electrochemical and conc gradients
Transcellular reabsorption requires...
a way to pass the cellular membrane (fat soluble, carrier protein)
Type of active transport directly coupled to an energy source, which is used to move solutes against their electrochemical gradient.
primary active transport
Type of active transport that uses the electrochemical gradient generated by primary active transport.
secondary active transport
Primary active transport of sodium via _________ decreases the _________ sodium content, creating a favorable gradient for sodium to move from _______ to _______; coupling sodium and ________ to a carrier molecule to carry the latter against its conc gradient is an example of secondary active transport.
Na+K+ATPase pump; intracellular; lumen; inside the cell; glucose
Type of passive transport in which molecules move down their conc gradient.
Type of passive transport that requires a carrier molecule for the molecule to pass down its electrochemical gradient.
Type of passive transport that involves the osmosis of water carrying small solutes with it.
osmosis and solvent drag
Pinocytosis is a form of ________; it occurs in the ________ to clear _______ that was not filtered at the glomerulus.
active transport; proximal tubule; protein
Substances that are __________ have a theoretical transport maximum.
reabsorbed via a carrier molecule
The limit to the rate at which a substance can be reabsorbed before all the nephrons start spilling it into the urine.
Low levels of a substance that may start to appear in the urine before the transport maximum is reached; due to the fact that some nephrons are not as efficient as others.
There is no transport maximum for substances that are __________.
passively reabsorbed without a carrier
For a substance that is passively reabsorbed without a carrier, no matter how high blood concs are,...
it will all be reabsorbed because it has no transport maximum.
The rate of transport for substances that are passively reabsorbed without a carrier is determined by... (3)
electrochemical gradient, permeability of the membrane, time the fluid is in the tubule
What two parts of the nephron have the highest metabolic activity? What is a possible repercussion of this?
proximal tubule and ascending thick limb of the loop of henle; prone to damage during ischemia
The Na+K+ATPase pump moves ________ out of the cell and ________ in the cell to create a relative ________ in the cell, allowing for its subsequent reabsorption.
3 Na+; 2K+; sodium deficit
The vast majority of sodium is reabsorbed to prevent _________.
The bulk of filtered sodium is reabsorbed in the _________ with ________ in the first half of the tubule and with ________ in the second half.
proximal tubule; glucose; chloride
Glucose is freely filtered at the __________; it is reabsorbed in the _________ via ___________ with sodium; it moves across the basolateral membrane back into the blood by _________.
glomerulus; proximal tubule; secondary active transport; facilitated diffusion
Glucose requires a __________ an therefore has a _________.
carrier molecule; transport maximum
Amino acids are reabsorbed in the ________ via ___________ coupled with ____________.
proximal tubule; secondary active transport; sodium reabsorption
Filtered urea is _________ reabsorbed in the ___________; as water is reabsorbed, urea conc increases, creating a favorable gradient for reabsorption; urea is also passively reabsorbed through ________ in the _____________ and ___________.