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R4
Basic Transport Mechanisms
14
Physiology
Professional
02/19/2013

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Cards

Term
What are the four types of transport processes?
Definition

1) primary active transport (ATP required, uphill)

2) secondary active transport (co-transporters required, uphill)

3) facilitated diffusion (protein shuttle required, downhill)

4) passive diffusion (permeability required, downhill)

Term
what does TM limited mean?
Definition
transport maximum limited = transport proteins become saturated
Term
what part of the kidney takes on water when you have edema?
Definition
the interstitium
Term
by what process are filtered proteins in the proximal tubule transported from the apical tubular epithelium to the basolateral endothelium on the blood side
Definition
receptor-mediated endocytosis (active process)
Term
what happens to protein load in the tubules with glomerular nephritis?
Definition
the glomerular membrane gets damaged and the protein load present in the proximal tubule is too great to be fully reabsorbed and the excess protein passes on to the urine
Term
what process of transcytosis helps the immune system prevent urinary tract infections?
Definition
immunoglobulins (proteins) are transported from the basolateral tubular endothelium (blood) to the apical epithelium (urine) [secretion]
Term
what is the molecular weight of albumin?
Definition
66kD
Term
how big of proteins can be filtered by the kidney?
Definition
up to 70kD
Term
what does "solvent drag" mean?
Definition
water is pushed into the capillary blood after a build up of hydrostatic pressure between the renal cells and it drags ions with it
Term
What does it mean that water is reabsorbed by isoosmotic reabsorption in the proximal tubule?
Definition
Water and salt stay together so the osmolality/oncotic pressure in the tubule does not change
Term
Where are tight junctions pretty loose in the nephron?
Definition
Proximal tubule
Term
Where are tight junctions very tight in the nephron?
Definition
Distal tubule
Term
What are the 4 steps involved in transporting solute and water from the tubular lumen to the peritubular capillary?
Definition
Step 1 – active extrusion of sodium into interstitium (Na/K ATPase) Step 2 – parallel transport of anions Step 3 – reabsorption of water (follows Na+ and anions) Step 4 – bulk flow of water and solute from interstitium into peritubular capillaries
Term
What two factors limit reabsorption rate?
Definition

-saturation status of transporters (Tm)

-gradient-limited systems

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