Physiology 4 and 5 Flashcards
What is the major site of reabsorption in the kidney?
proximal tubule
What osmolality does the fluid reabsorbed in the proximal tubule have?
iso-osmotic with filtrate
What is reabsorbed in the proximal tubule?
sugars; amino acids; phosphate; sulphate; lactate
What primary active transport?
ATP dependent
What is secondary active transport?
carrier molecule is transported coupled to a conc. grad of an ion
What is facilitated diffusion?
passive carrier-mediate transport of a substance down its conc. grad.
What transport mechanism is essential for sodium reabsorption?
Na/K ATPase at hte basolateral membrane
What are amino acids and glucose tranported with?
sodium- secondary active transport
What other substance does couple with in a transport?
hydrogen- but the other way- countertransport
What ion does the high conc. of sodium in the interstitial fluid attract?
chloride
what does NaCl pull down an osmotic gradient into the interstitial fluid?
water
What pulls the water into the blood?
oncotic drag of peritubular plasma (plasma proteins)
What is Tm?
transport maximum- transport systems involved in reabsorption and secretion are saturable
What is the function of the loop of Henle?
generates a cortico-medullar solute concentration gradient to enable the formation of hypertonic urine
What is the opposing flow in the 2 limbs of the loop called?
countercurrent flow
What happens in the ascending limb?
sodium and chloride are being reabsorbed, realtively impermeable to water
What happens in the descending limb?
does not reabsorb NaCl and is highly permeable to water
Waht is the tranporter found inthe ascending loop of Henle?
sodium/potassium/chloride co-transporter
What is the difference in solute between the descending limb and ascending limb?
descending-loses water so osmolality increases; ascending limb loses ions so osmolality decreases
What is concurrent mulitplication?
where a steady state has been reached where the water passively flowing down the osmotic gradient in response to solute pumped out of ascending limb
What type of fluid is found entering the distal convoluted tubule?
hypoosmotic fluid
What otehr substance contributes to medullar osmolality?
urea
What is the purpose of countercurrent mulitplication?
to enable kidney to produce urine of different bolume and concentration according to the amounts of ADH
What runs along side the long loop of Henle of juxtaglomedullary nephorns?
vasa recta
