Flashcards in Physiology 4 (easy) Deck (27)
How much urea is reabsorbed?
How much amino acid reabsorbed?
How much creatine reabsorbed?
Roughly how many mls filtered fluid is reabsorbed in the proximal tubule?
What is reabsorbed in the PT?
What is secreted in the PT?
What is primary active transport?
Energy is directly required to operate the carrier and move the substrate against its concentration gradient
What is secondary active transport?
The carrier molecule is transported coupled to the concentration gradient of an ion (usually Na+)
What is facilitated diffusion?
Passive carrier-mediated transport of a substance down its concentration gradient
Which transporter at basolateral membrane essential for Na+ reabsorption?
How is glucose reabsorbed?
Basoalteral: facilitated diffusion, and also in exchange for K+ (might be primary active transport)
Renal threshold for glucose reabsorption
(i.e. Tm (transport maximum))
(clearane of reabsorbed substance is not constant once Tm reached)
Percentage of all salt and water reabsorbed in the proximal tubule
Na+ reabsorption also drves reabsorption of what through the paracellular pathway?
Is the tubular fluid iso-osmotic when it leaves the proximal tubule?
Yes (i.e. 300mosmol/l)
Which part of the nephron is responsible for creating a cortico-medullary solute concentration gradient?
Loop of Henle
Is urine hypotonic or hypertonic?
Which part of the loop of henle reabsorbs Na+ and Cl-?
(thick - active transport
thin - passive)
This part of loop of henle does not reabsorb NaCl and is highly permeable to water
Is fluid entering the distal tubule iso-osmotic or hypo-osmotic?
Where is urea absorbed etc?
50% of urea diffuses passively into the loop of Henle
-distal tubule not permeable to urea
-Collecting ducts absorbs 50% urea
Effect of ADH on urea absorption?
ADH promotes urea absorption
What is the purpose of the countercurrent multiplier?
-Concentrates the medullary interstitial fluid and enable the kidney to produce urine of different volume and concentration according to the amounts of circulating antidiuretic hormone (ADH = vasopressin)
Vasa recta and the loop of henle
Blood osmolality rises as it dips down into the medulla (i.e. water loss, solute gained)
Blood osmolality falls as it rises back up into the cortex (i.e. water gained, solute lost)
Purpose of the vasa recta
Passive exchange across the endothelium preserves medullary gradient - blood equilibrates at each layer.
Ensures that the solute is not washed away
The high medullary osmolarity allows the production of hypertonic urine in the presence of