physiology -2 Flashcards
what are the substances that are reabsorbed in the PT?
Sugars Amino acids Phosphate Sulphate Lactate
what are the substances that are secreted in the PT?
H+ Hippurates Neurotransmitters Bile pigments Uric acid Drugs Toxins
steps the constituency (transcellular) tubular reabsorption?
the the peritubular capillary where substances are reabsorbed
there are barriers across which substances cross and eventually make their way into he blood
- must get across apical/lumenal membrane
- cytoplasma
- basolateral membranes
- interstitial fluid
- capillary wall endothelia
tight junctions
substances that can cross via the tight junctions can cause paracellular transport - some substances tighter than others and some are leakier than others
what is more specific reabsorption or filtration?
reabsorption
primary active transport?
Energy is directly required to operate the carrier and move the substrate against its concentration gradient
secondary active transport?
The carrier molecule is transported coupled to the concentration gradient of an ion (usually Na+)
more sodium outside cells than inside cells, they bring sodium ion inside cell and move other substance sometimes in the same direction or the opposite direction
symporters and antiporters
facilitated diffusion?
Passive carrier-mediated transport of a substance down its concentration gradient
function of the loop of henle?
Generates a cortico-medullary solute concentration gradient
This enables the formation of hypertonic urine
concentrated urine means more reabsorption of water into the blood
what is countercurrent flow?
Opposing flow in the two limbs is termed countercurrent flow
what functions as the countercurrent multiplier?
the entire fluid
what have the most longer loops of henle?
the juxtamedullary nephrons, that means the loops of henle are exposed to a greater range of corticomedullary fluid
together the loops and vasa recta establish?
a hyper-osmotic medullary interstitial fluid
what is the function of the ascending limb?
Along the entire length of the ascending limb Na+ & Cl- are being reabsorbed
(Thick [upper] AL this is achieved by active transport, in the thin [lower] AL this is passive)
The ascending limb is relatively impermeable to water
Little or no water follows salt reabsorption
what are the functions of the descending limb?
This segment does not reabsorb NaCl and is highly permeable to water
