Seclective reabsorption Flashcards
Selective reabsorption
Re absorption of glucose amino acids ions water and vitamins from the filtrate in the nephron back into the blood plasma
where does selective reabsorption occur
proximal convoluted tubule
Regarding need for energy, how can selective reabsorption be described for glucose and amino acids
Indirectly active
Adaptations of PCT cells for selective reabsorption 5
Micro villi
Basal channels
Surplus mitochondria
Peritubular capillaries close to PCT cells
Tight junctions between PCT cells
advantage of microvilli?
Increase SA= numerous carrier proteins embedded in mem
Basal channels and advantages
Invaginationns in surface facing capillaries = increase SA
Advantage of tight junctions between cells
Mean molecules must pass through cells to enter blood, provides control
Explain the proces of indirect active transport of glucose and amino acids
Na+ actively transported out of cell and K+ in via K/Na pump
Creates conc grad of Na+ ( higher in filtrate than in cell)
Na+ move into cell via facilitated diffusion but only when coupled with glucose molecules
Channel protein allows glucose to pass from cell to blood down conc gradvai facilitated diff
How does water re enter the blood and %
Freely via osmosis bc departure of ions and glucose from filtrate increases water potential above that of the blood
90% reabsorbed
How does urea re enter blood and %
50% reabsorbed
Via diffusion bc conc in filtrate is greater than in blood
How do creatine and uric acid move
Actively secreted into lumen of PCT
% of glucose reabsorbed normal and if not?
100% normally unless there was a very high con of glucose in the blood originally.
So may not have been enough transport molecules to reabsorbed it all
Indicative of diabetes
How can the filtrate be described compared to the blood at the base (end ) of the PCT
isotonic
% of ions reabsorbed and how
70% via active transport
What type of epithelial cells are PCT cells
Simple cuboidal
