Renal Tubular Transport Mechanism I Flashcards
What do juxtaglomerular (granular) cells do?
Synthesize store and secrete renin
What activates granular cells?
Macula densa
Stretch receptors in the vascular walls
How are podocytes connected?
Interdigitating processes that cover the basement membrane
What are found between Interdigitating processes?
Filtration slits
What connect filtration slits?
The slit diaphragm
Three layers of the glomerular basement membrane:
Lamina rara interna
Lamina densa
Lamina rara externa
What is the role of Neph 1 and Neph 2?
Anchors the podocytes to the glomerular basement membrane
What do macula densa do?
Chemoreceptors sensing NaCl concentrations in the proximal convoluted tubule
What proteins prevent large proteins from exiting the afferent arteriole?
Nephrin
Podocin
CD2AP
What is the molecular weight cut-off for filtration?
40kD MW
PCT three sections:
S1: proximal
S2: middle
S3: distal
What do S1 cells have?
Brush border cells for reabsorption of most nutrients
S3 cell morphology:
Loss of the brush border
What is the charge in the tubule lumen in S1 to S3?
S1: negative
S3: positive
Why does the PCT lumen change in charge?
The Na+/K+ are pulled out first making it go from +3 to -3 which then pushes the negative ions out to the blood
What is the paracellular route?
Between two cells in the tubule
Three cell types found in the distal nephron:
Connecting tubule cells
Intercalated cells
Principal cells
What do connecting tubule cells release?
Renal kallikrein
What do intercalated cells release?
Alpha-intercalated: secreted H+ and reabsorb K+
Beta-intercalated: secrete HCO3-
What do principal cells release?
Reabsorb Na+ and Cl-; secretes K+
What governs transport rates in the transcellular pathway?
Electrochemical gradients, ion channels, and transporters
What governs the transport rate of paracellular transport?
Electrochemical driving forces and permeability properties
What can occur to Na+ that are excreted via the transcellular pathway?
They can leak back through paracellularly due to the negative charge in the tubule lumen
