Renal Physiology Flashcards
What are the two capillary networks?
- Glomreular capillaries
2. Pertibular capillaries
What are the two important things about pertibular capillaries?
- Reside in the renal cortex, blood vessels that supply and drain those capillary networks
- Called the renal portal system, filter fluid out of the blood into the lumen of the nephron at the glomerular capillaries to reabsorb fluid from the tubule back into the blood at the particular capillaries
Where does the vasa recta leave?
The efferent arterioles and services the renal medulla
What is a nephron composed of? 2 things
- Glomerulus/renal corpusule (the filtering unit of the nephron)
- Renal tubule (the transport unit)
What are the 4 segments of the renal tubule?
Proximal tubule
Loop of henle
distal tubule
collecting duct
Define a superficial nephron
Proximal conulated tubule is in the outer part of the renal cortex and the loop of henle goes only a short way into the renal medulla
Define Juxtamedullary nephron
Proximal concluted tubule is close to the corticomedullary border and the loop of henle extends deep into the renal medulla
Vascular and nephron components in renal cortex/medulla
Renal artery branches to progressively form interloper arteries, which run between adjacent medullary pyramids, accurate arteries which run along the border between the cortex and medulla and the interlobular arteries, which extend towards the kidney surface through the cortex. small branches of the interlobular arteries rise to the afferent/efferent arterioles
Where does filtration happen?
From capillary lumen into the Bowman’s space
Where does reabsorption happen?
From the urine compartment (tubule lumen) into the interstitial compartment
Where does secretion happen?
From interstitual compartment into urine compartment (tubular lumen)
Where does the filtration barrier take place? What does it consist of?
In the renal corpsule
Consists of glomerular capillaries surrounded by Bowmans capsule. substances leaving the plasma must pass through 3 filtration barriers before entering the tubule lumen
What are the 3 filtration barriers?
- restarted capillary endothelium
- basement membrane
- Filtration slit
Define Starling force and what are the 2 types of forces
Determine either or not something is moved/filtered
The two types are FAVORING (pH) and OPPOSING (fluid)
Define net filtration pressure and what is the formula?
Equivalent to the force favoring filtration, the force opposed to filtration
pNET = PGC - (PBS+TGC)
Define paracellular
Pathway between cells, movement of solute and water across the tight junctions, passive event
Define transcellular
Pathway through cells, movement of solute and water across the apical and basolaeral cell membranes, active event
Define the transport maximum
Substrate concentrations equal or above the saturation point, transport occurs at a maximum rate
The transport rate at saturation is the transport maximum
It is a property of all carrier mediated transport
What are the transport mechanisms involved for sodium reabsorption in the proximal tube?
- 65% of filtered sodium is reabsorbed by the proximal tube
2. Sodium uptake
Sodium uptake is coupled to what 3 things?
- bicarbonate (via the Na-H exchanger)
- organic and nutrient solutes
- other electrocytes
Couples reabsorption to sodium reabsorption in the proximal tube
Sodium reabsorption sets up the osmotic gradient for water reabsorption across the proximal tubule epithelium-lumen to interstitial compartment
Elevated oncotic pressure in the particular capillaries draws water from the interstitial compartment into the capillary lumen
Oncotic pressure is a type of osmotic pressure excreted by proteins in blood vessels plasma
What is the starling force involved in the movement of sodium and water form the intersistal compartment to the capillary lumen
Significant increase in hydrostatic pressure and decrease in oncotic pressure therefore the net pressure does not favour reabsorption into the capillary lumen
Define oncotic pressure
Colloid pressure, pulls water into the circulatory system
What is the water INPUT per day?
700 mL food
300 mL metabolic
1500 mL of fluid intake
