Renal Physio (Nephron/function) Flashcards
What are the functions of the nephron
1) filtration
- filter the blood
2) reabsorption
- molecules in the tubules being sent back to the blood
3) Secretion
- molecules from the blood being sent to the tubules
Anatomy of glomerulus and loop on henle
Where does filtration happen in the nephron?
- only occurs in the glomerulus
- fluid/molecules move from glomerulus into PCT -proteins don’t cross;too big
What is the glomerular filtration rate?
125 ml/min
What causes filtration in the nephron?
-hydrostatic pressure (blood pressure)
What determines the GFR?
- Filtration pressure
- filtration coefficient
What is autoregulation?
Maintenance of constant GFR within a wide range of blood pressure.
What is the myogenic response when MAP is high (autoregulation)?
-Causes GFR to temporarily increase > Vasoconstriction of afferent arteriole (to decrease blood flow to glomerulus) -increases resistance -decrease renal blood flow
What is the myogenic response when MAP is low (autoregulation)?
-GFR is temporarily low > -increase resistance of efferent arteriole -decreases renal blood flow -increases PH and GFR
How does the tubuloglomerular feedback help GFR autoregulation?
What is the function of macula dense cells?
-sense distal tubule ‘flow’ and release paracrine signals that affect afferent and efferent arteriole diameter
What happens during reabsorption in the nephron?
-returns 99% of filtrate back to peritubular capillaries
What are the 2 ways reabsorption can occur?
1) epithelial transport
2) transcellular pathway
How is Na+ reabsorbed?
How is Glucose reabsorbed?
-in the PCT
-
What happens during saturation?
-‘transport rate of substance is proportional to the plasma concentration of the substance, up to the point at which transporters become saturated’
- once saturation occurs, transport rate reaches maximum - the plasma concentration of substrate at which the transport maximum occurs is called renal threshold
