Urogenital Flashcards
What is the rate of cardiac output
5L/min
What is the rate of renal blood flow
1 L/min
What are the 3 components of the glomerulus filtration barrier
Endothelial cells
Glomerular basement membrane
Podocytes
What is the negatively charged layer on endothelial cells of glomerulus
Glycocalyx. Consists of negatively charged glycosaminoglycans
Impact of the endothelial cell layer
- Fenestrations prevent RBCs from going through
- Cells have a negative glycocolax layer which repels negatively charged molecules
What is the negatively charged layer on endothelial cells of glomerulus
Glycocalyx. Consists of negatively charged glycosaminoglycans
What does the basement membrane consist of
Type 4 collagen, heparan sulfate proteoglycans and laninin
What are the 3 layers of the basement membrane
lamina rara interna, lamina densa, lamina rara externa
Are the podocytes charged
Negatively charged glycoproteins repel large anions
D) Ultrafiltration
Filtration under pressure
What determines the rate of ultrafiltration of a molecule
Size + charge of molecule, pressure, rate of blood flow, binding of molecule to plasma proteins
Can albumin pass through the glomerular capsule
No, molecular weight of 66kD (large) and is negatively charged
Is the efferent or afferent arteriole more constricted
Efferent arteriole (exit)
How is renal blood flow (GFR) regulated
1) Myogenic
2) Tubuloglomerular feedback
How does tubuloglomerular feedback work
- Arterial blood pressure decreases
- The filtration rate deceeases
- The rate at which NaCl is delivered to the macular densa (distal tubule) decreases
- Macular densa release prostaglandins which act on granular cells causing renin release which increases BP
How does myogenic regulation work
1) Systemic pressure in afferent arterioles increases
2) Stretches blood vessel walls
3) Afferent arteriole constricts
How is eGFR measured
The rate of excretion of a marker substance is recorded
What are the features of marker substances
1) Freely filtered
2) Not absorbed or secreted in tubule
3) Not metabolised
What marker substance is usually used to measure eGFR
usually creatine, inulin is gold standard
What is an issue with using creatine for gfr
Creatine is also secreted by the tubules so can lead to an overestimation of GFR
D) Renal clearance
The volume of plasma from which a substance is completely removed by the kidney/unit of time (usually a minute)
