Glomerular Filtration&RBF-Exam 2 Flashcards
What are the three renal processes?
Glomerular filtration
Tubular reabsorption
Tubular secretion
Where is the glomerular filtration process?
From glomerular capillaries to Bowman’s capsule
Where is tubular reabsorption?
From renal tubules to peritubular capilaries
Where is tubular secretion?
From peritubular capillaries to renal tubules
What is the equation for excretion?
Excretion = Filtration - Reabsorption + Secretion
How many membranes must be crossed for excretion?
2
Increased sodium; increased filtration; decreased reabsorption=
Increased excretion
Most substances see _______ filtration and _______ reabsorption rate
High; high
Small changes in filtration/reabsorption will produce significant changes in what?
Excretion rate
Why is there a high filtration rate?
- Allows rapid removal of waste products
- Allows multiple passes of blood vol. through kidneys/day
- Allows rapid and precise control of body fluid volume nad composition
What is the normal GFR?
180 L/day or 125 mls/min
How many liters of plasma volume is normal?
3-4 L
Plasma volume gets filtered how many times each day?
6x/day
Waste products depend on what for adequate removal?
Filtration (not reabsorbed or secreted)
What is the filtration fraction equation?
Filtration fraction = GFR/ Renal Plasma Flow
What is the normal filtration fraction?
20%; Each minute 20% of plasma flowing through the kidneys is filtered
What is normal reabsorption?
178.5 L/day (123 mls/min)
What is normal urine output?
180-178.5 = 1.5 L/day
125 (GFR) -123 (reabsoprtion) = 2 mls/min
How does the glomerular capillary membrane compare to the normal capillaries?
Glomerular capillary filters significantly more volume than normal capillaries; thicker but more porous
How many major layers are in the glomerular capillary membrane?
3 layers
What are the major layers of the glomerular capillary membrane?
- Endothelial cell layer
- Basement membrane layer
- Epithelial cell layer (podocyets)
What are podocytes
surround outer surface of basement membrane
Describe the anatomy of the endothelial layer.
Perforated by thousands of fenestrations (small holes)
How is protein passage prevented in the endothelial layer?
Negative charge on surface of endothelial cells