Renal - Lecture 2 Flashcards
What is the first step of urine formation?
glomerular filtration
What passes freely through the filtration barrier of the glomerular space?
water and low-molecular weight substances
What does not get filtered by the glomerulus?
cells
proteins
protein-bound substances
What kind of proteins are not filtered by the glomerulus?
albumins and globulins (large proteins)
Seeing proteins and blood cells in the urine is a sign of what disease?
glomerular disease
___ bound to proteins do not get filtered in the glomerulus?
fats and calcium
The composition of the glomerular filtrate is almost identical to that of ___.
plasma
What is the major force that drives the glomerular filtration?
pressure in the capillary (Pgc)
What is the glomerular capillary blood pressure in glomerular filtration?
60 mmHg
What are the 2 opposing forces in the glomerular filtration?
- pressure in the Bowman’s space
- oncotic pressure
The pressure in the Bowman’s space pushes ___ the filtration.
back
What is the protein in the oncotic pressure that pulls the water back from the Bowman’s space?
albumin
What is the pressure in the Bowman’s space equal to?
15 mmHg
What is the osmotic force (oncotic pressure) equal to?
29 mmhg
What is the net glomerular filtration pressure formula?
glomerular capillary blood pressure - Bowman’s space pressure - oncotic pressure
What is the value of net glomerular filtration pressure?
16 mmHg
Why is there no oncotic pressure from the Bowman’s space?
because there are no proteins in the Bowman’s space
What is glomerular filtration rate?
the volume of fluid filtered from the glomeruli into Bowman’s space per unit time
What 3 things regulate the GFR?
- net filtration pressure
- membrane permeability
- surface area available for filtration
What is the normal GFR of a 70 kg person?
180 L/day
What is the rate of the normal GFR in a 70 kg person?
125 mL/min
What is the NB plasma of a person who has a normal GFR of 180L/day?
3.5 L
How much plasma is filtered per day at glomeruli in someone who has a GFR of 180 L/day and a plasma volume of 3.5 L?
51
How can you decrease GFR? (2)
- constrict afferent arterioles
- dilating efferent arterioles