Physiology 3 Flashcards
What are the filtration barriers in the kidney?
(1) Glomerular Capillary Endothelium (barrier to RBC)
(2) Basement Membrane (basal lamina) (plasma protein barrier)
(3) Slit processes of podocytes (plasma protein barrier) (Glomerular epithelium)
Features of the glomerular capillary
pores/ gaps are 100x times bigger in the glomerular capillaries than in other capillaries
-> leaky barrier
What is the glomerular basement membrane made of?
collagen and glycoprotein
What does the basement membrane do to the negative plasma proteins?
repels negatively charged plasma proteins as the plasma membrane is negative
negative plasma proteins should be retained within the capillaries and shouldn’t pass through the capillary wall through to the tubular flow
What should happen to the RBC in the capillaries?
Shouldn’t move across the glomerular membrane as they are too big to cross the membrane
What is the importance of the podocytes?
Makes the inner layer of the bowmans capsule
Is the glomerular filtration process active or passive?
Passive - doesn’t need energy or transport proteins
What forces control the process of glomerular filtration?
The net filtration pressure as a result of the 4 forces:
2 hydrostatic pressures
2 oncotic pressures
What are the 2 hydrostatic forces?
Pressure of the blood as it passes through the glomerular capillary - 55mm/ Hg
What is the key determinant force in setting up the net filtration pressure?
glonmerular capillary blood pressure
Blood pressure remains relatively same throughout the glomerular cappilary. Why?
as the afferent arteriole is bigger in diameter than the efferent vessel, hence the build up of backstatic of the blood
What is the bowman’s capsule hydrostatic fluid and its
Bownmans capsule hydriostatic opposes the glomerular capillary blood pressure
What does oncotic/ colloid refer to?
Plasma proteins
Where is the plasma protein present in the glomerulus?
in the capillary and not in the capsule
What is the imp of cap oncotic pressure?
against the net filtration pressure
fluid back from the bowmans capsule into the capillary
What is the bowmans capsule oncotic pressure?
o mm / Hg
What is the net filtration pressure?
(Glomerular Capsillary BP + Bowmans capsule oncotic pressure ) - (Bowmans capsule hydrostatic fluid - capillary oncotic pressure)
What are the straling forces?
to describe the balance btw the hydrostatic and oncotic fluid
How is the tubular fluid similar to the blood plasma?
Tubular fluid in the bowmans capsule almost similar to plasma in the fluid except for the large plasma proteins
What does the GFR dependent on?
Net filtration pressure
What is the filtration coefficient in GFR?
How permeable or holey the glomerular membrane is
How does the GFR change on chnaging net filtration pressure?
increasinh the net filtration pressure increases GFR
How does the gfr affect urine output?
decrease gfr -> filtering less -> less urine
What is the key determinant factor for the net filtration pressure?
Blood pressure
How is the gfr regulated?
via two methods:
extrinsic regulation
intrinsic regulation