4. Introduction to Renal Blood Flow and GFR – DSA Flashcards
What is PAH used for?
Estimation of renal blood flow
Does the renal fraction of blood flow increase or decrease during exercise?
The renal fraction decreases, because blood is being shunted away from the kidneys to the muscles.
What is the Tam-Horsfall protein?
A protein that does not cross the filtration barrier, but is produced by the thick ascending loop of Henle. It is thought to prevent crystallization of calcium in the nephron – and may inhibit urinary tract infections
Where on the glomerulus does angiotensin II preferentially act?
The efferent arteriole
What is the normal GFR?
125 mL per minute
How small must a molecule be before it can freely pass through the filtration slits?
Less than 20 Å
Are positively charged, or negatively charged, ions more filterable?
Positively charged ions are more filterable.
Recall that the bio-gel of the endothelium is negatively charged, as such it repels negatively charged ions.
What are the 4 conditions that allow us to substitute clearance of a substance for GFR?
It must be very filterable
It must be neither absorbed nor secreted by renal tubules
It must not be affected by the kidney (synthesized, broken down, or accumulated)
It must not affect the kidney (it must be physiologically inert, not toxic, and without effect on renal function)
What receptors are used by the sympathetic nervous system to trigger renin release?
Beta-1 adrenergic receptors
What receptors affect the tubular epithelial cells to increase sodium reabsorption?
What specific structure is affected?
Alpha-1 adrenergic receptors
The Na/K pump
How large must a molecule be before it will not be filtered through the filtration slits?
42 Å
What is the normal blood urea nitrogen to creatinine ratio?
10/20:1
Somewhere between 10 and 20 to one.
What is the function of the protein Nephrin?
It is one of the adhesion molecules that holds adjacent podocytes together.
How does the sympathetic nervous system decrease glomerular filtration rate and renal blood flow?
By activating vasoconstriction via alpha-1 adrenergic receptors.
