Vanders Renal Ch2 Flashcards
What is renal blood flow (RBF)?
1 L/min, representing 20% of resting cardiac output
RBF is significant given that the kidneys constitute less than 1% of body mass.
What is the normal glomerular filtration rate (GFR)?
Approximately 125 mL/min
GFR is a key indicator of kidney function.
What formula relates flow, pressure, and resistance in any vascular bed?
Q = ΔP / R
Q is blood flow, ΔP is the pressure difference, and R is resistance.
What are the successive vessels blood flows through after leaving the renal artery?
Arcuate arteries, interlobular arteries, afferent arterioles, glomeruli
These vessels are crucial for delivering blood to the kidney’s filtration units.
What are the relative resistances of afferent and efferent arterioles?
About equal under most circumstances
Both types of arterioles account for most of the total renal vascular resistance.
How do changes in afferent and efferent arteriolar resistances affect renal blood flow?
They can be additive or offsetting depending on the direction of change
Changes in resistance can significantly impact renal blood flow.
What are the three layers of the glomerular filtration barrier?
Endothelial cells, capillary basement membrane, podocytes
Each layer has unique structures that contribute to filtration.
Define podocyte.
Epithelial cells that surround glomerular capillaries
Podocytes have foot processes that create filtration slits.
What determines the filterability of plasma solutes?
Molecular size and electrical charge
The structure of the filtration barrier restricts certain solutes based on these factors.
What is the filtration fraction?
The fraction of renal plasma flow that is filtered into the Bowman’s capsule
It is a measure of kidney function efficiency.
Why is the net filtration pressure in glomerular capillaries positive?
High hydrostatic pressure in glomerular capillaries
This pressure drives fluid out of the capillaries into the Bowman’s capsule.
What is autoregulation of renal blood flow?
The ability of the kidneys to maintain a constant blood flow despite changes in arterial pressure
This mechanism ensures stable kidney function.
What is the significance of the high blood flow through the peritubular network in the cortex?
Maintains interstitial environment close to blood plasma composition
This is crucial for the function of renal tubules.
What is the typical blood flow through the vasa recta into the medulla?
Approximately 0.1 L/min
Although low compared to cortical blood flow, it is sufficient for medullary function.
What is the role of hydrostatic pressures in the glomerular and peritubular capillaries?
High in glomerular capillaries for filtration, low in peritubular capillaries for reabsorption
This difference is essential for kidney function.
How does molecular size affect filterability?
Molecules < 7000 Daltons are freely filtered; larger molecules are restricted
Plasma albumin is largely excluded due to its size.
Fill in the blank: The primary function of the glomerular filtration barrier is to restrict the passage of _______.
plasma proteins
This selectivity is crucial for maintaining protein levels in the blood.
True or False: The glomerular filtrate contains significant amounts of albumin.
False
Albumin is largely restricted from passing through the filtration barrier.
What happens to filterability as molecular weight increases?
Filterability declines as molecular weight increases, especially above 70,000 Da.
Which type of macromolecules are filtered to a lesser extent?
Negatively charged macromolecules are filtered to a lesser extent than neutral molecules.
What is the role of electrical charge in the filtration process?
Electrical charge enhances filtration restriction; negatively charged molecules are repelled, while positively charged molecules are filtered more easily.
What is the significance of the filtration coefficient (Kf)?
Kf denotes the product of hydraulic permeability and surface area of the glomerular capillaries.
What are the Starling forces involved in glomerular filtration?
Starling forces are the algebraic sum of hydrostatic and oncotic pressures across the capillary wall.
What is the average net filtration pressure in glomeruli?
The average net filtration pressure is about 16 mm Hg.
