Renal Hemodynamics and blood flow- Lee Flashcards
80% of the blood supply in the kidney is located where?
renal cortex
Where is the macula densa located?
in the lumen of the nephron in the DCT
What are the two substance that are primarily used to measure GFR?
inulin and creatinine
What is the largest pressure force in determining GFR?
glomerular capillary hydrostatic pressure
roughly 50 mmHg
What are the factors that can affect filtration fraction ?
- decreased renal plasma flow
- decreased GFR
Substances that are not filtered through the glomeruli return to the blood through which vessel?
efferent arteriole
How does size and charge affect filterability?
Positive charged substances are more readily filtered than negative charged substances.
Small sized particles are more easily filtered than large sized particles.
T/F. Even though an individual has a high concentration of glucose all of it will be filtered at the glomeruli.
True
What is microalbuminuria and what are causes of it?
urine excretion of albumin >30 but <150 mg per day
- early DM
- HTN
- glomerular hyperfiltration
What are the forces that oppose filtrate movement out of the glomeruli capillary?
- glomerular colloid osmotic pressure
- Bowman’s capsule pressure
What is hydronephrosis and what causes it?
Hydronephrosis is the swelling of a kidney due to a build-up of urine.
causes: tubular obstruction ???
What is Kf? What is significant about its value in the kidney? How can it be reduced?
- it is a filtration coefficient that is important in determining GFR
- it is normally 12.5 ml/min in the kidneys which is 400 times greater than Kf in other tissues
- it can be reduced by chronic HTN, obesity/ DM, glomerulonephritis
Kf = hydraulic conductivity x surface area
How can DM decrease GFR?
there will be inflammation within the glomerulus which will decrease the surface area for which substances are filtered thus decreasing GFR
Give examples of conditions that can increase Bowman’s capsule hydrostatic pressure.
- tubular obstruction
- kidney stones
- tubular necrosis
- urinary tract obstruction
- prostate hypertrophy/cancer
The accumulation of proteins is higher at the end of the capillary than at the beginning. This accounted for by what?
increasing glomerular capillary oncotic pressure
________in afferent arteriole resistance and __________in efferent arteriole resistance will cause increase in glomerular capillary hydrostatic pressure. How is renal blood flow affected by constriction in the afferent arteriole vs. the efferent arteriole?
decrease
increase
renal blood flow will decrease in increases in both afferent and efferent arteriolar resistance
Why do increases in arterial pressure not substantially change glomerular capillary hydrostatic pressure?
important for maintaining GFR
Decreases in glomerular filtration rate will________ in glomerular capillary hydrostatic pressure causing what type of renal disease?
decrease
pre-renal???
Overtime as efferent arteriole resistance increase, the GFR begins to go down. Why?
Overtime decreased renal blood flow will lead to lower amounts of blood needed to maintain a normal GFR
What are the four Starling forces?
The four Starling forces are:
- hydrostatic pressure in the capillary
- hydrostatic pressure in the interstitium
- oncotic pressure in the capillary
- oncotic pressure in the interstitium
How does increase in efferent arteriole (Re) resistance result in increase in GFR although Re causes increase in glomerular capillary oncotic pressure?
glomerular capillary oncotic pressure is significantly less than glomerular capillary hydrostatic pressure
A large fraction of renal oxygen consumption is related to what?
renal tubular sodium reabsorption
Severe hemorrhage will result in what effects to the GFR?
decrease in GFR
as the afferent and efferent arteriole resistance will increase (afferent significantly higher)
Low sodium diet and volume depletion will result in what effects to the GFR?
increase in the efferent arteriole resistance which will maintain the GFR
you do not want an increase in GFR because you want to conserve volume to get pressure back to normal
low sodium diet decreases water reabsorption
