Lecture 2: Filtration And Renal Blood Flow Flashcards
What does filtration occur?
Glomerulus
Filtrate enters Bowman’s capsule, which is the beginning of what?
PCT
What forms the filtration membrane?
Capillary epithelial cells, basements membrane, and podocytes
Rate of filtration is measured by….
GFR
The best way to determine GFR is to determine clearance of molcules such as:
Inulin
Creatinine
Sugar that your body cant metabolize
Inulin
Byproduct of muscle metabolism
Creatinine
As GFR decreases, plasma creatinine __________
Increases
Small changes in creatinine mean…
Big changes in GFR
What filters and what doesn’t filters?
Does filter: water, ions, small molecules.
Doesn’t filter: plasma proteins and solutes bound to plasma proteins (thyroid hormone or bound calcium)
Amount of solute that entered the tubular fluid
Filtered load
What can filtered load be used for?
To determine HOW a solute is handled in the nephron.
Because filtration and secretion adds solute to the tubular fluid while secretion removes them
SO
Excretion=filtered load + secretion - reabsorption
If you constrict the afferent arteriole..
Reduce Pgc
Reduce GFR
Reduce RBF
If you dilate the afferent arteriole….
Increase Pgc
Increase GFR
Increase RBF
If you constrict the efferent arteriole…
Increase Pgc
Increase GFR
Decrease RBF
If you dilate the efferent arteriole….
Reduce Pgc
Reduce GFR
Increase RBF
Dilating the afferent arteriole will have what effect on GFR and RBF?
Increase GFR and RBF
If a patients filtered load of K+ is 10mg/min and excretion rate is 1mg/min, how is K handled in the nephron? (select all that apply).
Filtered, reabsorbed, and secreted
RBF is calculated by clearance of what?
PAH
Kidney is able to control its own blood flow in response to:
Change in pressure
Autoregulation
At a high blood pressure, will you have more or less urine?
More
What’re the 3 mechanisms of autoregulation in the kidney?
- Myogenic response, in smooth muscle
- Tubuloglomerular feedback, in the nephron
- RAAS system, due to release of renin
What is the myogenic response of the kidney?
Smooth muscles stretch, and it actively contracts against that force.
Maintains constant flow by changing resistance
What is the tubuglomerular feedback?
Nephron is able to sense GFR and regulate RBF
high sodium in tubular fluid, means a high GFR and BP
Occurs at JGA (macular densa and juxtaglomerular cells)
If GFR is high, NaCl will be filtered and taken up by the:
Which will result in what?
Macula densa
More sodium in the tubular fluid and more activity of the Na/K ATPase, which will produce more adenosine.
Also lowers Renin production
What does adenosine do??
Binds to smooth muscle cells and causes constriction of afferent arteriole
Which then reduces GFR and RBF
Renin is released under what 3 conditions ?
- Low arterial pressure
- Tubular sodium decreases
- Effective circulating volume decreases
Renin will increase levels of what?
AngII and aldosterone
Low levels of AngII…
Constrict efferent arterioles and increase GFR
What are high levels of AngII damaging?
It constricts both afferent and efferent arterioles
Aldosterone increases what?
Na and H2O retention (increases BV)
In which arteriole would the myogenic/autoregulatory response be most prominent?
Afferent
Myogenic and Macular Densa work most on the __________ arteriole
AFFERENT
AngII acts preferentially on the ____________ arteriole
EFFERENT
When and what do Norepinephrine and Epinephrine do to the kidney?
Constrict both afferent and efferent, only in times of high SNS stimulation, like a massive hemorrhage.
What does Nitric Oxide do to the kidney?
It’s a vasodilator.
Counteracts AngII on afferent
Doesn’t make it to the efferent
What do prostaglandins do to the kidney?
They’re vasodilators.
Counteracts AngII on afferents
NSAIDS block production of what vasodilators?
What could this lead to?
Prostaglandins.
Could lead to kidney ischemia in already hypotensive patients
GFR/RBF Regulation
Response to hemorrhage?
response to massive MI?
Response to a high dose of ACE-1?
Response to being scared?
Last slide of lecture 2, draw it out
