Lecture 3 Final Flashcards
T/F: The kidneys autoregulation blood flow is not perfect but it does it very well.
True
T/F: The imperfect autoregulation of the kidneys manages to keep it going for a long term.
True
In a healthy person, we should not be ____ any plasma colloids in the capillaries.
Losing
Due to loss of fluid in the capillaries at a rate of 125ml/min, what does that do to the venous side of the arteries?
More concentrated proteins inside and the new oncotic pressure is 36 mmHg.
starting from the arterial side, middle, venous side
(28mmHG > 32mmHg > 36mmHg)
What is the hydrostatic pressure inside the tubule?
18mmHg
Where does the glomerular capillaries send its filtered fluids?
Renal tubule
What is the protein osmotic pressure in the early part of the renal tubule?
0mmHg, Should not be any proteins if you’re healthy.
Are proteins in the renal tubule free floating?
No, they are tethered.
In a 30yo healthy person, what is the net filtration pressure in his
kidneys?
10mmHg
Formula for filtration rate (Kf)
Filtration rate = Kf (NFP)
125ml/min = Kf (10mmHG)
Kf = 12.5ml/min/mmHg
Where is the efferent arteriole located?
Right after the glomerular capillaries
What happens if the GFR is low? too high? What does the kidneys do?
Causes the efferent arteriole to constrict, causing a higher pressure in the glomerular capillaries and relaxes to lower the pressure.
What is the pressure at the end efferent arteriole?
18mmHg
The drop in pressure in the efferent arteriole is higher than the afferent arteriole.
- 100mmHg > afferent arteriole > 60mmHg
- 60mmHg > efferent arteriole > 18mmHg
What has the highest vascular resistance in the renal system?
Efferent arteriole
Where do most of the reabsorption occur?
Peritubular capillaries
How much of the filtered fluids are reabsorbed and excreted?
99% is reabsorbed and 1% is excreted from the body.
Where does reabsorption occur?
Through the cell wall of the renal tubule.
T/F: Everything that are reabsorbed goes through the cell wall of the renal tubule.
False, Sometimes small things travel in between the cells of the cell wall.
What makes up the renal interstitium?
The matrix (proteins, ions, electrolytes)
Where is the renal interstitium located?
Between the renal tubule and peritubular capillaries. (This is where reabsorption occurs)
After reabsorption in the peritubular capillaries occur, where does it go?
Back into the cardiovascular system
What is the oncotic pressure in the glomerular capillaries and peritubular capillaries?
32mmHg; 32mmHg
What is the pressure in the peritubular capillaries?
13mmHg
What is the (Pi symbol ISF) osmotic pressure outside of the peritubular capillaries?
- (Pi symbol ISF) 15mmHg
- (Physical/ PISF) fluid pressure 6mmHg
What is the NFP (net filtration pressure) and NRP (net reabsorption pressure) in the peritubular capillaries?
-10mmHg; 10mmHg
NRP = Pi CAP 32 + PISF 6 - Pi symbol ISF 15 - Pcap 13
What is normal renal blood flow?
1.1L/min
What is the normal CO for a healthy adult? How much plasma is filtered through the kidneys?
5L; 20% (1.1L)
All of the stuff reabsorbed will travel back to the CV system via….
Renal vein
Where does the renal tubule empty into?
Ureter and into the bladder
If the kidney recognizes toxins, what odes it do?
Physically pumps (secretes) it into the renal tubule via specialized transporters in reverse reabsorption process.
(peritubular caps > matrix > renal tubule cell wall > renal tubule)
Change in filtration fraction is dependent on the efferent arteriole action by….
If the efferent arteriole constricts > increase GFR
Efferent arteriole relaxes > decrease GFR
What is the normal filtration percent?
20%
(equation) renal plasma flow
GFR / RPF (125ml/min / 660ml/min)
What is our plasma volume out of the 1100 ml?
660 (1100 x 60%)
What is our HCT out of the 1100 ml?
440 (1100 x 40%)
- What down stream effect happens if the afferent arteriole constricts > glomerular pressure is low?
- Afferent arteriole relaxes > glomerular pressures is High?
GFR is low > decrease renal blood flow
GFR is high > increase renal blood flow
What if the efferent arteriole constricts?
If the efferent arteriole is relaxed
Glomerular pressure is high > GFR is high > increase renal blood flow
Glomerular pressure decrease > reduce GFR > decrease renal blood flow
In a healthy individual, autoregulation of the renal system can have pressures of
50-150mmHg
Autoregulation in the kidneys can prevent…
under perfusion and over perfusion
What are the risks if our renal autoregulation didn’t work?
We would lose massive amounts of fluid.
If we had a stroke and renal auto regulations isn’t functioning properly, what happens?
Our body wouldn’t be able to perfuse the area of damage in the brain d/t increase UOP.
What is normal UOP?
1ml/min
auto regulation without RAAS
High BP leads to… (renal system)
Low BP?
High GFR > High UOP > lower BP
Low GFR > Low UOP > increase BP
In a normal person, what route does glucose follow in the renal system?
Filtration with complete reabsorption in PCT
In a normal person, what route does sodium follow in the renal system?
Filtration with partial reabsorption in PCT
What is para-aminohippuric acid (PAH)?
This is when everything that was filtered is eventually secreted in the tubule.
This is also used to diagnose and estimate renal blood flow. (more renal PAH in the urine = high renal blood flow) vice versa
What are fenestrations
glomerular openings in the endothelium
What provides structural support to the capillary bed?
Epithelium (podocytes). Have foot openings called slit pores.
Inside the basement membrane of the kidneys are negatively charged to help….
repel other negatively charged proteins from floating out of the fenestrations.
What happens to the glomerular capillaries if exposed to chronic HTN (SBP 200s)
glomerular capillaries are blown out.
What are dextrans?
real big hetastarch. used to check renal filtration size and charge.
- increase size, negative charge = less filterable
- small in size, positive charge = filterable
Example of filterable substances
Water
Na+
Urea
glucose
sucrose
inulin
myoglobin - rare
albumin - not normal/never
What is inulin?
synthetic compound given as an injectable that provides a more accurate GFR with urine collection.
