FINAL EXAM - Lecture 3 Flashcards
Control point that the body manipulates to control blood flow and filtration in the glomerular capillaries
Afferent arteriole
If kidney sees that blood flow is too low, what happens?
Afferent arteriole relaxes to allow more blood flow
If kidney detects blood flow is too much, what happens?
Afferent arteriole constricts more to reduce blood flow
Characteristics of blood flow auto regulation?
Imperfect, it is not a flat line like brain and spinal cord. It is slightly increased along the regulated portion.
The “imperfect” significance of the slanted line in renal auto regulation is because of what?
It’s how the kidney gets rid of fluid when blood pressure is high, or retains fluid when blood pressure is low.
Plasma oncotic pressure in the Afferent arteriole
28mmHg
How does the glomerular capillary plasma oncotic pressure differ from general capillaries?
The pressure changes throughout the capillaries due to the filtration. In a healthy patient, there shouldn’t be any plasma colloids lost. Although, there is a lot of fluid lost, therefore the oncotic pressure goes up.
What the is the beginning and end plasma oncotic pressure of glomerular capillaries? Middle?
28 and 36. 32.
Hydrostatic pressure of container that fluid is initially being filtered into
It fills up until it reaches 18mmHg
Oncotic pressure of container initially being filtered into
Should be 0 in a healthy patient.
Net FILTRATION pressure of glomerular capillaries
60mmHg (capillary blood pressure)
- 32mmHg (average oncotic pressure opposing filtration)
- 18 mmHg (physical fluid pressure opposing fimtrstion)
= 10mmHg, drives filtration to a tune of 125mL/min
Kf means? What are the calculations?
Filtration coefficient that goes along with NFP.
Filtration rate = Kf (NFP)
125mL/min = Kf (10mmHg)
= 12.5mL/min/mmHg(?)
Efferent arteriole characteristics
Sits post-glomerular capillaries.
Kidney uses this to fine-tune GFR by constricting or relaxing.
How can the kidney increase GFR?
Contract efferent arteriole to increase upstream capillary blood pressure, increases filtration forced out.
Blood pressure at end of efferent arteriole is
18mmHg
Where is the greatest blood pressure drop in the blood vessels kidneys?
Efferent arteriole has the highest vascular resistance.
Blood pressure in the Afferent arteriole goes from 100 to 60 (40 point drop). But after the glomerular capillary, it drops to 18. Therefore, efferent arteriole has the highest drop of 42.
Second set of capillaries, directly after efferent arteriole
Peritubular capillaries
Role of PT capillaries
Reabsorption of fluid that was filtered in the tubule that the kidney decided to hang onto.
What % of everytning filtered will be re-absorbed?
99%
What is the route of re-absorption?
Through or between cells that make up wall of tubule. Some parts of kidneys have wide gaps that allow water and small ions to go in between the cells to be reabsorbed
What sits between tubule and the PT capillaries?
Matrix that makes up the renal interstitium. Made of proteins and ions. When things are reabsorbed, it has to pass through this.
Plasma oncotic pressure average of PT capillaries
32mmHg
Blood pressure of PT capillaries
Beginning: 18mmHg
Middle: 13mmHg
End: something lower than 13mmHg lol
PIEisf of renal interstitium
Lots of proteins in there, it’s 15mmHg
Physical fluid pressure of renal interstitium (Pisf)
6mmHg
NFP of PT capillaries
-10mmHg
NRP of peritubular capillaries
10mmHg
What is the 125mL/min being filtered?
Not the blood, it’s plasma. RBCs shouldn’t be filtered.