Session 3 - Filtration By The Glomerulus Flashcards
Describe the divisions that the renal artery undergoes from the renal artery to the afferent arterioles
Renal Artery -> Segmental Artery-> Interlobar Artery -> Arcuate Artery -> Interlobular Artery -> Afferent Arteriole
Why is it important that the diameter of the afferent arteriole is slightly bigger than that of its efferent arteriole?
This increases the hydrostatic pressure of the blood which helps to force the components out of the blood
What two ways stop proteins from passing through the filter?
- They are too big to fit through the filtration slits
- Large amounts of negatively charged glycoproteins in the podocytes repel protein movement
What are the three layers the filtrate must pass through to get through the filter?
- Capillary Endothelium
- Basement Membrane
- Podocyte Layer
What three forces have an effect on filtration of the plasma?
- Hydrostatic pressure in the capillary
- Hydrostatic pressure in the Bowman’s Capsule
- Oncotic pressure difference between capillary and tubular lumen
What path must solutes take to be reabsorbed?
Tubular lumen -> Tubular cell -> Interstitium -> Capillary
Name some substances which are secreted by the kidneys into the lumen.
- Hydrogen Ions
- Ammonium Ions
- Potassium Ions
- Urea
- Creatinine
How does glucose enter the tubular cells from the tubular lumen?
- Sodium/Potassium pump on basolateral membrane sets up gradient for sodium to enter tubular cells
- Sodium is now in higher conc in lumen than in cells
- It diffuses down concentration gradient through a symporter
- Glucose diffuses in with sodium
Define Clearance
Volume of which a substance can be completely cleared to ruin per unit time
What is the formula which can be used to calculate clearance?
Plasma Conc
Define Glomerular Filtration Rate (GFR)
Volume of plasma from which any substance is completely removed by the kidney in a given amount of time (usually 1 minute)
What are the conditions that a substance must meet for its GFR to be able to calculated?
It must not be reabsorbed, secreted or metabolised by the cells of the nephron.
Name some substances which can be used to calculate GFR
Creatinine + Inulin
What the myogenic response to an increase and decrease in arterial BP?
If Arterial BP rises = Afferent arteriole will constrict
If Arterial BP falls = Afferent arteriole will dilate
How do the Macula Densa cause changes in GFR, and what do the changes depend on?
Sodium Chloride concentrations in the DCT
If Concentration is high then:
- GFR needs to fall
- Adenosine released
- Causes vasoconstriction of Afferent arteriole
And vice versa (but Prostaglandins are released = vasodilation of Afferent arteriole)
