Kidneys Flashcards
Plasma K+ concentration
4mEq/L
Urine [K+]
20-70 mEq/L
Plasma [Urea]
10 mEq/L
Urine [Urea]
300 mEq/L
Plasma [Creatinine]
0.001 mEq/L
Urine [Creatinine]
10 mEq/L
Is glucose expelled in urine?
No
Parts of the nephron, in order 1 2 3 4 5 6 7
1) Bowman’s capsule
2) Proximal tubule
3) Descending limb
4) Loop of Henle
5) Ascending limb
6) Distal tubule
7) Collecting duct
What occurs between the glomerulus and Bowman’s capsule?
Filtration
Which blood vessels run beside the tubules?
Peritubular capillaries
Where does reabsorption occur?
Between tubule and peitubular capillaries
Proximal tubule
Descending, ascending limbs
Distal tubule
Collecting duct
Where does secretion occur?
From peritubular capillaries to tubule
Proximal tubule
Distal tubule
Collecting duct
What determines the amount of solute excreted?
Amount filtered - amount reabsorbed + amount secreted
What structure gives rise to peritubular capillaries?
Efferent arteriole
What do the peritubular capillaries become?
Renal vein
What is secreted?
K+
What is filtered? 1 2 3 4 5 6 7 8
1) Na
2) Water
3) K
4) Ca
5) PO4
6) Glucose
7) Creatinine
8) Urea
Where does water reabsorption occur?
Descending limb
Collecting duct
Where does Na reabsorption occur?
Ascending limb
What is reabsorbed? 1 2 3 4 5 6 7
1) Water
2) Na
3) K
4) ca
5) PO4
6) Glucose
7) Urea
Water excretion
1%
Na excretion
0.5%
K excretion
10%
Ca excretion
2%
PO4 excretion
20%
Glucose excretion
0%
Creatinine excretion
100%
Urea excretion
50%
What is filtration?
Movement of plasma and solutes from the glomerulus into Bowman’s capsule
What is reabsorption?
Movement of water and solutes from the lumen into the peritubular capillaries
Can be active or passive
What is secretion?
Active transport of solutes from the peritubular capillaries into the renal lumen
What is Bowman’s capsule made up of?
Capsular epithelium
What is wrapped around glomerular capillaries?
Podocytes
What do podocytes wrap around?
Glomerular capillaries
Which structure is in contact with the afferent and efferent arterioles?
Ascending limb of loop of Henle
Function of podocytes
Foot processes surround each capillary
Leave gaps where filtration can take place
What binds together glomerular capillaries?
Mesangial cells
What do solutes move through in filtration?
1
2
1) Endothelial pores
2) Between podocyte foot processes
Volume of plasma filtered through glomerulus and Bowman’s capsule
20%
Amount of plasma reabsorbed from nephron
<19% (20% of plasma was filtered)
Amount of filtered plasma excreted
1%
Ph
Hydrostatic pressure
Pi
Colloid osmotic pressure
Pfluid
Pressure created by fluid in Bowman’s capsule
Net filtration pressure
Hydrostatic pressure - colloid osmotic pressure - Fluid pressure in Bowman’s capsule
Ph - Pi - Pfluid
Does hydrostatic pressure promote or inhibit filtration?
Promote
Pressure of hydrostatic pressure
+55mmHg (into Bowman’s capsule)
Does colloid osmotic pressure promote or inhibit filtration?
INhibit
Pressure of colloid osmotic pressure
-30mmHg (out of Bowman’s capsule)
Does Pfluid promote or inhibit filtration?
Inhibit
Pressure of Pfluid
-15mmHg (out of Bowman’s capsule)
Net filtration pressure
10mmHg
