Renal structure and function Flashcards
What do renal arteries branch from?
The abdominal Aorta
Function of ureter
Carries urine to bladder
Function of urethra
Carries urine away from bladder to be excreted
Describe the course of renal arteries in the kidneys
- They pass into interlobar vesseles than branch into arcuate arteries in the renal cortex then terminate in the glomerulus (in the cortex). Each capillary glomerulus is enclosed inside bowmans capsule

What is bowmans capsule?
A bag of tissue which encloses a glomerulus capillary
What is the firsts stage or urine formation?
Blood plasma enters the glomerulus capillaries via afferent arterioles, this plasma enters bowmans capsule and is filtered. Blood leaves the glomerular capillaries via efferent arterioles, it then empties in the proximal tubule.
How does blood enter and leave the glomerulus?
Blood enters- Afferent arterioles
Blood laves- Efferent arterioles
What is the filtration pressure? How is it created?
Rate at which kidneys filter blood- From capillaries into the capsule space
Created by the drop in pressure between the afferent and efferent arteriole
What is the filtration fraction? What is the normal value?
Amount of plasma filtered into Bowman’s capsule
Normal- 20%
What would happen to the blood if the filtration fraction was too high?
Blood in efferent arteriole would be too viscouse
Haematocrit would be too high
Describe the morphology of the capillaries in the glomerulus
They are fenestrated (have gaps between the endothelial cells)
The outside is covered in podocytes which have slits

Explain the structure and function of podocytes. What happens to them during renal disease
Podocytes cover the outside of the glomerulus capillaries
They contain slits which form the filtration mechanism
During renal disease- Slits become large and inflammed- podocytes enable proteins (solutes) to enter the urine (proteinuria).

How does proteinuria occur?
When podocyte slits become large and enflammed enabling proteins to filter into the urine.
Describe the course of fluid after it leaves bowmans capsule
- Fluid leaves Bowman’s capsule and enters the proximal convoluted tubule.
- Then it enters the ‘Loop of Henle’.
- After the loop it enters the distal convoluted tubule.
- It leaves the distal tubule and enters the collecting duct.
- The collecting ducts drain into the ureter.

What is the nephron?
The complete set of tubes, from Capsule to Collecting Duct
Where is the glomerulus & proximal tubule located?
Renal cortex
Where is the loop of Henle located
Renal medulla
How would you calculate the amount of fluid excreted?
The amount filtered plus the amount secreted minus the amount reabsorbed
How is the cause of physical pressure in the glomerula controlled? What is the normal value for physical pressure?
Cause- balance between constriction of the afferent and efferent arterioles
Normal value- 55 mm Hg
How does starlings principal apply to establishing the net filtration pressure? (net outward pressure)
Starling’s principle applies. The net filtration pressure is the physical (hydrostatic) pressure in the capillaries minus an osmotic pressure.
The physical pressure of fluid in the capsule is about 15mm Hg, and the osmotic pressure is nearly zero (no proteins) so the net filtration pressure is about 10 mmHg.

What is is the Glomerular Filtration Rate? What is the normal value? Why dont we pee this much?
The Glomerular Filtration Rate is the total amount of fluid filtered through ALL the glomeruli in BOTH kidneys
Normal value- 120-125ml/min
We only pee out 1 ml/min. The rest is reabsorbed
Where is most of the filtered water from the glomerulus rebasorbed? Explain how absorbtion is possible at this location?
2/3 is absorbed in the proximal tubule
Sodium channel located in the lumen of the the proximal tubules transport sodium out of the lumen into the tubule cells down its concentration gradient, glucose is carried with it
Basal membranes of the cells at proximal tubule contain sodium pumps also which extrude sodium from the tubule cell into the interstitial fluid.
Water follows the sodium and is aborved down this osmotic gradient into the interstitial fluid.
Tubule lumen—-> cells—–> interstital fluid
How is the GFR measured and assessed? When will the clearence be the same as the GFR?
Clearence of a selected molecule (liters/min)
It is the volume of plasma completly cleared of a substance in 1min
If 100% of a blood compound is filtered through the glomerulus, and is removed at the same rate as water passes through the glomeruli and
all of the filtered compound appears in the urine (not rebaosrbed) then its clearnce will be the same as the glomerular filtration rate
Where does secretion of additional substances to be excreted occure?
Efferent arteriolar blood- substances secreted into tubular fluid
