Renal Blood Flow Flashcards
How many litres do the kidneys filter per minute?
1.1L
What name is given to the portion of a kidney consisting of a renal pyramid and the renal cortex above it?
The kidney lobe
Describe the different stages in blood flow from the aorta through the kidney and back to the inferior vena cava.
- Aorta
- Renal artery
- Segmental artery
- Lobular artery
- Arcuate artery
- Interlobular artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Peritubular capillaries
- Interlobular vein
- Arcuate vein
- Lobular vein
- Segmental vein
- Renal vein
- IVC
What is the difference between a cortical and juxtamedullary nephrons
A juxtamedullary nephron features long loops of Henle that extend far into a kidney’s medulla, whereas cortical nephrons have short loops of Henle and are almost entirely embedded in the kidney’s cortex.
What percentage of the blood from the renal artery is filtered at any one time?
20%
What percentage of the blood from the renal artery exits via efferent arterioles?
80%
Name the 3 layers of the ‘filtration barrier’.
- Capillary endothelium
- Basement membrane
- Podocyte layer
What is the function of the capillary endothelium layer of the ‘filtration barrier’?
Fenestrated structure, therefore the pores are only big enough to allow ions through, not cells.
What is the function of the basement membrane layer of the ‘filtration barrier’?
It has a negative charge which is important to repel negative proteins.
Describe what could happen in many disease processes, if the negative charge on the filtration barrier is lost.
A condition called proteinuria, when proteins are more readily filtered.
Describe the concept of myogenic response, an auto regulated response of the kidney.
Auto-regulatory mechanisms keep GFR within normal limits when blood pressure is within physiological limits.
I.e. when blood pressure raises, afferent arterioles constrict so that resistance increases hence the GFR further downstream is unaffected (and visa versa)
Describe the roll of macula densa cells.
Macula densa cells are a type of juxtoglomerular cells which are specialised to detect salt in the DCT.
If more blood is being filtered than it should (i.e. there is more salt in the DCT) these cells detect this change and produce a response. (and visa versa)
What substance is produced by juxtaglomerular cells in order to reduce GFR and how does it act?
Adenosine (vasodilator of efferent arterioles)
What substance is produced by juxtaglomerular cells in order to increase GFR and how does it act?
Prostaglandins (vasodilator of afferent arterioles)
What is reabsorbtion in the PCT mainly driven by?
Na/k pump as it sets up the concentration gradient
