Flashcards in Renal Physiology Deck (35):
What vessels supply the kidneys with which type of blood?
- Renal artery = oxygenated blood
- Renal vein = deoxygenated blood
Outer region of kidneys
Inner region of kidneys
What are the functions of the kidneys
1. Homeostasis = regulate blood volume, BP, osmolarity (ion levels) and pH
3. Endocrine/Hormonal = Produce erythropoietin and Vitamin D3
Why is erythropoietin important?
Why is Vitamin D3 important?
- Important for Ca2+ homeostasis
- low Ca2+ = lead to rickets
How to you obtain Vitamin D3?
Exposure to sunlight
Where does the nephron lie?
Top region lies in cortex and bottom in medulla
How does blood flow into the glomerulus?
Via the afferent arteriole
What is glomerular filtration?
Movement of molecules from plasma in the glomerulus into Bowman's space
How is blood filtered from the glomerulus?
Efferent arteriole (going out) is narrower than the afferent arteriole (going into G) so blood is under pressure in the glomerulus and this aids glomerular filtration
What happens to molecules that are filtered out of the glomerulus?
Compounds are filtered out of plasma, into bowman's space and move down Loop of Hendle, back up, and eventually into bladder
What happens to molecules that are not filtered out of the glomerulus?
They continue from efferent vessel into vasa recta, and back into systemic circulation
What happens in the Loop of Hendle?
Some molecules such as water, are reabsorbed here
What is the Bowman's capsule composed of?
1. Capillary endothelium
2. Basement membrane
3. Capsule cells/podocytes
What happens to a large molecule in the glomerulus?
Too large to pass through the endothelial gaps, therefore remains in the glomerulus and is secreted via the efferent arteriole into vasa recta and into systemic circulation
What happens to a small molecule in the glomerulus?
Small enough to pass though the endothelial gaps and move into Loop of Gendle
Glomerular filtration rate (GFR)
- Volume of fluid filtered into Bowman's capsule per unit time OR rate at which fluid is filtered by the kidneys.
- Used to measure kidney function
- As CKD worsens = GFR decreases = albuminuria increases
How do kidney stones affect kidney function?
Cause obstructions and inflammation. This may affect filtration
Role of insulin in measuring kidney function
- Before measuring eGFR, administer insulin i.v.
Advantages of insuline when measuring kidney function
- Freely filtered
- Not reabsorbed or secreted by the nephron
- Not metabolised by the kidney
- Excreted in the urine
Disadvantages of insuline when measuring kidney function
i.v. so invasine
Advantages of creatinine when measuring kidney function
- Produced naturally by our muscles so no need for i.v.
- Freely filtered
Disadvantages of creatinine when measuring kidney function
Secreted to a small extent by the nephron (approx. 10%) so need to make adjustments for this
What is renal clearance
Volume of plasma from which a substance is completely removed / unit time
Why is renal clearance important?
Important when developing new drugs as we need to understand how the patient will metabolise the drug and how it will be cleared from the body
Renal clearance equation
Cx = [Ux] x V / [Px]
What measurements are needed to calculate renal clearance?
- V = volume of urine produced in given time (vol/time)
- [Ux] = urine conc. of X
- [Px] = plasma conc of X
Organic anion transporter = uptake transporter
Organic anion transporting polypeptide
Organic cation transporter
Multidrug resistance-associated protein
Breast cancer resistance protein = efflux transporter
P-glycoprotein = efflux transporter