Functions Of The Kidney - Colin Geddes Flashcards
4 functions of kidney?
Remove metabolic waste eg urea and acids
Controlling blood pressure by maintaining ECF volume
Maintain optimal electrolyte concentrations
2nd hydroxylation step of vit D
Make erythropoietin in response to hypoxia
Name the body fluid compartments?
Intravascular space
Interstitial (ECF) space
Intracellular space
What determines the vascular fluid volumes?
Hydrostatic and osmotic
What are the most abundant ions in extracellular fluid? (+ve & -ve)
Sodium, chloride & bicarbonate
What are is most abundant ion in intracellular fluid?
K+
Protein is also abundant in cells
What happens to the volume and conc in each of the 3 body fluid compartments if 1 litre of water is added?
Volume increases in each of the 3 compartments therefore concentration in each decreases
What happens to the volume and concentration of each of the 3 body fluid compartments if 300mmol of sodium is added?
Number of particles in intravascular and interstitial compartments increases but not in the intracellular compartment.
Water then redistributes so all compartments change in size and conc.
Intravascular and interstitial spaces increase in sodium therefore increase in water
Intracellular space does not change in sodium but water moves out to the other spaces so intracellular volume FALLS
What happens to the volume and concentration of each of the 3 body fluid compartments if 300mmol of sodium is added along with 1Litre of water?
This isotonic addition of sodium and water leads to increased volume and increased number of sodiums in the intravascular and interstitial space but no change in volume or conc of intracellular space
What is the extraceullar fluid composition and volume dependent on?
Salt intake - hunger & food availability
Water intake - thirst & water availability
Salt and water loss - gut and sweat
All these are very variable so kidneys are required to maintain homeostasis
How much of the cardiac output do kidneys receive?
Approx 20%
Name the 3 processes in nephron?
Glomerular filtration Tubular reabsorption (selective absorption INTO blood) Tubular secretion (from blood into tubule)
What cells are in glomerus?
Mesangial cells - phagocytes, contractile
Bowmans capsule has parietal simple squamous epithelium and PODOCYTES (visceral layer)
Glomerular endothelial cells
Layers of the glomerular filtration barrier?
SPECIALISED Capillary endothelium
Glomerular Basement membrane - collagen based
PODOCYTE foot processes
Name 3 things that are 100% filtered in the glomerulus
Water, urea, glucose
What percentage of haemoglobin, albumin and RBCs are filtered? (Approx) why?
Hb 3%
Albumin < 0.01%
RBC 0
All too big to be filtered
What’s the normal glomerular filtration rate?
Approx 100ml/min
What aquaporin type is found in the THIN DESCENDING LIMB of loop of Henle?
Aquaporin I
What aquaporin type is found in the proximal convoluted tubule?
Aquaporin I