Urinary: Clearance and Electrolyte Balance Flashcards Preview

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Flashcards in Urinary: Clearance and Electrolyte Balance Deck (8)
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1
Q

What are normal adult glomerular filtration rates?

A

Males 115-125 ml/min

Females 90-100 ml/min

2
Q

How do we calculate renal clearance?

A

conc in urine x volume of urine / conc in plasma

3
Q

Whats the link between GFR and creatinine clearance?

A

Creatine clearance gives an estimate of GFR however slightly overestimates it because creatine is secreted by the proximal tubule as well as filtered by the glomerulus

4
Q

What is renal clearance?

A

The volume of plasma that can be cleared of a certain substance per unit time

5
Q

What are the volumes of fluid in each compartment?

A

ICF (cytosol) = 28L

ECF = 14L (interstitial fluid is 11L and plasma is 3L)

6
Q

Define osmolarity

Define osmolality

A

Osmolarity is the solute per kg of solvent
Osmolality is the number of osmoles of solute per litre

We usually measure in osmolality, units: milli-osmoles

7
Q

What are the electrolyte compositions of the ICF and ECF?

A
The ICF:
Low Na+  10mM
High K+  160mM
Low Cl-  3mM
Many large organic anions
The ECF:
High Na+  145mM
Low K+  4.5mM
High Cl-  114mM
Some HCO3-
8
Q

How are calcium levels regulated?

A

Parathyroid hormone stimulates calcium reabsorption in the kidney (asc limb and DCT)
, also stimulates synthesis of 1,25(OH)2 (active form of vit D) which stimulates calcium absorption in the small intestine

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