Card Set Information
Intravascular versus Interstitial Fluid
: blood plasma
: fluid outside of the cells and vascular system
Extracellular Fluid (ECF)
made up of the
Substances that dissociate into charged particles known as ions. e.g. Na⁺
Cations versus Anions
: positively charges ions (e.g. Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺)
: negatively charges ions (Cl⁻, HCO₃⁻, HPO₄⁻)
: most common cation in the ECF.
Maintains osmolarity in ECF.
Involved in water movement and
Relative increases/decreases in sodium are called:
Hypernatremia / Hyponatremia
: most common cation in the ICF.
Maintains osmolarity in ICF.
Involved in nerve impulses.
Relative increases/decreases in potassium are called:
Hyperkalemia / Hypokalemia
Involved in nerve impulses and
Relative increases/decreases are called:
Hypercalcemia / Hypocalcemia
: several biochemical processes and closely associated to phosphates.
Relative increases/decreases are called
: Hypermagnesemia / Hypomagnesemia
involved in fluid balance and renal function.
principle buffer of the body, neutralising highly acidic hydrogen ions (H⁺)
: used in ATP.
Closely associated with Mg⁺⁺ in renal function.
Acts as a buffer primarily in the ICF.
Acidosis versus Alkalosis
: pH below 7.35
: pH above 7.45
The body is constantly creating hydrogen ions (H⁺) through metabolism, creating acidity.
A variation of around 0.4 pH can be fatal
Passage of a solvent (usually water) through a membrane
Passage of molecules through a membrane from an area of greater concentration to an area of lesser concentration.
Equal concentration of solute molecules on either side of a membrane
water moves to saltier enviro
Movement of a substance against Osmotic gradient
Is faster than diffusion but requires energy.
Diffusion of a substance, such as glucose, through a cell membrane with the assistance of a "helper" or carrier protein.
It may or may not require energy.
Osmolarity / Osmolality
: concentration of solute/kg of water
: concentration of solute/litre of water
Pressure exerted by the concentration of solutes. Is a
, not a
Colloid osmotic pressure
Total loss of water from plasma to interstitial space.
Value is usually zero, because of Starling's Hypothesis
BP. It tends to force water out of the capillaries into the interstitial space, by a process called:
Net filtration = (Forces favouring filtration) - (Forces opposing filtration)
Bicarbonate buffer system
Fastest of the three mechanisms
H⁺ + HCO₃⁻ ↔ H₂CO₃
Hydrogen ion + bicarbonate ion ↔ carbonic acid
Healthy ratio of bicarbonate ions to molecules of carbonic acid.
Acid-Base 20:1 ratios and its relation to Respiratory/Metabolic acidosis
20:1 is normal pH [bicarbonate ions
: molecules of carbonic acid]
20:4 is an excess of carbonic acid and is Respiratory acidosis
15:1 is a deficit of bicarbonate and is Metabolic acidosis
Respiratory Acidosis versus Metabolic Acidosis
Erythrocytes contain the enzyme carbonic anhydrase which rapidly converts carbonic acid to CO₂ and water. This process can go in both directions:
H₂CO₃ ↔ H₂O + CO₂
Acidosis in relation to kidney function
pH can be lowered (made more acidic) by excretion of bicarbonate ions, because there is less bicarbonate available to bind with the H⁺ ions:
↓ HCO₃⁻ → ↑ H⁺
3 mechanisms of H⁺ removal
1. Bicarbonate buffer system
3. Kidney function
Acidosis in relation to CO₂ stress
Hypoventilation leads to a build up of CO₂ which creates a 'stress' that shifts the following equation to the left, thus leading to an excess of H⁺ and Respiratory acidosis:
H⁺ + HCO₃⁻ ↔ H₂CO₃ ↔ H₂O + CO₂
So an increase of CO₂ leads to an increase of H⁺ and a drop in pH (acidosis):
↑ CO₂ ↔ ↑ H⁺
So you can see that an increase in respiration will lower CO₂ levels and thus lower the excess of H⁺, resolving the acidosis:
↑ Respiration → ↓ CO₂ → ↓ H⁺