module 4 - acids-bases, electrolytes, fluids

Oncotic Pressure and Fluid Balance

• Oncotic pressure drives water and low molecular mass solutes out of the capillary
• The major cation in the extracellular fluid (ECF) is sodium
• Water and low molecular mass solutes move out of the capillary due to hydrostatic pressure

Osmolality and pH

• Osmolality increases if serum glucose concentration is high
• The formula to calculate plasma osmolality is not provided (but will be discussed later)
• The major anion in the intracellular fluid (ICF) is not provided (but will be discussed later)

Sodium and pH Regulation

• Sodium plays a crucial role in the body, but excessive sodium leads to volume expansion in the extracellular fluid (ECF)
• The body system that excretes acid in the form of CO2 is the respiratory system
• The pH range for arterial blood is not provided (but will be discussed later)

Acid-Base Balance

• The two broad classes of acid-base disorders are respiratory and metabolic disorders
• The pKa value of His is not provided (but will be discussed later)
• Acidosis is a consequence of an imbalance in the bicarbonate-carbonic acid buffer system
• The net result of an imbalance in the bicarbonate-carbonic acid buffer system is a change in pH

Osmosis and Tonicity

• Osmosis is the movement of water across cell membranes from high to low concentration
• Osmotic potential is related to the concentration of solutes in a solution
• Tonicity is the ability of a solution to change the volume of a cell
• Isotonic solutions have the same concentration of solutes as the cell
• Hypertonic solutions have a higher concentration of solutes than the cell
• The formula for osmolality is not provided (but will be discussed later)
• The main driving force for fluid shifts between the extracellular fluid (ECF) and intracellular fluid (ICF) is osmotic pressure
• Osmolality and osmolarity differ in their units of measurement (osmolality is in osmoles per kilogram of solvent, osmolarity is in osmoles per liter of solution)
• A cell in a hypotonic solution will swell and potentially lyse due to an influx of water