from audio: Fund. Body Fuids 1&2

These flashcards cover the key concepts presented in Chris Baylis' lecture on body fluid compartments, including definitions, mechanisms, and physiological implications.

What are the two main compartments of body fluid?

Intracellular and extracellular fluids.

How is body fluid volume estimated in a lean individual?

About 60% of body weight is water.

How much water is typically found inside cells?

About two thirds of total water or 40% of body weight.

What fluid surrounds the cells and constitutes part of extracellular fluid?

Interstitial fluid.

What is the approximate plasma volume of a 70 kg man?

About 3.5 liters.

Plasma is ¼ of ECF, interstitial fluid is ¾ of ECF.

ECF is 1/3 of total body water (or 40% of body weight). So 70 kg x 0.6=42 L of total body water.

42 L x 1/3 = 14 L

14 L x ¼ = 3.5 L

What are aquaporins?

Pores in the cell membrane that allow water to pass.

What principle is used to measure volumes of specific fluid compartments?

The dilution principle.

What happens to a cell placed in a hypertonic solution?

The cell shrinks as water exits the cell.

What causes hemolysis of red blood cells?

Water entering the cell when placed in a hypotonic solution.

What is osmolality?

The number of free particles in solution.

What is the typical osmolality of body fluids in milliosmoles?

Around 290 to 300 milliosmoles.

What happens to plasma volume during extracellular fluid volume contraction?

Plasma volume decreases, leading to hemoconcentration.

What occurs when an individual is lost in the desert and loses more water than salt?

Extracellular fluid volume decreases and osmolality increases.

What is the recommended treatment for a dehydrated unconscious person?

Administer IV fluids, preferably 5% glucose solution.

How does sodium chloride affect cell volume?

It is effectively impermeable, keeping water in the extracellular fluid.

What do you measure to assess extracellular fluid volume contraction?

Changes in plasma sodium concentration.

What is an example of a clinically relevant volume derangement when someone loses more solute than water? What happens to the intracellular fluid?

Hypotonic contraction leading to increased intracellular fluid volume.

What is the distribution of electrolytes between intracellular and extracellular fluids?

High potassium and low sodium inside cells; high sodium and low potassium outside cells.