Fluid & Electrolyte Balance

Where is intracellular fluid located?

Inside the cell

How much body fluid is intracellular fluid?

2/3 (about 40% of body weight)

What is the major electrolyte in intracellular fluid?

Potassium

Where is extracellular fluid located?

Outside the cell

How much body fluid is extracellular fluid?

1/3 (about 20% of body weight)

What are the major electrolytes in extracellular fluid?

Sodium and Chloride

What is transcellular fluid a part of?

1% of extracellular fluid

What types of fluid are transcellular?

Cerebrospinal, peritoneal, pericardial, and pleural fluids

What effect dooes isotonic solutions have on cell size?

No change

What effect does hypotonic solutions have on cell size?

The cell swells

What effect does hypertonic solutions have on cell size?

The cell shrinks

What is the effective circulating volume’s role in controlling body water levels and sodium concentration?

• Measures the portion of the ECF that is reaching and effectively perfusing tissues, NOT just total blood volume

• Triggers fluid-sparing responses

What is the sympathetic nervous system’s role in controlling body water levels and sodium concentration?

• Vasoconstricts to increase BP

• Conserves sodium and water

• Stimulated renin release

What is the renin-angiotensin-aldosterone system’s role in controlling body water levels and sodium concentration?

• Renin —> Angiotensin II —> Aldosterone

• Raises BP and makes you thirsty

What is the antidiuretic hormone’s role in controlling body water levels and sodium concentration?

• Retains water but not sodium

• Released with low volume/pressure

• Tells kidneys so hold onto water, making the