Chapter 1 Homeostasis: The Foundation of Physiology

A single cell organism is in contact with the extracellular environment.

Multicellular organism is not in contact with the extracellular environment, needs to create internal environment. Homeostasis comes into play.

Intracellular fluid, Interstitial fluid, Plasma

External - Air or lumen of body cavities
Internal - Extracellular fluid, Plasma, Interstitial fluid.

Surrounds the cell

Compartment, represents a distinct space within the body, separated from the intracellular fluid by cell membranes.

Serves as buffer zone between outside world and intracellular fluid.

Results in an internal change, internal change results in loss of homeostasis. Organism attempts to compensate. If compensation fails then it results in illness or disease.

Regulates both plasma and interstitial fluid.

- Nutrients for cells, can be brought in from external environment.
- Blood O2 or glucose levels can be regulated via exchange.

- pH
- Body temperature
- Chemical
- Nutrient levels

- Lungs will regulate the blood O2 and CO2 levels
- Kidneys will regulate the salt and water content