Unit 1.3 - Fluid Compartments and Homeostasis

Body Fluid Compartments

Intracellular (high K)

Extracellular (high Na) - Interstitial fluid, plasma, trancellular fluid.

Fluid Distribution

60% of body mass is fluids (55% in women), 2/3 of fluid is intracellular.

Homeostasis

To maintain nearly constant conditions in the internal environment (extracellular fluid).

Maintained through positive and negative feedback.

Homeostasis Feedback Mechanism

1. Senses the parameter using sensor/receptor

2. Compares the parameters to the normal value

3. Sensor/receptor produces an output signal to a control center

4. Output signal from the control center activates the effector to bring the parameter closer to normal

Positive vs. Negative Feedback

Positive Feedback - the effector increases the stimulus intensity.

Negative Feedback - the effector decreases the stimulus intensity.