Homeostasis Overview Quiz

Study Notes

Homeostasis is the maintenance of a stable internal environment within a narrow range despite external and internal changes.
Homeostasis is essential for survival and proper functioning of organisms.
Disease is caused by failed homeostatic mechanisms.
Homeostasis is critical for many physiological variables.
Regulation of Homeostasis is maintained by two systems:
- Nervous system - delivers messages quickly via electrical signals (neurons)
- Endocrine system - delivers messages slowly via chemical messengers (hormones)
Walter Cannon coined the term "homeostasis" in 1926.
Claude Bernard coined the term "internal milieu" in 1849 which laid the foundation for Cannon's work.

pH of blood: 7.35 - 7.45 or 7.00 - 7.50
Body temperature: 98.6℉ or 37℃
Blood glucose: 70 to 99 mg/dL
Blood oxygen levels: 95-100%
Blood carbon dioxide levels: 23-29 mmol/L
Blood pressure: Systolic pressure of 120 and diastolic pressure of 80 (120/80 mmHg)
Abnormalities in these values indicate the body is losing homeostasis and can lead to disease.

Electrolytes are substances that conduct electricity when dissolved in water.
"Ions" is an equivalent phrase for "electrolytes".
Electrolytes are critical for maintaining fluid balance, nerve function, and muscle contraction.
Electrolyte concentration differs between intracellular fluid and interstitial fluid.

Calcium (Ca2+): +2 charge
Sodium (Na+): +1 charge
Chloride (Cl−): -1 charge
Potassium (K+): +1 charge
Phosphate (PO43−): -3 charge
Bicarbonate (HCO3−): -1 charge
Magnesium (Mg2+): +2 charge
Sulfate (SO42−): -2 charge
Hydronium/Hydrogen (H3O+ or H+): +1 charge
Note: Not all electrolytes are charged atoms of elements.
- Polyatomic ions are ions composed of multiple atoms, such as PO43−, HCO3−, and SO42−.