Biology 346 General Physiology Dr. Tony Serino Introduction Biology 346 General Physiology Dr. Tony Serino

Physiology Physiology –study of body mechanisms (homeostasis)

Homeostasis Maintenance of a constant internal environment Uses a reflex arc to self regulate Reflex functions to maintain a certain set point with a narrow physiological range

Homeostasis Reflex

Homeostatic Pathways

Factors Affecting Homeostasis Feedback –negative or positive Feed-forward regulation Acclimatization Biorhythms

Internal vs. External Environment

Atmosphere External Environment Composition: 78% N2, 20% O2, 0.3% CO2 Pressure at Sea Level = 101kPa (760mm Hg) Pressure decline by half for every 5500m increase in altitude Partial Pressure (PP) of a gas = its fractional percent * total press. Temperature range: -70oC to 50oC; declines 6-10oC per 1000m altitude from sea level

Aquatic Environments Composition: salts, ions, dissolved gases Temp.: ~0-100oC Pressure increases 1 atm per 10 m depth Mean depth of ocean is 3800m Most light absorbed by 8m depth

Terrestrial Environments Biomes: classed by water abundance, temp. and dominant community Subterranean environments might have lower oxygen and higher carbon dioxide levels and of course little to no light sources

Internal Environment Composition by weight: 60-90% water, 18% protein, 15% fat, 7% mineral 63% H, 25% O, 9.5% C, 1.4% N Minor elements (<1%) Trace elements (<0.01%)

Body Fluids Transcellular fluids are filtrates of the plasma

Important Ions