LIFESCI 2 Lecture Notes - Lecture 13: Extracellular Fluid, Homeostasis, Sodium Chloride
Document Summary
Multicellular organisms and extracellular fluid- evolution: extracellular fluid around each cell provided nutrients, communication, and disposal of waste, became specialized- h20 and nacl, nutrients, gametes. Need: set point, feedback info, error signal. Neg: reverse error signal back to set point. Feedforward- anticipates internal changes and changes set point (birth) Gain heat from outside sources and produce or actively lose heat. Differences: resting metabolic rate, total energy expended at rest, response to temp change. Heat transfers: radiation- through radiation, evaporation- through water, conduction- direct contact, convection- through surrounding medium(fire water egg) Thermoneutral zone- metabolic rate is low and independent of temp. Basal metabolic rate- resting rate in thermoneutral zone correlates with body size and temp. When cooling further and further, different set points give different responses. Magnitude cooled proportional to heat metabolically produced. Can altar set points with environmental temp, sleep vs waking. Fevers- pyrogens cause increase in temp and hypothalamic set point (aspirin and tylenol reduce set point)
