3. Homeostasis Flashcards
Temperature of human environments
Outside: -10 and +40 C
Inside: 37 C
PO2 of human environments
Outside: 160 mmHg
Inside: PaO2 95mmHg
PCO2 (breathing) of human environments
Outside: 0.23 mmHg
Inside: 40 mmHg
Water of human environments
Outside: 0-90 g/kg of air
Inside: 600 g/kg tissue
pH of Human environments
Outside: ?/variable
Inside: pH 7.4
Ability of the body to maintain a relatively stable internal environment despite external variances
Homeostasis
The study of the various mechanisms that maintain homeostasis
Physiology
Water distribution
40% body weight; 28L
2/3 of total body water
Intracellular water
Water distribution
20% body weight; 14L
1/3 of total body water
Extracellular water
Water distribution
Part of extracellular
15% body weight; 10.5L
Interstitial fluid and lymph water
Water distribution
Part of extracellular water
5% body weight; 3.5L
Plasma (blood) water
Water distribution
60% body weight; 42L
Total body water
Gender with 60% water
Men
More testosterone leads to less body fat
Gender with 50% water
Women
More body fat
Ionic composition of ICF and ECF
Intracellular: 14 Extracellular: 140
Na+
Ionic composition of ICF and ECF
Intracellular: 120 Extracellular: 4
K+
Ionic composition of ICF and ECF
Intracellular: 1x10^4 (very low) Extracellular: 2.5
Ca2+
Ionic composition of ICF and ECF
Intracellular: 20 Extracellular: 0.8
Mg2+
Ionic composition of ICF and ECF
Intracellular: 10 Extracellular: 105
Cl-
Ionic composition of ICF and ECF
Intracellular: 10 Extracellular: 24
HCO3-
Ionic composition of ICF and ECF
Intracellular: 7.1 Extracellular: 7.4
pH
Ionic composition of ICF and ECF
Intracellular: 290 Extracellular: 290
Osmolarity
Cerebrospinal, synovial, and pleural fluids
Different from Plasma
Interstitial fluids
Maintenance of a state that does not change with time, and energy expenditure may be necessary
Eg. ICF [Na+] < ECF [Na+] and concentrations are maintained at a set level balanced over time → requiring energy
Steady state
Na/K - ATPase pump
Solutes are in a steady state (body expends effort and energy to maintain uneven solute concentrations to allow optimal function)