Excretion to external environment (through kidneys, lungs, gills, digestive tract, or body surface, e.g., sweat, tears, sloughed skin) Metabolically consumed in body (irretrievably altered) Internal pool (extracellular fluid concentration) of a substance Reversible incorporation into more complex molecular structures (fulfills a specific function) Metabolically produced by body Input from external environment (through ingestion, inhalation, absorption through body surface, or artificial injection) Storage depots within body (no function other than storage) Outputs from internal pool (Inside body) Inputs to internal pool Fig. 13-1, p.573

Fig. 13-2, p.574

Table 13-1, p.575

Difference between ECF and ICF Cellular proteins Cellular organic osmolytes Unequal distribution of Na + and K +

Fig. 13-3, p.576

Osmotic and volume balance Osmotic problems threaten cells and animals 1.Evaporation of body water into air (eg. sweating or breathing) 2.Osmosis into or out of environment (eg. fresh water or saline water) 3.Freezing (locks up water in ice crystals and concentrates ions in unfrozen water) 4.Excretion (require water for waste removal) 5.Diseases (eg. Diabetes)

Fig. 13-4a, p.577

Fig. 13-4c, p.577

Fig. 13-5, p.578

Fig. 13-6, p.579

Fig. 13-7, p.579

Table 13-2a, p.580

Table 13-2b, p.580

Table 13-2c, p.581

Fig. 13-8, p.582

Fig , p.585

Fig , p.586 Medium <5 mOsm Removes much water and some salt via dilute urine Salts lost via feces Obtains salts through “chloride” cells in gills and with food Absorbs water through gills and skin Body fluids ca. 300 mOsm

Adaptation of Freshwater Animals Active transport of ions Hypotonic urine Lower internal osmolarities Low permeability of integument

Fig , p.587 H 2 O lost via respiration NaCI retention NaCI lost via excretion NaCI H 2 O retention Terrestrial animals Dietary H 2 O H2OH2O

ECF Hypertonicity 1.Insufficient water intake (eg. Drought, desert) 2.Excessive water loss (heavy sweating, panting, vomiting, diarrhea, diabetes, breath in dry air, exposed to salt water) 3.Drinking hypertonic saline water 4.Alcohol inhibits vasopressin secretion

ECF Hypotonicity 1. Intake of relatively more water than solutes 2. Retention of excess water without solute

Table 13-3, p.590

Relieves ECF volumeOsmolarity Arterial blood pressure ThirstVasopressin Hypothalamic osmoreceptors (dominant factor controlling thirst and vasopressin secretion) Left atrial volume receptors (important only in large changes in plasma volume/arterial pressure) Hypothalamic neurons Arteriolar vasoconstriction H2O intake H2O permeability of distal and collecting tubules H2O reabsorption Urine output Plasma osmolarityPlasma volume Fig , p.591

Table 13-4, p.592

Na + load in bodyArterial blood pressureAldosteroneGFRNa + reabsorbedNa + filtered Excretion of Na + and accompanying Cl 2 and fluid Conservation of NaCl and accompanying fluid ba Fig , p.593

Fig , p.594

Fig , p.596

Fig , p.596

Three pH defenders and Four pH buffer systems Three defense against pH changes 1.Chemical buffer systems 2.Respiratory control 3.Excretory control

Fig , p.599

Three pH defenders and Four pH buffer systems Four buffer systems 1.Carbon dioxide-bicarbonate buffer 2.Peptide and protein buffer 3.Hemoglobin buffer 4.Phosphate buffer

p.600

Plasma [H + ] (or plasma [CO 2 ]) H + secretionHCO 3 – conservationH + excretionHCO 3 – excretionPlasma [H + ]Plasma [HCO 3 – ] Fig , p.603

Fig , p.606