Inputs to internal pool Outputs from internal pool

Inputs to internal pool Outputs from internal pool (Inside body) Input from external environment (through ingestion, inhalation, absorption through body surface, or artificial injection) Metabolically produced by body Storage depots within body (no function other than storage) Internal pool (extracellular fluid concentration) of a substance 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) Reversible incorporation into more complex molecular structures (fulfills a specific function) 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 -4 a, p. 577

Fig. 13 -4 c, p. 577

Fig. 13 -5, p. 578

Fig. 13 -6, p. 579

Fig. 13 -7, p. 579

Table 13 -2 a, p. 580

Table 13 -2 b, p. 580

Table 13 -2 c, p. 581

Fig. 13 -8, p. 582

Fig. 13 -10, p. 585

Medium <5 m. Osm Absorbs water through gills and skin Body fluids ca. 300 m. Osm Obtains salts through “chloride” cells in gills and with food Salts lost via feces Removes much water and some salt via dilute urine Fig. 13 -11, p. 586

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

Terrestrial animals Dietary H 2 O Na. CI H 2 O retention Na. CI retention H 2 O lost via respiration H 2 O Na. CI lost via excretion Fig. 13 -12, p. 587

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

ECF volume Relieves Osmolarity + Hypothalamic osmoreceptors (dominant factor controlling thirst and vasopressin secretion) + Arterial blood pressure + Left atrial volume receptors (important only in large changes in plasma volume/arterial pressure) Hypothalamic neurons Thirst Relieves + Vasopressin Arteriolar vasoconstriction H 2 O intake H 2 O permeability of distal and collecting tubules H 2 O reabsorption Urine output Plasma osmolarity Plasma volume Fig. 13 -13, p. 591

Table 13 -4, p. 592

Na+ load in body Arterial blood pressure a b GFR Aldosterone Na+ filtered Na+ reabsorbed Excretion of Na+ and accompanying Cl 2 and fluid Conservation of Na. Cl and accompanying fluid Fig. 13 -14, p. 593

Fig. 13 -15, p. 594

Fig. 13 -16, p. 596

Fig. 13 -17, p. 596

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

Fig. 13 -19, p. 599

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

p. 600

Plasma [H+] (or plasma [CO 2]) H+ secretion HCO 3– conservation H+ excretion HCO 3– excretion Plasma [H+] Plasma [HCO 3–] Fig. 13 -20, p. 603

Fig. 13 -23, p. 606