Water and Salt Physiology (Chapters 26
and 27)
I. The importance of animal body fluids 664
60% of body weight
A. Intracellular vs. extracellular (interstitial, blood and plasma)
B. Ionic component affects conformations of proteins, maintain correct electrical gradient
across cell membrane-- key in nerve impulse transmission
C. Active control exerted by animals over their fluid composition (fresh water vs. sea water)
II. The relations among body fluids 665
A. Exchange of water and ions between compartments across cell membranes
water and ion channels-- osmosis, diffusion, facilitated diffusion or active transport
B. Transport through holes in endothelial cells
C. Interstitial fluids similar to plasma in osmotic pressure and ionic composition
III. The types of regulation and conformity 665
A. Osmotic regulation--maintain a steady osmotic pressure in the blood plasma
B. Ionic regulation of any particular inorganic ions--maintain a steady conc. of that ion
C. Volume regulation-- maintain a steady volume of water intracellularly as a whole
IV. Natural aquatic environments 667
A. Animals living in open ocean-- 1000 mOsm.
B. Animals living in fresh water-- 0.5 -15 mOsm
'Hard' vs. 'soft' water-- Ca++ concentration
C. Brackish water--ocean water + fresh water-- estuaries, 15 to 850 mOsm
V. Organs of blood regulation 671
A. U/P ratio, if U/P =1, isoosmotic urine; if U/P <1, hyposmotic urine, if U/P>1, hyperosomotic urine
B. Kidney function--regulate composition of blood plasma
C. Kidneys can carry out separate functions--
i.e. they can carry out ionic regulation independently of osmotic regulation
VI. Food and drinking water 675
A. Predators regulates body osmolality according to their food
Marine animals and teleost are hyposmotic to seawater
Marine invertebrates are isosmotic to seawater
B. Salty drinking water-- does not provide water
C. Halophytes-- salt plants, salt exceeds that of seawater by as much as 50%
D. Air-dried foods contain water-- equilibrate with air moisture
Air humidity increases at night and below ground
VII. Metabolic water produced by catabolic reactions 674
A. Produced by chemical stoichiometry of the oxidative of organic molecules
B. Matters most in animals that conserve water effectively
C. Obligatory water losses-- respiration, urinary and fecal components
VIII. Cell volume regulation 676-677 see Figures
Water
and salt physiology of animals in their environments (chapter 27)
I. Animals in freshwater 681
II. Animals in ocean 687
III. Animals that face changes in salinity 696
IV. Responses to drying of the habitat in aquatic animals 699
V.
Animals on land:
Fundamental physiological principles 70
A.
Water gain- drinking, in the food, metabolites,
osmotic
flux across the body surface, and
absorption of water vapor from air
C6 H12
O6 + 6 O2 ---> 6CO2 + 6
H 2O+ 34 ATP
1 g of glucose is oxidized, 0.6 g of H2O is formed
1 g of fat yields 1.1 g of water; protein- .3g H2O
B. Water loss- in
urine, feces, by osmotic flux across the body surface, evaporation from skin
and lungs, and secretions from excretory glands
VI. Case studies 707