Water (PDF)

WATER  Water H2O.1  Tasteless, clear, odoulress fluid.  Humans c.‫ع‬ ‫عع‬ ٦‫غ‬. ‫اا‬ ‫غاغ‬ ‫اغت‬ ‫دنتننا`^ااده‬.‫ن& نظدددن...

WATER  Water H2O.1  Tasteless, clear, odoulress fluid.  Humans c.‫ع‬ ‫عع‬ ٦‫غ‬. ‫اا‬ ‫غاغ‬ ‫اغت‬ ‫دنتننا`^ااده‬.‫ن& نظدددنجظظظهزعمممكممظدتت‬ n servive for 4-6 weeks without food, but for only few days‫ج‬ without water  :Biological importance of water Water is the principle chemical constituents of the body. It represents -1.about 65% of the body weight in an adult male (55% in female) Water is the medium in which chemical reactions takes place inside -2.the cells.It is the universal solvent in the body -3 It is the important in regulation and maintenance of constant body -4.temperature It is the principle constituent of all body fluids “blood, lymph, tissue -5.”fluid.It is the transporting agent of the body -6 ,Water is the main constituent of secretions as saliva, gastric juice -7.bile, intestinal juice, sweat.”Water is the main constituent of the excretory fluid “urine -8  The reference daily intake of :water The daily needs of water depend on the water losses. Water losses are affected by the amount of physical exercise, the environmental.temperature and humidity and the condition of the subject  The recommended daily intake is about 2500 ml – 3000 ml/day) for.male  Normally the water input “intake should equal the water ”output losses Input = output  Water input=intake Water supply occurs through the following: a) Ingestion of fluids “drinking" = 1200 ml/day b) Ingestion of goods = 1000 ml/day c) Metabolic water = 300 ml/day Total = 2500 ml/day - Ingestion of fluids “drinking” is regulated by thirst. Water insufficiency increase osmolarity of extra cellular fluid stimulate osmoreceptors in the brain increase thirst sensation  Water output: Water losses or output occur through the following: a) Urine = 750-1500 ml/day b) Perspiration “sweating” + water vapor in expired air = 500-800 ml/day “insensible fluid losses as they cannot be easily measured. c) Water in the faces = 100-150 ml/day The sum of output 2500 ml/day   Water output is regulated by: a) ADH = Anti Diuretic Hormone = Vasopressin ADH is secreted by the hypothalamus and stored and released by the posterior pituitary gland. - If the body is deficient in water as in dehydration, the secretion of ADH increases to suppress “decreases” the volume of urine. - If the fluid “water: level in the body is increased, “Hydration”, the secretion of ADH is decreased and the urine volume increases. b) Aldosterone Hormone: The decreases in water in the body  Stimulates Rennin-angiotensin system in the kidney  Stimulates Secretion of Aldosterone hormone from the adrenal cortex which.stimulate the absorption of Na+ water form renal Tubules