Tortora, Ebaa M Alzayadneh, DDS, PhD Body Fluids & Blood Tortora, Ebaa M Alzayadneh, DDS, PhD University of Jordan

Body Fluid Compartments Barriers 1-plasma membrane 2- blood vessel wall 1L- has a mass of 1kg 40% 20%

Q? Calculate volume of blood plasma in a lean 60 kg female? University of Jordan

Source of daily water normal conditions University of Jordan

Renal excretion of water is regulated Route ml/day Water intake Fluid In food Metabolic product Total Water output Insensible Sweat Feces Urine 1200 1000 300 2500 700 100 200 1500 Water loss Normal temp. Hot weather Prolonged exercise Insensible loss Skin Lungs Sweat Feces Urine Total loss Intake 350 100 200 1500 2500 250 1400 1200 3400 650 5000 500 6700

Regulation of water gain (Intake) Metabolic water volume : depends on level of aerobic cellular respiration (ATP demand). Mainly; water intake (drinking): Thirst center in the hypothalamus is stimulated by Blood high osmolality (Osmoreceptors) neurons in the mouth Baroreceptors in the heart and blood vessels Dehydration occurs when water loss is greater than water intake. Decline in blood pressure stimulates RAS (Renin Angiotensin System) Angiotensin II RAS: Renin Angiotensin System University of Jordan

Regulation of water and solute loss Although loss of water by sweat and exhalation is increased during exercise, elimination of excess water and solutes is mainly controlled by urine output. The main factor that determines body fluids volume is the extent of urinary NaCl loss (Water follows solutes). Variable NaCl intake- variable urinary NaCl loss to maintain homeostasis. University of Jordan

Regulation of water and solute loss increased NaCl intake leads to increased blood volume by increased water movement from intracellular to ICF. The three most important hormones that regulate Na and Cl excretion are Angiotensin II, Aldosterone and ANP. Ang II : increases NaCl reabsorption in the kidney, water follows. Aldosterone: increases NaCl reabsorption in the kidney, water follows. Atrial Natruitic PeptideANP: decreases NaCl and water reabsorption; thus decrease blood volume. (Natriuresis) The main hormone that regulate water loss is antidiuretic hormone (ADH) which decreases water loss from kidney. University of Jordan