Fluid, Electrolyte, and Acid-Base Balance

• How many percent of water accounts of your body weight for men?

  60 percent
• How many percent of water accounts of your body weight for women?

  50 percent
• How many percent of water accounts of your body weight for babies?

  75 percent
• How many percent of water accounts of your body weight in old age?

  45 percent
• Water - the universal body solvent
• Intracellular Fluid - about 2/3 of body fluid; is contained within the living cells
• Extracellular Fluid - includes all body plasma, interstitial fluid between cells, lymph, and transcellular fluid
• Thirst Mechanism - the driving force for water intake
• Osmoreceptors - are highly sensitive cells in the hypothalamus that respond to changes in water concentration
• Antidiuretic Hormone - produces by posterior pituitary gland, which prevents excessive water loss in the urine
• Aldosterone - a second hormone that helps to regulates blood composition and blood volume by acting on the kidney
• Aldosterone - the major factor regulating sodium ion content of the ECF and in the process helps regulate the concentration of other ions as well
• Sodium ions - are the electrolytes most responsible for osmotic water flow
• What organ produces aldosterone?

  Adrenal Cortex
• Juxtaglomerular Apparatus - consists of a complex of modified smooth muscle cells; the naming reflects its location close to glomerulus
• Angiotensin II - acts directly on the blood vessels to cause vasoconstriction and on the adrenal cortical cells to promote aldosterone release
• Baroreceptors - alert sympathetic nervous system centers of the brain to cause vasoconstriction; this mechanism, however, focuses on blood pressure regulation
• What is the normal blood pH level?

  7.35 to 7.45
• Alkalosis - when the pH of arterial blood rises above 7.45
• Acidosis - a drop in the arterial pH to below 7.35
• Chemical Buffers - are systems of one or two molecules that act to prevent dramatic changes in the hydrogen ion concentration when acids or bases are added
• What are the three major chemical buffer systems of the body?

  Bicarbonate, Phosphate, Protein
• Bicarbonate Buffer System - a mixture of carbonic acid and its salt, sodium bicarbonate