![]() ![]() Antidiuretic hormone (ADH) (also called vasopressin) Urine solutes must be flushed out of the body in waterġ.Kidneys excrete 900-1200 mOsm of solutes to maintain blood homeostasis.Obligatory water loss reflects the fact that: Water that accompanies undigested food residues in feces.Insensible water losses from lungs and skin.Activation of stomach and intestinal stretch receptors.Moistening of the mucosa of the mouth and throat.Feedback signals that inhibit the thirst centers include:.Thirst is quenched as soon as we begin to drink water.Baroreceptor input, angiotensin II, and other stimuli.The hypothalamic thirst center is stimulated by:.Increases in plasma osmolality trigger thirst and release of antidiuretic hormone ( ADH).Insensible losses through the skin and lungs (28%).Metabolic water or water of oxidation (10%).Ingested fluid (60%) and solid food (30%).To remain properly hydrated, water intake must equal water output.Body content of water or electrolytes rises if intake exceeds outflow.All water moves passively in response to osmotic gradients.Response is to changes in plasma volume or osmotic concentrations.No receptors directly monitor fluid or electrolyte balance.Homeostatic mechanisms respond to changes in ECF.If ECF becomes hypotonic relative to ICF, water moves from ECF into cells.If ECF becomes hypertonic relative to ICF, water moves from ICF to ECF.Exchanges between interstitial and intracellular fluids due to the selective permeability of the cellular membranes.Net leakage of fluid from the blood is picked up by lymphatic vessels and returned to the bloodstream.Compartmental exchange is regulated by osmotic and hydrostatic pressures.Osmolalities of all body fluids are equal changes in solute concentrations are quickly followed by osmotic changes.Plasma is the only fluid that circulates throughout the body and links external and internal environments.Nutrients, respiratory gases, and wastes move unidirectionally.Ion fluxes are restricted and move selectively by active transport.Electrolytes determine the chemical and physical reactions of fluids.This reflects the activity of cellular ATP-dependent sodium-potassium pumps.Sodium and potassium concentrations in extra- and intracellular fluids are nearly opposites.ECFs are similar except for the high protein content of plasma.Water moves according to osmotic gradientsĮach fluid compartment of the body has a distinctive pattern of electrolytes.Electrolytes have greater osmotic power than nonelectrolytes.Nonelectrolytes – examples include glucose, lipids, creatinine, and urea.Electrolytes are inorganic salts, all acids and bases, and some proteins.Metabolic water produced during dehydration synthesis of anabolism.Ingested foods and liquids (preformed water).Water is the main component of all body fluids making up 45-75% of the total body weight.Blood Plasma - 20% of ECF found in circulatory system.Humor and vitreous body of eyes, between serous and visceral membranes, glomerular filtrate of kidneys. Interstitial Fluid - 80% of ECF is found in localized areas: lymph, cerebrospinal fluid, synovial fluid, aqueous.Extracellular Fluid (ECF) - all fluids found outside the cells, comprises 40% of all body fluids.Intracellular Fluid (ICF) - fluid found in the cells (cytoplasm, nucleoplasm) comprises 60% of all body fluids.Respiratory/Renal Compensation/Metabolic Acidosisįluid Balance- The amount of water gained each day equals the amount lostĮlectrolyte Balance - The ions gained each day equals the ions lostĪcid-Base Balance - Hydrogen ion (H +) gain is offset by their loss Regulation of Sodium Balance: Aldosterone Associate Degree Nursing Physiology Review ![]()
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