Chapter 9 Outline Nutrients Involved in Fluid and Electrolyte Balance 1 Body Fluids Liquid portion of cells and tissues a b Able to move freely and adapt to shapes c About 50 70 of healthy adult body weight d Intracellular fluid ICF within the cell i 2 3 of body fluid i ii Interstitial fluid muscle liver Intravascular fluid e Extracellular fluid ECF outside the cell 1 3 of body fluid between cells that make up a particular tissue or organ plasma water in the blood and lymph 1 transports blood cells within arteries veins and capillaries Fluid composition of tissue varies by f g 1 Tissue type fluid content is lean tissue 70 vs fatty tissue 10 20 h 2 Gender males have more lean tissue i j 3 Age decrease in body water results partly from loss of lean tissue as people age Elderly can have as low as 50 water weight 2 Electrolytes a Gatorade monopotassium phosphate b Dissolved substances solutes that disassociate in solution into electrically charged particles called ions i Positive charge Na K ii Negative charge Cl HPO4 2 c Predominant electrolytes i Extracellular sodium chloride ii Intracellular potassium phosphorus 3 Functions of Body Fluids a Fluids dissolve and transport substances i Water is an excellent solvent dissolves a variety of substances AAs glucose ii Water soluble substances are readily transported in the bloodstream amino acids glucose vitamins minerals medications iii Fatty substances must be attached to or surrounded by water soluble proteins minerals such as b Fluids account for blood volume essential for healthful blood volume i Proper body fluid levels ii Blood pressure increases when blood volume rises 1 Risk factor for stroke and heart disease iii Kidneys help regulate blood volume and blood pressure iv Change in blood volume pressure concentration of solutes change in volume concentration of urine c Antidiuretic hormone ADH stimulates the kidneys to reabsorb water reducing urine d Kidney responds to blood pressure i Releases Renin is an angiotensinogenase 1 e Angiotensinogen precursor from liver released f Angiotensin II vasoconstrictor increases blood pressure g Aldosterone signals the kidneys to retain sodium and chloride thereby retaining water increasing blood pressure and decreasing urine output h Fluids help maintain body temperature i Body temperature must be within a safe range ii Water has a high capacity for heat which means that can increase body temperature 1 A high amount of energy is needed to raise the temp iii Sweating releases heat as the evaporation of water from the skin cools the skin and blood i Protect and lubricate tissues i Cerebrospinal fluid protects the brain and spinal cord ii Amniotic fluid protects the fetus iii Synovial fluid lubricates joints iv Tears cleanse and lubricate eyes v Saliva moistens food for swallowing 4 Functions of Electrolytes a Electrolytes help regulate fluid balance i Cell membranes permeable to water but not freely permeable to electrolytes ii Water moves by osmosis iii Low concentration to high concentration iv A means to control movement of water into and out of the cells v Osmotic pressure keeps electrolytes from drawing liquid toward them across a semi permeable membrane b Cells Regulate osmotic pressure Isotonic stabilized i ii Hypotonic swells bursts cell death iii Hypertonic shrinks cell death c Electrolytes enable nerves to respond to stimuli i Nerve impulses are initiated at nerve cell membranes in response to a change in electrical charge across the membrane ii Depolarization Action Potential Repolarization iii Na K pump ensure that nerve impulses are generated transmitted and completed d Muscle Contractions i Stimulated to contract in response to stimulation of nerve cells ii iii Muscles can relax after contraction once the electrical signal is complete and Influx of Ca2 into the muscle from the extracellular space contraction calcium is pumped out of the muscle cell 5 Fluid Balance a Thirst mechanism hypothalamus prompts us to drink when it is stimulated by Increased concentration of salt and other dissolved substances in the blood i ii A reduction in blood volume and blood pressure 2 1 e g profuse sweating vomiting diarrhea or low fluid intake iii Dry mouth and throat from reduced saliva b ADH signals the kidneys to retain water c Body Gains Fluids i Water enters the body through beverages ii Some foods have very high water content iii Water from metabolic reactions hydrolysis and condensation contributes 10 14 of daily water needs d Sensible water loss i Kidneys excrete water as urine ii Sweat during exercise or in hot environment iii Some can lose as much as 4 pounds of sweat hour e Insensible water loss not perceived i Skin not sweating or lungs during exhalation 1 Significant loss f Lose 1L per day i Illness injury exercise high altitude high respiration rate pregnancy breastfeeding diuretics 6 Water a Water b Essential for life can only go a few days without it c Amount needed varies with gender age body size health status physical activity level environment d Sources of drinking water carbonated mineral distilled purified tap bottled e Men 3 7L total 1 gallon f Women 2 7L total g What happens if we drink too much water i Becoming overhydrated is rare ii Dilution of blood sodium concentration h What happens if we don t drink enough water i Dehydration based on of weight loss ii One of the leading causes of death around the world 7 Sodium a Major electrolyte in ECF extracellular fluid i Affects 1 Blood pressure and acid base balance 2 Nerve impulse transmission 3 Muscle contraction and relaxation 4 Glucose absorption active transport from the small intestine a Na dependent transporters b AI 1 500 mg most recommend 2 300 mg day processed foods are high in sodium i High blood pressure more common from high sodium diets ii Excessive intake may increase urinary calcium excretion in some people which in turn may increase the risk for bone loss 3 8 Potassium c Hypernatremia too much is an abnormally high blood sodium concentration i Patients with congestive heart failure or kidney disease cannot sodium ii Causes high blood volume edema swelling and high blood pressure d Hyponatremia too little is an abnormally low blood sodium level i From prolonged sweating vomiting diarrhea ii Symptoms headaches dizziness fatigue nausea vomiting and muscle cramps iii If untreated seizures coma and death iv Here is where Gatorade becomes useful a Major electrolyte in intracellular fluid b Together with sodium
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