Fluid and Electrolytes 2024 Week 8 Chapter 8 PDF

CHAPTER 8 FLUID & ELECTROLYTE BALANCE LOCATION AND COMPOSITION OF BODY FLUIDS Body Fluids – liquid portion of our cells & tissues 50-70% of healthy adult body weight is fluid Fluid composition of body; Intracellular Fluid - found within cells (cytosol)...

CHAPTER 8 FLUID & ELECTROLYTE BALANCE LOCATION AND COMPOSITION OF BODY FLUIDS Body Fluids – liquid portion of our cells & tissues 50-70% of healthy adult body weight is fluid Fluid composition of body; Intracellular Fluid - found within cells (cytosol) Extracellular Fluid –found outside cells Interstitial fluid - tissue fluid surrounding cells Intravascular fluid – fluid within vessels (blood or lymph) FLUID COMPOSITION VARIES… Tissue type (leaner tissue has more fluid) Muscle tissue is lean (70% fluid by weight) Adipose tissue is not (10-20% fluid by weight) Gender influences fluid water retention Males have more lean muscle Women have more body fat (reproductive hormones) Age As we age lean muscle tissue decreases BODY FLUID COMPOSITION ….WHAT EXACTLY IS IT??? 1. Water (H20) Essential to life, yet cells unable to survive with water alone… 2. Solutes – dissolved substances Sodium, potassium, chloride, phosphorus, calcium & magnesium Also essential to life WHAT ARE ELECTROLYTES? Water is the universal solvent  can dissolve sugars, amino acids, vitamins, and minerals  Water is polar attracted to different parts of molecules, pulling them apart Solutes dissolve in water  Mineral salts (NaCl, KCl etc.) consumed in diet  Water disassociates salts into elements having a charge… called ions (referred to as electrolytes)!! Sodium (Na+) Chloride (Cl-) Potassium (K+) CONTRIBUTIONS OF WATER AND ELECTROLYTES TO HUMAN FUNCTIONING 7-6 WATER TRANSPORTATION Whole blood composed primarily of water  Plasma makes up 55% of whole blood  Water soluble nutrients (glucose)  Gases (oxygen)  Waste  Hormones Fat soluble vitamins - attached / surrounded by water soluble proteins WATER BLOOD VOLUME & BLOOD PRESSURE  Blood Volume = plasma + RBC + WBC (male-5-6L, females-4-5L) Increased blood volume …greater fluid being pressed against the walls of the arteries … causes increase blood pressure (stroke & heart disease) Decreased blood volume …less fluid pressed against the walls …causes low blood pressure (leads to lethargy, confusion) WATER BODY TEMPERATURE REGULATION Water has a high specific heat capacity  lots of external energy req. to raise temperature of water  body fluids maintain stable temperature Body fluids keep us cool  Blood vessels dilate - increase blood flow to skin surface  Sweat glands activate to produce sweat (mostly water) for evaporation WATER LUBRICATION & PROTECTION Lubrication  Joints (synovial fluid) & eye tissue  Mucin from salivary glands Cerebrospinal fluid protects the brain & spinal cord Amniotic fluid protects the fetus Pleural cavity surrounding the lungs ELECTROLYTES SUPPORT MANY BODY FUNCTIONS 7-11 ELECTROLYTES a solute that carries a charge and has capacity to conduct electrical impulses in the human body  Na+, Ca++, Cl-, K+ & HPO42- carry charges ELECTROLYTES REGULATE FLUID BALANCE Electrolytes attract water molecules  Water moves via osmosis towards high solute concentration (due to charge of electrolyte) ELECTROLYTES NERVE IMPULSE CONDUCTION  Depolarization Influx of Na+ into the cell making cell less negative If enough Na+ moves over…an action potential is triggered  Repolarization Outflow of K⁺ out of the cell repolarizes the membrane & returns cells to resting state 7-14 ELECTROLYTES MUSCLE CONTRACTION Action potential triggers release of Ca+ ions stored in the endoplasmic reticulum of the muscle cell 7-15 HOW DOES THE BODY MAINTAIN FLUID BALANCE? HYPOTHALAMUS REGULATES THIRST  Bundle of neurons (cells) in hypothalamus detect change in causes you to consciously desire fluids.  Ideal solute: water ratio is ~ 9 g of Na+ / L of water (equivalent to physiological saline) THIRST MECHANISM TRIGGERED BY Three process 1. Tissue dryness (mouth/throat) – reflects lowering fluid in bloodstream  Stimulates reduction of saliva production 2. Osmoreceptors (specialized cells of the hypothalamus) detect changes in extracellular tonicity stimulating; Physical search for water Release of antidiuretic hormone (ADH) – triggers kidney to reduce water output THIRST MECHANISM TRIGGERS CONTINUED…. 3. Baroreceptors – neurons lining blood vessels  → Baroreceptors detect decrease in extracellular fluid (internal bleeding / vomiting) send message to hypothalamus → hypothalamus sends message to the kidneys → release renin (enzyme)  Renin works on converting Angiotensinogen (liver molecule found in plasma) to Angiotensin (hormone)  Angiotensin regulates blood pressure by constricting blood vessels and stimulating water and salt reabsorption FLUID GAIN VS FLUID LOSS 7-20 FLUID GAINS Fluid (60%) + Food (30%) + Metabolic (10%)  Most through beverages (tap water, juices, pop, tea)  Some foods - very high-water content (fruits & veggies > 90% water)  Metabolic water – product of chemical reactions ATP & Water produced when breaking fat, carbs & proteins FLUID LOSS Urine (60%) + Sweating (5%) + Feces (5%) + Insensible (30%) Urine - kidneys maintain fluid balance by excreting/retaining water Sweating - water is lost to evaporation Feces -~150-200 mL per day loss of water as intestinal tract reabsorbs Insensible water evaporation through the skin (not sweat) evaporation through lungs during exhalation/speech. rest UL NATURAL SOURCES OF SODIUM Tomato (11 mg of Na) vs canned tomatoes (355 mg of Na)  = approx. 5000 mg SODIUM CONTENT OF FOOD AI 1.5 g/day (1500 mg/day) UL 2.3 g/day (2300 mg/day)  SODIUM TOXICITY AND DEFICIENCY Hypertension tends to occur in people who consume high sodium/ low potassium diets seems to pose the greatest risk…  Hypernatremia High blood sodium level – causing high blood volume due to water moving in from extracellular environment towards high solute concentration healthy kidneys excrete excess sodium individuals with congestive heart failure / kidney disease unable to excrete excess sodium  Hyponatremia Low blood sodium level Headaches, dizziness, nausea, vomiting POTASSIUM  Considered an essential ions  major +ve charged electrolyte in intracellular fluid  Na-K pump (cell membrane) maintains electrolyte balance across plasma membrane maintains fluid balance, blood-pressure & acid base balance assists in nerve transmission & muscle contraction  assists in the absorption/ transport of nutrients Glucose uses Na-K pump (active transport) POTASSIUM Major ion found in the intracellular fluid. maintains fluid & pH balance conducts electrical impulses (maintains regular heartbeat) Lower blood pressure (esp. in salt-sensitive individuals)  K causes kidneys to excrete excess sodium …lowering blood pressure  Substitute KCl for NaCl Plays role in muscle contraction Acts as a blood buffer – keeps Ca & P from being leached (bones)  = approx. 5000 mg POTASSIUM (K-) Recommended intake  AI 4.7 g/day (4700 mg/day)  Most Canadians do not consume AI ~68.8% of children (1-3y.o) do not consume AI Adult female ~2200 - 2500 mg/daily & males ~3300 – 3400 mg/daily Hyperkalemia  High blood potassium level –associated with kidney disease  Can result in heart attack & death (due to role in cardiac muscle contraction) Hypokalemia  Low blood potassium level  Associated with kidney disease patients, poorly controlled diabetes, use of diuretics (promotes excretion of fluids as urine) 7-34 SOURCES OF POTASSIUM Found in abundance in fresh fruit & vegetables processed foods are low in K See chapter for Quick Tips on Increasing this mineral 7-35 CHLORIDE Consumed bound to sodium as NaCl ~90% found in blood Functions Assists with maintaining fluid balance Assists WBC in the immune response Aids in digestion.. contributes to HCl in stomach Helps remove CO2 from the blood 8-36 CHLORIDE Recommended intake  AI is 2.3 g/day (2300 mg/day)  found naturally in seaweed, tomatoes, olives, lettuce, celery and rye 8-37 PHOSPHORUS Functions of …  major intracellular –ve charged electrolyte  Required for fluid balance  Plays critical role in bone formation (P + Ca = Bone)  Make up ATP (key role in creating energy for our bodies)  Essential for DNA & RNA synthesis  Component of cell membranes (phospholipids) 8-38 PHOSPHORUS Recommended intake  RDA for phosphorus is 700 mg/day Sources of phosphorus  Found widespread in many foods  Found in high amounts in foods that contain protein (e.g., nuts, soy, meat, eggs) REPLENISHING ELECTROLYTES 8-40 4-41