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B Fluids s VIII. Distribution of Body’s C s A) Fluid Compartments - Water oc ccupies three e main locations within the human body:: c s: cytoplasm 1. Intracellularr Fluid (ICF) compartments within w a cell, ac ccounts for 2//3 volume of body b fluids. 2. & 3. Extrace ellular Fluid (ECF) comparrtments – water w outside cells. c 2 main areas: Plasma Intersttitial fluid) - Also, oth her minor loca ations - lymph h, CSF, humo ors of eye, serous flu uid, and GI se ecretions. - Must sta ay in relative abundances a within w the com mpartments. B) Compo osition of Bod dy Fluids - Water is s a universal solvent and dissolves varrious ionic an d covalent bonded b comp pounds that arre classified in 2 ways: 1. No onelectrolyte es contain cov valent bonds that prevent them from dissocia ating in solutio on and therefo ore have no electrrical charge. Exam mples: glucose, lipids, and urea. 2. Ele ectrolytes dis ssociate into ions (ionize) in water; ionss are ch harged particlles and condu uct an electric cal current. Exam mples: Mg+, Na a+, Cl-, K+

NaCl Na+ + ClMgCl2 Mg2+ + C Cl- + ClGlucose stays as glucose (nonelectrrolytes do nott ionize)

Disso olved solutes increase i osm motic activity of o a fluid; elecctrolytes have higher osmo otic power tha an nonelectrolytes because each electrolyte e mo olecule dissocciates into at lleast two ionss There efore electroly ytes have a grreater ability to t cause fluid d shift NOTE: review the chem mical propertiies of water and a functions of ions coverred previouslyy (i.e. AP I)

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C) Movem ment of Fluids s between Co ompartments - Exchang ge of body fluids regulated by osmotic and/or hyd drostatic pres ssures * Osm motic pressure - pressure e resulting from m the movement m of water w through a membrane e and against a its con ncentration grradient (i.e. the proce ess of osmosis s). * Hyd drostatic pres ssure - press sure exerted to countteract the proc cess of osmo osis. - Solutes are unequally y distributed because b of molecularr size, electric cal charge, or dependence on active tran nsport; thereffore changes in solute concentrration causes s net water movement. m

Which leads l us to o the next section…… s ….. IX. Electrrolyte Balanc ce - The body contains a large variety of o ions, or electrolyte es, which perfform a variety y of functions. - All of the e ions in plasm ma contribute e to the osmottic balance th hat controls th he movementt of water betw ween cells and their environm ment. - Six electtrolytes are most m important: sodium, potassium m, chloride, bicarbonate, ca alcium, and phosphate e. These e six ions aid in nerve excitability, endoc crine secretion, membra ane permeability, buffering body fluids,, and controlliing the movem ment of fluids s betwe een compartm ments. - These io ons enter the body through h the digestive e tract. - Excretion of ions occu urs mainly thrrough the kidn neys. Lesser am mounts lost in sweat and in n feces. * Exce essive sweatiing may caus se a significan nt loss, especcially of sodium m and chlorid de. * Severe vomiting or o diarrhea will w cause a los ss of chloride e and bicarbon nate ions. * Adju ustments in re espiratory and d renal functio ons allow the body to regulate the levelss of these ion ns in the EC CF. - I will incllude a discussion of proteins in this sec ction. Althoug gh not an elecctrolyte, it playys an importa ant role in osm motic pressurre and pH balance.

Shuster’s A&P A Notes Serie es

Urinary ry: Water & Elec ctrolyte Balance e

A) Sodium  - Sodium’s role in the body: b * Sodium is the e major cation n of the extrac cellular fluid. * It is responsib ble for one-ha alf of the osm motic pressure e gradient thatt exists betwe een th he interior of cells c and theirr surrounding environmentt. - Excretion of sodium is s accomplished primarily by b the kidneyss. - Hyponattremia: lowerr-than-normal concentratio on of sodium, usually assocciated with exxcess water acc cumulation in the body, which dilutes the e sodium. * Also, an abno ormal loss of sodium from the body can n result from sseveral condittions, in ncluding excessive sweatin ng, vomiting, or o diarrhea. * At the cellular level, hypon natremia resu ults in increase ed entry of w ater into cellss by os smosis. The excess e water causes swelling of the cellls. * The swelling of neurons in n the brain can result in bra ain damage o or even death.  - Hyperna atremia: abno ormal increase of blood sodium. * Associated with w dehydratio on (concentra ation of sodiu m goes up). Most associa ated with elde erly pa atients or infa ants. Sometim mes vomiting and a excessivve sweating. Lethargy, L wea akness, irritab bility, neuromu uscular excita ability, and ed dema. With m more severe ellevations of th he sodium lev vel, seizures and a coma ma ay occur. B) Potass sium  - Potassiu um’s roles in the t body: * Potassium is the major inttracellular cation. * It helps estab blish the restin ng membrane e potential in neurons and muscle fiberss. * Potassium is part of the bo ody's buffer system. s - Potassiu um balance is s maintained primarily p by Aldosterone A att the kidney. - Hypokalemia: abnorm mally low pota assium blood level. * An absolute loss l of potass sium can arise e from decrea ased intake, ffrequently rela ated to o starvation. Itt can also com me about from m vomiting orr diarrhea. alemia: high levels in the blood. b - Hyperka * It can result from f increase ed dietary inta ake of potassi um. In such a situation, po otassium from m the blood ends up in the ECF in abno ormally high cconcentrationss.

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* This can resu ult in a partial depolarizatio on (excitation)) of the plasm ma membrane e of skeletal muscle m fibers, neurons, and d cardiac cells s of the heart,, and can also o lead to an in nability of cells to re epolarize. Bec cause of such h effects on th he nervous syystem, a persson with hyperkalemia mayy also ex xhibit mental confusion, nu umbness, and d weakened rrespiratory mu uscles. * For the heartt, this means that t it won’t re elax after a co ontraction, an nd will effectivvely “seize” and sttop pumping blood, b which is fatal within minutes. C) Chloride - Chloride e is the predom minant extrac cellular anion.. - Chloride e’s role in the body: * Major contrib butor to the os smotic pressu ure gradient b between the IC CF and ECF, an nd plays an im mportant role in maintainin ng proper hyd dration. * Functions to balance catio ons in the ECF, maintaining g the electrica al neutrality off this fluid. * Part of hydrochloric acid (c chemical dige estion) and in nvolved in bloo od chemistry (e e.g. chloride shift s in oxygen n/carbon diox xide circulation n) - Hypochloremia: lowe er-than-norma al blood chloride levels, ca n occur beca ause of kidneyy failure, vo omiting, diarrh hea. - Hyperch hloremia: high her-than-norm mal blood chlo oride levels, ccan occur due e to dehydratio on, excessive e intake of die etary salt (NaC Cl) or swallow wing of sea w water, among many othe er things. D) Bicarb bonate - Bicarbon nate is the second most ab bundant anion n in the blood d. Its principal function is to o maintain your y body’s acid-base bala ance by being g part of buffe er systems. Th his role will be e discussed d in a different section. - We do not n talk about “hyper-“or “hy ypo-“conditions. Rather, itt is associated with alkalosis and a acidosis. See later section on “p pH Balance”.

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E) Calciu um and Phosp phate – stored d in body in hydroxyapatite es in skeleton n. - Calcium’s role in the body:  * More than 90 0 percent of th he calcium an nd phosphate that enters th he bo mineral ody is incorpo orated into bo ones and teeth, with bone sserving as a m re eserve for the ese ions. * Calcium ions, Ca2+, are necessary n for muscle contrraction, includ ding ca ardiac, enzym me activity, an nd blood coag gulation. In ad ddition, calcium is es ssential for ex xocytosis and d the release of neurotranssmitters from neurons an nd of hormon nes from endo ocrine glands.. - Calcium ion concentration is regula ated by intera action of two h hormones: pa arathyroid hormone and calcitonin n. Also, Vitam min D. PTH - released by the parathyroid p ce ells, promotess increase in blood calcium lev vels by targetting. Bo ones - PTH ac ctivates osteo oclasts, which h breakdown tthe matrix Sm mall intestines s - increases intestinal abssorption of calcium ions. Kid dneys - PTH increases callcium reabsorrption by rena al tubes. Calcitonin n - targets bon ne to encoura age depositio n of calcium ssalts and inhibits bone reabsorption (therefore e an antagonisst of PTH and d decreases s blood calcium m levels) Also, a defficiency of Vittamin D leads s to a decrea se in absorbe ed calcium an nd, eventuallyy, a depletion of o calcium sto ores from the skeletal syste em, potentially leading to rrickets in child dren and osteom malacia in adults, contributting to osteop porosis. * Hypocalcemia: low calcium blood levels, is seen in hypoparathyrroidism, which may follow the re emoval of the thyroid gland d, because the four nodule es of the paratthyroid gland are embedde ed in it.. * Hypercalcem mia: abnormally high calciu um blood leve els, is seen in primary hype erparathyroidism. - Phospha ate’ role in the e body: * Found in pho ospholipids. * Also, in ATP, nucleotides (genetic mate erial). * Important intrracellular bufffers. * Hypophospha atemia, or abnormally low phosphate bllood levels, o occurs with he eavy use of an ntacids, and during d malnou urishment. * Hyperphosph hatemia, or ab bnormally increased levelss of phosphates in the bloo od, occurs if th here is s decreased re enal function (kidney failurre).  

Shuster’s A&P A Notes Serie es

Urinary ry: Water & Elec ctrolyte Balance e

F) Protein ns: - Found mostly m in the in ntracellular flu uid. Then, ne ext highest co oncentration iss in the plasm ma. Of course, most m physiolog gical and struc ctural function ns of the bodyy are perform med by protein ns. - Here, we e will focus on n its role in pH H and homeo ostasis of wate er balance. A Acts as an important buffer in the blood. Als so, maintains blood hydros static pressure e.

Which leads l us to o the next section…… s …..

X. The Body’s Water Balance A) Overv view - If things work correctlly, water intak ke = water output. But, see “imba alances” section below. * Intake = 2500 0 ml/day, water ingested as a fluids (6 60%), foods (3 30%), and pro oduced from cell metabolism m or also called metabolic m wate er (10%) * Water outputt - vapor in lun ngs/diffusion from f the skin (2 28%), perspira ation (8%), an nd feces (4%); rest is ex xcreted by kid dneys as urine (60%) Sensib ble water los ss: you can sense s (perce eive) the loss (urine, sweat, feces) Insens sible water lo oss: those yo ou cannot dettect (vaporr in lungs, diffusion through h skin) B) Regulation of Wate er Output and Electrolyte Balance B 1) Introduction - Rise in plasma p osmo olarity (solute e concentratio on) triggers: 1. Thirst, prov voking water in ntake. no detail Regulation R off Water Intak ke (Thirst Me echanism) – n 2. ADH releas se, causing th he kidneys to excrete conce entrated urine e - Disorde ers of Water Balance B Dehy ydration - watter loss excee eds water inta ake Hypo otonic hydrattion – ECF is diluted; sodiu um concentra ation is norma al but there is an increase in waterr, causing ECF sodium leve els to lower (h hyponatremia a), increase in n osmosis occcurs and tissu ue cells swell s (edema)

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ation of Sodium Balance and Water Balance B (sod ium-water ba alance, BP, an nd Blood Volu ume) 2) Regula - Role of Sodium S in Flu uid and Electrrolyte Balance e * Sodium most abu undant cation in the ECF. The only catiion exerting a significant o osmotic pressure * Sodium does nott easily cross cellular membranes, and sstays out of th he cells; there efore, it is a contro olling factor of ECF volume e and water distrib bution. * While the sodium m content of th he body may be altere ed, its concenttration in the ECF remains s stable becau use of immediate adjustme ents in water volume; v WATE ER FOLLOWS SALT! - Because e all body fluid ds are in osm motic equilibriu um, a change in n plasma sodium levels affe ects: 1. Pla asma volume e and blood prressure 2. Th he fluid volumes of the othe er two compa artments (ICF and a ECF) - Influence e of ADH * Increase in ADH A secretion n = increase in n water re esorption. *R Recall: for aq quaporin on CD. C - Influence e of Aldostero one * Recall that 75 5-80% of sodium (NaCl) in n renal filtrate is re eabsorbed in proximal tubu ules of kidney ys. * Aldosterone aids a in actively reabsorbing remaining Na N +Cl- in distall convoluted tubule/collecti t ing tubule by in ncreasing tubu ule permeabillity; therefore aldosterone prromotes both sodium and water retentio on

NOTE: wa ater reabsorption is high h with ADH, v very high with aldosterone e + ADH - Influence e of Atrial Nattriuretic Facto or (ANF) * Reduces bloo od pressure and a blood volu ume by inhibiiting ne early all even nts that promo ote vasoconsttriction and so odium and wa ater retention * In essence, in nhibits ADH and a Aldostero one productio n

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ce XI. Acid--Base Balanc - All bioch hemical reactions are influe enced by pH of o their fluid e environment, therefore optimum conditions and balance (acid-base) is requ uired. Also, proteins denature d rapid dly in high or low pH conditions. - Changes s in pH in bloo od: arterial blood >7.45 = alkalosis a and