Fluid-Electrolyte & Fluid-Electrolyte & Acid-Base BalanceAcid-Base Balance

Chapter 19Chapter 19

Water CompartmentsWater CompartmentsWater CompartmentsWater Compartments

Fluid compartmentsFluid compartments

Intracellular fluid—about 2/3 of totalIntracellular fluid—about 2/3 of total

Extracellular fluid—plasma, lymph, Extracellular fluid—plasma, lymph, tissue fluids tissue fluids

Cerebrospinal fluid in central nervous Cerebrospinal fluid in central nervous system, synovial fluid in joints, system, synovial fluid in joints, aqueous humor of eye, serous fluids aqueous humor of eye, serous fluids between organs & membranesbetween organs & membranes

Fluid compartmentsFluid compartments

Intracellular fluid—about 2/3 of totalIntracellular fluid—about 2/3 of total

Extracellular fluid—plasma, lymph, Extracellular fluid—plasma, lymph, tissue fluids tissue fluids

Cerebrospinal fluid in central nervous Cerebrospinal fluid in central nervous system, synovial fluid in joints, system, synovial fluid in joints, aqueous humor of eye, serous fluids aqueous humor of eye, serous fluids between organs & membranesbetween organs & membranes

Movement of WaterMovement of Water

Water moves via two processesWater moves via two processes

FiltrationFiltration

OsmosisOsmosis

Fluid compartmentsFluid compartmentsFluid compartmentsFluid compartments

Figure 22-1

Water Intake & OutputWater Intake & Output

Intake: 2500 ml/dayIntake: 2500 ml/day Oral liquids: 1600 ml/day (about 6½ Oral liquids: 1600 ml/day (about 6½

8 oz glasses)8 oz glasses) Food: 700 ml/day (about 3 glasses)Food: 700 ml/day (about 3 glasses) Internal source: 200 ml (less than 1 Internal source: 200 ml (less than 1

glass)glass)

Water Intake & OutputWater Intake & Output

Output: 2500 ml/dayOutput: 2500 ml/day Urine 1500 ml/dayUrine 1500 ml/day Sweat 500 ml/daySweat 500 ml/day Exhaled water vapor 300 ml/dayExhaled water vapor 300 ml/day Feces 200 ml/dayFeces 200 ml/day

Intake & output SHOULD BE EQUALIntake & output SHOULD BE EQUAL Sweating, vomiting or diarrhea: DRINK MORESweating, vomiting or diarrhea: DRINK MORE Too much intake: urinate moreToo much intake: urinate more

Intake and outputIntake and outputIntake and outputIntake and output

Figure 22-2• Intake of water• Output of water

RegulationRegulation

Hypothalamus of brain Hypothalamus of brain Regulates water contentRegulates water content Osmolarity—concentration of Osmolarity—concentration of

dissolved materials in a fluiddissolved materials in a fluid Osmoreceptors in hypothalamus Osmoreceptors in hypothalamus

detect changes in blood detect changes in blood osmolarityosmolarity

Regulation of Body WaterRegulation of Body Water

If body is dehydratedIf body is dehydrated Osmolarity of blood increasesOsmolarity of blood increases Less fluid in body makes body fluids Less fluid in body makes body fluids

more concentratedmore concentratedPerson feels thirsty & drinks fluids for Person feels thirsty & drinks fluids for

reliefreliefWater absorbed by intestinesWater absorbed by intestinesOsmolarity of blood decreasesOsmolarity of blood decreases

Regulation of WaterRegulation of Water

ADH (antidiuretic hormone) ADH (antidiuretic hormone) Produced by hypothalamus, stored in Produced by hypothalamus, stored in

posterior pituitaryposterior pituitaryFunction: tells kidneys to save Function: tells kidneys to save

(reabsorb) water to relieve dehydrated (reabsorb) water to relieve dehydrated statestate

Result: less urine is producedResult: less urine is produced

Regulation of WaterRegulation of Water

Aldosterone Aldosterone Produced by adrenal cortexProduced by adrenal cortex Function: tells kidneys to conserve Function: tells kidneys to conserve

(reabsorb) water to relieve a (reabsorb) water to relieve a lowered blood pressure or a lowered blood pressure or a lowered blood Nalowered blood Na++ level level

Regulation of WaterRegulation of Water

Water intoxication—lowers Water intoxication—lowers concentration of dissolved materialsconcentration of dissolved materials

Blood volume & blood pressure Blood volume & blood pressure increaseincrease Atria natriuretic peptide (ANP) from Atria natriuretic peptide (ANP) from

heartheartFunction: tells kidneys to excrete NaFunction: tells kidneys to excrete Na++ & &

water to lower BP & blood volumewater to lower BP & blood volume

ElectrolytesElectrolytes

Electrolytes are formed when Electrolytes are formed when molecules in water dissociatemolecules in water dissociate

Electrolytes are either positive or Electrolytes are either positive or negativenegative

Positive ions are called cationsPositive ions are called cations NaNa++, K, K++, Ca, Ca2+2+

Negative ions are called anionsNegative ions are called anions ClCl--, HCO, HCO33

--, HPO, HPO442-2-

ElectrolytesElectrolytes

Most are inorganic moleculesMost are inorganic molecules Salts (NaCl, KCl, CaCl)Salts (NaCl, KCl, CaCl) Acids (HAcids (H22COCO33 or HCl) or HCl) Bases (NaHCOBases (NaHCO33 or Na or Na22HPOHPO44))

Are part of tissues like bones, muscle & Are part of tissues like bones, muscle & nervesnerves

Are part of proteins like enzymes or insulinAre part of proteins like enzymes or insulin

ElectrolytesElectrolytes

Help to establish the osmolarity of body Help to establish the osmolarity of body fluidsfluids

AND, their presence helps regulate an AND, their presence helps regulate an important processimportant process Movement of water: osmosisMovement of water: osmosis Water moves to attempt at diluting Water moves to attempt at diluting

concentrated fluidsconcentrated fluids Moves from LOW concentration to HIGHMoves from LOW concentration to HIGH

ElectrolytesElectrolytes KK++ is most predominant ICF cation is most predominant ICF cation

(remember “KICK”)(remember “KICK”) NaNa++ is most predominant ECF cation is most predominant ECF cation

(remember “NECK”)(remember “NECK”) ClCl-- is most predominant anion in ECF is most predominant anion in ECF

Few protein anions found in tissue fluidFew protein anions found in tissue fluid Many protein anions found in plasmaMany protein anions found in plasma

HPOHPO44-2-2 (phosphate) & protein anions are (phosphate) & protein anions are

found in ICFfound in ICF

Regulation of ElectrolytesRegulation of Electrolytes

We eat & drink these molecules dailyWe eat & drink these molecules daily We lose these in urine & feces but also in We lose these in urine & feces but also in

sweatsweat Sweat is mostly NaCl (ever taste it??)Sweat is mostly NaCl (ever taste it??) Electrolytes end up in urine if there is too Electrolytes end up in urine if there is too

much of that substance in the bloodmuch of that substance in the blood

Regulation of ElectrolytesRegulation of Electrolytes Hormonal regulationHormonal regulation

Aldosterone:Aldosterone: Increases NaIncreases Na++ reabsorption reabsorption

(conservation) by kidneys(conservation) by kidneys Increases KIncreases K++ excretion by kidneys excretion by kidneys Urine ends up with less NaUrine ends up with less Na++ but but

more Kmore K+ + in itin it

Regulation of ElectrolytesRegulation of Electrolytes ANPANP

Increases excretion of NaIncreases excretion of Na++ by kidneys by kidneys Urine has more Na+ ions in itUrine has more Na+ ions in it

Parathyroid (PTH)Parathyroid (PTH) Increases CaIncreases Ca2+ 2+ & P reabsorption from & P reabsorption from

bones into bloodbones into blood Results in weaker bones & increased Results in weaker bones & increased

values of both ions in bloodvalues of both ions in blood

Regulation of ElectrolytesRegulation of Electrolytes

CalcitoninCalcitonin Increases CaIncreases Ca2+ 2+ & P removal from blood (into & P removal from blood (into

bones)bones) Results in lowered blood values of both ions & Results in lowered blood values of both ions &

stronger bonesstronger bones

Acid-Base pH Acid-Base pH scalescale

Acid-Base pH Acid-Base pH scalescale

Acid-Base BalanceAcid-Base Balance

Normal blood pH: 7.35 – 7.45 (slightly Normal blood pH: 7.35 – 7.45 (slightly alkaline)alkaline) ICF is slightly acidic: 6.8 – 7.0 ICF is slightly acidic: 6.8 – 7.0 Tissue fluid pH is closer to blood but varies Tissue fluid pH is closer to blood but varies

pH scale: 7.0 is neutralpH scale: 7.0 is neutral Acidic: pH < 6.99Acidic: pH < 6.99 Alkaline: pH > 7.01Alkaline: pH > 7.01

BuffersBuffers

Recall: substances that are able to deflect Recall: substances that are able to deflect drastic changes in body pH drastic changes in body pH

Consist of weak acid, weak baseConsist of weak acid, weak base When they react with STRONG acid or When they react with STRONG acid or

STRONG base, the resultant substance STRONG base, the resultant substance have little effect on overall pH of bodyhave little effect on overall pH of body

3 systems in body: bicarbonate, 3 systems in body: bicarbonate, phosphate & protein systemsphosphate & protein systems

Bicarbonate systemBicarbonate system

Recall: weak acid (HRecall: weak acid (H22COCO33) & weak base ) & weak base

(NaHCO(NaHCO33)) Each easily dissociates in blood plasma, Each easily dissociates in blood plasma,

ready to give up or take up Hready to give up or take up H++ ions ions whenever the need existswhenever the need exists

Adding HCl to bodyAdding HCl to body

HCl + NaHCOHCl + NaHCO33 NaCl + H NaCl + H22COCO33

Salt (NaCl) has no effect on pHSalt (NaCl) has no effect on pH Weak acid (HWeak acid (H22COCO33) makes little change ) makes little change

to pHto pH

Adding Sodium Hydroxide to bodyAdding Sodium Hydroxide to body

NaOH + HNaOH + H22COCO33 H H22O + NaHCOO + NaHCO33

Water has no effect on pHWater has no effect on pH Weak base (NaHCOWeak base (NaHCO3 3 which is sodium which is sodium

bicarbonate) has little effect on pH. bicarbonate) has little effect on pH.

Phosphate SystemPhosphate System

Phosphate system—sodium dihydrogen phosphate Phosphate system—sodium dihydrogen phosphate (NaH(NaH22POPO44), a weak acid & sodium monohydrogen ), a weak acid & sodium monohydrogen

phosphate (NaHPOphosphate (NaHPO44), a weak base.), a weak base.

Adding strong acid does not have major effect on Adding strong acid does not have major effect on pH (NaCl = no effect on pH)pH (NaCl = no effect on pH)

Adding strong base does not have major effect on Adding strong base does not have major effect on pH (water = no effect on pH)pH (water = no effect on pH)

HCl + NaHPO4 NaCl + NaH2PO4

NaOH + NaH2PO4 H2O + NaHPO4

Protein Buffer SystemProtein Buffer System Important in ICFImportant in ICF Amino acids may act as either acid or Amino acids may act as either acid or

basebase Carboxyl (COOH) can act as an Carboxyl (COOH) can act as an

acid & donate H+ ions to acid & donate H+ ions to pH pH Amine group (NHAmine group (NH22) can act as a ) can act as a

base & pick up extra H+ ions to base & pick up extra H+ ions to pHpH

React immediately but little long-term React immediately but little long-term capacitycapacity

Respiratory Regulation of pHRespiratory Regulation of pH

Can regulate COCan regulate CO22 in body by increasing or in body by increasing or

decreasing respiratory ratedecreasing respiratory rate COCO2 2 Can form HCan form H22COCO33 with water in body with water in body

fluids; Hfluids; H++ ion affects pH ion affects pHCOCO2 2 + H + H22O O H H22COCO33 H+ + HCO H+ + HCO33

--

Respiratory Regulation of pHRespiratory Regulation of pH

Respiratory AcidosisRespiratory Acidosis COCO22 (waste product) is retained in (waste product) is retained in

systemsystem Occurs with respiratory diseases Occurs with respiratory diseases

(pneumonia, emphysema, asthma)(pneumonia, emphysema, asthma) Any decrease in respiratory rate or Any decrease in respiratory rate or

breathing efficiencybreathing efficiency Excess H+ ions are produced by Excess H+ ions are produced by

reaction on previous slidereaction on previous slide This lowers pH of body fluidsThis lowers pH of body fluids

Respiratory Regulation of pHRespiratory Regulation of pH

Respiratory AlkalosisRespiratory Alkalosis Usually caused by hyperventilationUsually caused by hyperventilation Less common Less common Exhale too much COExhale too much CO22

Fewer H+ ions are producedFewer H+ ions are produced Result in rise in body fluid pH Result in rise in body fluid pH

Respiratory Compensation—Respiratory Compensation—Metabolic AcidosisMetabolic Acidosis

Caused by kidney disease, diabetic Caused by kidney disease, diabetic ketoacidosis, excessive diarrhea or ketoacidosis, excessive diarrhea or vomiting vomiting

Respiratory rate Respiratory rate in response in response Exhale more COExhale more CO22, less H, less H++ ion produced ion produced pH increases back up toward normalpH increases back up toward normal

Respiratory Compensation—Respiratory Compensation—Metabolic AlkalosisMetabolic Alkalosis

Not common, caused by overingestion of Not common, caused by overingestion of antacids or vomiting of stomach contents antacids or vomiting of stomach contents onlyonly

Respiratory rate slows breathingRespiratory rate slows breathing Exhale LESS COExhale LESS CO22 (more retained) (more retained) More H+ ions produced, result is More H+ ions produced, result is

lowering of pH in body fluids back to lowering of pH in body fluids back to normalnormal

Works within a few minutesWorks within a few minutes

Respiratory Respiratory system control of system control of

pHpH

Respiratory Respiratory system control of system control of

pHpH

Renal MechanismsRenal Mechanisms

Best ability for long-term control of pH in Best ability for long-term control of pH in acidosis situationacidosis situation

Take hours to days to reach full capacityTake hours to days to reach full capacity Compensating for acidosis: will excrete HCompensating for acidosis: will excrete H++

ions, conserve Naions, conserve Na++ & & HCOHCO33- - ionsions

Compensating for alkalosis: will excrete Na+ Compensating for alkalosis: will excrete Na+ & & HCOHCO33

-- ions while conserving H ions while conserving H++ ions ions

CompensationCompensation

First line is ECF buffersFirst line is ECF buffers Bicarb, phosphate and proteinBicarb, phosphate and protein

Second line is respiratory systemSecond line is respiratory system Breathing rate Breathing rate to exhale more CO to exhale more CO22, to , to H H++

formation (which would lead to acidic pH)formation (which would lead to acidic pH) This This is limited, however is limited, however

Lastly, renal systemLastly, renal system Keep patient alive Keep patient alive Excrete HExcrete H++ ions in urine (urine very acidic) ions in urine (urine very acidic)

Manifestations of Acidosis & AlkalosisManifestations of Acidosis & Alkalosis

Acidosis: depression of nerve Acidosis: depression of nerve transmissions results in confusion transmissions results in confusion & disorientation, finally coma, death& disorientation, finally coma, death

Alkalosis: irritability, muscle Alkalosis: irritability, muscle twitches & progression leads to twitches & progression leads to severe muscle spasms & severe muscle spasms & convulsions.convulsions.