Fluid, Electrolyte, Acid-Base Balance

Body Fluid Compartments 

• _____ are 73% or more water (LOW body fat, low bone mass) 

• Adult _____ = 60% water 

• Adult _____ = 50% water (HIGHER fat content, less skeletal muscle mass) 

  • _____ tissue is LEAST hydrated of all 

  • Total body water in adults avg 40% 

• Water content _____ in OLD age = becomes 45%

infants, males, females, adipose, declines

2 Main Fluid Compartments 

1. ICF compartment → fluid _____ cells accounts for 2/3 of total body fluid 

• About 25L of 40L total 

2. ECF compartment → fluid in 2 main ECF compartments _____ cells 

• Accounts for 1/3 of total body fluid 

• Plasma = 3L 

• Interstitial fluid (IF) = 12L in spaces _____ cells 

  • Also considered part of IF → lymph, CSF, humors of eye, synovial fluid, serous fluid, and GI secretions

inside, outside, between

Composition of Body Fluids 

• Water is the UNIVERSAL _____

• Solutes are substances dissolved in water 

• Solutes → classified as NONelectrolytes and electrolytes

solvent

Nonelectrolytes

• Most are _____ molecules 

• Do NOT _____ in water 

• Ex. glucose, lipids, creatinine, and urea 

  • No _____ particles are created

organic, dissociate, charged

Electrolytes

• DISSOCIATE into ions in water 

• Ex. inorganic salts, all acids and bases, some proteins 

• Ions conduct _____ _____

• Greater _____ _____ than NON electrolyte

  • Means greater ability to CAUSE fluid shifts due to ability to dissociate into 2 or more ions 

  • NaCl → Na+ and Cl- (2 particles, elec) 

  • MgCl2 → Mg2+ and 2Cl- (3 particles, elec) 

  • Glucose → glucose (1 particle, NONelec)

electrical current, osmotic power

ECF vs. ICF

• Each fluid compartment has a distinctive pattern of electrolytes

• ECF = electrolyte contents are all similar except for higher protein [ ]  (has lower Cl- content of plasma) 

  • Major cation → Na+ 

  • Major anion → Cl- 

• ICF = contains more _____ _____ than plasma 

  • Low Na+ and Cl- 

  • Major cation → _____

  • Major anion → HPO4 (2- charge, hydrogen phosphate) 

• Electrolytes are most abundant _____ in body fluids 

  • Determine most chemical and physical reactions 

• Most of dissolved solutes consists of proteins, phospholipids, cholesterol, and triglycerides 

  • 90% in plasma, 60% in IF, 97% in ICF

soluble proteins, K+, solutes

Fluid Movement among Compartments 

• _____ and _____ pressures regulate continuous exchange and mixing of fluids 

• Water moves freely along osmotic gradients 

• Change in solute [ ] of any compartment = leads to net water flow 

  • ⬆⬆ ECF osmolarity = water _____ cells 

  • ⬇⬇ECF osmolarity = water _____ cell

osmotic, hydrostatic, leaves, enters

Plasma & IF 

• Exchanges occur across _____ _____

• Fluid leaks from arteriolar end of capis → reabsorbed at _____ end 

• Lymphatics pick up remaining fluid and return it to blood

capillary walls, venule

IF & ICF 

• Exchanges occur across _____ _____

• 2-way osmotic flow of water 

• Ions move selectively into or out of cell 

• Nutrients, wastes, gases have _____ flow

cell membrane, unidirectional

Water Balance and ECF Osmolarity 

• Water intake must EQUAL water output → 2500 mL/day

• Water intake = most water is taken in by ingesting foods and drinks 

  • Small amount from _____

  • Metabolic water (water of oxidation) → water produced by cellular metabolism 

• Water output = urine (60%), _____ water loss (through skin and lungs), perspiration, and feces 

• Osmolarity is maintained around 280-300 mOsm 

• RISE in osmolarity = Stimulates _____ + causes ADH _____

• DECREASE in osmolarity = Causes inhibition + ADH _____

metabolism, insensible, thirst, release, inhibition

Regulation of Water INTAKE

• _____mechanism drives water intake

• Controlled by _____thirst center 

• Hypothalamic osmoreceptors detect _____osmolarity (through stretch) + activated by: 

  • Increased _____osmolarity of 1-2%

  • _____ mouth → LESS saliva is produced due to higher blood osmolarity 

  • Decreased blood volume or pressure → signaled by angiotensin II or _____input 

• Drinking water INHIBITS thirst center 

• Inhibitory feedback signals: 

  • Relief of dry mouth 

  • Activation of _____and _____stretch receptors

thirst, hypothalamic, ECF, plasma, dry, baroreceptor, stomach, intestinal

Regulation of Water OUTPUT

• Obligatory water loses = unavoidable output of certain amounts of water 

• Explains why we CAN’T live without water very long 

  • Insensible water loss from _____or _____

  • Sensible water loss from _____to excrete wastes, obvious sweat, and feces 

• Volume of urine excreted + solute [ ] depend on fluid intake, diet, and water loss via other avenues (areas)

lung, skin, urine

Influence of Antidiuretic Hormone (ADH) 

• Water reabsorption in collecting ducts is _____ to ADH release → triggers _____ expression (showing up)

• DECREASED ADH = _____ urine and _____ in volume of body fluids 

• INCREASED ADH = _____ urine, due to reabsorption of water, causes _____ volume of body fluids 

• Hypothalamic osmoreceptors sense ECF solute [ ] and regulate ADH based on that 

• Other factors may trigger ADH release:

  • “Large” changes in blood volume or pressure

  • _____ BP = INCREASED ADH due to blood vessel baroreceptors and RAA mechanism 

  • Decreased BP/volume can be caused by: 

    • Intense sweating, vomiting, diarrhea, severe blood loss, traumatic burns, and prolonged fever

proportional, aquaporin, dilute, drop, concentrated, increased, decreased

DISORDERS of WATER BALANCE (3)

1. Dehydration

• ECF water loss due to hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, diuretic abuse, endocrine disturbances 

• Signs and symptoms → “cottony” or sticky _____ _____ , thirst, dry flushed skin, _____ (decreased urine output) 

• Can lead to: weight loss, fever, mental confusion, _____ _____ (due to inadequate circulation), and loss of electrolytes

oral mucosa, oliguria, hypovolemic shock

DISORDERS of WATER BALANCE (3)

2. Hypotonic Hydration 

• Cellular _____ or water intoxication 

• Occurs with renal insufficiency or rapid excess water ingestion 

• ECF osmolarity DECREASES → causes _____

  • Result = net osmosis of water INTO tissue cells and _____ of cells 

  • Symptoms: severe metabolic disturbances, nausea, vomiting, muscular cramping, cerebral edema, and possible death 

• Treated with _____ _____

overhydration, hyponatremia, swelling, hypertonic saline

DISORDERS of WATER BALANCE (3)

3. Edema 

• Atypical accumulation of _____ _____ → results in _____ SWELLING (NOT cell) 

  • Only volume of IF is increased NOT of other compartments 

• Can impair tissue function by increasing _____ for diffusion of O2 and nutrients from blood into cells 

• Could be caused by increased fluid flow out of blood or decreased return of fluid to blood 

• Malnutrition resulting in _____ and edema

interstitial fluid, tissue, distance, hypoproteinemia

Electrolyte Balance 

• Electrolyte balance → usually refers only to _____ balance even though electrolytes also include acids, bases, and some proteins 

• Salts = control fluid movements, provide _____ for excitability, secretory activity, and membrane _____

• Salts enter body by ingestion and metabolism + lost through perspiration, feces, urine, vomit

salt, minerals, permeability

Central Role of Na in Fluid and Electrolyte Balance 

• Na is MOST abundant cation in ECF 

  • Na salts in ECF contribute 280 mOsm of total 300 mOsm ECF solute [ ] 

• ONLY cation that exerts SIGNIFICANT _____ _____

  • Controls ECF volume and water distribution b/c water follows salt 

  • Changes in Na+ levels affects plasma volume, BP, and ECF and IF volumes 

• Na+ that leaks into cells is pumped OUT _____ its electrochemical gradient 

• Na moves back and forth b/w ECF and body secretions (ex. Digestive secretions) 

• _____ acid-base control mechanisms are coupled to Na ion transport

osmotic pressure, against, renal

Na [ ] vs. Na content 

• Na [ ] → determines _____ of ECF 

  • And influences excitability of neurons and muscles 

  • Remains stable b/c of water shifts out of or into ICF 

• Content of Na → total body content determines _____ volume so therefore _____

osmolarity, ECF, BP

Regulation of Sodium Balance (5)

• There are NO known receptors that monitor Na levels in body fluids → macula densa cells monitor _____ NOT Na

• Na-water balance is linked to _____ and blood _____ control mechanisms 

• Changes in these trigger neural and hormonal controls to regulate Na content

filtrate, BP, volume

Regulation of Sodium Balance (5)

Aldosterone

• Plays the BIGGEST role in regulation of Na by kidneys 

• Regardless of aldosterone presence: 

  • 65% of Na is reabsorbed in _____ _____ and 25 % is reclaimed in nephron loops

  • Na is NEVER _____ into filtrate 

• When aldosterone [ ] are HIGH: 

  • Na is actively reabsorbed in DCT and CT and water follows = ECF volume _____

• Aldosterone [ ] are LOW: 

  • Na is NOT actively reabsorbed and is lost to urine = more _____ of water 

proximal tubule, secreted, increases, loss

Regulation of Sodium Balance (5)

Angiotensin II

• RAA mechanism is main TRIGGER for _____ release 

• _____ cells of JGC secrete renin in response to: 

  • _____ NS stimulation 

  • DECREASED _____ NaCl [ ] 

  • DECREASED _____ of granular cells (b/c of decreased BP) 

• _____ catalyzes production of angiotensin II

  • Causes aldosterone release from adrenal cortex 

  • Result = INCREASED Na _____ by kidney tubules 

• Aldosterone release is also triggered by elevated _____ levels in ECF 

• Aldosterone brings its effects _____ (hours to days) 

aldosterone, granular, sympathetic, filtrate, stretch, renin, reabsorption, K+, slowly

Homeostatic Imbalance

• People w/ Addison’s disease (_____ ) → do NOT produce aldosterone 

• Result = they lose a LOT of NaCl and water to urine 

• At risk of _____ (low blood volume) 

• They can avoid problems w/ Na balance by ingesting enough salts and fluids

hypoaldosteronism, hypovolemia

Regulation of Sodium Balance (5)

Influence of Atrial _____ _____ (ANP) 

• Released by atrial cells in response to stretch caused by increased BP 

• Effects: 

  • Decreases BP and blood volume 

    • Inhibits _____ , _____ , and aldosterone production 

    • Increases excretion of Na+ and water 

    • Promotes _____ directly and also by decreasing production of angiotensin II

natriuretic peptide, ADH, renin, vasodilation

Regulation of Sodium Balance (5)

Other Hormones

• Female sex hormones

  • _____ → INCREASES NaCl reabsorption (like aldosterone) 

    • Result = water retention during period and pregnancy 

  • _____ → DECREASES Na reabsorption (blocks _____ ) 

    • Result = promote Na and water LOSS 

• _____ : INCREASE Na reabsorption and promote _____

estrogen, progesterone, aldosterone, glucocorticoids, edema

Regulation of Sodium Balance (5)

Cardiovascular Baroreceptors 

•  Baroreceptors alert brain of INCREASES in BP and blood volume 

• Sympathetic NS impulses to kidneys decline, cause: 

  • Afferent arterioles to _____

  • GFR _____

  • Increased Na and water output 

  • Reduced BP and blood volume 

dilate, increases

Importance of Potassium

• Affects RMP in neurons and muscle cells (especially cardiac muscle) 

  • Increases in ECF [K+] (_____) = _____RMP → causes depolarization → then reduced excitability 

  • Decreases in ECF [K+] (_____) = _____and nonresponsiveness 

• Disruption in [K+] in heart can interfere with electrical conduction → can lead to sudden death

hyperkalemia, decreased, hypokalemia, hyperpolarization

Regulation of K Balance

• K is also part of body’s buffer system 

• H+ shifts in and out of cells in OPPOSITE direction of K to maintain cation balance: 

  • ECF K levels RISE with _____

  • ECF K levels DROP with _____

    • Interferes w/ activity of excitable cells

acidosis, alkalosis

Regulatory Site: DCT and Collecting Duct

• K balance is controlled in cortical collecting ducts by regulating amount _____ into filtrate 

  • HIGH K+ in ECF → makes _____ cell secrete K+ 

  • LOW K+ → cause principal cells to reduce secretion of K to a minimum 

    • Also, type _____ _____ cells can reabsorb some K+ left in filtrate

• Kidneys have limited ability to retain K+ so most K+ is lost in urine → may lead to deficiency if not replaced in diet

secreted, principal, A intercalated

Influence of plasma K [ ]

• Most IMPORTANT factor affecting K+ secretion = its _____ in ECF

• HIGH K+ diet = increased K content of ECF 

  • K entry into principal cells → leads to INCREASED K secretion 

• LOW K+ diet or fast loss → REDUCES its secretion and promotes limited reabsorption 

concentration

Influence of Aldosterone

• Aldosterone stimulates K secretion (and Na+ reabsorption) by _____ cells 

• Adrenal _____ _____ are directly sensitive to K content of ECF 

  • Increased K in adrenal cortex = release aldosterone = _____ K+ secretion 

• Means that K+ controls its OWN ECF [ ] via feedback regulation of aldosterone release

principal, cortical cells, increases

Regulation of Ca and PO4

• 99% of body’s Ca is found in bones as Ca and PO4 salts 

• Ca balance is controlled by _____ _____ (PTH) + rarely deviates from normal limits 

• PTH promotes INCREASE in Ca levels by targeting: 

  • Bones = osteoclasts break down matrix → release Ca and PO4 to blood 

  • Kidneys = _____ Ca reabsorption + _____ PO4 ion reabsorption 

  • Small intestine = increases Ca absorption (indirectly through stimulation of kidney to activate Vitamin D precursor) 

parathyroid hormone, increase, decrease

Regulation of Ca and PO4

• 98% of filtered Ca reabsorbed is due to PTH 

• If ECF Ca levels are normal → PTH is _____

• 75% of filtered PO4 are reabsorbed in _____

  • PTH inhibits this by decreasing the _____ _____

• PO4 reabsorption is also affected by: 

  • _____ = increases it 

  • _____ = decreases it

inhibited, PCT, total maximum, insulin, glucagon

Regulation of Anions 

• Cl- is a major anion accompanying Na in ECF 

  • Helps maintain osmotic pressure of blood 

  • 99% of Cl- is reabsorbed under NORMAL pH

    • _____ follows Na in PCT + coupled to activate transport of Na in other tubule segments 

• In _____ → FEWER Cl ions are reabsorbed, instead HCO3 is absorbed more

passively, acidosis

 Acid-Base Balance 

• pH affects ALL functional proteins and biochemical reactions → so it is closely regulated by the body 

• NORMAL pH of body fluids: 

  • _____ blood = pH 7.4 

  • _____ blood and _____ = pH 7.35

  • _____ = pH 7.0

• Alkalosis or alkalemia = arterial pH is GREATER than 7.45 

• Acidosis or acidemia = arterial pH is LESS than 7.35 

  • pH 7.35 is not actually acidic on the pH scale, but 7.35 is higher than optimal H+ [ ] for most cells so its physiological acidosis

arterial, venous, IF, ICF

 Acid-Base Balance 

• Small amounts of acidic substances enter body in food but MOST H+ is produced as a _____ of metabolism:

  • Phosphorus-containing protein breakdown releases _____ acid into ECF 

  • _____ acid from anaerobic respiration of glucose 

  • _____ acids and ketone bodies from fat metabolism 

  • H+ is freed when CO2 is converted to HCO3 in blood

by-product, phosphoric, lactic, fatty

Regulation of H ions (3 mechanisms)

1. Chemical Buffer Systems → FAST, FIRST line of defense 

• Acids are _____ donors 

• Strong acids dissociate _____ in water → freeing all their H+ in water which can dramatically affect pH 

• Weak acids dissociate _____ in water 

  • They are also efficient at preventing pH changes (can be chemical buffers)

• Strong bases dissociate easily in water → quickly tie up H+ (link to balance) 

• Weak bases accept H+ more slowly 

• Chemical buffer = a system of 1 or more compounds that act to _____ pH changes when strong acid or base is added 

  • Will _____ H+ if pH drops OR _____ H+ if pH rises 

  • 3 major systems

proton, completely, partially, resist, bind, release

Chemical Buffer System - Bicarbonate Buffer System

• Mixture of H2CO3 (carbonic acid = weak acid) and sodium bicarbonate NaHCO3 (weak base) 

• Buffers BOTH ICF and ECF but is ONLY important _____ buffer 

• If strong acid is added → HCO3 gets H+ → forms H2CO3

  • pH _____ only SLIGHTLY unless all available HCO3 (_____ _____) is used up 

  • [HCO3] is closely regulated by _____

• If strong base is added → H2CO3 dissociates → DONATE H+ 

  • pH RISES only slightly 

  • H+ ties up the base (ex. OH-) 

  • H2CO3 supply is almost _____ (from CO2 released by respiration) + controlled by _____

ECF, decreases, alkaline reserve, kidneys, limitless, respiratory

Chemical Buffer System - Phosphate Buffer System

• Action nearly identical to bicarbonate buffer

• Components are sodium salts of: 

  • Dihydrogen phosphate (H2PO4) → weak _____

  • Monohydrogen phosphate (HPO4) → weak _____

• Unimportant in buffering _____

• Effective buffer in _____ and _____ → where PO4 [ ] are HIGH 

• H+ released by strong acids is _____ w/ a weak acid 

• Strong bases are converted _____ to weak bases

acid, base, plasma, urine, ICF, linked, back

Chemical Buffer System - Protein Buffer System

• Intracellular proteins are the most abundant and POWERFUL buffers → plasma proteins also important 

• Protein molecules are _____ = can function as BOTH a weak acid and weak base

• When pH RISES → organic acid or _____ (COOH) groups can release H+ 

• When pH DROPS → NH2 groups can bind H+ 

• _____ functions as intracellular buffer

amphoteric, carboxyl, hemoglobin

Regulation of H ions (3 mechanisms)

2. Brain Stem Respiratory Centers → acts within 1-3 minutes 

• Respiratory and renal systems are _____ buffering systems

  • Means they act more _____ than chemical buffers but have MORE buffering power 

• Respiratory system eliminates CO2 (an acid) 

• A reversible equilibrium exists in blood: 

• During CO2 unloading = reaction shifts to _____ → H+ is incorporated into H2O (water is made)

• During CO2 loading = reaction shifts _____ → H+ is buffered by proteins 

• Hypercapnia = PCO2 in blood RISES 

  • This activates _____ _____ → causes INCREASED respiratory rate and depth 

physiological, slowly, left, right, medullary chemoreceptors

Brain Stem Respiratory Centers Cont’d

• Rising plasma H+ (acidosis) = activates _____ chemoreceptors 

  • Causes increased respiratory rate and depth 

• Both cause MORE CO2 to be removed from blood → push reaction _____ → REDUCES H+ [ ] 

• _____ inhibits/reduces respiratory center 

  • Respiratory rate and depth DECREASE → CO2 accumulates → H+ [ ] INCREASE (feedback restoration)

• Resp system impairment causes acid-base imbalances: 

  • Hypoventilation = causes CO2 _____ + respiratory _____

  • Hyperventilation = CO2 _____ + respiratory _____

left, peripheral, alkalosis, retention, acidosis, elimination, alkalosis

Regulation of H ions (3 mechanisms)

3. Renal Regulation → MOST potent, but needs hours to days to effect pH changes 

• Chemical buffers CANNOT eliminate excess acids or bases from body 

  • Lungs eliminate _____ carbonic acid by eliminating CO2 

  • Kidneys eliminate _____ (fixed) acids produced by cellular metabolism to prevent metabolic acidosis 

    • Phosphoric, uric, and lactic acids and ketones

  • Kidneys also regulate blood levels of alkaline substances → renew chemical buffers 

• Kidneys regulate acid-base balance by adjusting amount of _____ in blood by: 

  • Conserving (reabsorbing) or generating new HCO3- 

  • Excreting HCO3-

volatile, nonvolatile, bicarbonate

Renal Regulation

• Generating or reabsorbing 1 HCO3- is the same as LOSING 1 H+ 

  • Drives reaction to _____

  • Build up of HCO3, H+ gets converted to water 

• Excreting 1 HCO3 is the same as GAINING 1 H+ 

  • Drives reaction to the _____

• Renal regulation of acid-base balance depends on kidney’s ability to secrete or retain _____

  • To reabsorb _____ → kidney must secrete H+ 

• To excrete → kidney must _____ (not secrete) H+

left, right, H+, bicarbonate, retain

Conserving Filtered HCO3: Bicarbonate Reabsorption 

• To maintain _____ _____ → kidneys must replenish (reabsorb) bicarbonate 

• Tubule cells have NO transporters for bicarbonate on apical membranes but are _____ to CO2

  • Bicarbonate can gain entry BACK into body in a roundabout way → by being _____ _____ to CO2 

  • Once back in cell → CO2 can be converted back into bicarb or can leave cells as CO2 

• Mechanism is coupled to H+ secretion: 1 H+ secreted = 1 bicarb reabsorbed

• H+ secretion is coupled to HCO3 reabsorption and occurs in _____ and CT _____ _____ cells 

• Rate of H+ secretion changes w/ ECF CO2 levels 

alkaline reserve, permeable, converted back, PCT, Type A intercalated

Conserving Filtered HCO3: Bicarbonate Reabsorption 

1.  CO2 + H2O form H2CO3 in reaction catalyzed by _____ _____

2. H2CO3 breakdown into H+ and HCO3- 

3. H+ is actively secreted into _____ , HCO3 enters _____ in exchange for Cl-

• 1 H+ secreted = Na+ is reabsorbed 

4.  H+ combines w/ HCO3- = H2CO3 (in filtrate) 

5. H2CO3 _____ into CO2 + H2O 

6. CO2 diffuses BACK into _____ _____

carbonic anhydrase, lumen, blood, dissociates, tubule cell

Generating NEW Bicarbonate Ions (2 mechanisms)

• Secreted H+ used to reclaim filtrate HCO3- is NOT really excreted from body → it is incorporated into a _____ molecule → which can reabsorbed 

  • So body has SAME number of HCO3 and H+ as it STARTED with 

  • NO _____ _____

• Metabolism of food generates NEW H+ → can lead to _____ → must be balanced by generating new HCO3- 

• 2 mechanisms in PCT and _____ _____ cells generate a new HCO3 by getting RID of new H+

H20, net gains, acidosis, type A intercalated

Generating NEW Bicarbonate Ions (2 mechanisms)

1. Via Excretion of Buffered H+ 

• MOST important urine buffer is _____ buffer system 

• Intercalated cells actively secrete H+ into _____ → which is buffered by phosphates (monohydrogen phosphate) + excreted in urine 

• “New” HCO3- is generated in process and moves into interstitial space via _____ system → then moves _____ into peritubular capillaries blood

phosphate, urine, cotransport, passively

Generating NEW Bicarbonate Ions (2 mechanisms)

2. Via NH4+ excretion 

• MORE important mechanism for _____ acid 

• Involves metabolism of glutamine in PCT cells 

• Each glutamine = produces 2 NH4+ and 2 “new” HCO3- 

• HCO3- moves to _____ and NH4 is excreted in _____

• Replenishes _____ _____ of blood

excreting, blood, urine, alkaline reserve

Bicarbonate Ion Secretion 

• When body is in alkalosis → _____ _____ cells can: 

  • Secrete HCO3-

  • Reclaim H+ to acidify blood 

• Mechanism is OPPOSITE of bicarb ion reabsorption process by Type A 

• Even during alkalosis → nephrons and collecting ducts _____ MORE HCO3- than they _____

type B intercalated, conserve, excrete

Abnormalities of Acid-Base Balance (2)

1. Respiratory acidosis & alkalosis 

• Caused by FAILURE of resp system to perform pH-balancing role 

• Single most IMPORTANT indicator is blood _____ (normally 35-45 mm Hg)

  • PCO2 ABOVE = respiratory _____

    • Common cause of acid-base imbalances 

    • Due to _____ in ventilation or gas exchange (ex. Emphysema, pneumonia, cystic fibrosis) 

    • CO2 accumulates in blood + blood pH drops 

  • PCO2 BELOW = respiratory _____

    • Common result of _____ (often due to stress or pain) 

    • CO2 is eliminated _____ than produced
      

PCO2, acidosis, decrease, alkalosis, hyperventilation, faster

Abnormalities of Acid-Base Balance (2)

2. Metabolic Acidosis and Alkalosis 

• ALL abnormalities other than those caused by PCO2 levels in blood 

• Indicated by abnormal _____ levels 

bicarbonate

Metabolic Acidosis 

• LOW blood pH and HCO3- 

• NOT caused by too much or too little CO2 

• Causes: 

  • Ingestion of too much _____ (converts to acetic acid)

  • Excessive _____ of HCO3- (ex. Persistent diarrhea) 

  • Accumulation of _____ _____ (exercise or shock), ketosis in diabetic crisis, starvation, and kidney failure 

alcohol, loss, lactic acid

Metabolic Alkalosis 

• Indicated by RISING blood pH and HCO3- 

• Much LESS common than metabolic acidosis 

• Causes: _____ of acid contents of stomach or intake of excess _____

  • Ex. over ingestion of _____

vomiting, base, antacids

Effects of Acidosis and Alkalosis 

• Blood pH BELOW 6.8 → causes _____ (inhibition) of _____→ can lead to coma and death 

• Blood pH ABOVE 7.8 → causes _____of _____→ lead to muscle tetany, extreme nervousness, convulsions, and death 

  • Often from respiratory arrest

depression, CNS, overexcitation, NS

Compensations 

• If acid-base imbalance is due to malfunction of one physiological buffer system, other system tries to compensate 

  • Resp system attempts to correct _____acid-base imbalances 

  • Kidneys (renal) attempt to correct _____ acid-base imbalance

metabolic, respiratory

Respiratory Compensation 

• Lungs try to compensate for metabolic pH by changing respiratory _____ and _____

• Metabolic acidosis: 

  • Increases rate and depth of breathing 

  • _____ H+ levels stimulate resp centers 

  • Indicated by blood pH below 7.35, _____ HCO3- level, and PCO2 levels _____ normal as lungs blow off more CO2

rate, depth, high, low, below

Respiratory Compensation 

In metabolic alkalosis : 

• Resp system tries to compensate by _____ breathing 

• Slow, shallow breathing → allows CO2 to accumulate in blood = lower pH 

• Metabolic alkalosis w/ resp compensation is indicated by HIGH pH (over 7.45) due to _____ HCO3 levels, and a PCO2 _____ 45 mm Hg as lungs try to build up H+ levels

decreasing, elevated, above

Renal Compensation 

• Kidneys try to compensate for pH problems caused by lungs by adjusting _____ levels 

• RESPIRATORY system CANNOT compensate for respiratory acidosis or alkalosis 

• Renal system cannot compensate for acid-base imbalances caused by renal problems

• In resp acidosis: 

  • Kidneys reabsorb _____HCO3-, create _____HCO3-, and _____ more H+ 

  • _____ can cause elevated PCO2

  • Resp acidosis w/ renal compensation is indicated by LOW pH, _____ PCO2 and HCO3-levels (indicated compensation by kidneys)

bicarbonate, more, new, secrete, hypoventilation, high

Resp alkalosis: 

• Kidneys _____ MORE HCO3

• Indicated by HIGH pH, _____ PCO2, and _____ HCO3- levels 

excrete, low, decreasing