Acid-Base Balance

What is the purpose of acid-base balance?

maintain homeostasis of H+ concentration

What is an H+ donor?

an acid

What is a base?

a H+ acceptor that forms hydroxyl ions

What does pH stand for?

power of Hydrogen

What does pH reflect?

hydrogen ion concentration

What kind of relationship does pH have with hydrogen?

inverse

What is the normal ECF pH range?

7.35 - 7.45

Normally, the ECF is slightly ___________.

basic

What could happen if the body remained at a pH of 7.0?

cellular death, organ damage

What is the range for alkalosis?

7.45 - 7.90

What is the range for acidosis?

6.8 - 7.35

What are the ranges for cellular death caused by pH?

<6.8 or >7.9

What is acidosis?

increased H+ concentration

What is alkalosis?

decreased H+ concentration

What does acidosis cause?

CNS depression; symptoms range from disorientation to coma

What does alkalosis cause?

CNS overstimulation; symptoms range from tingling sensations in extremities, tetany, to convulsions

What are the body’s defense mechanisms for pH changes? (in order)

buffer system, respiratory system, and renal system

Give a brief overview of the buffer system

first defense, primary system, detects pH changes within seconds and starts to correct problems

Give a brief overview of the respiratory system defense mechanism

second defense, kicks in within 1-3 minutes

Give a brief overview of the renal system defense mechanism

most protective system, last defense, most powerful, takes hours to day to fully kick in

What is the buffer system aka? why?

chemical sponge; soaks up excess H+ or releases H+

What would the buffer system do in an acidic state?

soak up excess H+

What would the buffer system do in an alkalinic state?

release H+

What is a buffer?

a solution of 2 or more chemical compounds that prevent excessive pH changes by combining with an acid or base and neutralizing harmful effects until other regulatory mechanisms take over

What are the body’s three buffer systems?

bicarbonate buffer system, phosphate buffer system, protein buffer system

Describe the bicarbonate buffer system

major buffer system that buffers blood and interstitial fluid; consists of carbonic acid and sodium bicarbonate

What is the balanced ratio of acids to bases? (how many bases does it take to neutralize an acid?)

1:20

How does the phosphate buffer system work?

phosphate reacts with acids or bases to form compounds that slightly alter pH, entire system consists of two ions

Where does the phosphate buffer system mostly occur?

ICF and renal tubules (to regulate urine pH)

What are the major roles of the phosphate buffer system?

H+ elimination (via kidneys) and Na & H exchange

Describe the protein buffer system

proteins (like hemoglobin and albumin) will consume acids or bases before they get the chance to affect pH

How does the protein buffer system react to pH changes?

in acidic states, the protein buffer will drop oxygen and accept CO2; in alkalinic states, the protein buffer will release hydrogen ions and absorb oxygen

What is the objective of the respiratory system (acid-base balance)?

regulate blood carbon dioxide levels

What do the lungs do in response to pH changes?

in acidic states, the lungs will hyperventilate to try and excrete CO2; in alkalinic states, the lungs will hypoventilate to hold on to CO2

What is the objective of the renal system (acid-base balance)?

regulate blood bicarbonate levels

How do the kidneys react in response to pH changes?

in acidic states, kidneys will allow hydrogen to bind with nitrogen (yields ammonia) to be excreted in urine; in alkalinic states, kidneys will excrete bicarbonate and absorb hydrogen

What are the four acid-base imbalances?

respiratory acidosis, respiratory alkalosis, metabolic acidosis, metabolic alkalosis

What does metabolic refer too?

kidney (or sometimes GI) issue

What does respiratory refer too?

breathing

What is respiratory acidosis?

excess carbonic acid in blood

What are causes of respiratory acidosis?

hypoventilation: inadequate inspiratory processes, inadequate expiratory processes, decreased rate or depth

What are examples of inadequate inspiratory processes?

COPD, asthma, bronchitis, emphysema

What are examples of inadequate expiratory processes?

crushed chest trauma, abdominal or thoracic surgery, cerebral edema, obstructed airway

What are examples of depressed rate or depth?

narcotics, sedatives, electrolyte imbalances, stroke, obesity, myasthenia gravis

What are symptoms of respiratory acidosis?

decreased oxygen saturation (due to protein buffers), pulse ox <93, hypoxia (first sign: restlessness, late stage: cyanosis), intravascular headache, confusion, lethargic, SOB, flushed skin, anxiety, N/V, potassium imbalances, lactic acid buildup, reduced binding of calcium

What are treatments for respiratory acidosis?

bronchodilators, oxygen, pulmonary toiletry, hyperventilate with bag-mask, AVOID SODIUM BICARBONATE (causes alkalosis)

What is respiratory alkalosis?

carbonic acid deficit

What causes respiratory alkalosis?

mostly hyperventilation, pulmonary emboli, hypoxia, fever, pregnancy, anxiety/emotional stress

What are symptoms of respiratory alkalosis?

angina, restlessness, diaphoresis, dyspnea, paresthesia, hypocalcemia, hyperphosphatemia

How do you treat respiratory alkalosis?

rebreathe CO2 (brown paper bag or device), sedatives for extreme anxiety

What is metabolic acidosis?

H+ excess or bicarbonate deficit

What are causes of metabolic acidosis?

increased intake of salicylic acid, renal failure, loss of bicarbonate through GI (V/D/nasogastric suction), aspirin overdose

What are symptoms of metabolic acidosis?

decreased oxygen saturation, hyperventilation

What are treatments for metabolic acidosis?

mainly sodium bicarbonate (be certain bc can cause IC bleeding or stroke, extreme case), Ringer’s Lactate (mild case), insulin and fluid for diabetics

What is metabolic alkalosis?

bicarbonate excess or H+ deficit

What causes metabolic alkalosis?

excess antacids, hypoxia (anaerobic metabolism causes lactic acid buildup), low-carb diets, GI loss

What are symptoms of metabolic alkalosis?

hypoventilation, alkaline urine, hypokalemia

How do you treat metabolic alkalosis?

antiemetics, ammonium chloride (acidifying agent)

Describe the acidifying agent: ammonium chloride

lowers pH, used for metabolic alkalosis and UTIs, may cause metabolic acidosis and extravasation, monitor blood pH and give full glass of water

What are examples of alkalinizing agents?

sodium bicarbonate, sodium lactate, THAM, shohl’s solution

Describe alkalinizing agents

raises pH, used for metabolic acidosis and raising urine pH to remove drugs, may cause gastric distention, tissue necrosis, metabolic alkalosis, and water retention, educate pt of side effects, avoid OTC sodium bicarbonate, and monitor blood pH