module three | BIO 224

cation

ions with a positive charge

anions

ions with a negative charge

acids

substances that donate hydrogen ions

bases

substance that accept hydrogen ions

pH

clinical measurement of acid

anion gap

difference between major cations (Na+) and anions (Cl- and HCO3-) in the blood

• represents the unmeasurable anions like phosphates, organic acids serum proteins, etc.

• normal range: 12 (142 of sodium - (103 of Chloride - 27 of Bicarbonate) = 12 of gap)

• metabolic acidosis = anion gap higher than 12 or excess chloride ions, low bicarbonate

buffers

act to resist pH change by sequestering or releasing H+

• mix acids and bases to resist pH change

• trade stronger acids and bases for weaker

plasma buffers

reacts in seconds to hydrogren ion level

• bicarbonate buffer

• protein buffer (albumin)

• H+/K+ exchange

respiratory buffers

reacts in minutes to excrete oxygen

renal buffers

reacts in hours to days to produce, absorb, and excrete acid, bases, and ions

to compensate for LOW BLOOD PH in metabolic acidosis:

respiratory rate will increase to excrete CO2; increase the pH level

to compensate for HIGH BLOOD PH in metabolic alkalosis:

respiratory rate will decrease, which causes CO2 to be retained (increase levels) leading to a build up of H+ and the pH levels will decrease

respiratory buffers are controlled by:

brainstem

• pons and medulla

chemoreceptors

• sence H+ concentration

hypoxemia

decreased oxygen in the arterial blood

• leads to decrease in pressure of oxygen in the blood; partial pressure of O2 less than 80 mmHg

hypoxia

oxygen deprivation in the cells

• causes: decreased ventilation or decreased perfusion

• patients become restless, confused, tachypneic, tachycardia

hypercapnia

increased carbon dioxide in the blood

hypoventilation (respiratory acidosis)

carbon dioxide is retained in the lungs causing the increase of carbonic acid; excess of hydrogen ion concentration in the blood

• renal compensation: kidneys will reabsorb bicarbonate and/or excess hydrogen ion concentration secreted in urine

respiratory acidosis

etiology:

• COPD (retaining carbon dioxide)

• pneumonia

• atelectasis (collapsed alveoli)

• anesthesia

• drug overdose

pH is less than 7.35

pressure of carbon dioxide is greater than 45

hyperventilation (respiratory alkalosis)

increase exhalation of carbon dioxide causing a decrease to carbonic acid in the blood; respiratory alkalosis can occur

• renal compensation: kidneys will compensate by bicarbonate secretion in the urine high pH and low pressure of carbon dioxide

respiratory alkalosis

• seizures

• deep, rapid breathing

• tachycardia

• low or normal BP

• hypokalemia

• numbness and tingling of extremities

• lethargy and confusion

• light headedness

• nausea, vomiting

causes: hyperventilation (anxierty, fear); mechanical ventilation

metabolic acidosis