A Short Introduction to Acids and Bases

pH of humans

7.35-7.45

Acidosis and Alkalosis further broken down into:

Respiratory acidosis or alkalosis and metabolic acidosis or alkalosis.

Two overarching control mechanism

• Buffering solutions in both intracellular and extracellular fluids.

• Organs - Physiological mechanisms

Organs (physiological mechanisms) (for maintaining acid/base balance)

• Lungs - Elimination of CO2

• Kidneys - Reabsorption/elimination of bicarbonate and elimination of metabolic acids

• Bone - Exchanges of calcium and release of carbonate

Biggest buffering system

carbonic acid - bicarbonate system:

• Can take H+ or OH- ions in intra or/and extra cellular fluids.

Primary Deference (bicarbonate system)

Carbonate present in intra/extra cellular fluids

Secondary Deference (bicarbonate system)

Exhalation of CO2 from lungs

Tertiary Deference (bicarbonate system)

Renal reabsorption of bicarbonate

Levels of bicarbonate and carbonic acid

20:1

• 20 parts HCO3-

• 1 part H2CO3

Acidemia

Blood pH under 7.4

Alkalemia

Blood pH over 7.4

Volatile acids

Can be eliminated via CO2 (breathing)

• High levels of CO2 lead to formation of carbonic acid (decreased pH)

Non-volatile acids

• Can be eliminated via urine (kidney)

• Usually strong acids, include small amounts of sulphonic, phosphoric and other organic acids.

Metabolic Acidosis (occurs)

Occurs to decrease levels of bicarbonate, or from levels of non-carbonic acids

• Ketoacidosis, shock, acute ingestion of toxin

• Levels of carbonate in blood decrease below 22mmol/L

Metabolic Acidosis (Early symptons)

Headache, lethargy, progresses to confusion and coma.

Death (from dysrhythmias and hypotension).

Metabolic Alkalosis (occurs)

Due to increased retention of bicarbonate, decreased levels of certain metabolic acids.

• Sometimes due to excessive vomiting

• Increased retention of bicarbonate due to lack of anions in extracellular fluid signals the kidney to retain bicarbonate.

Metabolic Acidosis (How can body respond)

Through hyperventilation, an increasing amount of CO2 is present.

Metabolic Alkalosis (How can body respond)

Through hypoventilation, increasing amount of CO2 present.

Can be treated through sodium chloride solution, helps replace Cl, allowing kidney to properly excrete bicarbonate

Metabolic Alkalosis (clinical signs)

• Weakness, muscle cramps, hyperactive reflexes, confusion.

Left untreated can lead to convulsions and tachycardia

Respiratory Acidosis (results from)

Hypoventilation leads to an excessive amount of CO2 in the blood.

Respiratory Acidosis (Diagnosed)

Through measurement of partial pressure of CO2 of over 45mmHg (38-42 is normal)

Respiratory Acidosis (Body attempts to do what)

through retention of bicarbonate from kidneys

Respiratory Alkalosis (Results from)

From hyperventilation and leads to reduction of CO2 in blood.

Respiratory Alkalosis (Diagnosed)

measurement of partial pressure of CO2 of under 45mmHg and blood pH of above 7.45.

Respiratory Alkalosis (Causes)

Hypocapnia - decrease in carbonic acid concentration.

Respiratory Alkalosis (body does what)

The body attempts to compensate through the retention of H+ ions and the excretion of bicarbonate from the body.

Acids and bases are either

Are proton donors or proton acceptors.

Strong acids and bases

Completely dissociate into constituent components in water.

• Acid: H+ ions

• Base: OH- ions

Weak acids and bases

Do not completely dissociate in water

Buffers

Compounds, when in solution, work to resist changes in pH.

Generally, salts of an acid/weak base or salts of a weak acid/base.