Chapter 22: Acid-Base Balance

Comprehensive vocabulary flashcards covering acid-base balance, the pH scale, physiological control mechanisms (respiratory and urinary), buffer pairs, and clinical imbalances such as acidosis and alkalosis.

pH

A number that indicates the relative hydrogen ion ($H^+$) concentration (compared with $OH^-$) of a fluid.

Neutral Solution

A fluid with a pH of $7.0$ where the concentration of $[H^+] = [OH^-]$.

Alkaline (Basic) Solution

A fluid with a pH higher than $7.0$ where the concentration of $[H^+] < [OH^-]$.

Acid Solution

A fluid with a pH less than $7.0$ where the concentration of $[H^+] > [OH^-]$.

Normal Blood pH Range

Approximately $7.35$ to $7.45$.

Arterial Blood pH

Approximately $7.45$.

Venous Blood pH

Approximately $7.35$, slightly lower than arterial blood due to the presence of carbonic acid ($H_2CO_3$).

pH Scale Basis

A scale based on multiples of $10$, where the $H^+$ concentration changes by $10$ times for each pH unit.

Carbonic Anhydrase

An enzyme that catalyzes the conversion of carbon dioxide and water into carbonic acid, playing a key role in the bicarbonate buffer system.

Chemical pH Control Mechanism

A homeostatic mechanism based on buffers in blood/RBCs and body fluids that acts immediately to prevent pH swings.

Physiological pH Control (Respiratory)

A mechanism that regulates changes in pH within minutes by altering the respiratory rate, which changes blood $CO_2$ levels.

Physiological pH Control (Urinary)

A mechanism that regulates changes in pH within hours through altered renal activity.

Buffer

Substances that prevent a sharp change in the pH of a fluid when an acid or base is added to it.

Fixed Acids

Acids buffered mainly by sodium bicarbonate ($NaHCO_3$).

Buffer Pair Components

In the body, these consist of sodium bicarbonate ($NaHCO_3$) and carbonic acid ($H_2CO_3$).

Normal Buffer Ratio

The ratio of amount of $NaHCO_3$ to the amount of $H_2CO_3$ in blood, which is normally $20:1$.

Respiratory Mechanism of pH Control

The removal of $CO_2$ from the blood as it flows through lung capillaries, decreasing $H_2CO_3$ and $H^+$ concentration to increase blood pH.

Urinary Mechanism of pH Control

The process by which distal tubules secrete hydrogen ions ($H^+$) and ammonia ($NH_3$) into the urine while reabsorbing $NaHCO_3$ into the blood.

Acidosis

A pH imbalance resulting from anything that causes decreased respirations over time or a loss of bicarbonate.

Alkalosis

A pH imbalance resulting from anything that causes increased respirations over time or an excess of bicarbonate.

Metabolic Acidosis

A disturbance characterized by a bicarbonate ($NaHCO_3$) deficit.

Metabolic Alkalosis

A disturbance characterized by a bicarbonate ($NaHCO_3$) excess; it can be a complication of severe vomiting.

Respiratory Acidosis

A disturbance characterized by an excess of carbonic acid ($H_2CO_3$).

Respiratory Alkalosis

A disturbance characterized by a deficit of carbonic acid ($H_2CO_3$).

Compensated Metabolic Acidosis

A state where the normal $20:1$ ratio of $NaHCO_3$ to $H_2CO_3$ is maintained, but the total amount of both substances changes.

Uncompensated Metabolic Acidosis

A state where the normal $20:1$ ratio of $NaHCO_3$ to $H_2CO_3$ is changed.