26.5 Disorders of Acid-Base Balance
3 min read•june 18, 2024
Acid-base balance is crucial for our body's function. It's all about keeping our blood pH just right - not too acidic, not too basic. Our and work together to maintain this delicate balance.
When things go wrong, we can end up with acidosis or alkalosis. These conditions can be caused by breathing problems, kidney issues, or other health problems. Understanding how our body regulates pH helps us diagnose and treat these imbalances.
Disorders of Acid-Base Balance
Blood variables for acid-base diagnosis
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- Blood pH indicates overall acid-base balance
- Normal range 7.35-7.45 maintains optimal cellular function
- Acidosis occurs when pH drops below 7.35 (excess H+)
- Alkalosis occurs when pH rises above 7.45 (deficiency of H+)
- measures acidity or alkalinity of a solution
- Partial pressure of carbon dioxide () reflects respiratory component
- Normal range 35-45 mmHg ensures proper CO2 elimination
- occurs when PaCO2 exceeds 45 mmHg ()
- occurs when PaCO2 falls below 35 mmHg ()
- () concentration reflects metabolic component
- Normal range 22-26 mEq/L buffers acid-base changes
- Metabolic acidosis occurs when HCO3- falls below 22 mEq/L (excess acid production or loss of HCO3-)
- occurs when HCO3- rises above 26 mEq/L (excess HCO3- retention or loss of H+)
- helps differentiate causes of metabolic acidosis
- Normal range 8-16 mEq/L represents unmeasured anions (albumin, phosphate)
- Increased anion gap (, ) suggests acid accumulation
- Normal anion gap (diarrhea, ) suggests HCO3- loss
Compensation for respiratory imbalances
- (increased PaCO2) triggers
- increases H+ excretion and HCO3- reabsorption
- Leads to increased blood HCO3- concentration to buffer excess CO2
- Buffering by and plasma proteins helps minimize pH changes
- increases H+ excretion and HCO3- reabsorption
- (decreased PaCO2) triggers opposing compensations
- Renal compensation decreases H+ excretion and HCO3- reabsorption
- Leads to decreased blood HCO3- concentration to offset low CO2
- Buffering by hemoglobin and plasma proteins helps resist pH increase
- Renal compensation decreases H+ excretion and HCO3- reabsorption
- Respiratory compensations occur more slowly than metabolic compensations
- Renal adjustments to HCO3- take hours to days to reach steady state
- Hemoglobin and protein buffers provide immediate but limited compensation
Compensation for metabolic imbalances
- Metabolic acidosis (decreased HCO3-) triggers respiratory and renal responses
- Respiratory compensation involves to decrease PaCO2
- Leads to increased elimination of CO2 and H+ to offset acidosis
- Renal compensation increases H+ excretion and generates new HCO3-
- Tubular cells secrete more H+ and synthesize HCO3- from CO2
- Respiratory compensation involves to decrease PaCO2
- (increased HCO3-) triggers hypoventilation and renal adjustments
- Respiratory compensation involves hypoventilation to increase PaCO2
- Leads to increased retention of CO2 and H+ to counteract alkalosis
- Renal compensation decreases HCO3- excretion and increases H+ excretion
- Tubular cells reabsorb more HCO3- and eliminate H+ in urine
- Respiratory compensation involves hypoventilation to increase PaCO2
- Metabolic compensations occur more quickly than respiratory compensations
- Ventilatory changes in PaCO2 can be achieved within minutes
- Renal adjustments to H+ and HCO3- excretion take hours to days
Acid-Base Homeostasis Mechanisms
- provide immediate chemical neutralization of acids or bases
- system is the most important extracellular buffer
- Protein buffers, including hemoglobin, contribute to intracellular buffering
- Phosphate buffer system is important in urine and intracellular fluid
- describes the relationship between pH, bicarbonate, and CO2
- Used to calculate pH based on bicarbonate concentration and partial pressure of CO2
- Compensatory mechanisms work to restore acid-base balance
- Respiratory system adjusts CO2 levels through changes in ventilation
- Renal system regulates bicarbonate reabsorption and acid excretion
- Both systems work together to maintain
Key Terms to Review (41)
Acid-Base Homeostasis: Acid-base homeostasis refers to the body's tight regulation of the pH levels in the blood and other bodily fluids. It involves the delicate balance between acids and bases to maintain a slightly alkaline pH, which is crucial for proper physiological functioning.
Anion Gap: The anion gap is a calculation used to evaluate the balance of electrolytes and acid-base status in the body. It represents the difference between the measured cations (positively charged ions) and the measured anions (negatively charged ions) in the blood, providing insights into potential metabolic disturbances.
Antidiuretic Hormone: Antidiuretic hormone (ADH), also known as vasopressin, is a peptide hormone produced by the hypothalamus and released by the posterior pituitary gland. It plays a crucial role in the regulation of fluid balance and osmotic homeostasis within the body by promoting water reabsorption in the kidneys, thereby reducing urine output and increasing water retention.
Antidiuretic hormone (ADH): Antidiuretic hormone (ADH) is a peptide hormone produced primarily by the hypothalamus and released by the posterior pituitary gland, which regulates water balance in the body by increasing the absorption of water in the kidneys. This process decreases urine volume, conserves body water, and increases blood pressure.
Arterial Blood Gas: Arterial blood gas (ABG) analysis is a medical test that measures the levels of oxygen, carbon dioxide, and other important gases in the blood drawn from an artery. This test provides critical information about the body's acid-base balance and respiratory function, which are essential for evaluating and managing disorders of acid-base balance.
Baroreceptors: Baroreceptors are specialized sensory receptors that detect changes in blood pressure within the body. They play a crucial role in the homeostatic regulation of the cardiovascular system, helping to maintain blood pressure within a normal range.
Bicarbonate: Bicarbonate, also known as hydrogen carbonate, is a chemical compound with the formula HCO3-. It is an essential ion involved in various physiological processes within the human body, including maintaining acid-base balance, facilitating gas exchange, and supporting digestive functions.
Bicarbonate Buffer: The bicarbonate buffer system is a crucial acid-base regulatory mechanism in the body. It involves the reversible reaction between carbonic acid (H2CO3) and bicarbonate ions (HCO3-), which helps maintain a stable pH within a narrow range essential for proper physiological function.
Buffer Systems: Buffer systems are chemical mechanisms that help maintain a relatively stable pH in the body, despite the production of acidic or basic substances. They play a crucial role in regulating the acid-base balance, which is essential for proper human functioning and health.
Carbonic Acid: Carbonic acid is a weak acid formed when carbon dioxide (CO2) dissolves in water. It plays a crucial role in the regulation of acid-base balance and the transport of gases within the human body.
Carbonic Anhydrase Reaction: The carbonic anhydrase reaction is a crucial enzymatic process that facilitates the interconversion between carbon dioxide (CO2) and carbonic acid (H2CO3) in the body. This reaction plays a central role in maintaining the delicate acid-base balance and regulating the transport of respiratory gases, which are essential for proper physiological function.
Chemoreceptors: Chemoreceptors are specialized sensory cells that detect chemical stimuli in the body and transmit this information to the central nervous system. They play a crucial role in maintaining homeostasis, sensing the body's internal environment, and initiating appropriate physiological responses.
Chloride: Chloride is a negatively charged ion (anion) that is essential for various physiological processes in the human body. It is the second most abundant electrolyte in the body and plays a crucial role in maintaining fluid balance, nerve impulse transmission, and acid-base balance.
Chronic Obstructive Pulmonary Disease (COPD): Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung disease characterized by persistent airflow limitation and respiratory symptoms, such as breathlessness, cough, and sputum production. It is a major cause of morbidity and mortality worldwide, and its development is strongly associated with exposure to noxious particles or gases, primarily from smoking.
Compensatory Mechanisms: Compensatory mechanisms refer to the body's physiological processes that act to restore homeostasis and maintain normal function when there is a disturbance or imbalance in the body's internal environment. These mechanisms help the body adapt and respond to various challenges, including disorders of acid-base balance.
Diabetic ketoacidosis: Diabetic ketoacidosis (DKA) is a serious complication of diabetes that occurs when the body produces high levels of ketones due to a lack of insulin. It leads to metabolic acidosis, characterized by increased acidity in the blood, and can result from poorly managed diabetes, infection, or missed insulin doses. DKA is a critical condition requiring immediate medical attention, as it can lead to severe dehydration and electrolyte imbalances.
HCO3-: HCO3- is the bicarbonate ion, a negatively charged particle that plays a crucial role in the body's acid-base balance. It is an important buffer system that helps maintain the optimal pH level in the blood and other bodily fluids.
Hemoglobin: Hemoglobin is the iron-containing protein found in red blood cells that is responsible for transporting oxygen from the lungs to the body's tissues and carbon dioxide from the tissues back to the lungs. It is a crucial component in maintaining the requirements for human life, participating in chemical bonds, and supporting various essential functions within the human body.
Henderson-Hasselbalch equation: The Henderson-Hasselbalch equation is a mathematical expression that describes the relationship between the pH of a solution and the concentrations of the acid and conjugate base components of a buffer system. It is a fundamental tool used to understand and predict the acid-base balance in the body.
Hyperventilation: Hyperventilation is a condition in which you start breathing very fast or deeply, often more than what your body requires at rest, leading to a significant reduction in carbon dioxide levels in the blood. This can occur as a response to stress, fear, or due to a medical condition affecting the respiratory system.
Hyperventilation: Hyperventilation is a condition characterized by an abnormally rapid and deep breathing pattern, leading to a decrease in the levels of carbon dioxide (CO2) in the bloodstream. This disruption in the normal balance of gases can have significant impacts on various physiological processes within the body.
Hypoventilation: Hypoventilation is a respiratory condition characterized by inadequate ventilation, leading to an abnormal buildup of carbon dioxide (CO2) in the blood and a decrease in oxygen levels. This imbalance in the body's acid-base status is a central feature of this term and its connection to the topics of acid-base balance and its disorders.
Kidneys: The kidneys are a pair of vital organs located in the lower back that play a crucial role in the body's overall health and functioning. They are responsible for filtering waste and excess water from the blood, regulating fluid and electrolyte balance, and maintaining acid-base balance, among other essential functions.
Kussmaul Breathing: Kussmaul breathing is a deep, labored, and rapid breathing pattern that occurs in response to severe metabolic acidosis, a condition characterized by an abnormal accumulation of acid in the body. This breathing pattern is named after the German physician Adolf Kussmaul, who first described it in the 19th century.
Lactic Acidosis: Lactic acidosis is a metabolic condition characterized by an abnormal accumulation of lactic acid in the bloodstream, leading to a disruption in the body's acid-base balance. It is a serious complication that can arise from various underlying medical conditions or factors.
Lungs: The lungs are the primary respiratory organs responsible for gas exchange in the human body. They are located in the thoracic cavity and play a vital role in the respiratory system, facilitating the intake of oxygen and the removal of carbon dioxide from the bloodstream.
Metabolic alkalosis: Metabolic alkalosis is a condition characterized by an increase in the body's pH level due to a loss of acid or an excess of bicarbonate in the bloodstream. It occurs when the body has too much base relative to acid, leading to a higher-than-normal blood pH.
Metabolic Alkalosis: Metabolic alkalosis is a condition in which the body's pH is elevated above the normal range due to an excess of bicarbonate (HCO3-) or a loss of hydrogen ions (H+) in the blood. This disruption in the body's acid-base balance can have significant impacts on the urinary system and overall homeostasis.
Oxygen–hemoglobin dissociation curve: The oxygen–hemoglobin dissociation curve is a graphical representation that shows the relationship between the partial pressure of oxygen and the percentage saturation of hemoglobin in blood. It illustrates how easily hemoglobin picks up and releases oxygen molecules into tissues, depending on the oxygen concentration.
PaCO2: PaCO2, or partial pressure of carbon dioxide in arterial blood, is a crucial parameter in the assessment of acid-base balance within the body. It reflects the balance between carbon dioxide production and its removal through respiration, providing valuable insights into respiratory function and the body's ability to maintain pH homeostasis.
PH Scale: The pH scale is a measure of the acidity or basicity (alkalinity) of a solution. It ranges from 0 to 14, with 7 being neutral, values less than 7 being acidic, and values greater than 7 being basic or alkaline. The pH scale is essential for understanding the balance of acids and bases in the human body, which is crucial for maintaining homeostasis and proper functioning.
Potassium: Potassium is an essential mineral that plays a crucial role in various physiological processes within the human body. It is involved in maintaining fluid and electrolyte balance, nerve impulse transmission, muscle contraction, and the regulation of heart function. Potassium is a key player in many of the topics covered in this course, including inorganic compounds, action potentials, neuron communication, nutrition, fluid balance, and acid-base regulation.
Renal Compensation: Renal compensation refers to the kidney's ability to adjust its function in response to disturbances in the body's acid-base balance. This process helps maintain normal pH levels in the blood and tissues, ensuring optimal physiological functioning.
Renal Tubular Acidosis: Renal tubular acidosis (RTA) is a group of disorders characterized by the inability of the kidneys to properly regulate the body's acid-base balance, leading to the accumulation of acid in the body. This disruption in the normal pH levels can have significant consequences on various physiological processes.
Respiratory acidosis: Respiratory acidosis is a condition characterized by an excess of carbon dioxide in the bloodstream due to inadequate ventilation, leading to decreased blood pH. It indicates a disturbance in acid-base balance where the body accumulates too much acid or cannot effectively remove enough CO2.
Respiratory Acidosis: Respiratory acidosis is a condition in which the body accumulates too much carbon dioxide (CO2) due to inadequate ventilation or breathing, leading to a decrease in blood pH and an imbalance in the body's acid-base balance.
Respiratory alkalosis: Respiratory alkalosis occurs when there's a decrease in carbon dioxide levels in the blood due to rapid or deep breathing, leading to an increase in blood pH. This condition can result from hyperventilation caused by anxiety, fever, or other medical conditions.
Respiratory Alkalosis: Respiratory alkalosis is a condition in which the body's pH becomes too alkaline due to a decrease in carbon dioxide (CO2) levels. This occurs when breathing rate or depth increases, leading to excessive removal of CO2 from the body. Respiratory alkalosis is closely linked to modifications in respiratory functions, acid-base balance, and disorders of acid-base balance.
Sodium bicarbonate: Sodium bicarbonate is a chemical compound with the formula NaHCO₃, commonly known as baking soda, which acts as a buffer to maintain pH balance in the body, especially relevant during protein metabolism where it helps neutralize the acidic by-products. It plays a crucial role in maintaining acid-base homeostasis in tissues and blood.
Tetany: Tetany is a neuromuscular disorder characterized by involuntary muscle contractions and spasms, often caused by a deficiency or imbalance of certain electrolytes, particularly calcium. This condition is closely linked to the regulation of calcium homeostasis, the function of the parathyroid glands, and acid-base balance in the body.
The Lungs: The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax), primarily responsible for gas exchange between the air and the bloodstream. They remove carbon dioxide from the blood and replace it with oxygen during the breathing process.