Acid-Base Balance

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Questions and Answers

What is the primary role of buffers in the human body?

To stabilize fluid pH levels (correct)

To promote rapid changes in blood composition

To increase the acidity of bodily fluids

To convert weak acids into strong acids

Which of the following substances primarily act as buffers in blood?

Weak acids and weak bases (correct)

Only proteins

Organic solvents

Strong acids

Which mechanism can adjust blood pH in minutes?

Respiratory adjustment by exhaling CO2 (correct)

Bicarbonate excretion by kidneys

Hemoglobin reaction with oxygen

Nutrient absorption in the intestines

How do amino acids act as buffers in the body?

Through their ability to ionize and exchange protons Signup and view all the answers

Which two forms are phosphates found in the blood?

Dihydrogen and monohydrogen phosphate Signup and view all the answers

What is the buffering power of proteins in blood primarily attributed to?

The natural ionization of their amino acids Signup and view all the answers

What happens to sodium dihydrogen phosphate when it interacts with a strong base?

It reverts to a weak base and produces water Signup and view all the answers

In what way do renal systems adjust blood pH?

By excreting hydrogen ions and conserving bicarbonate Signup and view all the answers

What is the primary function of hemoglobin in terms of buffering?

To accept hydrogen ions during the conversion of CO2 Signup and view all the answers

Which statement correctly describes the relationship between strong acids, weak acids, and buffers?

Weak acids help mitigate the effects of strong acids and bases Signup and view all the answers

What is the primary buffering system of interstitial fluid in tissues throughout the body?

Bicarbonate buffer Signup and view all the answers

How does the renal system regulate blood bicarbonate levels?

By reabsorbing bicarbonate from the renal filtrate Signup and view all the answers

What effect does hyperventilation have on blood pH?

Decreases CO2 levels and increases pH Signup and view all the answers

Which enzyme catalyzes the hydration of CO2 into bicarbonate?

Carbonic anhydrase Signup and view all the answers

What is the consequence of elevated potassium levels in the kidneys regarding bicarbonate conservation?

It leads to reduced bicarbonate conservation Signup and view all the answers

What is a primary symptom of ketoacidosis related to blood pH regulation?

Fruity smelling breath Signup and view all the answers

In which condition may blood bicarbonate levels be particularly low?

Chronic adrenal insufficiency Signup and view all the answers

What happens to blood pH when CO2 levels rise due to retention from conditions like pneumonia?

Blood pH falls, becoming more acidic Signup and view all the answers

What is the role of chemoreceptors in respiratory regulation?

To monitor CO2 levels and adjust breathing rate Signup and view all the answers

How does the process of bacterial infection impact the bicarbonate buffer system?

It can lead to metabolic acidosis Signup and view all the answers

Study Notes

Buffer Systems in the Human Body

Buffers: Chemical systems that prevent drastic pH changes in bodily fluids by reducing hydrogen ion concentration fluctuations. Weak acids and weak bases are common buffer substances.
Acid-Base Balance: Crucial for physiological function; measured by pH scale.
Buffering Efficiency: The body's buffering systems are highly efficient, with different systems acting at differing speeds.

Types of Buffering Systems

Plasma proteins: Account for a substantial portion of blood buffering power and intracellular buffering.
- Mechanism: Amino acids within proteins ionize in response to pH fluctuations. Amino groups accept H+ to increase pH, while carboxyl groups release H+ to decrease pH.
- Hemoglobin: Vital protein in red blood cells; buffers hydrogen ions released during CO2 conversion into bicarbonate.
Phosphates: Exist in two forms as weak acid or weak base in the blood.
- Sodium dihydrogen phosphate (weak acid): Reverts to a weak base upon contact with strong bases.
- Sodium monohydrogen phosphate (weak base): Reacts with strong acids, accepting hydrogen ions.
Bicarbonate-Carbonic Acid Buffer: Primary buffer in interstitial fluid.
- Mechanism: Sodium bicarbonate reacts with strong acids to form carbonic acid and other salt. Carbonic acid reacts with strong bases to form bicarbonate and water.
- Ratio: Bicarbonate and carbonic acid exist in a 20:1 ratio for normal blood pH.
- Regulation: CO2 expulsion through lungs regulates carbonic acid levels, while renal functions control bicarbonate levels.

Respiratory Regulation

CO2 and pH Relationship: CO2 reacts with water to form carbonic acid, impacting blood pH. Elevated CO2 levels (e.g., holding breath) lower pH, while reduced CO2 levels (e.g., hyperventilation) increase pH.
Hyperventilation: Rapid and deep breathing expels excess CO2, reducing carbonic acid and leading to alkalosis.
Hypoventilation: Impaired breathing increases carbonic acid and causes acidosis.
Hypercapnia: Elevated blood CO2 level; caused by issues with respiratory function, or certain drugs.
Hypocapnia: Low blood CO2 level; commonly resulting from hyperventilation conditions.
Carbonic Anhydrase: Enzyme catalyzing CO2 hydration to bicarbonate—vital to the reaction.
Chemoreceptors: Monitor CO2 levels within blood and CSF to adjust respiratory rate. Peripheral sensors in the aorta and carotid arteries, and central sensors in the medulla oblongata, immediately modulate breathing.
Respiratory Adjustments: Minor changes in breathing can adequately adjust pH; increasing respiratory rate by twofold for minimal duration can raise blood pH by 0.2 units.

Renal Regulation

Bicarbonate Conservation: The kidneys control blood bicarbonate level, a vital part of metabolic pH regulation.
Renal Tubule Mechanism:
- Reabsorption of sodium by antiport mechanism exchange H+ from filtrate.
- Production of bicarbonate.
- Formation of carbonic acid leading to bicarbonate that transfers to peritubular capillaries.
- Secretion of hydrogen ions that may combine with substances and be removed from body.
Factors affecting Bicarbonate Conservation: Diuretics inhibition of carbonic anhydrase, diarrhea, Addison's disease, renal damage, and uncontrolled diabetes.
Chloride and Bicarbonate Relationship: Loss of chloride can lead to greater bicarbonate reabsorption to maintain electrolyte balance.
Hydrogen Ion Interactions: Hydrogen ions and potassium compete for exchange with sodium—the availability of K+ affects the amount of H+ and consequently bicarbonate retention.

Ketoacidosis

Mechanism: Inadequate glucose availability causes fatty acid breakdown; ketone bodies form, lowering blood pH.
Symptoms: Deep and rapid breathing, fruity breath (presence of acetone, a ketone). Other symptoms include dry skin/mouth, flushed face, nausea, vomiting, and stomach pain.

Blood pH

Normal Range: 7.35-7.45
Acidosis: Blood pH below 7.35. (Symptoms include cognitive impairment, tingling, muscle twitching/spasms, nausea and vomiting). Caused by metabolic or respiratory disorders.
Alkalosis: Blood pH above 7.45. (Symptoms include cognitive impairment, tingling, muscle twitching/spasms, nausea and vomiting). Caused by metabolic or respiratory disorders.
Impact of Extreme pH Changes: Extreme pH fluctuations can damage proteins, disrupting metabolic function, leading to tissue damage, and potentially death.

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Description

Explore the critical role of buffer systems in maintaining pH balance within the human body. This quiz covers the types of buffers, their mechanisms, and their efficiency in physiological functions. Understand how proteins and phosphates contribute to acid-base balance.