Buffer Systems in Human Physiology

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What happens to the amino group in proteins at low pH conditions?

It remains uncharged.

It releases H⁺ ions, becoming negatively charged.

It becomes a carboxyl group.

It accepts H⁺ ions, becoming positively charged. (correct)

How does the carboxyl group behave in acidic conditions?

It becomes negatively charged.

It accepts additional H⁺ ions.

It releases H⁺ ions into the solution.

It remains protonated and does not release H⁺. (correct)

What is the primary role of hemoglobin in buffering blood pH?

It binds to H⁺ ions after oxygen release. (correct)

It alkalizes the blood directly.

It binds to CO₂ exclusively.

It mainly increases H⁺ levels.

What occurs in the respiratory system during acidosis?

The respiratory rate increases to remove CO₂. Signup and view all the answers

How do the kidneys respond to alkalosis?

They excrete HCO₃⁻ and retain H⁺. Signup and view all the answers

What occurs to the amino group at high pH conditions?

It remains uncharged and does not accept H⁺. Signup and view all the answers

What does an increase in H⁺ from the carboxyl group accomplish in basic conditions?

It stabilizes the pH by increasing acidity. Signup and view all the answers

How does the bicarbonate buffering system interact with hemoglobin?

Bicarbonate buffering aids hemoglobin in binding H⁺. Signup and view all the answers

In what location is the hemoglobin buffer system primarily found?

In red blood cells. Signup and view all the answers

Which adjustment do the kidneys make during respiratory acidosis?

They excrete H⁺ and retain HCO₃⁻. Signup and view all the answers

What is the primary function of buffer systems in the human body?

To resist changes in pH upon the addition of acids or bases Signup and view all the answers

Which components make up the bicarbonate buffer system?

Bicarbonate ion and carbonic acid Signup and view all the answers

What occurs when excess H⁺ ions are present in the bicarbonate buffer system?

HCO₃⁻ combines with H⁺ to form H₂CO₃ Signup and view all the answers

Where is the phosphate buffer system primarily located?

In intracellular fluid and kidney tubules Signup and view all the answers

How does the phosphate buffer system stabilize pH when it decreases?

By binding H⁺ ions with HPO₄²⁻ to form H₂PO₄⁻ Signup and view all the answers

What is the total concentration of the phosphate buffer system in plasma compared to other buffers?

Less than that of other major buffer systems Signup and view all the answers

Which of the following is a component of the protein buffer system?

Amino acids and proteins Signup and view all the answers

What role do amino acids play in the protein buffer system?

Contain negatively charged carboxyl groups and positively charged amino groups Signup and view all the answers

What is the pH range considered normal for arterial blood?

7.35–7.45 Signup and view all the answers

Which system closely interacts with the bicarbonate buffer to manage pH changes?

Respiratory and renal systems Signup and view all the answers

What is the primary role of hemoglobin during the isohydric shift?

To bind hydrogen ions and buffer pH changes Signup and view all the answers

During the chloride shift, what happens to bicarbonate in the red blood cells?

It diffuses out of the RBCs into plasma Signup and view all the answers

Which of the following best defines isohydric shift?

A process that buffers H⁺ ions without changing pH Signup and view all the answers

What initiates the formation of carbonic acid in red blood cells?

The combination of carbon dioxide and water Signup and view all the answers

What occurs in red blood cells as bicarbonate ions leave?

Chloride ions from plasma enter the red blood cells Signup and view all the answers

Which enzyme catalyzes the conversion of carbon dioxide and water into carbonic acid?

Carbonic anhydrase Signup and view all the answers

What happens during the reverse of the chloride shift in the lungs?

Bicarbonate re-enters red blood cells and forms CO₂ Signup and view all the answers

What is the major consequence of the isohydric shift during CO₂ transport?

Maintenance of blood pH stability Signup and view all the answers

How do bicarbonate ions contribute to acid-base balance in the blood?

By acting as a buffer, absorbing excess hydrogen ions Signup and view all the answers

What defines the 'Hamburger phenomenon'?

The exchange of chloride ions and bicarbonate across RBC membranes Signup and view all the answers

Study Notes

Buffer Systems

The human body maintains a stable pH (7.35-7.45 in arterial blood) for cellular functions, enzymes, and overall physiological processes.
Buffer systems neutralize excess acids or bases, preventing sudden pH changes.
A buffer solution resists pH changes when an acid or base is added.
It comprises a weak acid and its conjugate base, or a weak base and its conjugate acid.
These neutralize added acids/bases to maintain a relatively steady pH.

Bicarbonate Buffer System

Components: bicarbonate ion (HCO3-) and carbonic acid (H2CO3).
Location: extracellular fluid (blood plasma).
Mechanism: When excess H+ ions are present, bicarbonate ions combine to form carbonic acid. Carbonic acid then breaks down into CO2 and H2O, releasing CO2 through respiration. If pH rises, carbonic acid releases H+ ions, lowering pH.
Importance: This is the primary buffer in the blood, working closely with respiratory and renal systems to maintain pH.

Phosphate Buffer System

Components: dihydrogen phosphate (H2PO4-) and hydrogen phosphate (HPO42-).
Location: primarily in intracellular fluid and kidney tubules.
Mechanism:
- When pH decreases, HPO42- binds with H+ ions to form H2PO4-.
- When pH increases, H2PO4- donates H+ ions, stabilizing pH.
- These two ions are in equilibrium.
The overall plasma concentration is lower than other major buffer systems (only around 5% of the non-bicarbonate buffer value of plasma).

Protein Buffer System

Nearly all proteins act as buffers.
Proteins are made of amino acids, with positively charged amino groups and negatively charged carboxyl groups.
Components: amino acids and proteins (e.g., hemoglobin).
Location: both intracellular and extracellular fluids.
Mechanism: Amino groups accept H+ ions; carboxyl groups release H+ ions, depending on pH.

Low pH (Acidic) Conditions

High H+ ion concentration.
The amino group (-NH2) accepts an additional H+ ion, becoming -NH3+, reducing excess H+ and preventing further pH decrease.
The carboxyl group (-COOH) already protonated, doesn't release H+ in acidic environments.
Overall, amino groups accepting H+ helps stabilize pH.

High pH (Basic) Conditions

Low H+ ion concentration.
The carboxyl group (-COOH) releases an H+ ion, becoming -COO-, adding protons to counter the pH increase.
The amino group (-NH2), deprotonated at high pH, remains uncharged and doesn't readily accept H+ ions.
Overall, carboxyl groups releasing H+ in countering the basic environment help stabilize pH.

Hemoglobin Buffer System

Location: red blood cells.
Mechanism: Hemoglobin binds H+ ions, especially when oxygen is released from tissues, buffering changes in pH.
- Also helps transport CO2 from tissues to lungs for exhalation.
Importance: Key role in maintaining blood pH, especially in venous blood (high CO2).

Buffer Systems and Acid-Base Disorders

Buffer systems work with respiratory and renal systems to compensate for acid-base imbalances.
Respiratory System Compensation (Lungs): Rapidly regulates blood pH by adjusting CO2 levels through breathing.
Renal System Compensation (Kidneys): Adjusts blood pH more slowly through H+ excretion/HCO3- reabsorption.

Isohydric and Chloride Shift

Isohydric shift: Movement of H+ ions by hemoglobin, without changing overall blood pH.
Chloride shift: Exchange of bicarbonate (HCO3-) and chloride (Cl-) ions across red blood cell membranes to maintain balance, facilitating CO2 transport.

Compensatory Mechanisms

Compensatory mechanisms are physiological processes to restore homeostasis when encountering stressors, diseases, or other disruptions.
They help sustain essential functions, especially under acute or chronic stress, but prolonged compensation may lead to pathologic conditions if underlying causes aren't addressed (diabetic example).

Types of Compensatory Mechanisms

Renal (Kidneys): Regulation of acid-base balance through bicarbonate reabsorption or hydrogen ion excretion, compensation for respiratory issues.
Respiratory (Lungs): Adjusting breathing rate and depth to maintain blood gas levels (CO2, O2).
Hormonal (e.g., RAAS): Activates in response to low blood pressure or sodium depletion, leading to water and sodium retention to increase blood volume.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the essential buffer systems that help maintain stable pH levels in the human body. This quiz covers key concepts including the bicarbonate buffer system and its role in balancing acidity and alkalinity in blood. Test your knowledge on how these systems interact with respiratory and renal functions.