Hemoglobin Function and Structure Quiz
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Questions and Answers

What is the primary function of hemoglobin in red blood cells?

  • Transports oxygen from lungs to tissues (correct)
  • Transports carbon dioxide from lungs to body tissues
  • Stores oxygen for prolonged periods
  • Regulates blood pH levels

What structural form of hemoglobin has a low affinity for oxygen?

  • D form (Dissociated form)
  • S form (Saturated form)
  • R form (Relaxed form)
  • T form (Tense form) (correct)

How many oxygen molecules can hemoglobin bind?

  • Four oxygen molecules (correct)
  • Three oxygen molecules
  • Two oxygen molecules
  • One oxygen molecule

Which type of bond holds the dimers of hemoglobin less tightly together?

<p>Hydrogen and ionic bonds (D)</p> Signup and view all the answers

Which structure in red blood cells acts as a buffer?

<p>Hemoglobin/oxy-Hb system (B)</p> Signup and view all the answers

What is the shape of the oxygen dissociation curve for myoglobin?

<p>Hyperbolic (A)</p> Signup and view all the answers

What type of structure does hemoglobin have?

<p>Quaternary (C)</p> Signup and view all the answers

Which term describes the increase in hemoglobin's affinity for oxygen after the first oxygen binds?

<p>Allosteric effect (D)</p> Signup and view all the answers

Where is myoglobin primarily located in the body?

<p>In Cardiac &amp; Skeletal Muscles (B)</p> Signup and view all the answers

What is characteristic of β-thalassemia minor?

<p>Patients make some β chains and do not require specific treatment. (C)</p> Signup and view all the answers

What occurs if all four α-globin genes are defective?

<p>Bart’s hydrops fetal syndrome. (B)</p> Signup and view all the answers

Which form of β-thalassemia is known as Cooley anemia?

<p>β-thalassemia major. (D)</p> Signup and view all the answers

What is the result of having three defective α-globin genes?

<p>Mild to moderate anemia with hemoglobin H disease. (A)</p> Signup and view all the answers

What are the main components of the pulmonary extracellular matrix?

<p>Collagen, elastic fibers, and proteoglycans (B)</p> Signup and view all the answers

Which function do proteoglycans serve in the pulmonary extracellular matrix?

<p>Influencing microvascular fluid dynamics (C)</p> Signup and view all the answers

Where is α-thalassemia most commonly found?

<p>Southern China and Southeast Asia. (D)</p> Signup and view all the answers

What is the primary fuel utilized by lung tissues for metabolic processes?

<p>Glucose (C)</p> Signup and view all the answers

What process converts glucose in the cytoplasm of lung cells?

<p>Glycolysis (D)</p> Signup and view all the answers

How does glucose oxidation in lung tissue compare to other metabolically active organs?

<p>It is equal to or greater than most organs. (C)</p> Signup and view all the answers

Which type of cells interact with the pulmonary extracellular matrix via integrins?

<p>Epithelial and mesenchymal cells (B)</p> Signup and view all the answers

What is the estimated rate of glucose oxidation in lung tissue?

<p>40–50 μmol/(h·g) of dry lung weight (B)</p> Signup and view all the answers

What is a key role of integrins in pulmonary tissue?

<p>Facilitating cell-cell adhesion (C)</p> Signup and view all the answers

What is the primary function of Type I alveolar cells?

<p>Create the air sac (C)</p> Signup and view all the answers

How much oxygen can one gram of hemoglobin combine with?

<p>1.34 mL (C)</p> Signup and view all the answers

Why is hemoglobin necessary for oxygen transport in the blood?

<p>Oxygen's low solubility in plasma requires a carrier. (D)</p> Signup and view all the answers

What is a unique feature of myoglobin compared to hemoglobin?

<p>Formed of one heme and one globin chain (B)</p> Signup and view all the answers

What is the main purpose of surfactant secreted by Type II alveolar cells?

<p>Prevent alveolar collapse (A)</p> Signup and view all the answers

How much oxygen can 1 liter of blood transport due to hemoglobin presence?

<p>200 mL (D)</p> Signup and view all the answers

Which of the following is NOT a heme-protein?

<p>Insulin (C)</p> Signup and view all the answers

What role does the heme group in hemoglobin serve?

<p>Holds oxygen molecules (C)</p> Signup and view all the answers

What is the primary product of glycolysis?

<p>Pyruvate (C)</p> Signup and view all the answers

Which metabolic pathway is utilized by lung cells during nutrient deprivation?

<p>β-oxidation (B)</p> Signup and view all the answers

How much ATP is yielded from the complete breakdown of one molecule of glucose?

<p>38 ATP (A)</p> Signup and view all the answers

What percentage of glucose consumed by the healthy rat lung is converted to lactate?

<p>40% (A)</p> Signup and view all the answers

What is a potential source of energy for lung cells during nutrient deficiency?

<p>Lactate (A)</p> Signup and view all the answers

What can excessive fatty acid breakdown lead to in cells?

<p>Oxidative stress (B)</p> Signup and view all the answers

What pathway generates NADPH and ribose-5-phosphate from glycolytic intermediates?

<p>Pentose Phosphate Pathway (A)</p> Signup and view all the answers

In terms of oxygen consumption, how does β-oxidation compare to glycolysis?

<p>It consumes more O2 than glycolysis. (C)</p> Signup and view all the answers

Flashcards

Pulmonary Extracellular Matrix (ECM)

A complex network of molecules that provides structural support, helps regulate tissue fluids, and facilitates cell communication within the lungs. It mainly consists of collagen, elastic fibers, and proteoglycans.

Proteoglycans

Large molecules found in the ECM that play a crucial role in fluid dynamics within the lung tissues. They act like sieves in capillaries and help regulate tissue elasticity.

Versican

A specific type of proteoglycan found in the interstitial matrix of the lung. It binds with hyaluronic acid to form large aggregates, contributing to the structure and function of the ECM.

Glycolysis

A multi-step process that occurs within the cytoplasm of cells, converting glucose into pyruvate (and then into ATP) to provide energy for cellular functions. It's the primary way the lungs obtain energy.

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Glucose Oxidation

The process of breaking down glucose into pyruvate and then into ATP, a vital form of energy for cells. It's the main way lung tissues generate energy.

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Lung Metabolism

Metabolic processes, including glucose oxidation, that help the lungs perform their vital functions: secretion, clearance, and other maintenance tasks.

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Glucose Oxidation Rate

A measure of how fast glucose is broken down in the lungs. It is high in lungs compared to many other organs, reflecting their high energy demands.

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Glucose

The main fuel source for lung tissues. It is readily available in the body and can be efficiently broken down by cells to produce energy.

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Pyruvate

A 3-carbon molecule produced from glucose during glycolysis. A key intermediate in energy metabolism.

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Lactate Production

A series of chemical reactions that converts pyruvate into lactate. It occurs when oxygen is limited and is a way to recycle NADH.

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β-oxidation

The main energy-producing pathway in the lungs. It breaks down fatty acids to generate ATP.

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Biosynthesis of lipids

A process where lung cells create lipids for their internal and external membranes.

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Lactate as an Energy Source

A major source of energy for lung cells, it's readily produced by the lungs, even under normal oxygen conditions.

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Pentose Phosphate Pathway

The pentose phosphate pathway (PPP) is a metabolic pathway that generates NADPH and ribose-5-phosphate, both essential for various cellular processes.

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Metabolic Processes

A complex and interconnected system that involves glycolysis, the TCA cycle, beta-oxidation, and other pathways. It's a powerful engine that sustains life in the lungs and other tissues.

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Heme-proteins

Specialized proteins that contain heme, a molecule with an iron atom that binds oxygen.

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Myoglobin

A protein found in muscle cells that binds oxygen, providing a reserve for muscle use.

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Hemoglobin

The protein found in red blood cells that transports oxygen throughout the body.

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Ventilation

The process of moving air into and out of the lungs.

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Gas exchange in the alveoli

The exchange of oxygen and carbon dioxide between the air in the alveoli and the blood.

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Perfusion

The movement of blood through the blood vessels.

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Cellular respiration

The process by which cells use oxygen to produce energy and release carbon dioxide as a waste product.

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Surfactant

A substance that reduces surface tension in the alveoli, preventing them from collapsing.

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Structure of Hemoglobin

Hemoglobin's structure is a tetramer, consisting of two alpha (α) and two beta (β) chains, held together by hydrophobic interactions. The two dimers, each containing an α and β chain, move relative to each other during oxygenation and deoxygenation.

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T form (Hb)

Hemoglobin in its low-oxygen affinity form, characterized by a network of ionic bonds between its dimers, limiting their movement and making it difficult for the molecule to bind oxygen.

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R form (HbO2)

Hemoglobin's high-oxygen affinity form. Oxygen binding disrupts the ionic and hydrogen bonds between dimers, making the molecule more flexible and allowing it to readily bind oxygen.

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Oxygen Dissociation Curve

A graphical representation of the relationship between the oxygen saturation of hemoglobin and the partial pressure of oxygen (pO2). It demonstrates the sigmoid shape of the oxygen binding curve, revealing hemoglobin's cooperative binding behavior.

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Myoglobin's oxygen binding

Myoglobin has a single polypeptide chain and binds one oxygen molecule, resulting in a hyperbolic oxygen dissociation curve. This means myoglobin binds oxygen with high affinity even at low oxygen partial pressures.

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Hemoglobin's cooperative binding

Hemoglobin has four polypeptide chains (subunits) and binds four oxygen molecules. The binding of one oxygen molecule to a heme group increases the affinity of the remaining heme groups for oxygen, leading to a sigmoidal oxygen dissociation curve.

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Hemoglobin's conformational changes

The change in hemoglobin's conformation (shape) upon oxygen binding is crucial for its function. The tense (T) state has low oxygen affinity, while the relaxed (R) state has high affinity. This transition allows hemoglobin to efficiently load oxygen in the lungs and unload it in tissues.

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Hemoglobin's increasing oxygen affinity

Hemoglobin's affinity for the fourth oxygen molecule is much higher than its affinity for the first oxygen molecule. This property allows hemoglobin to efficiently deliver oxygen to tissues even when oxygen levels are low.

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Hemoglobin's allosteric effect

The oxygen saturation of hemoglobin is influenced by factors like pH, temperature, and carbon dioxide levels. These factors affect hemoglobin's affinity for oxygen, allowing it to deliver oxygen to tissues that need it most.

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β-Thalassemia Major

A condition where both β-globin genes are defective, leading to severe anemia and requiring regular blood transfusions.

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β-Thalassemia Minor

A condition where only one β-globin gene is defective, resulting in milder anemia and usually requiring no specific treatment.

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α-Thalassemia

A genetic condition where the synthesis of α-globin chains is decreased or absent, leading to various levels of anemia depending on the number of defective genes.

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Bart's Hydrops Fetal Syndrome

A severe form of α-thalassemia where all four α-globin genes are defective, causing fetal death due to severe anemia and fluid accumulation in fetal tissues.

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Hemoglobin H Disease

A milder form of α-thalassemia where three α-globin genes are defective, resulting in mild to moderate anemia.

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