The Respiratory System Overview
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Questions and Answers

What is the primary function of the conducting zone in the respiratory system?

  • Transport of oxygen molecules
  • Warming and humidifying air (correct)
  • Gas exchange
  • Regulation of breathing rate

    • Which property of the lungs allows them to return to their original size after expansion?

  • Elasticity (correct)
  • Compliance
  • Surface tension
  • Resistance

    • How does gas exchange primarily occur in the alveoli?

  • Using specialized proteins for gas transport
  • By active transport mechanisms
  • Through diffusion due to temperature changes
  • Via gradients of partial pressures (correct)

    • What is the role of surfactants in the alveoli?

    <p>To prevent alveolar collapse</p> Signup and view all the answers

    Which muscles are primarily involved in the process of inspiration?

    <p>Diaphragm and external intercostals</p> Signup and view all the answers

    What term describes the volume of air remaining in the lungs after maximum expiration?

    <p>Residual volume</p> Signup and view all the answers

    What primarily drives the neural control of breathing?

    <p>Changes in thoracic cavity volume</p> Signup and view all the answers

    What is the approximate partial pressure of oxygen (PO2) in alveolar air?

    <p>105 mm Hg</p> Signup and view all the answers

    What is the approximate partial pressure of O2 in the air?

    <p>160 mm Hg</p> Signup and view all the answers

    What percentage of oxygen is transported bound to hemoglobin in red blood cells?

    <p>97%</p> Signup and view all the answers

    Which component of hemoglobin actually binds oxygen?

    <p>Heme</p> Signup and view all the answers

    What physiological condition favors the release of oxygen from hemoglobin in tissues?

    <p>High temperature and low pH</p> Signup and view all the answers

    What is the role of 2,3-diphosphoglycerate (DPG) in oxygen transport?

    <p>It decreases the affinity of hemoglobin for oxygen.</p> Signup and view all the answers

    Which of the following increases oxygen binding to hemoglobin?

    <p>High pH</p> Signup and view all the answers

    What happens to deoxyhemoglobin when oxygen binds to it?

    <p>It becomes oxyhemoglobin.</p> Signup and view all the answers

    Which factor is NOT associated with oxygen release at tissues?

    <p>High pH</p> Signup and view all the answers

    What is the primary form in which carbon dioxide is transported in the blood?

    <p>Converted to bicarbonate</p> Signup and view all the answers

    Which enzyme facilitates the conversion of carbon dioxide to bicarbonate in red blood cells?

    <p>Carbonic anhydrase</p> Signup and view all the answers

    What condition causes low pH in the blood?

    <p>High CO2 concentration</p> Signup and view all the answers

    What role does the medulla oblongata play in the regulation of breathing?

    <p>Activates motoneurons for inspiration</p> Signup and view all the answers

    Which type of chemoreceptors are sensitive to pH changes in the cerebrospinal fluid?

    <p>Central chemoreceptors</p> Signup and view all the answers

    How does carbon monoxide affect hemoglobin compared to oxygen?

    <p>Binds with 250 times stronger affinity than O2</p> Signup and view all the answers

    Which center in the pons promotes inspiration?

    <p>Apneustic center</p> Signup and view all the answers

    Where does the majority of carbon dioxide transport occur after being converted to bicarbonate?

    <p>In the red blood cells</p> Signup and view all the answers

    Which factor does not influence the regulation of breathing?

    <p>Oxygen binding affinity</p> Signup and view all the answers

    What happens to bicarbonate after it exits the red blood cell?

    <p>It moves into the plasma</p> Signup and view all the answers

    What effect does cutting the vagus nerve have on the duration of inspiration?

    <p>It prolongs inspiration</p> Signup and view all the answers

    Which response occurs when CO2 levels in the blood rise?

    <p>Increased respiratory rate</p> Signup and view all the answers

    What leads to the inhibition of inspiration during the Hering-Breuer reflex?

    <p>Activation of stretch receptors</p> Signup and view all the answers

    Which phenomenon does not enhance CO2 diffusion out of the blood in the lungs?

    <p>High oxygen saturation of hemoglobin</p> Signup and view all the answers

    Study Notes

    The Respiratory System

    • The respiratory system includes structure and properties, mechanics of breathing, gas exchange, transport of gases, and regulation of breathing.

    • A mammalian lung is composed of multiple lobes, lobar bronchi, main bronchi, segmental bronchi, pleurae and pleural space.

    • The pleura is a double-layered membrane surrounding the lungs. The parietal pleura lines the thoracic cavity, while the visceral pleura covers the lungs.

    • A mammalian lung also contains an esophagus, trachea, diaphragm, and ribs.

    • The conducting zone prepares air for gas exchange by warming, humidifying and filtering it (through mucus and cilia).

    • The respiratory zone (respiratory bronchioles and alveoli) facilitates gas exchange.

    • Alveoli are tiny air sacs in the lungs

    • A capillary network surrounds the alveoli to facilitate gas exchange.

    Physical Properties of Lungs

    • Lungs have compliance (stretch ability) and elasticity (return to original size).
    • Surface tension at the inner surface of alveoli is reduced by surfactant. This prevents alveolar collapse.

    Respiratory Proteins

    • Type I and II pneumocytes are types of cells in the alveoli.

    • Pulmonary surfactant is a layer covering the alveoli.

    • DPPC (dipalmitoyl phosphatidylcholine) and other lipids are key components of pulmonary surfactant.

    Mechanics of Breathing

    • Breathing has two phases: Inspiration (inhalation) and expiration (exhalation).

    • Changes in thoracic cavity volume drive breathing.

    • Inspiration involves the diaphragm and external intercostals muscles expanding the thoracic cavity.

    • Expiration is usually passive, with relaxation of inspiratory muscles and recoil of the chest wall.

    Gas Exchange

    • Gas exchange is driven by partial pressure gradients. Gases move from high to low pressure regions.

    • Composition of air: H₂O (variable), N₂ (~590 mmHg), O₂ (~160mmHg), CO₂ (~10mmHg)

    • Atmospheric pressure is ~760 mmHg.

    • Alveolar air is saturated with water (H₂O), and PO2 is ~105 mmHg and PCO2 is ~40mmHg.

    Transport of Respiratory Gases

    • Oxygen (O2): ~3% dissolved in plasma, ~97% bound to hemoglobin in red blood cells (RBCs).

    • Hemoglobin is a protein with 4 subunits (2 alpha and 2 beta). Each subunit contains a heme pigment with iron (Fe++), binding to one O2 molecule.

    Factors Affecting Oxygen Binding to Hemoglobin

    • Low temperature, high partial pressure of O2 (high PO2) and high pH favor oxygen binding to hemoglobin.

    • High temperature, low partial pressure of O2 (low PO2) and low pH favor oxygen release from hemoglobin.

    • Organic phosphate compounds (e.g., DPG) decrease hemoglobin's O2 affinity.

    Carbon Monoxide (CO)

    • CO binds to hemoglobin ~250 times more strongly than O2 reducing O2 transport significantly.

    Carbon Dioxide (CO2) Transport

    • ~10% of CO2 is dissolved in plasma, ~20% is bound to hemoglobin (carbaminohemoglobin). ~70% is transported as bicarbonate in red blood cells (RBCs), mediated by carbonic anhydrase.

    Regulation of Breathing

    • The medulla oblongata acts as the rhythmicity center, generating rhythmic breathing patterns.

    • E neurons inhibit inspiratory motor neurons, resulting in expiration.

    • Herning-Breuer reflex involves stretch receptors in bronchi and bronchioles for regulating the length of inspiration.

    • Pons centers (pneumotaxic and apneustic) further modulate breathing patterns.

    • Higher brain centers influence breathing as well.

    Regulation of Breathing: pH and CO2 Influence

    • Central chemoreceptors in the medulla oblongata are sensitive to changes in CSF pH (related to PCO2).
    • Peripheral chemoreceptors (in carotid and aortic bodies) are sensitive to changes in blood pH and PO2.
    • Changes in PO2 are only detected by peripheral chemoreceptors in very low O2 conditions.

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    The Respiratory System PDF

    Description

    This quiz covers the structure and functions of the respiratory system, including the mechanics of breathing and gas exchange. Explore the components of mammalian lungs, the roles of pleurae, and the physical properties essential for effective respiration.

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