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Questions and Answers

What is the thickness of the alveolar gas exchange membrane?

  • 0.5 μm (correct)
  • 1 mm
  • 0.5 mm
  • 1 μm

    • What effect does pulmonary edema have on the respiratory membrane?

  • It repairs the membrane
  • It thickens the membrane (correct)
  • It causes inflammation
  • It thins the membrane

    • Which factor is crucial for adequate gas exchange in the lungs?

  • Good ventilation and perfusion (correct)
  • Only good ventilation
  • High air pressure
  • Efficient muscular contraction

    • What happens to pulmonary blood vessels if an area of the lungs is poorly ventilated?

    <p>They constrict</p> Signup and view all the answers

    How does bronchodilation occur in the lungs?

    <p>When an area is well perfused</p> Signup and view all the answers

    What is a consequence of having a thicker respiratory membrane?

    <p>Gases have farther to travel</p> Signup and view all the answers

    Why is ventilation-perfusion coupling important?

    <p>It matches air flow with blood flow for gas exchange</p> Signup and view all the answers

    Which of the following conditions can cause thickening of the respiratory membrane?

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

    What is a key characteristic of pneumonia?

    <p>Alveoli fill with pus and fluid.</p> Signup and view all the answers

    Which condition involves the encapsulation of bacteria in tubercles?

    <p>Pulmonary Tuberculosis</p> Signup and view all the answers

    How does smoking contribute to health issues?

    <p>It increases the risk of multiple types of cancer.</p> Signup and view all the answers

    Which lung condition results in a reduced capacity for gas exchange due to loss of elasticity?

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

    What symptom is commonly associated with bronchitis?

    <p>Coughing up mucus and pus</p> Signup and view all the answers

    What happens to blood flow in pulmonary vessels when there is decreased airflow?

    <p>Blood flow decreases due to vasoconstriction</p> Signup and view all the answers

    How is most oxygen transported in the blood?

    <p>Bound to hemoglobin</p> Signup and view all the answers

    What percentage of carbon dioxide transported in the blood is dissolved as a gas in plasma?

    <p>5%</p> Signup and view all the answers

    What is the maximum number of oxygen molecules that one hemoglobin molecule can carry?

    <p>4 O2 molecules</p> Signup and view all the answers

    In which form is the majority of carbon dioxide transported during gas transport?

    <p>As bicarbonate ions formed from carbonic acid</p> Signup and view all the answers

    What is the term for hemoglobin that has bound oxygen?

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

    What occurs as a response to increased ventilation in pulmonary blood vessels?

    <p>Elevated blood flow due to vasodilation</p> Signup and view all the answers

    What defines oxyhemoglobin saturation when hemoglobin has four oxygen molecules bound?

    <p>100% saturation</p> Signup and view all the answers

    When blood flow is adjusted to match changes in ventilation, what is this process called?

    <p>Ventilation-perfusion coupling</p> Signup and view all the answers

    What is the function of the iron atom within hemoglobin's heme groups?

    <p>To bind oxygen molecules</p> Signup and view all the answers

    What is the vital capacity of the lungs in milliliters?

    <p>4,700 mL</p> Signup and view all the answers

    What is the expiratory reserve volume of the lungs?

    <p>1,200 mL</p> Signup and view all the answers

    What is the purpose of residual volume in the lungs?

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

    How is the total lung capacity calculated?

    <p>RV + VC</p> Signup and view all the answers

    Which lung disorder is characterized by narrowed airways making it difficult to breathe?

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

    What is hyperventilation?

    <p>Increased ventilation exceeding metabolic demand</p> Signup and view all the answers

    What is the primary purpose of spirometry?

    <p>To recapture expired breath</p> Signup and view all the answers

    Which volume represents the amount of air inhaled during normal breathing?

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

    What effect does hyperbaric oxygen therapy have on gas exchange?

    <p>Increases the pressure gradient for oxygen diffusion</p> Signup and view all the answers

    What measurement reflects the average amount of air inhaled per minute?

    <p>Minute respiratory volume (MRV)</p> Signup and view all the answers

    What condition is characterized by labored breathing and shortness of breath?

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

    Which law states that the total atmospheric pressure equals the sum of the partial pressures of individual gases?

    <p>Dalton's law</p> Signup and view all the answers

    Which gas has the highest partial pressure in alveolar air?

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

    What is the primary force driving air into the lungs during inspiration?

    <p>Negative intrapulmonary pressure</p> Signup and view all the answers

    How does Boyle's Law relate to the mechanics of breathing?

    <p>Pressure is inversely proportional to volume</p> Signup and view all the answers

    What happens during relaxed expiration?

    <p>Elastic recoil compresses the lungs</p> Signup and view all the answers

    What is the term used for the air leftover in the lungs after a maximal expiration?

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

    Which factor does NOT directly influence the flow of respiratory air?

    <p>Air temperature</p> Signup and view all the answers

    What condition is characterized by the presence of air in the pleural cavity?

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

    What describes the volume of air that reaches the alveoli during a normal inhalation of 500 mL, assuming 150 mL remains in dead space?

    <p>350 mL</p> Signup and view all the answers

    Which of the following gases is primarily involved in gas exchange in the alveoli?

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

    What mechanism explains the cohesion of water that keeps the pleura together during respiration?

    <p>Surface tension</p> Signup and view all the answers

    What is the role of the accessory muscles during forced breathing?

    <p>Raise intrapulmonary pressure</p> Signup and view all the answers

    In which situation would physiological dead space increase?

    <p>Presence of lung pathology</p> Signup and view all the answers

    What is the normal atmospheric pressure at sea level?

    <p>760 mm Hg</p> Signup and view all the answers

    How does Charles’s Law contribute to the inflation of the lungs?

    <p>Volume increases with increasing temperature</p> Signup and view all the answers

    What is the normal range for blood pH values in the human body?

    <p>7.35 to 7.45</p> Signup and view all the answers

    What primarily stimulates ventilation when blood pH decreases?

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

    Which of the following conditions is commonly associated with chronic bronchitis?

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

    How does hyperventilation affect blood pH?

    <p>It raises blood pH.</p> Signup and view all the answers

    What is the primary trigger for respiration during exercise?

    <p>Motor commands from the brain</p> Signup and view all the answers

    What characterizes emphysema in the lungs?

    <p>Breakdown of alveolar walls resulting in fewer, larger airspaces</p> Signup and view all the answers

    Which type of hypoxia results from inadequate circulation of blood?

    <p>Ischemic hypoxia</p> Signup and view all the answers

    The most common cause of respiratory acidosis is:

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

    What is a potential result of breathing 100% oxygen at high pressures?

    <p>Oxygen toxicity</p> Signup and view all the answers

    What may induce Kussmaul respiration?

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

    Which cancer type originates in the mucus glands of the respiratory system?

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

    What is a characteristic symptom of COPD?

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

    Which condition is not typically associated with lower respiratory tract infections?

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

    What is an effect of CO2 accumulation in the body?

    <p>Stimulated chemoreceptor response</p> Signup and view all the answers

    Study Notes

    Respiratory Volumes and Capacities

    • A graph displays different respiratory volumes and capacities.
    • Lung volume (mL) is plotted against time.
    • Maximum possible inspiration is the highest point on the graph.
    • Inspiratory reserve volume is the volume of air inhaled beyond a normal breath.
    • Tidal volume is the volume of air inhaled and exhaled in one breathing cycle.
    • Expiratory reserve volume is the volume of air exhaled in excess of a normal breath.
    • Residual volume is the amount of air that remains in the lungs after maximum exhalation.
    • Inspiratory capacity is the sum of tidal volume and inspiratory reserve volume.
    • Functional residual capacity is the sum of expiratory reserve volume and residual volume.
    • Vital capacity is the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume.
    • Total lung capacity is the total volume of air the lungs can hold.

    Pressure, Resistance, and Airflow

    • Air flow is directly proportional to pressure difference and inversely proportional to resistance.
    • Atmospheric pressure at sea level is about 760 mm Hg (1 atmosphere).
    • Boyle's law describes the inverse relationship between pressure and volume of a gas at a constant temperature.
    • If lung volume increases, intrapulmonary pressure decreases, and air flows into the lungs.
    • If lung volume decreases, intrapulmonary pressure increases, and air flows out of the lungs.

    Inspiration

    • Intrapleural pressure is slightly negative.
    • This negative pressure keeps the lungs inflated.
    • Recoil of lung tissue causes the lungs to want to collapse.
    • Recoil of chest wall causes the chest wall to want to expand.
    • The small space between the parietal and visceral pleura is filled with fluid, keeping them adhered.
    • -5 cm H2O of intrapleural pressure keeps the lungs inflated.
    • The two pleural layers adhere due to water cohesion.
    • During inspiration, rib movement expands the thoracic cavity, and the lungs follow.
    • Inhaled air is warmed to a normal body temperature by the time it reaches the alveoli.
    • A small change in thoracic cage dimension increases total lung volume by 500 mL during quiet breathing.
    • This is enough for 500 mL of air to flow into the lungs.

    Expiration

    • Relaxed breathing is a passive process.
    • Elastic recoil of the chest wall and lungs compresses the lungs.
    • Raises intrapulmonary pressure to about 1 cm H2O.
    • Air flows out of the lungs due to the pressure gradient.
    • Forced breathing involves accessory muscles.
    • Intrapulmonary pressure can be raised up to 40 cm H2O.

    Pneumothorax and Atelectasis

    • Pneumothorax, air in pleural cavity, caused by puncture of thoracic wall, allows lungs to recoil and collapse.
    • Atelectasis, lung collapse, may also be caused by airway obstruction.

    Alveolar Ventilation

    • Alveolar ventilation is the volume of fresh air that reaches the alveoli.
    • Not all inhaled air gets to the alveoli.
    • 150 mL of air remains in the conducting passages.
    • Alveolar ventilation rate, 4,200 mL/min, is the rate at which air ventilates alveoli.
    • Respiratory rate is also a factor determining alveolar ventilation rate.

    Spirometry

    • Spirometry measures pulmonary ventilation.
    • Measuring tidal volume, inspiratory reserve volume, and expiratory reserve volume.
    • Useful in diagnoses of restrictive and obstructive pulmonary diseases.

    Respiratory Volumes and Capacities

    • Spirometer measures pulmonary volumes like tidal volume, inspiratory reserve volume and expiratory reserve volume.
    • Residual volume is the amount of air remaining in lungs after maximum exhalation.
    • Vital capacity is total amount of air that can be inhaled and exhaled.

    Respiratory Volumes and Capacities (Continued)

    • Functional residual capacity is the amount of air remaining in lungs after normal exhalation.
    • Total lung capacity is the maximum amount of air the lungs can contain.

    Respiratory Disorders

    • Restrictive disorders limit lung expansion (e.g., fibrosis, pneumonia).
    • Obstructive disorders interfere with airflow (e.g., asthma, chronic bronchitis).

    Forced Expiratory Volume

    • Forced expiratory volume (FEV) is the percentage of vital capacity exhaled in a given time.
    • Peak flow measures maximum speed of expiration.
    • Minute respiratory volume (MRV) is the amount of air inhaled per minute, which can be used to estimate pulmonary function.
    • Maximum voluntary ventilation (MVV) is maximum respiratory rate during heavy exercise.

    Variations in Respiratory Rhythm

    • Eupnea is relaxed, quiet breathing (tidal volume 500 mL, rate 12-15 bpm).
    • Apnea is temporary cessation of breathing.
    • Dyspnea is labored, gasping breathing.
    • Hyperpnea is increased rate and depth of breathing.
    • Hyperventilation is increased pulmonary ventilation.
    • Hypoventilation is reduced pulmonary ventilation.
    • Kussmaul respiration is deep, rapid breathing (often induced by acidosis).
    • Orthopnea is dyspnea that occurs when lying down.
    • Respiratory arrest is permanent cessation of breathing.
    • Tachypnea is accelerated respiration.

    Composition of Air

    • Air is composed of 78.6% nitrogen, 20.9% oxygen, 0.04% carbon dioxide, and minor gases (with variable amounts of water).
    • Dalton's Law states that total pressure is the sum of the partial pressures of individual gases.

    Alveolar Gas Exchange

    • Alveolar gas exchange involves O₂ and CO₂ exchange across respiratory membrane.
    • O₂ dissolves in water film and then diffuses into bloodstream.
    • CO₂ diffuses out of water film and into alveolar air.
    • Henry's law states that gas solubility in water depends on its partial pressure and solubility.

    Alveolar Gas Exchange (Continued)

    • Pressure gradients drive gas exchange.
    • Hyperbaric oxygen therapy uses increased partial pressure of oxygen to treat conditions such as gangrene.
    • At high altitudes, partial pressures of gases are lower, and less oxygen diffuses into the blood.

    Changes in Gases (Diagram)

    • Diagram depicts gas exchange in pulmonary and systemic circuits.
    • Labels indicate partial pressures of O₂ and CO₂ at different points in the system.

    Pulmonary Alveoli in Health and Disease (Diagram)

    • Diagrams show normal alveoli and those affected by pneumonia.

    Alveolar Gas Exchange (Membrane Thickness)

    • Alveolar membrane is very thin (0.5µm), facilitating diffusion.
    • Conditions like pulmonary edema and pneumonia can increase membrane thickness, hindering diffusion.

    Ventilation-Perfusion Coupling

    • Ventilation perfusion coupling adjusts blood flow and airflow to match each other for efficient gas exchange in different lung sections.
    • Bronchi diameters and blood vessels change depending on airflow and blood flow in the lung areas to maintain matching.

    Gas Transport

    • Oxygen is transported primarily (98.5%) bound to hemoglobin and less (1.5%) dissolved in plasma.
    • Carbon dioxide is transported primarily (70%) as bicarbonate ions.

    Oxygen

    • Arterial blood has about 20 mL of oxygen per deciliter.
    • Hemoglobin is the primary carrier of oxygen.
    • Oxyhemoglobin is hemoglobin bonded to oxygen.
    • Deoxyhemoglobin is hemoglobin without oxygen.

    Oxyhemoglobin Dissociation Curve

    • The curve shows the relationship between hemoglobin saturation and PO2.
    • At higher PO2 values, hemoglobin is almost fully saturated.
    • The curve shifts right with increased temperature, increased PCO2, and decreased pH.

    Carbon Dioxide

    • Carbon dioxide is transported in three forms: carbonic acid, carbamino compounds, and dissolved gas.
    • 90% is transported as bicarbonate ions, 5% as carbamino compounds, and 5% as dissolved gas.
    • CO₂ and O₂ are carried simultaneously by hemoglobin.

    Carbon Monoxide Poisoning

    • CO competes for oxygen-binding sites on hemoglobin.
    • CO binding is much stronger than O₂, binding about 210 times stronger than O2.

    Adjustment to Metabolic Needs

    • Hemoglobin unloading of oxygen matches tissue metabolic needs.
    • Factors influencing oxygen unloading include ambient PO2, temperature, Bohr effect, and plasma concentrations of biphosphoglycerate (BPG).
    • Tissues with higher metabolic rates will have faster O₂ unloading.

    Adjustment to Metabolic Needs (Continued)

    • Temperature, CO₂, and pH of blood affect the affinity of hemoglobin for oxygen.
    • BPG, produced by red blood cells, promotes oxygen unloading.
    • Rate of CO₂ loading is adjusted to match oxygen needs.

    Effects of Temperature on Oxyhemoglobin Dissociation (Diagram)

    • Diagram illustrates how temperature affects oxygen unloading.

    Effects of pH on Oxyhemoglobin Dissociation (Diagram)

    • Diagram shows the effect of blood pH on oxygen unloading (Bohr effect).

    Blood Gases and Respiratory Rhythm

    • Respiration rate and depth adjust to maintain blood pH (7.35-7.45) and gas levels of PO2 and PCO2 (40-43 mm Hg).
    • Brainstem respiratory centers receive input from chemoreceptors in CSF and blood to monitor blood gas levels.

    Hydrogen Ions

    • Pulmonary ventilation is adjusted to maintain blood pH.
    • CO2 diffuses across the blood-brain barrier and reacts with water to create carbonic acid.
    • Central chemoreceptors are sensitive to hydrogen ions in the CSF.
    • Peripheral chemoreceptors monitor H+ levels in the blood.

    Hydrogen Ions (Continued)

    • Acidosis is when blood pH is below 7.35.
    • Alkalosis is when blood pH is above 7.45.
    • Hypocapnia is low PCO2.
    • Hypercapnia is high PCO2.

    Hydrogen Ions (Continued)

    • Respiratory acidosis and alkalosis occur due to mismatch between ventilation and CO2 production rate.
    • Hyperventilation compensates for acidosis by removing CO2.
    • Hypoventilation compensates for alkalosis by increasing CO2 levels.

    Hydrogen Ions (Continued)

    • Ketoacidosis occurs due to rapid fat oxidation.
    • Increased ketone bodies lower blood pH, triggering hyperventilation.

    Carbon Dioxide

    • Carbon dioxide has indirect effects on respiration, through its influence on pH as described earlier.
    • CO2 can also have direct effects.
    • Increased CO2 can trigger peripheral chemoreceptors, initiating ventilation changes more promptly than central chemoreceptor responses.

    Oxygen

    • PO2 typically has minor effects on respiration.
    • Chronic low PO2 may stimulate ventilation more than high PCO2 or pH.

    Respiration and Exercise

    • Increased respiration during exercise anticipantly adjusts ventilation to match increased metabolic demands.
    • Proprioceptors from muscles and joints signal respiratory centers to increase ventilation.
    • Increase in pulmonary ventilation keeps blood gas levels at normal levels despite increased metabolic rates.

    Oxygen Imbalances

    • Hypoxia: tissue oxygen deficiency, a consequence of respiratory diseases.
    • Hypoxemic hypoxia: low arterial PO2, resulting from inadequate pulmonary gas exchange.
    • Ischemic hypoxia: inadequate blood circulation.
    • Anemic hypoxia: inability of blood to carry sufficient oxygen.
    • Histotoxic hypoxia: metabolic poisons interfere with tissue oxygen use.
    • Cyanosis: bluish discoloration of skin, a sign of hypoxia.

    Oxygen Imbalances (Continued)

    • Hyperbaric oxygen: potentially toxic at increased pressure.
    • It may damage tissue, causing seizures, coma, and death.

    Chronic Obstructive Pulmonary Diseases (COPD)

    • COPD represents a long-term airflow obstruction, reducing pulmonary ventilation.
    • Common causes are smoking, air pollution, and occupational factors.
    • Types of COPD include chronic bronchitis and emphysema.

    Chronic Bronchitis

    • Severe, persistent lower respiratory inflammation.
    • Goblet cells increase mucus production.
    • Immobilized cilia worsen mucus removal.
    • Thick mucus accumulation creates a risk of bacterial growth.
    • Smoking often compromises alveolar macrophages, further contributing to mucus accumulation and difficulty clearing sputum.
    • Symptoms often include hypoxemia and cyanosis.

    Emphysema

    • Alveolar walls break down, reducing respiratory surface area.
    • Resulting in fewer, larger air spaces.
    • Lungs become less elastic and fibrotic.
    • Difficulty exhaling air and air trapping.
    • Patients develop a characteristic barrel chest.
    • Breathing requires substantial energy.

    COPD (Continued)

    • COPD leads to hypoxemia, hypercapnia (increased CO2), and respiratory acidosis.
    • In response to hypoxemia, kidneys release erythropoietin which increases red blood cell production.
    • This can lead to polycythemia (increased blood viscosity).
    • COPD can cause cor pulmonale, a right heart hypertrophy due to pulmonary circulation obstruction.

    Smoking and Lung Cancer

    • Smoking is a major risk factor for lung cancer.
    • Lung cancer is the leading cause of cancer-related deaths.
    • Common types of lung cancer include squamous cell carcinoma, adenocarcinoma, and small cell carcinoma.
    • Squamous cell carcinoma originates in bronchial lining and often leads to bleeding lesions.
    • Adenocarcinoma originates in mucous glands and can spread quickly.
    • Small cell carcinoma is commonly found in primary bronchi.
    • Characteristics include blood coughing, tumor invading bronchial wall impeding airflow.
    • Metastasis occur rapidly, common sites include pericardium, heart, liver and brain.

    Upper Respiratory Tract Infections

    • Sinusitis is blockage of sinuses.
    • Otitis media is infection of middle ear.
    • Tonsillitis is tonsil inflammation.
    • Laryngitis is larynx infection, leading to voice loss.

    Lower Respiratory Tract Infections

    • Pneumonia is lung infection with thick fluid.
    • Tuberculosis is bacterial infection with tubercles.
    • Pulmonary fibrosis is lung scarring due to fibrous connective tissue development.
    • Emphysema is gas exchange surface impairment due to alveoli damage
    • Asthma is bronchial inflammation that causes breathing difficulty.
    • Lung cancer is uncontrolled lung cell division, often due to smoking.

    Some Respiratory Diseases (Diagram)

    • Diagram illustrating some common respiratory diseases and their effects on lungs

    Health Focus: Tobacco and Health

    • All forms of tobacco cause damage.
    • Smoking increases risk factors for several cancers (lung, mouth, larynx, esophagus, bladder, kidney, pancreatic, stomach, cervix).
    • Smoking is also linked to increased risk of chronic bronchitis, emphysema, heart disease, stillbirths, and harm to unborn children.
    • Passive smoke exposure raises a nonsmoker risk of pneumonia, bronchitis, and lung cancer.

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