Untitled Quiz

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.