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Explore the structure, functions, and key terms of the respiratory system. Learn about phases of respiration, lung anatomy, gas exchange, and respiratory processes to enhance your understanding of breathing mechanisms.
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Chapter 18 The Respiratory System
Key Terms alveoli (sing., alveolus) diaphragm pharynx asthma dyspnea phrenic nerve bicarbonate ion emphysema pleura bronchiole epiglottis pneumothorax bronchus (pl., bronchi) epistaxis pulmonary ventilation carbonic acid hypercapnia respiration carbonic anhydrase hypoxia spirometer chemoreceptor larynx surfactant compliance lung trachea
Phases of Respiration Respiration • Process of obtaining oxygen from environment and delivering it to cells Phases of Respiration • Pulmonary ventilation • External gas exchange • Gas transport in the blood • Internal gas exchange
Structure of the Respiratory System (cont.) • Conducts air into and through the lungs • Main components • Nasal cavities • Pharynx • Larynx • Trachea • Bronchi • Lungs • Pleura What organ is located in the medial depression of the left lung?
Structure of the Respiratory System (cont.) The Nasal Cavities • Nostrils (nares) • Nasal cavities • Mucous membrane • Filters foreign bodies • Warms air • Moistens air • Conchae • Nasal septum • Sinuses
Structure of the Respiratory System (cont.) The Pharynx • Carries air to the respiratory tract and food to the digestive system • Nasopharynx • Superior portion • Oropharynx • Middle portion • Laryngeal pharynx • Inferior portion
Structure of the Respiratory System (cont.) The Larynx • Located between the pharynx and trachea • Cartilage framework • Thyroid cartilage (Adam’s apple) • Vocal folds (vocal cords) • Used for speech • Glottis • Epiglottis
Figure 18-4 Vocal folds, superior view.. What cartilage is named for its position above the glottis?
Structure of the Respiratory System (cont.) The Trachea • Conducts air between the larynx and lungs • Framework of separate cartilages • Horseshoe shaped • Open at back for expansion of trachea during swallowing
Structure of the Respiratory System (cont.) ? Pop Quiz 18.1 What is the most superior portion of the pharynx? A) Laryngeal pharynx B) Septum C) Nasopharynx D) Oropharynx
Structure of the Respiratory System (cont.) ? Pop Quiz Answer 18.1 What is the most superior portion of the pharynx? A) Laryngeal pharynx B) Septum C) Nasopharynx D) Oropharynx
Structure of the Respiratory System (cont.) The Bronchi • Trachea divides into two primary bronchi that enter the lungs: • Hilum • Epithelial tissue lining • Pseudostratified with cilia
Structure of the Respiratory System (cont.) The Lungs Located on either side of mediastinum in the thoracic cavity • Alveoli • Lobes • Right lung has three lobes. • Left lung has two lobes. • Bronchial tree • Bronchioles
Structure of the Respiratory System (cont.) Lung Cavities and the Pleurae • Diaphragm • Pleura—continuous double sac covers the lung • Parietal pleura • Visceral pleura • Pleural space
Structure of the Respiratory System (cont.) ? Pop Quiz 18.2 Where is the pleural space located? A) Between neighboring alveoli B) Between the layers of the membrane covering the lungs C) Between the ribs D) In the nasal cavity
Structure of the Respiratory System (cont.) Pop Quiz Answer 18.2 Where is the pleural space located? A) Between neighboring alveoli B) Between the layers of the membrane covering the lungs C) Between the ribs D) In the nasal cavity
The Process of Respiration (cont.) • Ventilation of lungs • Exchange of gases • Transport of gases in blood
The Process of Respiration (cont.) Pulmonary Ventilation • Inhalation (inspiration) is active phase. • Diaphragm contracts and flattens. • Surfactant • Compliance • Exhalation (expiration) is passive phase. • Respiratory muscles relax. • Spirometry: • Records volumes of air inhaled and exhaled
The Process of Respiration (cont.) Pulmonary Ventilation (cont.) • Lung volumes • Tidal volume • Residual volume • Inspiratory reserve volume • Expiratory reserve volume • Lung capacities • Vital capacity • Functional residual capacity
Figure 18-6 Pulmonary ventilation. What muscles are located between the ribs?
Figure 18-7 The relationship of gas pressure to volume. What happens to gas pressure as the volume of its container increases?
The Process of Respiration (cont.) Gas Exchange • Requires a pressure gradient • External exchange—between lung alveoli and capillary blood • Oxygen leaves alveoli and enters capillaries. • Carbon dioxide leaves capillaries and enters alveoli. • Internal exchange—between blood and tissues • Oxygen leaves capillaries and enters tissue. • Carbon dioxide leaves tissue and enters capillaries.
The Process of Respiration (cont.) Transport of Oxygen • Most oxygen, 98.5%, is transported in blood by hemoglobin. Transport of Carbon Dioxide • 10% is dissolved in plasma and fluid in red blood cells. • 15% is combined with protein of hemoglobin and plasma proteins. • 75% dissolves in blood fluids and is converted to bicarbonate ion.
Figure 18-8 A spirogram. What lung volume cannot be measured with a spirometer? Which lung capacities cannot be measured with a spirometer?
The Process of Respiration (cont.) ? Pop Quiz 18.3 Which of the following describes what occurs in the lungs? A) Both oxygen and carbon dioxide diffuse from the blood into the alveoli. B) Oxygen diffuses into the blood and carbon dioxide diffuses into the alveoli. C) Carbon dioxide diffuses into the blood and oxygen diffuses into the alveoli. D) Both oxygen and carbon dioxide diffuse from the alveoli into the blood.
The Process of Respiration (cont.) ? Pop Quiz Answer 18.3 Which of the following describes what occurs in the lungs? A) Both oxygen and carbon dioxide diffuse from the blood into the alveoi. B) Oxygen diffuses into the blood and carbon dioxide diffuses into the alveoli. C) Carbon dioxide diffuses into the blood and oxygen diffuses into the alveoli. D) Both oxygen and carbon dioxide diffuse from the alveoli into the blood.
Regulation of Respiration (cont.) • Complex process regulated by changes in cellular oxygen demands and carbon dioxide production • Controlled by central nervous system centers • Partly in medulla (main control center), partly in pons (modifies patterns set in the medulla) • Fundamental respiratory patterns controlled by the central nervous system
Regulation of Respiration (cont.) Central Nervous Control • Control center is located in the medulla (sets basic pattern of respiration) and pons of the brain stem. • Motor nerve fibers extend into the spinal cord. • Fibers extend through phrenic nerve to the diaphragm.
Regulation of Respiration (cont.) Chemical Control • Central chemoreceptors • Located near the medullary respiratory center • Respond to raised CO2 level (hypercapnia) • Peripheral chemoreceptors • Located in carotid and aortic bodies (in the neck and aortic arch) • Respond to oxygen level considerably below normal
Regulation of Respiration (cont.) Breathing Patterns Measured in breaths per minute • Adults: 12 to 20 • Children: 20 to 40 • Infants: more than 40
Regulation of Respiration (cont.) Some Terms for Altered Breathing • Hyperpnea • Hypopnea • Tachypnea • Apnea • Dyspnea • Orthopnea • Kussmaul respiration • Cheyne-Stokes respiration
Regulation of Respiration (cont.) Abnormal Ventilation • Hyperventilation • High oxygen level and low CO2 level (hypocapnia) • Increases blood pH • Hypoventilation • Insufficient air in alveoli • Decreases blood pH (acidosis) • Results of hypoventilation: • Cyanosis • Hypoxia • Hypoxemia
Regulation of Respiration (cont.) ? Pop Quiz 18.4 Where are chemoreceptors that regulate breathing located? A) Brachiocephalic vein and superior vena cava B) Carotid artery and aorta C) Cerebellum and pons D) Coronary sinus and alveoli
Regulation of Respiration (cont.) ? Pop Quiz Answer 18.4 Where are chemoreceptors that regulate breathing located? A) Brachiocephalic vein and superior vena cava B) Carotid artery and aorta C) Cerebellum and pons D) Coronary sinus and alveoli
Respiratory Disorders (cont.) Disorders of the Nasal Cavities and Related Structures • Sinusitis • Deviated septum • Epistaxis
Respiratory Disorders (cont.) Infection • Common cold (acute coryza) • Respiratory syncytial virus (RSV) • Croup • Influenza • Pneumonia • Lobar pneumonia • Bronchopneumonia • Pneumocystis pneumonia • Tuberculosis
Respiratory Disorders (cont.) Allergic Rhinitis (Hay Fever) and Asthma • Hypersensitivity to allergens • Watery discharge from eyes and nose • Seasonal or chronic • Inflammation of airway tissues • Spasm in bronchial tubes
Respiratory Disorders (cont.) Chronic Obstructive Pulmonary Disease (COPD) • Includes both chronic bronchitis and emphysema • Normal air flow obstructed • Reduced exchange of oxygen and carbon dioxide • Air trapping and overinflation of lungs • Dyspnea