Chapter 18 The Respiratory System

1. Chapter 18The Respiratory System p.430

2. The Respiratory System • Respiratory & cardiovascular systems work together • Respiratory system • Intake of O2 and elimination of CO2 • Cardiovascular system • Transport of blood containing O2 & CO2 between lungs & tissue cells

3. 4 Processes of Respiration • Ventilation • Inhalation • Exhalation • External respiration • Exchange of O2 & CO2 between air in the lungs & blood • Transport of O2 from lungs to tissue cells and CO2 back to the lungs via the bloodstream • Internal respiration • The exchange of O2 & CO2 between blood & tissue cells

4. Functions of the Respiratory System • Provide for gas exchange • Helps regulate blood pH • Contains receptors for the sense of smell • Filters inspired air • Produces sounds

5. Organs of the Respiratory System (p. 431)Organization • Structural organization • Upper respiratory system • Nose, pharynx, & associated structures • Lower respiratory system • Larynx, trachea, bronchi, and lungs • Functional organization • Conducting portion • A series of interconnecting cavities & tubes that conduct air into the lungs • Respiratory portion • Structures where gas exchange occurs

6. Organs of the Respiratory SystemNose • Structure • External • External nares • Nostrils • Internal • Nasal cavity • Divided into 2 sides by the nasal septum • Connecting structures • Internal nares, Paranasal sinuses, Nasolacrimal ducts • Functions • Filtering, warming, & moistening incoming air to facilitate gas exchange • Conchae, mucous, & cilia • Receiving olfactory stimuli • Providing a resonating chamber for speech sounds

7. Organs of the Respiratory SystemPharynx (Throat) • Extends from internal nares part-way down the neck • Skeletal muscle walls • Lined with mucous membrane • Function • Passageway for air and food • Resonating chamber for speech sounds • Structure • Nasopharynx (superior portion) • Respiratory pathway only • Oropharynx (middle portion) • Respiratory & digestive • Contains tonsils • Laryngopharynx (lowest portion) • Respiratory & digestive • Connects to esophagus & larynx

8. Organs of the Respiratory System Larynx • Structure • Cartilaginous wall • Thyroid cartilage (Adam’s apple) • Epiglottis • Cover opening to trachea during swallowing • Circoid cartilage • Arytenoid cartilages • Attach to true vocal cords & pharyngeal muscles • Voice production • (false vocal cords) • Hold breath when strain to lift something heavy • True vocal cords • Tension is controlled by muscles • Tension; length & thickness determine pitch • Breath causes vibration – amount determines volume • Laryngitis – inflammation of the larynx • Interferes with contraction/vibration of vocal cords

9. Organs of the Respiratory System Trachea (Windpipe) • Passageway for air • Extends from larynx to upper part of the 5th thoracic vertebra where it divides into right & left primary bronchi • Wall is lined by mucous membrane & supported by cartilage • Mucous & cilia trap foreign particles & move them upward • C-shaped cartilage rings keep tracheal wall from collapsing • Obstruction may occur due to: • Crushed c-rings • Inflamed & swollen mucous membrane • Aspiration of large object/water • Heimlich maneuver • Tracheostomy • Intubation

10. Organs of the Respiratory System Bronchi (Figure 18.4, p.434) Branching of bronchial tree Smaller amounts of smooth muscle • Primary bronchi • Right & left • Right is more vertical, shorter, & wider • Extend from trachea into each lung (respectively)  • Secondary bronchi • Divisions of primary bronchi to lobes of lungs  • Right – 3 branches • Left – 2 branches • Tertiary bronchi • Continued branches – successively smaller • Bronchioles • Bronchoconstriction • Bronchodilation • Smooth muscle spasms (asthma) • Terminal bronchioles Incomplete cartilaginous rings Strips of cartilage No cartilage

11. Organs of the Respiratory SystemLungs ~ General Info. • Paired, cone-shaped organs in thoracic cavity • Separated by heart & other structures in mediastinum • Pleural membrane encloses & protects • Parietal pleura • Outer layer, attached to wall of thoracic cavity & diaphragm • Pleural cavity • Narrow space between pleurae • Contains lubricating fluid to reduce friction & allow easy movement • Visceral pleura • Inner layer, covers lungs • Pleurisy – inflammation of membranes • Causes friction during breathing • Very painful

12. Organs of the Respiratory SystemLungs ~ Structure • Extend from diaphragm to slightly above the clavicles • Lie against the ribs • Contain • Base • Broad bottom portion • Apex • Narrow top portion • Hilus • Area on medial side where bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter & exit) • Cardiac notch – left lung only • About 10% smaller than right • Right lung is thicker & broader, but shorter • Diaphragm is higher to accommodate liver

13. Organs of the Respiratory SystemLungs ~ Lobes, Fissures, & Lobules(Figure 18.5, p.435) • Lungs divided into lobes by fissures (deep grooves) • Left lung • 1 fissure – oblique / 2 lobes – superior & inferior • Right lung • 2 fissures – oblique & horizontal / 3 lobes – superior, middle, & inferior • Lobes (each supplied by secondary bronchus) • Divide into regions–bronchopulmonary segments (each supplied by tertiary bronchus) • Divide into small compartments – lobules • Contain: • Lymphatic vessel • Arteriole • Venule • A branch from a terminal bronchiole wrapped in elastic connective tissue • Subdivide into respiratory bronchioles • Subdivide into alveolar ducts

14. Organs of the Respiratory SystemLungs ~ Alveoli • About 300 million, providing a surface area of 750 ft2 • Alveolar ducts open to • Alveolar sacs • Contain 2 or more alveoli • Cell types • Type I cells – mostly continuous lining • 95% of alveolar cells • Main sites of gas exchange • Type II cells – secrete alveolar fluid (with surfactant to prevent collapse) • Alveolar macrophages • Exchange of O2 & CO2 – diffusion through 4-layered respiratory membrane

15. Organs of the Respiratory SystemLungs ~ Blood Supply • 2 sets of arteries • Pulmonary arteries • Bring deoxygenated blood from heart • Divides into right & left • Bronchial arteries • Bring oxygenated blood from aorta to lung tissue • 2 sets of veins • Pulmonary veins • Returns oxygenated blood to heart • Bronchial veins • Drains deoxygenated blood from lung tissue

16. Lung Volumes and Capacities (p.438) • Eupnea – normal quiet breathing • Typical, healthy adult at rest • 12 breaths/minute • 500 mL of air • Tidal volume – volume of one breath • Varies greatly by person • Only 70% reaches respiratory portion of respiratory system • 30% remains in anatomic dead space (conducting airways)

17. Ventilation (Breathing) (p.438)Inhalation/Inspiration • Size of thoracic cavity is increased (active process) • Diaphragm contracts • Accessory muscles elevate ribs and sternum • Pleural membrane is pulled outward • Alveolar pressure drops • Pressure difference is created between alveoli & atmosphere • Pressure inside is lower than in atmosphere • Air flows into the lungs

18. Ventilation (Breathing)Exhalation/Expiration • Elastic recoil of chest wall and lungs (passive process) • Diaphragm relaxes and curves upward • Pressure in lungs rises • Lung volume decreases • Alveolar pressure is greater than that in atmosphere • Can be an active process during forceful breathing • Activities • Playing wind instrument • Exercising • Muscles of exhalation contract to move ribs, compress abdominal viscera, and force diaphragm upward

19. Ventilation (Breathing)Collapsed Lung • Low pressure in pleural cavity (intrapleural pressure) • Helps keep alveoli slightly inflated • Prevent alveoli from collapsing on themselves • Increased intrapleural pressure can cause a collapsed lung • Surgical incision • Chest wound • Airway obstruction • Insufficient surfactant

20. Exchange of Oxygen & Carbon Dioxide (p.442)Partial Pressure • Each gas contained in air has its own pressure • Nitrogen • Oxygen • Carbon dioxide • Water vapor • And others • Total pressure of air is calculated by adding all partial pressures

21. Exchange of Oxygen & Carbon DioxideExternal Respiration • Exchange of O2 and CO2 • Between air in alveoli & blood in pulmonary capillaries • Results in conversion of deoxygenated blood (from right side of heart) to oxygenated blood (returning to left side of heart) • O2 diffuses from alveoli into blood in capillaries • CO2 diffuses from blood into alveoli • Enhanced by: • Thin respiratory membrane • Huge surface area of alveoli • Large numbers of capillaries surrounding alveoli • Narrowness of capillaries for red blood cells to flow single file

22. Exchange of Oxygen & Carbon DioxideExternal Respiration (cont.) • Efficiency depends on: • Altitude • Total surface area available for gas exchange • Affected by pulmonary disorders • Rate of respiration • Affected by certain drugs • Amount of O2 that reaches alveoli • Affected by passageways & sufficient oxygen

23. Exchange of Oxygen & Carbon DioxideInternal Respiration • Exchange of O2 and CO2 • Between tissue capillaries & tissue cells • Occurs throughout the body • Results in conversion of oxygenated blood (from left side of heart) to deoxygenated blood (returning to right side of heart) • O2 diffuses from blood into tissue cells • Cell PO2 is lower due to ATP production • CO2 diffuses from tissue cells into blood • Cell PCO2 is higher to constant production of CO2

24. Transport of Respiratory Gases (p.444)Oxygen • O2 binds chemically to hemoglobin in red blood cells • 4 atoms of iron (heme portion of hemoglobin) are each capable of combining with a molecule of O2 • Affected by: • High blood PO2 (allows blood to become fully saturated) • pH of blood • Temperature (higher temps release more O2 • Carbon monoxide (CO) binds more strongly to hemoglobin and blocks O2 binding

25. Transport of Respiratory GasesCarbon Dioxide • Carried by blood in several forms • Dissolved in plasma • Combined with globin portion of hemoglobin • Transported in plasma • (during diffusion, enters red blood cells, then chemical reactions eventually cause diffusion into plasma) • Reverse of events occurs during transfer from blood into alveoli

26. Control of Respiration (p.445) *Several mechanisms help match respiratory effort to metabolic demand • Respiratory center • Medullaryrhythmicity area • Controls the basic rhythm of respiration • Neurons bring nerve impulses to: • Inspiratory area • Expiratory area • Pneumotaxic area • Transmits inhibitory impulses to inspiratory area • Limit duration of inhalation • Apneustic area • Sends stimulatory impulses to inspiratory area • Activate and prolong inhalation

27. Control of Respiration (cont.) • Regulation of the respiratory center • Cortical influences on respiration • Allow voluntary alteration of breathing • Prevent water or irritating gases from entering airway • Impossible to kill oneself by holding breath • Allow emotional stimuli to alter respirations • Chemoreceptor regulation of respiration • Chemical stimuli affect rate & depth of respiration • Negative feedback system (typically)

28. Control of Respiration (cont.) • Regulation of the respiratory center (cont.) • Other influences on respiration • Limbic system stimulation (anticipation of activity or emotional anxiety) • Proprioceptor stimulation of respiration (exercise) • Temperature • Pain • Stretching the anal sphincter muscle • Irritation of airways • Inflation reflex • Blood pressure

29. Exercise and the Respiratory System (p.449) • Increased blood flow from the heart • Increased oxygen uptake • Increased diffusion to tissue cells • Different levels of exercise intensity determine respiratory effect • Change in: • Rate • Depth

30. Aging and the Respiratory System (p.449) • Airways and tissues lose elasticity • Decrease in lung capacity • Decreased activity of alveolar macrophages & diminished ciliary action of epithelium lining the respiratory tract • Increased susceptibility to pulmonary sickness & disorders

31. Common Disorders (p.451) • Asthma • Characterized by chronic airway inflammation, airway hypersensitivity, and airway obstruction • Chronic obstructive pulmonary disease • Emphysema • Progressive destruction of alveoli & collapse of respiratory bronchioles • Chronic bronchitis • Inflammation of the upper respiratory tract • Characterized by excessive mucus production • “Smoker’s cough” • Lung cancer • Pneumonia • Tuberculosis • Coryza and influenza • Pulmonary edema • Cystic fibrosis Chances of contracting these diseases is greatly increased by cigarette smoking

32. Cigarette smoking is the single most preventable cause of death and disability worldwide.