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Chapter 13 The Respiratory System

Chapter 13 The Respiratory System. Respiratory System Functions. Oversees gas exchanges (oxygen & carbon dioxide) between the blood and external environment Exchange of gases takes place within the lungs specifically within the alveoli

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Chapter 13 The Respiratory System

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  1. Chapter 13The Respiratory System

  2. Respiratory System Functions • Oversees gas exchanges (oxygen & carbon dioxide) between the blood and external environment • Exchange of gases takes place within the lungs specifically within the alveoli • Only site of gas exchange = alveoli; other structures are passageways • Passageways to the lungs purify, warm, and humidify the incoming air • Shares responsibility with cardiovascular system

  3. Respiratory System Organs • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs – alveoli

  4. Upper Respiratory Tract Figure 13.2

  5. Anatomy of the Nasal Cavity • Olfactory receptors • Located in the mucosa on the superior surface • Rest of the cavity is lined with respiratory mucosa • Rich network of thin walled veins  warms the entering air • Mucosa’s glands- produce a sticky mucus • Traps incoming foreign particles

  6. Anatomy of the Nasal Cavity • Lateral walls have projections called conchae • Increases surface area • Increases air turbulence within the nasal cavity • The nasal cavity is separated from the oral cavity by the palate • Anterior hard palate (bone) • Posterior soft palate (muscle)

  7. Cleft Palate • Genetic defect  bones forming the palate fail to fuse medially • Breathing, chewing & speaking difficulty Statistics: • Occurs in 1 in 700 newborns • Not racially influenced • Occurs in more males than females

  8. Cleft Palate Normal Roof of Mouth Complete cleft of soft palate Cleft of soft and hard palates Complete cleft of lip and palate

  9. Paranasal Sinuses • Cavities within bones surrounding the nasal cavity • Frontal bone • Sphenoid bone • Ethmoid bone • Maxillary bone

  10. Paranasal Sinuses • Function of the sinuses • Lighten the skull • Act as resonance chambers for speech • Produce mucus that drains into the nasal cavity

  11. Upper Respiratory Tract

  12. Pharynx (Throat) • Muscular passage from nasal cavity to larynx • Three regions of the pharynx • Nasopharynx – superior region behind nasal cavity • Oropharynx – middle region behind mouth • Laryngopharynx – inferior region attached to larynx • Oropharynx & laryngopharynx  Common passageways for air and food

  13. Structures of the Pharynx • Pharyngotympanic tubes • Drain the middle ear • Open into the nasopharynx • Tonsils of the pharynx • Pharyngeal tonsil (adenoids) in the nasopharynx • Palatine tonsils in the oropharynx • Lingual tonsils at the base of the tongue

  14. Larynx (Voice Box) • Routes air and food into proper channels • Plays a role in speech • Composed of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)

  15. Structures of the Larynx • Thyroid cartilage • Largest hyaline cartilage • Protrudes anteriorly (Adam’s apple) • Epiglottis • Protects the superior opening of the larynx • Routes food to the esophagus and air toward the trachea

  16. Structures of the Larynx • Vocal cords (vocal folds) • Vibrate with expelled air to create sound (speech) • Glottis – opening between vocal cords

  17. Trachea (Windpipe) • Connects larynx with bronchi • Lined with ciliated mucosa • Beat continuously in the opposite direction of incoming air • Expel mucus loaded with dust and other debris away from lungs • Walls are reinforced with C-shaped hyaline cartilage

  18. Primary Bronchi • Formed by division of the trachea • Enters the lung at the hilus (medial depression) • Right bronchus is wider, shorter, and straighter than left • Bronchi subdivide into smaller and smaller branches that terminate at the air sacs (alveoli)

  19. Lungs • Occupy most of the thoracic cavity • Apex is near the clavicle (superior portion) • Base rests on the diaphragm (inferior portion) • Each lung is divided into lobes by fissures • Left lung – two lobes • Right lung – three lobes

  20. Lungs

  21. Coverings of the Lungs • Pulmonary (visceral) pleura covers the lung surface • Parietal pleura lines the walls of the thoracic cavity • Pleural fluid fills the area between layers of pleura to allow gliding

  22. Respiratory Tree Divisions • After the primary bronchi enter the lungs, they subdivide into smaller & smaller branches • Secondary & Tertiary bronchi • Bronchioles • Alveoli

  23. Bronchioles • Smallest branches of the bronchi • All but the smallest branches have reinforcing cartilage • Terminal bronchioles end in alveoli Figure 13.5a

  24. Respiratory Zone • Structures • Respiratory bronchioles • Alveolar ducts • Alveoli • Site of gas exchange

  25. Alveoli • Structure of alveoli • Alveolar duct • Alveolar sac • Alveolus

  26. Respiratory Membrane (Air-Blood Barrier) • Alveolar walls- Composed of a thin layer of squamous epithelial cells • “Cobweb” of pulmonary capillaries cover external surfaces of alveoli Slide 13.18a

  27. Gas Exchange • Gases cross the respiratory membrane by diffusion • Oxygen enters the blood • Carbon dioxide enters the alveoli • Macrophages add protection • Surfactant coats gas-exposed alveolar surfaces

  28. Respiratory Membrane (Air-Blood Barrier)

  29. Events of Respiration • Pulmonary ventilation • Moving air in and out of the lungs… breathing • External respiration • Gas exchange between pulmonary blood and alveoli • Respiratory gas transport • Transport of oxygen and carbon dioxide via the bloodstream • Internal respiration • Gas exchange between blood and tissue cells in systemic capillaries

  30. Mechanics of Breathing (Pulmonary Ventilation) • Completely mechanical process • Depends on volume changes in the thoracic cavity • Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure

  31. Mechanics of Breathing (Pulmonary Ventilation) • Two phases • Inspiration – flow of air into the lungs • Expiration – air leaving the lungs

  32. Inspiration • Diaphragm and intercostal muscles contract • Size of the thoracic cavity increases • External air is pulled into the lungs due to an increase in intrapulmonary volume

  33. Inspiration

  34. Exhalation • Largely a passive process which depends on natural lung elasticity • As muscles relax, air is pushed out of the lungs • Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage

  35. Exhalation

  36. Nonrespiratory Air Movements • Can be caused by reflexes or voluntary actions • Examples • Cough and sneeze – clears lungs of debris • Laughing • Crying • Yawn • Hiccup

  37. Respiratory Volumes & Capacities • Factors that affect an individuals respiratory capacity • A person’s size • Sex • Age • Physical condition • Normal breathing moves about 500 ml of air into and out of the lungs with each breath  Tidal volume [TV]

  38. Respiratory Volumes & Capacities • Inspiratory reserve volume (IRV) • Amount of air that can be taken in forcibly over the tidal volume • Usually between 2100 and 3200 ml • Expiratory reserve volume (ERV) • Amount of air that can be forcibly exhaled • Approximately 1200 ml

  39. Respiratory Volumes & Capacities • Residual volume • Air remaining in the lungs even after the most strenuous expiration • About 1200 ml • Allows continuous gas exchange between breaths • Helps keep the alveoli inflated

  40. Respiratory Volumes & Capacities • Vital capacity • Total amount of exchangeable air • Vital capacity = TV + IRV + ERV • 4800 ml in healthy young males • Dead space volume • Air that remains in conducting zone and never reaches alveoli • About 150 ml

  41. Respiratory Volumes & Capacities • Functional volume • Air that actually reaches the respiratory zone & contributes to gas exchange • Usually about 350 ml • Respiratory capacities are measured with a spirometer

  42. Respiratory Capacities

  43. Respiratory Sounds • Stethoscope • Used to monitor respiratory sounds • Bronchial sounds – produced by air rushing through trachea and bronchi • Vesicular breathing sounds – soft sounds of air filling alveoli

  44. External Respiration • Oxygen movement into the blood • The alveoli always has more oxygen than the blood • Oxygen moves by diffusion towards the area of lower concentration • Pulmonary capillary blood gains oxygen

  45. External Respiration • Carbon dioxide movement out of the blood • Blood returning from tissues has higher concentrations of carbon dioxide than the air in the alveoli • Pulmonary capillary blood gives up carbon dioxide • Blood leaving the lungs is oxygen-rich and carbon dioxide-poor

  46. Gas Transport in the Blood • Oxygen transport in the blood • Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) • A small amount is carried dissolved in the plasma

  47. Gas Transport in the Blood • Carbon dioxide transport in the blood • Most is transported in the plasma as bicarbonate ion (HCO3–) • A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen

  48. Internal Respiration • Exchange of gases between blood and body cells • An opposite reaction to what occurs in the lungs • Carbon dioxide diffuses out of tissue to blood • Oxygen diffuses from blood into tissue

  49. Internal Respiration

  50. External Respiration, Gas Transport, and Internal Respiration Summary

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