Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea

Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea Right main (primary) bronchus Right lung Left main (primary) bronchus Left lung Diaphragm © 2018 Pearson Education, Inc. 1

Cribriform plate of ethmoid bone Frontal sinus Sphenoidal sinus Posterior nasal aperture Nasal cavity • Nasal conchae (superior, middle, and inferior) Nasopharynx • Pharyngeal tonsil • Nasal meatuses (superior, middle, and inferior) • Opening of pharyngotympanic tube • Nasal vestibule • Nostril • Uvula Hard palate Oropharynx • Palatine tonsil Soft palate • Lingual tonsil Tongue Laryngopharynx Hyoid bone Esophagus Trachea Larynx • Epiglottis • Thyroid cartilage • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract © 2018 Pearson Education, Inc. 2

Pharynx • Nasopharynx • Oropharynx • Laryngopharynx (a) Regions of the pharynx © 2018 Pearson Education, Inc. 3

Posterior Mucosa Esophagus Trachealis muscle Submucosa Lumen of trachea Seromucous gland in submucosa Hyaline cartilage (a) © 2018 Pearson Education, Inc. Adventitia Anterior 4

Intercostal muscle Trachea Rib Parietal pleura Pleural cavity Visceral pleura Lung Thymus Apex of lung Left superior lobe Right superior lobe Oblique fissure Horizontal fissure Right middle lobe Oblique fissure Left inferior lobe Right inferior lobe Heart (in pericardial cavity of mediastinum) Diaphragm Base of lung (a) Anterior view. The lungs flank mediastinal structures laterally. © 2018 Pearson Education, Inc. 5

Vertebra Posterior Right lung Parietal pleura Esophagus (in posterior mediastinum) Root of lung at hilum • Left main bronchus • Left pulmonary artery • Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior (b) Transverse section through the thorax, viewed from above © 2018 Pearson Education, Inc. 6

Alveolar duct Respiratory bronchioles Terminal bronchiole Alveoli Alveolar duct Alveolar sac (a) Diagrammatic view of respiratory bronchioles, alveolar ducts, and alveoli © 2018 Pearson Education, Inc. 7

Alveolar duct Alveolar pores Alveolus (b) Light micrograph of human lung tissue, showing the final divisions of the respiratory tree (120×) © 2018 Pearson Education, Inc. 8

Red blood cell Capillary Endothelial cell nucleus Alveolar pores Capillary Macrophage Nucleus of squamous epithelial cell Respiratory membrane Alveoli (gas-filled air spaces) Red blood Surfactant. Squamous cell in secreting cell epithelial cell capillary of alveolar wall © 2018 Pearson Education, Inc. O 2 CO 2 Alveolus Alveolar epithelium Fused basement membranes Capillary endothelium 9

Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs are elevated as external intercostals contract External intercostal muscles Full inspiration (External intercostals contract) Diaphragm moves inferiorly during contraction (a) Inspiration: Air (gases) flows into the lungs © 2018 Pearson Education, Inc. 10

Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs are depressed as external intercostals relax External intercostal muscles Expiration (External intercostals relax) Diaphragm moves superiorly as it relaxes (b) Expiration: Air (gases) flows out of the lungs © 2018 Pearson Education, Inc. 11

Pressure relative to atmospheric pressure +2 +1 Inspiration Expiration Intrapulmonary pressure 0 – 1 – 2 Volume (L) (a) © 2018 Pearson Education, Inc. (b) 0. 5 Volume of breath 0 – 0. 5 12

6, 000 Milliliters (ml) 5, 000 4, 000 3, 000 2, 000 1, 000 Inspiratory reserve volume 3, 100 ml Tidal volume 500 ml Expiratory reserve volume 1, 200 ml Vital capacity 4, 800 ml Total lung capacity 6, 000 ml Residual volume 1, 200 ml 0 © 2018 Pearson Education, Inc. 13

© 2018 Pearson Education, Inc. 14

Alveoli of lungs: Inspired air: O 2 CO 2 External respiration Pulmonary arteries Pulmonary veins Alveolar capillaries Blood leaving lungs and entering tissue capillaries: Blood leaving tissues and entering lungs: Heart O 2 CO 2 Systemic veins Internal respiration O 2 CO 2 Tissue capillaries CO 2 Systemic arteries O 2 Tissue cells: O 2 CO 2 © 2018 Pearson Education, Inc. 15

(a) External respiration in the lungs (pulmonary gas exchange) Oxygen is loaded into the blood, and carbon dioxide is unloaded. Alveoli (air sacs) O 2 Loading of O 2 Hb. O 2 (Oxyhemoglobin is formed) CO 2 Unloading of CO 2 HCO 3 H Bicarbonate ion H 2 CO 3 CO 2 H 2 O Carbonic acid Water Plasma Red blood cell Pulmonary capillary © 2018 Pearson Education, Inc. 16

(b) Internal respiration in the body tissues (systemic capillary gas exchange) Oxygen is unloaded and carbon dioxide is loaded into the blood. Tissue cells CO 2 Loading of CO 2 H 2 O Water Plasma H 2 CO 3 Carbonic acid O 2 Unloading of O 2 H HCO 3 Bicarbonate ion Hb. O 2 Hb O 2 Systemic capillary Red blood cell © 2018 Pearson Education, Inc. 17

Breathing control centers: • Pons centers • Medulla centers Efferent nerve impulses from medulla trigger contraction of inspiratory muscles: • Phrenic nerves • Intercostal nerves Afferent impulses to medulla Breathing control centers stimulated by: CO 2 and H increase in tissue. Nerve impulse from O 2 sensor indicating O 2 decrease Intercostal muscles Diaphragm O 2 sensor in aortic body of aortic arch © 2018 Pearson Education, Inc. 18