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Cribriform plate of ethmoid bone Sphenoidal sinus Frontal sinus Posterior nasal aperture Nasal cavity • Nasal conchae (superior, middle, and inferior) Nasal cavity Nasopharynx Oral cavity • Pharyngeal tonsil • Nasal meatuses (superior, Nostril Pharynx middle, and inferior) • Opening of pharyngotympanic • Nasal vestibule Larynx tube • Nostril • Uvula Hard palate Trachea Oropharynx • Palatine tonsil Soft palate

Left main Tongue Right main (primary) • Lingual tonsil (primary) bronchus bronchus Left lung Laryngopharynx Hyoid bone Right lung Larynx Diaphragm Esophagus • Epiglottis • Thyroid cartilage Trachea • Vocal fold • Cricoid cartilage

(b) Detailed anatomy of the upper respiratory tract © 2018 Pearson Education, Inc. 1 © 2018 Pearson Education, Inc. 2

Posterior Mucosa

Pharynx Esophagus • Nasopharynx Submucosa • Oropharynx Trachealis Lumen of Seromucous • Laryngopharynx muscle trachea gland in submucosa Hyaline (a) Regions of the pharynx cartilage Adventitia (a) Anterior © 2018 Pearson Education, Inc. 3 © 2018 Pearson Education, Inc. 4

Intercostal muscle Rib Parietal pleura Posterior Lung Vertebra Esophagus Trachea Pleural cavity Visceral pleura (in posterior mediastinum) Thymus Root of lung at hilum Right lung • Left main bronchus Apex of lung Left Parietal pleura • Left pulmonary artery superior lobe • Left pulmonary vein Right superior lobe Visceral pleura Oblique Left lung Horizontal fissure fissure Pleural cavity Right middle lobe Left inferior lobe Thoracic wall Oblique fissure Pulmonary trunk Right inferior lobe Pericardial Heart membranes Heart (in mediastinum) (in pericardial cavity Anterior mediastinum Sternum of mediastinum) Diaphragm Anterior Base of lung (b) Transverse section through the thorax, viewed from above

(a) Anterior view. The lungs flank mediastinal structures laterally.

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Alveolar duct Alveolar Alveoli Alveolar duct pores

Respiratory bronchioles Alveolar duct

Terminal Alveolus bronchiole Alveolar sac

(a) Diagrammatic view of respiratory bronchioles, alveolar ducts, and alveoli (b) Light micrograph of human lung tissue, showing the final divisions of the respiratory tree (120×)

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Changes in anterior-posterior and Changes in lateral Red blood superior-inferior dimensions dimensions cell Endothelial cell nucleus Capillary

Alveolar Ribs are elevated pores as external intercostals Capillary O2 contract CO2 Macrophage External Alveolus Full inspiration Nucleus of intercostal muscles (External squamous intercostals contract) epithelial cell Respiratory Alveolar epithelium membrane Fused basement membranes Diaphragm moves Capillary endothelium Alveoli Red blood Surfactant- Squamous inferiorly during (gas-filled cell in secreting cell epithelial cell contraction air spaces) capillary of alveolar wall (a) Inspiration: Air (gases) flows into the lungs

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Changes in anterior-posterior and Changes in lateral +2 Inspiration Expiration superior-inferior dimensions dimensions Intrapulmonary +1 pressure

0

Ribs are depressed –1

as external relative Pressure intercostals relax –2 toatmospheric pressure

Expiration (a) External (External intercostal Volume of intercostals relax) muscles breath 0.5

Diaphragm moves 0 superiorly as Volume (L) it relaxes (b) Expiration: Air (gases) flows out of –0.5 the lungs (b) © 2018 Pearson Education, Inc. 11 © 2018 Pearson Education, Inc. 12 4/3/20

6,000

5,000 Inspiratory reserve volume 4,000 3,100 ml Vital capacity 3,000 4,800 ml Total lung Tidal volume 500 ml capacity

Milliliters (ml) 6,000 ml 2,000 Expiratory reserve volume 1,200 ml 1,000 Residual volume 1,200 ml 0

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Inspired air: Alveoli (a) External respiration in the lungs of lungs: (pulmonary gas exchange)

Oxygen is loaded into the blood, and carbon dioxide is unloaded. CO2 O 2 O 2 CO2 O 2 CO2

Alveoli (air sacs) External respiration

Pulmonary Alveolar Pulmonary O2 CO2 arteries capillaries veins

Blood Blood leaving leaving tissues and lungs and entering entering Loading lungs: tissue of O2 Unloading capillaries: of CO2

Heart

O 2 CO2 O 2 CO2 Tissue Hb + O2 HbO2 HCO3- + H+ H2CO3 CO2 + H2O capillaries Systemic Systemic (Oxyhemoglobin Bicar- Carbonic Water veins arteries is formed) bonate acid Internal ion respiration CO2 O 2 Plasma

Red blood cell Tissue cells:

O 2 CO2 Pulmonary capillary © 2018 Pearson Education, Inc. 15 © 2018 Pearson Education, Inc. 16

(b) Internal respiration in the body tissues (systemic capillary gas exchange) Breathing control centers: Oxygen is unloaded and carbon • Pons centers dioxide is loaded into the blood. • Medulla centers

Tissue cells Afferent Efferent nerve impulses from CO2 O2 impulses to medulla trigger contraction of medulla inspiratory muscles: • Phrenic nerves • Intercostal nerves Loading Unloading of CO2 Breathing control centers of O2 stimulated by:

CO2 and H+ increase Nerve impulse Intercostal in tissue. 2 from O sensor muscles CO2 + H2O H2CO3 H+ + HCO3- indicating O2 decrease Diaphragm Water Carbonic Bicar- HbO2 Hb + O2 acid bonate Plasma ion

O2 sensor in aortic body Systemic capillary of aortic arch Red blood cell

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