1. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Chapter objectives: –To learn the structures of the respiratory system and their functions –To understand the processes of inspiration and expiration –To learn about the way in which gas exchange takes place –To learn about problems with the nervous, musculoskeletal, and pulmonary systems that can affect breathing –To understand the role of the lungs in acid-base balance

2. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Functions: –Maintains the exchange of oxygen and carbon dioxide in the lungs and tissues –Helps regulate the body’s acid-base balance Structures: –Upper respiratory tract: nose, mouth, nasopharynx, oropharynx, laryngopharynx, larynx –Lower respiratory tract: trachea, bronchi, lungs –Thoracic cavity: mediastinum, thoracic cage

3. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Upper respiratory tract Nostrils and nasal passages –Vibrissae—small hairs in the nares that filter foreign particles –Septum—partition that separates the two nasal passages –Conchae—cartilage of the posterior wall of the nasal passages; warms and humidifies air before it passes into the nasopharynx –Cilia—small, hairlike projections that trap finer foreign particles and carry then to the pharynx to be swallowed

4. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Upper respiratory tract Sinuses and nasopharynx –Four paranasal sinuses in the frontal, sphenoid, and maxillary bones –Sinuses provide speech resonance –Choanae—pair of posterior openings in the nasal cavity that allow air passage into the nasopharynx

5. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Upper respiratory tract Oropharynx and laryngopharynx –Oropharynx—located at the posterior wall of the mouth; connects the nasopharynx and laryngopharynx –Laryngopharynx—extends to the esophagus and larynx Larynx –Contains the vocal cords; connects the pharynx with the trachea –Walls formed by muscle and cartilage, including thyroid cartilage

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7. Chapter 11: Respiratory system Lower respiratory tract Trachea –Extends from the cricoid cartilage to the carina –C-shaped cartilage rings reinforce and protect the trachea Bronchi –Supply air to the lungs –Right mainstem bronchus—shorter, wider, and more vertical than the left –Divide into secondary bronchi; enter pleural cavity at the hilum –Divide into bronchioles and then terminal bronchioles

8. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Lower respiratory tract Acinus –Terminal bronchioles divide into respiratory bronchioles, which feed directly into alveoli –Alveolar sacs—clusters of alveoli at the end of alveoli ducts; where gas exchange takes place

9. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Lungs and accessory structures Lungs –Cone-shaped structures in the right and left pleural cavities –Right lung—three lobes; shorter, broader, and larger than the left lung –Left lung—two lobes –Both lungs rest on the diaphragm

10. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Lungs and accessory structures Pleura and pleural cavities –Pleura—membrane enclosing the lung; composed of a visceral and parietal layer –Pleural cavity—tiny area between the visceral and parietal layers Functions: –Lubricates the pleural surfaces –Creates a bond between the layers that causes the lungs to move with the chest wall during breathing

11. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Thoracic cavity Mediastinum—space between the lungs; contains the heart, pericardium, thoracic aorta, pulmonary vessels, venae cavae, azygos veins, thymus, lymph nodes and vessels, trachea, esophagus, thoracic duct, vagus, cardiac, and phrenic nerves

12. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Thoracic cavity Thoracic cage –Supports and protects the lungs, allowing them to expand and contract Posterior thoracic cage—vertebral column and 12 pair of ribs Anterior thoracic cage—manubrium, sternum, xiphoid process, ribs

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14. Chapter 11: Respiratory system Inspiration and expiration Inspiration—active process –Process: diaphragm descends to lengthen the chest cavity  external intercostal muscles contract to expand the anteroposterior diameter  intrapleural pressure decreases  inspiration occurs

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16. Chapter 11: Respiratory system Inspiration and expiration Expiration—relatively passive process –Process: diaphragm rises  intercostal muscles relax  intrapleural pressure increases  expiration occurs

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18. Chapter 11: Respiratory system Inspiration and expiration Forced inspiration and active expiration –Occurs when the body needs increased oxygenation –Uses accessory muscles of respiration: Forced inspiration: pectoral muscles, sternocleidomastoid muscles, scalene muscles, posterior trapezius muscles Active expiration: internal intercostal muscles, abdominal rectus muscles

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20. Chapter 11: Respiratory system Inspiration and expiration External respiration –Gas exchange in the lungs –Takes place through: Ventilation—distribution of gases into and out of the pulmonary airways Pulmonary perfusion—blood flow from the right side of the heart, through pulmonary circulation, and into the left side of the heart Diffusion—gas movement through a semipermeable membrane from an area of greater concentration to one of lesser concentration

21. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Inspiration and expiration Internal respiration –Gas exchanges in the tissues –Takes place through diffusion: Oxygen moves from the alveoli into the bloodstream and is taken up by hemoglobin in red blood cells Carbon dioxide is displaced by the oxygen to the alveoli and is removed during exhalation

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23. Chapter 11: Respiratory system Acid-base balance Carbon dioxide forms bicarbonate (base) in the blood and small amounts of carbonic acid (acid) Lungs convert bicarbonate to carbon dioxide and water for excretion Medulla signals the lungs to change the rate and depth of breathing in response to blood pH; allows for adjustments on the amount of carbon dioxide lost

24. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Respiratory system Acid-base balance Metabolic alkalosis –Results from excessive bicarbonate retention –Rate and depth of ventilation decrease to retain carbon dioxide and lower pH Metabolic acidosis –Results from excess acid retention or excess bicarbonate loss –Rate and depth of ventilation increase to eliminate excess carbon dioxide and raise pH