1 Hole’s Human Anatomy and Physiology Twelfth Edition Shier  Butler  Lewis Chapter 16 Respiratory System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 16.1: Introduction The respiratory system consists of passages that filter incoming air and transport it into the body, into the lungs, and to the many microscopic air sacs where gases are exchanged Respiration is the process of exchanging gases between the atmosphere and body cells It consists of the following events: Ventilation External respiration Transport of gases Internal respiration Cellular respiration

3 16.2: Why We Breathe Respiration occurs on a macroscopic level at the organ system Gas exchange, oxygen and carbon dioxide, occur at the cellular and molecular levels Aerobic reactions of cellular respiration allow for: ATP production Carbon dioxide generation forming carbonic acid

16.3: Organs of the Respiratory System The organs of the respiratory system can be divided into two tracts: Upper respiratory tract The nose Nasal cavity Sinuses Pharynx Lower respiratory tract Larynx Trachea Bronchial tree Lungs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Larynx Bronchus Nostril Right lung Left lung Soft palate Pharynx Epiglottis Esophagus Frontal sinus Nasal cavity Hard palate Oral cavity Trachea 4

5 Nose Frontal sinus Nostril Hard palate Uvula Epiglottis Hyoid bone Larynx Superior Middle Inferior Sphenoidal sinus Pharyngeal tonsil Nasopharynx Palatine tonsil Oropharynx Lingual tonsil Laryngopharynx Esophagus Tongue Trachea Nasal conchae Opening of auditory tube Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

6 Nasal Cavity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mucus Particle Goblet cell Cilia Nasal cavity Epithelial cell (b)(a) b: © Biophoto Associates/Photo Researchers, Inc.

7 Sinuses The sinuses are air-filled spaces in the maxillary, frontal, ethmoid, and sphenoid bones of the skull

8 Pharynx The pharynx is posterior to the oral cavity and between the nasal cavity and the larynx Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Frontal sinus Nostril Hard palate Uvula Epiglottis Hyoid bone Larynx Superior Middle Inferior Sphenoidal sinus Pharyngeal tonsil Nasopharynx Palatine tonsil Oropharynx Lingual tonsil Laryngopharynx Esophagus Tongue Trachea Nasal conchae Opening of auditory tube

9 Larynx The larynx is an enlargement in the airway superior to the trachea and inferior to the pharynx It is composed of a framework of muscles and cartilages bound by elastic tissue Epiglottic cartilage Hyoid bone Thyroid cartilage Cricoid cartilage Hyoid bone Epiglottic cartilage Thyroid cartilage Cricoid cartilage (b) (a) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Trachea False vocal cord Glottis Epiglottis Hyoid bone Thyroid cartilage Cricoid cartilage Hyoid bone Epiglottis Thyroid cartilage Cricoid cartilage (b) (a) False vocal cord True vocal cord Thyroid cartilage Cuneiform cartilage Corniculate cartilage Arytenoid cartilage True vocal cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glottis Corniculate cartilage (a) (b) Epiglottis Glottis (c) Posterior portion of tongue False vocal cord True vocal cord Cuneiform cartilage Inner lining of trachea c: © CNRI/PhotoTake Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Trachea The trachea (windpipe) is a flexible cylindrical tube about 2.5 centimeters in diameter and 12.5 centimeters in length As it extends downward anterior to the esophagus and into the thoracic cavity, it splits into the right and left primary bronchi Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Larynx Carina Trachea Superior (upper) lobe bronchus Right primary bronchus Middle lobe bronchus Inferior (lower) lobe bronchi Thyroid cartilage Cricoid cartilage Cartilaginous ring Left primary bronchus Superior (upper) lobe bronchus 10

11 Hyaline cartilage Ciliated epithelium Smooth muscle Lumen of trachea Connective tissue Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Connective tissue Hyaline cartilage Ciliated epithelium Lumen of trachea Smooth muscle © Ed Reschke Thyroid gland Incision Trachea Hyoid bone Thyroid cartilage Cricoid cartilage Jugular notch Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Bronchial Tree The bronchial tree consists of branched airways leading from the trachea to the microscopic air sacs in the lungs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Larynx Right middle lobe Right superior (upper) lobe Right primary bronchus Secondary bronchus Right inferior (lower) lobe Alveolar duct Alveolus Respiratory bronchiole Tertiary bronchus Terminal bronchiole Trachea Left superior (upper) lobe Left inferior (lower) lobe 12

13 The successive divisions of the branches from the trachea to the alveoli are: 1.Right and left primary bronchi 2.Secondary or lobar bronchi 3.Tertiary or segmental bronchi 4.Intralobular bronchioles ( generations) 5.Terminal bronchioles 6.Respiratory bronchioles 7.Alveolar ducts 8.Alveolar sacs 9.Alveoli Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ralph Hutchings/Visuals Unlimited Branches of the Bronchial Tree

14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Intralobular bronchiole Blood flow Alveolus Smooth muscle Alveoli Blood flow Pulmonary artery Pulmonary vein Terminal bronchiole Respiratory bronchiole Pulmonary arteriole Pulmonary venule Capillary network on surface of alveolus Alveolar duct Alveolar sac Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Capillary Alveolus Simple squamous epithelial cells © McGraw-Hill Higher Education, Inc./Bob Coyle

15 The structure of the bronchus is similar to that of the trachea, but the C-shaped cartilaginous rings are replaced with cartilaginous plates where the bronchus enters the lung These respiratory tubes become thinner and thinner, and the cell layers thin and change until the alveoli is reached It is the alveoli that provides surface area for gas exchange Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood flow Arteriole Alveolus Capillary Air O2O2 CO 2 Alveolar wall Venule O2O2 The Respiratory Tubes

16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood vesselCapillaryAlveolus Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, by R.G. Kessel and R.H. Kardon. © 1679 W.H. Freeman and Company Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Courtesy of the American Lung Association Bronchiole Alveolus

17 Lungs The right and left lungs are soft, spongy, cone-shaped organs in the thoracic cavity The right lung has three lobes and the left lung two lobes Thyroid cartilage Cricoid cartilage Clavicle Scapula Rib cartilage Sternum Superior (upper) lobe of right lung Middle lobe of right lung Inferior (lower) lobe of right lung Superior (upper) lobe of left lung Inferior (lower) lobe of left lung Trachea Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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: Breathing Mechanism Breathing or ventilation is the movement of air from outside of the body into the bronchial tree and the alveoli The actions responsible for these air movements are inspiration, or inhalation, and expiration, or exhalation

20 Inspiration Atmospheric pressure due to the weight of the air is the force that moves air into the lungs At sea level, atmospheric pressure is 760 millimeters of mercury (mm Hg) Moving the plunger of a syringe causes air to move in or out Air movements in and out of the lungs occur in much the same way Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphragm Air passageway Atmospheric pressure of 760 mm Hg on the outside Atmospheric pressure of 760 mm Hg on the inside Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a)(b)

21 Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges due to diaphragm downward movement caused by impulses carried by the phrenic nerves Atmospheric pressure then forces air into the airways Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphragm (a) (b) Intra-alveolar pressure (760 mm Hg) Atmospheric pressure (760 mm Hg) Intra-alveolar pressure (758 mm Hg) Inspiration

22 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a)(b) External intercostal muscles pull ribs up and out Diaphragm contracts Sternum moves Up and out Sternocleidomastoid elevates sternum Pectoralis minor elevates ribs Diaphragm contracts more Inspiration

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24 Expiration The forces responsible for normal resting expiration come from elastic recoil of lung tissues and from surface tension These factors increase the intra-alveolar pressure about 1 mm Hg above atmospheric pressure forcing air out of the lungs

25 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphragm (a)(b) Abdominal organs recoil and press diaphragm upward Posterior internal intercostal muscles pull ribs down and inward Abdominal organs force diaphragm higher Abdominal wall muscles contract and compress abdominal organs Expiration

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27 Respiratory Air Volumes and Capacities Different degrees of effort in breathing move different volumes of air in and out of the lungs This measurement of volumes is called spirometry Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lung volume in milliliters (mL) 6,000 5,000 4,000 3,000 2,000 1,000 0 Inspiratory reserve volume Tidal volume Residual volume Expiratory reserve volume Vital capacity Inspiratory capacity Total lung capacity Functional residual capacity

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29 Alveolar Ventilation The volume of new atmospheric air moved into the respiratory passages each minute is minute ventilation It equals the tidal volume multiplied by the breathing rate Much of the new air remains in the physiologic dead space The tidal volume minus the physiologic dead space then multiplied by breathing rate is the alveolar ventilation rate This is the volume of air that reaches the alveoli This impacts the concentrations of oxygen and carbon dioxide in the alveoli

30 Nonrespiratory Air Movements Air movements other than breathing are called nonrespiratory movements They clear air passages, as in coughing and sneezing, or express emotions, as in laughing and crying

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: Control of Breathing Normal breathing is a rhythmic, involuntary act that continues when a person is unconscious Respiratory muscles can be controlled as well voluntarily

33 Respiratory Areas Groups of neurons in the brainstem comprise the respiratory areas that control breathing Impulses travel on cranial nerves and spinal nerves, causing inspiration and expiration Respiratory areas also adjust the rate and depth of breathing The respiratory areas include: Respiratory center of the medulla Respiratory group of the pons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphragm Medulla oblongata Pons Midbrain Dorsal respiratory group Pontine respiratory group Ventral respiratory group Fourth ventricle Medullary respiratory center Internal (expiratory) intercostal muscles External (inspiratory) intercostal muscles

34 Respiratory muscles Forceful breathing Nerve impulses Pontine respiratory group Ventral respiratory group Dorsal respiratory group Medullary respiratory center Respiratory areas Basic rhythm of breathing Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

35 Factors Affecting Breathing A number of factors affect breathing rate and depth including: Partial pressure of oxygen (Po 2 ) Partial pressure of carbon dioxide (Pco 2 ) Degree of stretch of lung tissue Emotional state Level of physical activity Receptors involved include mechanoreceptors and central and peripheral chemoreceptors Carotid bodies Aorta Heart Aortic bodies Medulla oblongata Sensory nerve (branch of glossopharyngeal nerve) Common carotid artery Sensory nerve (branch of vagus nerve) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

36 Changes in blood pH, O 2 and CO 2 concentration stimulates chemoreceptors Motor impulses can travel from the respiratory center to the diaphragm and external intercostal muscles Contraction of these muscles causes the lungs to expand stimulating mechanoreceptors in the lungs Inhibitory impulses from the mechanoreceptors back to the respiratory center prevent overinflation of the lungs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Respiratory center Motor pathways Spinal cord Intercostal nerve Rib Diaphragm Sensory pathway Phrenic nerve Stretch receptors Lung External intercostal muscles Vagus nerve –– Factors Affecting Breathing

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: Alveolar Gas Exchanges The alveoli are the sites of the vital process of gas exchange between the air and the blood

39 Alveoli Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Courtesy of the American Lung Association

40 Capillary lumen Alveolus Macrophage Capillary Alveolus Red blood cell Diffusion of CO 2 Diffusion of O 2 Capillary endothelium Interstitial space Alveolar epithelium Type I (squamous epithelial) cell of alveolar wall Type II (surfactant- secreting) cell Fluid with surfactant Respiratory membrane Cell of capillary wall Alveolar fluid (with surfactant) Basement membrane of alveolar epithelium Basement membrane of capillary endothelium Respiratory membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

41 Respiratory Membrane Part of the wall of an alveolus is made up of cells (type II cells) that secrete pulmonary surfactant The bulk of the wall of an alveolus consists of a layer of simple squamous epithelium (type I cells) Both of these layers make up the respiratory membrane through which gas exchange takes place

42 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. AS BM IS RBC EP © Imagingbody.com

43 Alveolus Diffusion of CO 2 Diffusion of O 2 Capillary Alveolar wall Blood flow (from body tissues) Blood flow (to body tissues) P CO 2 = 45 mm Hg Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P CO 2 = 40 mm Hg P O 2 = 40 mm Hg P O 2 = 104 mm Hg P CO 2 = 40 mm Hg

44 Diffusion Through the Respiratory Membrane Molecules diffuse from regions where they are in higher concentration toward regions where they are in lower concentration It is important to know the concentration gradient In respiration, think in terms of gas partial pressures Gases diffuse from areas of higher partial pressure to areas of lower partial pressure The respiratory membrane is normally thin and gas exchange is rapid Increased diffusion is favored with more surface area, shorter distance, greater solubility of gases and a steeper partial pressure gradient Decreased diffusion occurs from decreased surface area

: Gas Transport Blood transports O 2 and CO 2 between the lungs and the body cells As the gases enter the blood, they dissolve in the plasma or chemically combine with other atoms or molecules

46 Oxygen Transport Almost all oxygen carried in the blood is bound to the protein hemoglobin in the form of oxyhemoglobin Chemical bonds between O 2 and hemoglobin are relatively unstable Oxyhemoglobin releases O 2 into the body cells About 75% of the O 2 remains bound to hemoglobin in the venous blood ensuring safe CO 2 levels and thereby pH

47 Alveolus Capillary (a)(b) Blood flow (from body tissues) Alveolar wall Oxygen molecules Hemoglobin molecules Diffusion of oxygen Oxyhemoglobin molecule Hemoglobin molecules Diffusion of oxygen Blood flow (to lungs) Blood P O = 40 mm Hg Blood P O = 95 mm Hg Tissue cells Tissue P O = 40 mm Hg Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

48 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Oxyhemoglobin dissociation at 38°C % saturation of hemoglobin P O 2 (mm Hg)

49 The amount of oxygen released from oxyhemoglobin increases with: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display % saturation of hemoglobin Oxyhemoglobin dissociation at 38°C 20 mm Hg 40 mm Hg 80 mm Hg P CO 2 = P O 2 (mm Hg) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Oxyhemoglobin dissociation at 38°C % saturation of hemoglobin pH = P O 2 (mm Hg) % saturation of hemoglobin °C 38°C 30°C 20°C 10°C 0°C P O 2 (mm Hg) Oxyhemoglobin dissociation at various temperatures Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

50 Carbon Dioxide Transport Blood flowing through capillaries gains CO 2 because the tissues have a high Pco 2 The CO 2 is transported to the lungs in one of three forms: As CO 2 dissolved in plasma As part of a compound with hemoglobin As part of a bicarbonate ion

51 Tissue cell Cellular CO 2 PlasmaRed blood cellCapillary wall Blood flow to systemic venule Tissue P CO 2 = 45 mm Hg Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CO 2 dissolved in plasma P CO 2 = 40 mm Hg Blood flow from systemic arteriole CO 2 combined with hemoglobin to form carbaminohemoglobin H 2 CO 3 H + combines with hemoglobin P CO 2 = 45 mm Hg HCO H + CO 2 + H 2 O HCO 3 -

52 HCO 3 - Red blood cell HCO 3 - Cl - HCO 3 - PlasmaCapillary wall Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

53 CO 2 Alveolus Alveolar wall Capillary wall CO 2 HCO 3 - Carbaminohemoglobin Plasma Red blood cell P CO 2 = 45 mm Hg P CO 2 = 40 mm Hg CO 2 CO 2 dissolved in plasma Blood flow from pulmonary arteriole HCO H + H 2 CO 3 H + released from hemoglobin Blood flow to pulmonary venule P CO 2 = 40 mm Hg + H 2 O CO 2 + hemoglobin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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: Lifespan Changes Lifespan changes reflect an accumulation of environmental influences and the effects of aging in other organ systems, and may include: The cilia become less active Mucous thickening Swallowing, gagging, and coughing reflexes slowing Macrophages in the lungs lose efficiency An increased susceptibility to respiratory infections A “barrel chest” may develop Bronchial walls thin and collapse Dead space increasing

56 Important Points in Chapter 16: Outcomes to be Assessed 16.1: Introduction Identify the general functions of the respiratory system. 16.2: Why We Breathe Explain why respiration is necessary for cellular survival. 16.3: Organs of the Respiratory System Name and describe the locations of the organs of the respiratory system. Describe the functions of each organ of the respiratory system. 16.4: Breathing Mechanism Explain how inspiration and expiration are accomplished. Name and define each of the respiratory air volumes and capacities.

57 Important Points in Chapter 16: Outcomes to be Assessed Calculate the alveolar ventilation rate. List several non-respiratory air movements and explain how each occurs. 16.5: Control of Breathing Locate the respiratory areas and explain control of normal breathing. Discuss how various factors affect breathing. 16.6: Alveolar Gas Exchanges Define partial pressure and explain its importance in diffusion of gases. Describe gas exchange in the pulmonary and systemic circuits.

58 Important Points in Chapter 16: Outcomes to be Assessed Describe the structure and function of the respiratory membrane. 16.7: Gas Transport Explain how the blood transports oxygen and carbon dioxide. 16.8: Lifespan Changes Describe the effects of aging on the respiratory system.