1 / 59

Chapter 13

Chapter 13. The Respiratory System. Outline. Functions of the Respiratory System Respiratory System Anatomy The Nose The Pharynx The Larynx The Trachea The Bronchi The Lungs Microscopic Anatomy of Alveoli Mechanics of Breathing Inspiration and Expiration Lung Volumes & Capacities

aknox
Download Presentation

Chapter 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 The Respiratory System

  2. Outline • Functions of the Respiratory System • Respiratory System Anatomy • The Nose • The Pharynx • The Larynx • The Trachea • The Bronchi • The Lungs • Microscopic Anatomy of Alveoli • Mechanics of Breathing • Inspiration and Expiration • Lung Volumes & Capacities • Exchange of Oxygen & Carbon Dioxide • Transport of Oxygen & Carbon Dioxide • Control of Respiration

  3. Functions of the Respiratory System • Gas exchange: Oxygen is brought into the body and carbon dioxide to eliminated from the body • Helps maintain blood pH • Cleans, warms, and moistens incoming air • Provides ability to smell, protects against noxious compounds • Provides ability to produce sounds, hence communicate effectively within the species • Assists defense against pathogens • Aids venous blood return to the heart and lymphatic fluid return to the cardiovascular system

  4. The Respiratory System

  5. The Respiratory System • During inspiration or inhalation, air is conducted toward the lungs. • During expiration or exhalation, air is conducted away from the lungs.

  6. Respiratory System Anatomy Pharynx • Nasopharynx • Oropharynx • Laryngopharynx Figure 13.2 Basic anatomy of the upper respiratory tract, sagittal section. (a) Regions of the pharynx Cribriform plate of ethmoid bone Frontal sinus Sphenoidal sinus Nasal cavity Posterior nasal aperture • Nasal conchae (superior, • middle and inferior) Nasopharynx • Nasal meatuses (superior, • middle, and inferior) • Pharyngeal tonsil • Opening of • pharyngotympanic • tube • Nasal vestibule • Nostril • Uvula Hard palate Soft palate Oropharynx • Palatine tonsil Tongue • Lingual tonsil Hyoid bone Larynx Laryngopharynx • Epiglottis Esophagus • Thyroid cartilage • Vocal fold Trachea • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract

  7. Respiratory System Anatomy (Cont.) • The Nose • As air moves into the nose it is cleansed (by coarse hairs, cilia, and mucus) warmed, and moistened • Special cells in upper part of cavities detect odors; olfactory epithelium • Involved with modifying speech sounds; areas act as resonating chambers, e.g. paranasal sinuses • Tears drain into the nasal cavities via nasolacrimal ducts • Paranasal sinuses drain mucus into nasal cavities; additional mucus flow • Auditory tubes (pharyngotympanic; Eustachian) lead from the nasopharynx to the middle ears • Respiratory epithelium on bony folds (nasal conchae; increase surface area); produce mucus; cilia move mucus to esophagus for swallowing or spitting

  8. Respiratory System Anatomy Pharynx • Nasopharynx • Oropharynx • Laryngopharynx Figure 13.2 Basic anatomy of the upper respiratory tract, sagittal section. (a) Regions of the pharynx Cribriform plate of ethmoid bone Frontal sinus Sphenoidal sinus Nasal cavity Posterior nasal aperture • Nasal conchae (superior, • middle and inferior) Nasopharynx • Nasal meatuses (superior, • middle, and inferior) • Pharyngeal tonsil • Opening of • pharyngotympanic • tube • Nasal vestibule • Nostril • Uvula Hard palate Soft palate Oropharynx • Palatine tonsil Tongue • Lingual tonsil Hyoid bone Larynx Laryngopharynx • Epiglottis Esophagus • Thyroid cartilage • Vocal fold Trachea • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract

  9. Respiratory System Anatomy (Cont.) • The Pharynx • The pharynx is a funnel-shaped passageway that connects the nasal and oral cavities to the larynx. • Three sections. • Nasopharynx - Nasal cavities open above soft palate. • Oropharynx - Oral cavity opens. • The tonsils (defensive lymphatic tissue containing lymphocytes) form protective ring at junction of oral cavity with pharynx. • Laryngopharynx - Opens into the larynx. • In the pharynx, air and food pathways cross. • Air cleansed by cilia and mucus.

  10. Respiratory System Anatomy Pharynx • Nasopharynx • Oropharynx • Laryngopharynx Figure 13.2 Basic anatomy of the upper respiratory tract, sagittal section. (a) Regions of the pharynx Cribriform plate of ethmoid bone Frontal sinus Sphenoidal sinus Nasal cavity Posterior nasal aperture • Nasal conchae (superior, • middle and inferior) Nasopharynx • Nasal meatuses (superior, • middle, and inferior) • Pharyngeal tonsil • Opening of • pharyngotympanic • tube • Nasal vestibule • Nostril • Uvula Hard palate Soft palate Oropharynx • Palatine tonsil Tongue • Lingual tonsil Hyoid bone Larynx Laryngopharynx • Epiglottis Esophagus • Thyroid cartilage • Vocal fold Trachea • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract

  11. Respiratory System Anatomy (Cont.) • The Larynx (Voice Box) • The larynx serves as a passageway for air between the pharynx and the trachea. • When food is swallowed, the larynx moves up against the epiglottispreventing food from passing into the larynx. • Food moves into the esophagus. • The larynx (voice box) houses the vocal cords which are stretched across the glottis. • Air cleansed by cilia and mucus.

  12. Respiratory System Anatomy Pharynx • Nasopharynx • Oropharynx • Laryngopharynx Figure 13.2 Basic anatomy of the upper respiratory tract, sagittal section. (a) Regions of the pharynx Cribriform plate of ethmoid bone Frontal sinus Sphenoidal sinus Nasal cavity Posterior nasal aperture • Nasal conchae (superior, • middle and inferior) Nasopharynx • Nasal meatuses (superior, • middle, and inferior) • Pharyngeal tonsil • Opening of • pharyngotympanic • tube • Nasal vestibule • Nostril • Uvula Hard palate Soft palate Oropharynx • Palatine tonsil Tongue • Lingual tonsil Hyoid bone Larynx Laryngopharynx • Epiglottis Esophagus • Thyroid cartilage • Vocal fold Trachea • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract

  13. Tongue Thyroid cartilage Epiglottis Glottis: Cricoid cartilage Vocal folds (true vocal cords) Vocal fold Rima glottidis Ventricular folds (false vocal cords) Arytenoid cartilage Cuneiform cartilage Posterior cricoarytenoid muscle Corniculate cartilage Superior view of cartilages and muscles View through a laryngoscope (a) Movement of vocal folds apart (abduction) Lateral cricoarytenoid muscle (b) Movement of vocal folds together (adduction)

  14. View Larynx Anterior Epiglottis Vocal folds (true vocal cords) Rima glottidis Cuneiform cartilage Ventricular folds (false vocal cords) Corniculate cartilage (c) Superior view Posterior

  15. Respiratory System Anatomy (Cont.) • The Trachea • Tube, containing C-shaped cartilage (to maintain patency during breathing), connecting larynx to primarybronchi; spanning open part of the C is fibromuscular membrane containing trachealis muscle- contraction & relaxation can change diameter slightly • Pseudostratified ciliated columnar epithelium sweeps mucus up toward the pharynx (Mucus escalator) for swallowing or spitting • The trachea divides into left and right primarybronchi which eventually branch into secondary bronchi and then into bronchioles

  16. Posterior Mucosa Figure 13.3a Structural relationship of the trachea and esophagus. Esophagus Submucosa Seromucous gland in submucosa Trachealis muscle Lumen of trachea Hyaline cartilage Adventitia Anterior (a)

  17. Figure 13.3b Structural relationship of the trachea and esophagus. (b)

  18. The Trachea: Mucus escalator

  19. BRANCHING OF BRONCHIAL TREE Trachea Larynx Primary bronchi Trachea Secondary bronchi Left lung Right lung Tertiary bronchi Visceral pleura Bronchioles Parietal pleura Terminal bronchioles Pleural cavity Location of carina Right primary bronchus Left primary bronchus Left secondary bronchus Right secondary bronchus Left tertiary bronchus Left bronchiole Right tertiary bronchus Right bronchiole Left terminal bronchiole Right terminal bronchiole Cardiac notch Diaphragm Anterior view

  20. Respiratory System Anatomy (Cont.) • The Lungs • Each bronchiole leads to an elongated space enclosed by alveoli. The alveoli make up the lungs. • The lungs lie on either side of the heart within the thoracic cavity. • Right lung has three lobes and the left lung has two lobes • Each lobe is divided into lobules, further divided into bronchioles serving many alveoli. • Contain large quantities of elastic fibers- permit stretching- have a tendency to want to collapse • Gas exchange takes place in the alveoli

  21. Esophagus (in posterior mediastinum) Posterior Vertebra Figure 13.4b Anatomical relationships of organs in the thoracic cavity. Root of lung at hilum • Left main bronchus Right lung • Left pulmonary artery Parietal pleura • Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior Transverse section through the thorax, viewed from above. (b)

  22. Respiratory System Anatomy (Cont.) • Lungs (Cont.) • Microscopic anatomy • Lobules- wrapped in elastic connective tissue with lymphatic vessel, arteriole, venule, & a terminal bronchiole • Terminal bronchiole lead to respiratory bronchioles (have alveoli budding on surface), then to alveolar ducts, then to alveolar sacs, then alveoli • All gas exchange occurs in alveoli

  23. MICROSCOPIC AIRWAYS Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli Terminal bronchiole Pulmonary arteriole Pulmonary venule Lymphatic vessel Respiratory bronchiole Elastic connective tissue Alveoli Alveolar ducts Pulmonary capillary Alveolar sac Visceral pleura Alveoli (a) Diagram of portion of lobule of lung

  24. Respiratory System Anatomy (Cont.) • Lungs (Cont.) • Microscopic anatomy • Alveoli • Wall composed of Type I alveolar cells- simple squamous epithelium- main site of gas exchange • Type II alveolar cells- produce alveolar fluid containing surfactant- extremely important mixture of phospholipids & lipoproteins- lower surface tension due to hydrogen bonding of water molecules-prevents collapse of the alveoli • Alveolar macrophages- remove particular debris • Respiratory membrane- type I alveolar cells, their basement membrane; capillary basement membrane, capillary endothelial cells

  25. Monocyte Reticular fiber Elastic fiber Type II alveolar (septal) cell Respiratory membrane Alveolus Red blood cell Diffusion of O2 Capillary endothelium Type I alveolar cell Capillary basement membrane Diffusion of CO2 Alveolar macrophage (dust cell) Epithelial basement membrane Alveolus Type I alveolar cell Red blood cell in pulmonary capillary Interstitial space Alveolar fluid with surfactant (a) Section through alveolus showing cellular components (b) Details of respiratory membrane

  26. Red blood cell Capillary Endothelial cell nucleus Alveolar pores Figure 13.6 Anatomy of the respiratory membrane (air-blood barrier). O2 Capillary CO2 Macrophage Alveolus Nucleus of squamous epithelial cell Respiratory membrane Alveolar epithelium Fused basement membranes Capillary endothelium Squamous epithelial cell of alveolar wall Alveoli (gas- filled air spaces) Red blood cell in capillary Surfactant- secreting cell

  27. Ventilation: Inspiration and Expiration • Normally there is a continuous column of air from the pharynx to the alveoli. • Lungs lie within sealed thoracic cavity. • Rib cage forms top and side of the cavity, while the diaphragm forms the floor. • Thoracic cavity and lungs are enclosed by two membranes,pleura. • Visceral pleura surround the lungs • Parietal pleura sticks to the rib cage and diaphragm. • Fluid separates these two. Pressure in fluid is normally negative due to lungs trying to collapse (elastic recoil).

  28. Inspiration • A respiratory center located in the brain triggers inspiration. • Inspiration is the active phase of breathing. • The diaphragm and the rib muscles (intercostals) contract,intrapleural pressure decreases, the lungs expand, and air rushes in. • Creation of apartial vacuum in the alveoli causes air to enter the lungs.

  29. Inspiration Versus Expiration

  30. Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs elevated as external intercostals contract External intercostal muscles Full inspiration (External intercostals contract) Figure 13.7 Rib cage and diaphragm positions during breathing. Diaphragm moves inferiorly during contraction Inspiration: Air (gases) flows into the lungs (a) Ribs depressed as external intercostals relax External intercostal muscles Expiration (External intercostals relax) Diaphragm moves superiorly as it relaxes Expiration: Air (gases) flows out of the lungs (b)

  31. Inspiration Expiration +2 Intrapulmonary pressure +1 Pressure relative to atmospheric pressure 0 −1 Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration. −2 (a) Volume of breath 0.5 Volume (L) 0 −0.5 (b)

  32. Expiration • When the respiratory center stops sending signals to the diaphragm and the rib cage, the diaphragm relaxes. • Abdominal organs press up against the diaphragm, and the rib cage moves down and inward. • Expiration is usually passive as the diaphragm and intercostal muscles are relaxed and the lung tissuerecoils.

  33. Inspiration Versus Expiration

  34. Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs elevated as external intercostals contract External intercostal muscles Full inspiration (External intercostals contract) Figure 13.7 Rib cage and diaphragm positions during breathing. Diaphragm moves inferiorly during contraction Inspiration: Air (gases) flows into the lungs (a) Ribs depressed as external intercostals relax External intercostal muscles Expiration (External intercostals relax) Diaphragm moves superiorly as it relaxes Expiration: Air (gases) flows out of the lungs (b)

  35. Inspiration Expiration +2 Intrapulmonary pressure +1 Pressure relative to atmospheric pressure 0 −1 Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration. −2 (a) Volume of breath 0.5 Volume (L) 0 −0.5 (b)

  36. Lung Volumes & Capacities • Spirometer- generates spirogram • Tidal volume (TV)= mL/breath • Anatomic dead space- 30% of TV • Inspiratory reserve volume (IRV) • Expiratory reserve volume (ERV) • Residual volume • Vital capacity (VC) • Total lung capacity

  37. 6,000 5,000 Inspiratory reserve volume 3,100 ml Figure 13.9 Idealized tracing of the various respiratory volumes of a healthy young adult male. 4,000 Vital capacity 4,800 ml Milliliters (ml) 3,000 Total lung capacity 6,000 ml Tidal volume 500 ml Expiratory reserve volume 1,200 ml 2,000 1,000 Residual volume 1,200 ml 0

  38. Exchange of Oxygen & Carbon Dioxide • Gas laws: Dalton’s law & Henry’s law • Dalton’s law- each gas in a mixture exerts it’s own pressure independent of the other gas- this pressure is called it’s partial pressure (in mmHg) • Henry’s law- quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas & to it’s solubility- solubility of CO2 is 24 times greater than the solubility of O2 in water • External & internal respiration- exchange of gases between alveolar air & blood • Dependent on • Partial pressure difference of the gases- the larger the partial pressure difference of O2 in alveolar air vs. partial pressure in the blood, the greater the rate of diffusion; the larger the partial pressure of CO2 in the blood vs. the partial pressure in the alveolar air, the greater the rate of diffusion

  39. Exchange of Oxygen & Carbon Dioxide (Cont.) • External & internal respiration (Cont.) • Surface area available for gas exchange- normally 750 ft2 ; any disorder that decreases functional surface area decreases rate of exchange (e.g. emphysema; destruction of alveolar walls • Diffusion distance- respiratory membrane very thin (just two cells thick); RBCs moving through capillaries in single file; slow blood flow through capillaries; any disease that builds up interstitial fluid slows rate of exchange (e.g. asthma, pulmonary edema) • Molecular weight & solubility of the gases- O2 is smaller but CO2 is 24 times more soluble- net is that CO2 diffusion is ~20 times faster than O2 ; thus in disease states hypoxia comes before hypercapnia

  40. CO2 exhaled Atmospheric air: PO2 = 159 mmHg PCO2 = 0.3 mmHg O2 inhaled Alveolar air: PO2 = 105 mmHg PCO2 = 40 mmHg Alveoli CO2 O2 Pulmonary capillaries (a) External respiration: pulmonary gas exchange To lungs To left atrium Deoxygenated blood: PO2 = 40 mmHg PCO2 = 45 mmHg Oxygenated blood: PO2 = 100 mmHg PCO2 = 40 mmHg To right atrium To tissue cells (b) Internal respiration: systemic gas exchange Systemic capillaries O2 CO2 Systemic tissue cells: PO2 = 40 mmHg PCO2 = 45 mmHg

  41. Inspired air: Alveoli of lungs: CO2 O2 O2 CO2 O2 CO2 External respiration Figure 13.10 Gas exchanges in the body occur according to the laws of diffusion. Pulmonary arteries Pulmonary veins Alveolar capillaries Blood leaving tissues and entering lungs: Blood leaving lungs and entering tissue capillaries: Heart O2 CO2 O2 CO2 Tissue capillaries Systemic veins Systemic arteries Internal respiration CO2 O2 Tissue cells: O2 CO2

  42. Transport of Oxygen & Carbon Dioxide • Oxygen transport- hemoglobin (Hb) • Hb + O2 = Hb-O2 (oxyhemoglobin); reversible • Relationship between hemoglobin & oxygen partial pressure • As partial pressure of O2 increases have rapid binding to Hb but then binding plateaus & reaches saturation • At 100 mmHg, 100% saturation of Hb

  43. Transport of Oxygen & Carbon Dioxide (Cont.) • Carbon dioxide transport • Dissolved CO2– 7% is dissolved in plasma • Carbamino compounds- 23% bound to Hb; higher the partial pressure of CO2 the greater the binding • Hb + CO2 = Hb-CO2 ; reversible • Binds to terminal amino acids of globin portions of Hb • Bicarbonate ions- 70%- generated by equation below- carried inside RBCs CA Bicarbonate Ion Carbonic Acid Hydrogen Ion Carbon Dioxide

  44. (b) (a) External respiration in the lungs (pulmonary gas exchange) Internal respiration in the body tissues (systemic capillary gas exchange) Oxygen is unloaded and carbon dioxide is loaded into the blood. Oxygen is loaded into the blood and carbon dioxide is unloaded. Alveoli (air sacs) Tissue cells Figure 13.11 Diagrammatic representation of the major means of oxygen (O2) and carbon dioxide (CO2) loading and unloading in the body. O2 CO2 CO2 O2 Loading of CO2 Unloading of O2 Loading of O2 Unloading of CO2 Hb + O2 HbO2 HCO3−+ H+ CO2 + H2O H2CO3 CO2 + H2O H2CO3 H++ HCO3− (Oxyhemoglobin is formed) Bicar- bonate ion Carbonic acid Water Water Carbonic acid Bicar- bonate ion HbO2 Hb + O2 Plasma Plasma Red blood cell Systemic capillary Red blood cell Pulmonary capillary

  45. Control of Respiration • Respiratory Center- control rate & depth of breathing • Three important areas in brain stem • Medullary rhythmicity area- medulla oblongata • Pneumotaxic area- upper pons • Apneustic area- lower pons • Medullary rhythmicity area- controls the basic rhythm of respiration • Pneumotaxic area- sends inhibitory signals to the inspiratory area of the medulla oblongata; prevents over expansion of lungs • Apneustic area- sends stimulatory signals to the inspiratory area of the medulla oblongata; activates it; prolongs inhalation, result is long deep inhalations; overridden by the pneumotaxic area when active

  46. Breathing control centers: • Pons centers • Medulla centers Figure 13.12 Breathing control centers, sensory inputs, and effector nerves. Efferent nerve impulses from medulla trigger contraction of inspiratory muscles. Afferent impulses to medulla • Phrenic nerves • Intercostal nerves Breathing control centers stimulated by: CO2 increase in blood (acts directly on medulla centers by causing a drop in pH) Nerve impulse from O2 sensor indicating O2 decrease Intercostal muscles Diaphragm O2 sensor in aortic body of aortic arch

  47. Control of Respiration (Cont.) • Respiratory Center (Cont.) • Regulation of the respiratory center • Cortical influence on respiration • Chemoreceptor regulation of respiration • Proprioceptor stimulation of respiration • The inflation reflex • Other influence on respiration • Limbic system stimulation • Temperature • Pain • Stretching of the anal sphincter • Irritation of airways • Blood pressure

  48. Control of Respiration (Cont.) • Respiratory Center (Cont.) • Regulation of the respiratory center (Cont.) • Cortical influence on respiration- cerebral cortex connected to the respiratory center- can voluntarily alter breathing patterns- provides voluntary protect effect; input from hypothalamic & limbic systems- emotional stimuli can alter breathing, e.g. laughing & crying • Chemoreceptor regulation of respiration- very sensitive to CO2 & O2 levels • Two locations • Central chemoreceptors- in medulla oblongata- respond to changes H+ & partial pressure of CO2 • Peripheral chemoreceptors- PCO2 , H+ , PO2 • Carotid bodies- most sensitive to PCO2 • Aortic bodies- most sensitive to PCO2

  49. Breathing control centers: • Pons centers • Medulla centers Figure 13.12 Breathing control centers, sensory inputs, and effector nerves. Efferent nerve impulses from medulla trigger contraction of inspiratory muscles. Afferent impulses to medulla • Phrenic nerves • Intercostal nerves Breathing control centers stimulated by: CO2 increase in blood (acts directly on medulla centers by causing a drop in pH) Nerve impulse from O2 sensor indicating O2 decrease Intercostal muscles Diaphragm O2 sensor in aortic body of aortic arch

More Related