The Respiratory System Sonya Schuh-Huerta, Ph.D. Human Anatomy Sonya Schuh-Huerta, Ph.D. Leonardo Da Vinci

The Upper Respiratory Tract Cribriform plate of ethmoid bone Frontal sinus Sphenoid sinus Nasal cavity Posterior nasal aperture Nasal conchae (superior, middle and inferior) Nasopharynx Pharyngeal tonsil Nasal meatuses (superior, middle, and inferior) Opening of pharyngotympanic tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Esophagus Vestibular fold Thyroid cartilage Vocal fold Trachea Cricoid cartilage Thyroid gland

Organs of the Respiratory System Nasal cavity Oral cavity Nostril Pharynx Larynx Left main (primary) bronchus Trachea Bronchi Carina of trachea Alveoli Right main (primary) bronchus Left lung Right lung Diaphragm Parietal pleura

Bronchi in the Conducting Zone Superior lobe of right lung Trachea Superior lobe of left lung Left main (primary) bronchus Lobar (secondary) bronchus Segmental (tertiary) bronchus Inferior lobe of left lung Inferior lobe of right lung Middle lobe of right lung (a) The branching of the bronchial tree

Structures of the Respiratory Zone Alveolar duct Alveoli Alveolar sac Respiratory bronchioles Terminal bronchiole (a)

Alveoli & the Respiratory Membrane Terminal bronchiole Respiratory bronchiole Smooth muscle Elastic fibers Alveolus Capillaries (a) Diagrammatic view of capillary-alveoli relationships

Anatomy of Alveoli & the Respiratory Membrane Red blood cell Nucleus of type I (squamous epithelial) cell Alveolar pores Capillary O2 Capillary CO2 Macrophage Alveolus Endothelial cell nucleus Alveolus Alveolar epithelium Respiratory membrane Fused basement membranes of the alveolar epithelium and the capillary endothelium Red blood cell in capillary Type I cell of alveolar wall Capillary endothelium Alveoli (gas-filled air spaces) Type II (surfactant- secreting) cell (c) Detailed anatomy of the respiratory membrane

The Respiratory System Basic functions of the respiratory system Supplies body with oxygen Disposes of carbon dioxide 4 processes involved in respiration: Pulmonary ventilation External respiration Transport of respiratory gases Internal respiration

Functional Anatomy of the Respiratory System Respiratory organs Nose, nasal cavity, & paranasal sinuses Pharynx, larynx, & trachea Bronchi & smaller branches Lungs & alveoli

Organs of the Respiratory System Divided into Conducting zone Respiratory zone

The Nose Provides an airway for respiration Moistens & warms air (humidifies air) Filters inhaled air Resonating chamber for speech Houses olfactory receptors (olfaction)

The Nose Size variation due to differences in nasal cartilages Skin is thin  contains many sebaceous glands Frontal bone Nasal bone Septal cartilage Maxillary bone (frontal process) Lateral process of septal cartilage Minor alar cartilages Major alar Dense fibrous connective tissue (b) External skeletal framework Epicranius, frontal belly Ala of nose Root and bridge of nose Dorsum nasi Apex of nose Philtrum Naris (nostril) (a) Surface anatomy

The Nasal Cavity External nares  nostrils Divided by nasal septum Continuous with nasopharynx

Nasal Cavity 2 types of mucous membrane: Olfactory mucosa Near roof of nasal cavity Houses olfactory receptors Respiratory mucosa Lines nasal cavity Pseudostratified ciliated columnar epithelium

The Upper Respiratory Tract Cribriform plate of ethmoid bone Frontal sinus Sphenoid sinus Nasal cavity Posterior nasal aperture Nasal conchae (superior, middle and inferior) Nasopharynx Pharyngeal tonsil Nasal meatuses (superior, middle, and inferior) Opening of pharyngotympanic tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Esophagus Vestibular fold Thyroid cartilage Vocal fold Trachea Cricoid cartilage Thyroid gland

Respiratory Mucosa Consists of: Pseudostratified ciliated columnar epithelium Goblet cells within epithelium Underlying layer of lamina propria Cilia move contaminated mucus posteriorly

Nasal Conchae Superior & middle nasal conchae Inferior nasal conchae Part of the ethmoid bone Inferior nasal conchae Separate bone Project medially from the lateral wall of the nasal cavity Particulate matter: Deflected to mucus-coated surfaces

The Pharynx Funnel-shaped passageway Connects nasal cavity & mouth Divided into 3 sections by location: Nasopharynx Oropharynx Laryngopharynx Type of mucosal lining changes along its length

The Nasopharynx Superior to the point where food enters Only an air passageway Closed off during swallowing Pharyngeal tonsil (adenoids) Located on posterior wall Destroys pathogens that enter Contains the opening to the pharyngotympanic tube (auditory or eustachian tube) Tubal tonsil Provides some protection from infection

The Oropharynx Arch-like entrance-way  fauces Epithelium Extends from soft palate to epiglottis Epithelium Stratified squamous epithelium 2 types of tonsils in the oropharynx Palatine tonsils  in lateral walls of the fauces Lingual tonsils  covers the posterior surface of the tongue

The Laryngopharynx Passageway for both food & air Epithelium Stratified squamous epithelium Continuous with the esophagus & larynx

The Larynx 3 functions  Voice production Provides an open airway Routes air & food into the proper channels Superior opening (epiglotis) is: Closed during swallowing Open during breathing

9 Cartilages of the Larynx Thyroid cartilage Shield-shaped, forms laryngeal prominence (= Adam’s apple) 3 pairs of small cartilages Arytenoid cartilages Corniculate cartilages Cuneiform cartilages Epiglottis Tips inferiorly during swallowing

The Larynx Vocal ligaments of the larynx Epithelium of the larynx: Vocal folds (= true vocal cords) Function in sound production Vestibular folds (= false vocal cords) No role in sound production Epithelium of the larynx: Stratified squamous  superior portion Pseudostratified ciliated columnar  inferior portion

Anatomy of the Larynx Body of hyoid bone Laryngeal prominence (Adam’s apple) Cricoid cartilage Sternal head Clavicular head Sternocleidomastoid Clavicle Jugular notch (a) Surface view Epiglottis Body of hyoid bone Thyrohyoid membrane Thyroid cartilage Laryngeal prominence (Adam’s apple) Cricothyroid ligament Cricoid cartilage Cricotracheal ligament Tracheal cartilages (b) Anterior view

Anatomy of the Larynx Epiglottis Hyoid bone Thyrohyoid membrane Corniculate cartilage Thyroid cartilage Arytenoid cartilage Cricoid cartilage Glottis Tracheal cartilages (c) Photograph of cartilaginous framework of the larynx, posterior view Epiglottis Thyrohyoid membrane Body of hyoid bone Thyrohyoid membrane Cuneiform cartilage Fatty pad Corniculate cartilage Vestibular fold (false vocal cord) Arytenoid cartilage Thyroid cartilage Arytenoid muscle Vocal fold (true vocal cord) Cricoid cartilage Cricothyroid ligament Cricotracheal ligament Tracheal cartilages (d) Sagittal section (anterior on the right)

Movements of the Vocal Cords Anterior Thyroid cartilage Cricoid cartilage Vocal ligaments of vocal cords Glottis Lateral cricoarytenoid muscle Arytenoid cartilage Corniculate cartilage Posterior cricoarytenoid muscle Posterior Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Inner lining of trachea Cuneiform cartilage Corniculate cartilage (a) Vocal folds in closed position; closed glottis (b) Vocal folds in open position; open glottis

The Larynx Voice production Sphincter function of the larynx Length of the vocal folds changes with pitch Loudness depends on the force of air across the vocal folds Sphincter function of the larynx Valsalva’s maneuver  straining Innervation of the larynx Recurrent laryngeal nerves (branch of vagus)

The Trachea Descends into the mediastinum C-shaped cartilage rings keep airway open! Carina Marks where trachea divides into 2 primary bronchi Epithelium  Pseudostratified ciliated columnar epithelium ~remember this?

The Trachea Mucosa Pseudostratified ciliated columnar epithelium Lamina propria (connective tissue) Submucosa Seromucous gland in submucosa Posterior Hyaline cartilage Mucosa Esophagus Submucosa (b) Photomicrograph of the tracheal wall (250) Trachealis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior (a) Cross section of the trachea and esophagus

Bronchi in the Conducting Zone Bronchial tree Extensively branching respiratory passageways Primary bronchi (main bronchi) Largest bronchi Right main primary bronchi Wider & shorter than the left Right lung also bigger than the left

Bronchi in the Conducting Zone Superior lobe of right lung Trachea Superior lobe of left lung Left main (primary) bronchus Lobar (secondary) bronchus Segmental (tertiary) bronchus Inferior lobe of left lung Inferior lobe of right lung Middle lobe of right lung (a) The branching of the bronchial tree

Bronchi in the Conducting Zone Secondary (lobar) bronchi Three on the right Two on the left Tertiary (segmental) bronchi Branch into each lung segment Bronchioles Little bronchi, less than 1 mm in diameter Terminal bronchioles Less than 0.5 mm in diameter

Bronchi in the Conducting Zone Mucosa Pseudostratified epithelium Lamina propria Fibromusculo- cartilaginous layer Lumen Cartilage plate Smooth muscle (b) Photomicrograph of a bronchus (13)

Changes in Tissue Along Conducting Pathways Supportive connective tissues change C-shaped rings replaced by cartilage plates Epithelium changes First, pseudostratified ciliated columnar Replaced by simple columnar, then simple cuboidal epithelium Smooth muscle becomes important: Airways widen with sympathetic stimulation Airways constrict with parasympathetic stim.

Structures of the Respiratory Zone Consists of air-exchanging structures Respiratory bronchioles  branch from terminal bronchioles Lead to alveolar ducts Lead to alveolar sacs

Structures of the Respiratory Zone Alveolar duct Alveoli Alveolar sac Respiratory bronchioles Terminal bronchiole (a)

Structures of the Respiratory Zone Alveolar pores duct Respiratory bronchiole Alveoli sac (b)

Structures of the Respiratory Zone Alveoli ~300 million alveoli account for tremendous surface area of the lungs! Surface area of alveoli is ~140 square meters!!! Why such a large surface area?

Structures of the Respiratory Zone Structure of alveoli Type I cells  single layer of simple squamous epithelial cells Surrounded by basal lamina Alveolar & capillary walls plus their basal lamina form The Respiratory membrane

Anatomy of Alveoli & the Respiratory Membrane Terminal bronchiole Respiratory bronchiole Smooth muscle Elastic fibers Alveolus Capillaries (a) Diagrammatic view of capillary-alveoli relationships

Structures of the Respiratory Zone Structures of alveoli (cont.) Type II cells  scattered among type I cells Are cuboidal epithelial cells Secrete  surfactant (very important!) Detergent-like molecule, that reduces surface tension within alveoli (prevents them from collapsing) Alveolar macrophages also present

Anatomy of Alveoli & the Respiratory Membrane Red blood cell Nucleus of type I (squamous epithelial) cell Alveolar pores Capillary O2 Capillary CO2 Macrophage Alveolus Endothelial cell nucleus Alveolus Alveolar epithelium Respiratory membrane Fused basement membranes of the alveolar epithelium and the capillary endothelium Red blood cell in capillary Type I cell of alveolar wall Capillary endothelium Alveoli (gas-filled air spaces) Type II (surfactant- secreting) cell (c) Detailed anatomy of the respiratory membrane

The Respiratory Zone Features of alveoli Surrounded by elastic fibers Interconnect by way of alveolar pores Internal surfaces A site for free movement of alveolar macrophages

Gross Anatomy of the Lungs Major landmarks of the lungs Apex, base, hilum, & root Left lung Superior & inferior lobes Right lung Superior, middle, & inferior lobes

Gross Anatomy of the Lungs Anterior View of Thoracic Structures Intercostal muscle Rib Parietal pleura Apex of lung Lung Pleural cavity Visceral pleura Trachea Pulmonary artery Thymus Apex of lung Left superior lobe Left superior lobe Left main bronchus Right superior lobe Oblique fissure Oblique fissure Pulmonary vein Horizontal fissure Right middle lobe Left inferior lobe Left inferior lobe Impression of heart Oblique fissure Right inferior lobe Hilum Oblique fissure Heart (in mediastinum) Diaphragm Aortic impression Cardiac notch Base of lung Lobules (a) Anterior view. The lungs flank mediastinal structures laterally. (b) Photograph of medial view of the left lung

Bronchial Tree Right lung Left lung Right superior lobe (3 segments) Left superior lobe (4 segments) Right middle lobe (2 segments) Right inferior lobe (5 segments) Left inferior lobe (5 segments)

Blood Supply & Innervation of the Lungs Pulmonary arteries Deliver oxygen-poor blood to the lungs Pulmonary veins Carry oxygenated blood to the heart Innervation Sympathetic, parasympathetic, & visceral sensory fibers Parasympathetic  constrict airways Sympathetic  dilate airways

Transverse Cut Through Lungs Posterior Vertebra Esophagus (in mediastinum) Root of lung at hilum Right lung Left main bronchus 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 (d) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown.

The Pleurae (review) A double-layered sac surrounding each lung Parietal pleura Visceral pleura Pleural cavity Potential space between the visceral & parietal pleurae Pleurae help divide the thoracic cavity Central mediastinum 2 lateral pleural compartments

Diagram of the Pleurae & Pleural Cavities Intercostal muscle Rib Parietal pleura Lung Pleural cavity Visceral pleura Trachea Thymus Apex of lung Left superior lobe Right superior lobe Oblique fissure Horizontal fissure Left inferior lobe Right middle lobe Oblique fissure Right inferior lobe Heart (in mediastinum) Diaphragm Cardiac notch Base of lung (a) Anterior view. The lungs flank mediastinal structures laterally.

The Mechanisms of Ventilation 2 phases of pulmonary ventilation Inspiration  inhalation Expiration  exhalation

Inspiration Volume of thoracic cavity increases Decreases internal gas pressure Action of the diaphragm Diaphragm flattens Action of intercostal muscles Contraction raises the ribs

Inspiration Deep inspiration requires Scalenes Sternocleidomastoid Pectoralis minor Erector spinae  extends the back

Expiration Quiet expiration  chiefly a passive process! Inspiratory muscles relax Diaphragm moves superiorly Volume of thoracic cavity decreases Forced expiration  an active process Produced by contraction of Internal & external oblique muscles Transverse abdominis muscles

Changes in Thoracic Volume Ribs are elevated and sternum flares as external intercostals contract. Diaphragm and intercostal muscles contract (diaphragm descends and rib cage rises). Thoracic cavity volume increases. Diaphragm moves inferiorly during contraction. External Changes in superior- inferior and anterior- posterior dimensions Changes in lateral (superior view) (a) Inspiration Inspiratory muscles relax (diaphragm rises and rib cage descends due to recoil of the costal cartilages). Thoracic cavity volume decreases. Ribs and sternum are depressed as external intercostals relax. External Diaphragm moves superiorly as it relaxes. (b) Expiration

Changes in Thoracic Volume At rest, no air movement: Air pressure in lungs is equal to atmospheric (air) pressure. Pressure in the pleural cavity is less than pressure in the lungs. This pressure difference keeps the lungs inflated. 1 Trachea Thoracic wall Parietal pleura Main bronchi Pleural cavity Visceral pleura Lung Pleural cavity Thoracic wall Lung Diaphragm Air Inspiration: Inspiratory muscles contract and increase the volume of the thoracic and pleural cavities. Pleural fluid in the pleural cavity holds the parietal and visceral pleura close together, causing the lungs to expand. As volume increases, pressure decreases and air flows into the lungs. At rest 2 V Expanded P V P Air flows in Air 3 Expiration: Inspiratory muscles relax, reducing thoracic volume, and the lungs recoil. Simultaneously, volumes of the pleural cavity and the lungs decrease, causing pressure to increase in the lungs, and air flows out. Resting state is reestablished. V V P P Air flows out

Neural Control of Ventilation Respiratory center Generates baseline respiration rate In the reticular formation of the medulla oblongata Chemoreceptors Sensitive to rising & falling oxygen levels Central chemoreceptors  located in medulla Peripheral chemoreceptors Aortic bodies Carotid bodies

Location of Peripheral Chemoreceptors Brain Sensory nerve fiber in cranial nerve IX (pharyngeal branch of glossopharyngeal) External carotid artery Internal carotid artery Carotid body Common carotid artery Cranial nerve X (vagus nerve) Sensory nerve fiber in cranial nerve X Aortic bodies in aortic arch Aorta Heart

Disorders of Lower Respiratory Structures Bronchial asthma A type of allergic inflammation Hypersensitivity to irritants in the air or to stress Asthma attacks characterized by Contraction of bronchiole smooth muscle Secretion of mucus in airways

Disorders of Lower Respiratory Structures Cystic fibrosis (CF)  inherited disease Exocrine gland function is disrupted Respiratory system affected by Oversecretion of viscous mucus Pneumonia  infectious disease Accumulation of fluid in alveoli Interferes with gas exchange (drowning)

Disorders of Lower Respiratory Structures Chronic obstructive pulmonary disease (COPD) Airflow into & out of the lungs is difficult Obstructive emphysema Chronic bronchitis History of smoking usually associated

Disorders of Lower Respiratory Structures Figure 22.18

Alveolar Changes in Emphysema Figure 22.19

Lung Cancer Most common cause of cancer-related death! 1.3 million deaths/year worldwide Treated by surgery, radiation, and/or chemotherapy Symptoms  shortness of breath, coughing (up blood), weight loss History of smoking or 2nd- hand smoke usually associated 14% survival rates

Aging of the Respiratory System The number of glands in nasal mucosa declines Nose dries Produces thickened mucus Thoracic wall becomes more rigid Lungs lose elasticity Oxygen levels in the blood may fall Again…Exercise throughout life important for respiratory health!

Questions…. What’s Next. Wed Lecture: Lecture Exam 4 Questions…? What’s Next? Wed Lecture: Lecture Exam 4! Wed Lab: Start Digestive System Mon Lecture: Digestive Sys. & class Potluck! ~We’ll eat while we learn about eating & digestion