Respiratory System Day 1 PDF

Respiratory System Getty Introduction 2 The respiratory system consists of a system of tubes that delivers air to the lungs → Oxygen diffuses into the blood → Carbon dioxide diffuses out Respiratory and cardiovascular systems work together to deliver oxy...

Respiratory System Getty Introduction 2 The respiratory system consists of a system of tubes that delivers air to the lungs → Oxygen diffuses into the blood → Carbon dioxide diffuses out Respiratory and cardiovascular systems work together to deliver oxygen to the tissues and remove carbon dioxide → Considered jointly as cardiopulmonary system → Disorders of lungs directly affect the heart and vice versa Respiratory system and the urinary system collaborate to regulate the body’s acid–base balance 22.1 Anatomy of the Respiratory System Expected Learning Outcomes: → State the functions of the respiratory system. → Name and describe the organs of this system. → Trace the flow of air from the nose to the pulmonary alveoli. → Relate the function of any portion of the respiratory tract to its gross and microscopic anatomy. Anatomy of the Respiratory System 1 Principal organs: nose, pharynx, larynx, trachea, bronchi, lungs → Incoming air stops in the alveoli → Millions of thin-walled, microscopic air sacs → Exchanges gases with the bloodstream through the alveolar wall, and then flows back out Conducting zone of respiratory system → Includes those passages that serve only for airflow → No gas exchange Functions of the Respiratory System 1 → Respiration refers to ventilation of the lungs (breathing) → Can also be used to refer to part of cellular metabolism → Functions of respiration include: → Gas exchange → O2 and CO2 exchanged between blood and air → Communication → Speech and other vocalizations → Olfaction → Sense of smell Functions of the Respiratory System 2 → Blood pressure regulation → By helping in synthesis of angiotensin II → Blood and lymph flow → Breathing creates pressure gradients between thorax and abdomen that promote flow of lymph and blood → Platelet production → More than half of platelets are made by megakaryocytes in lungs (not in bone marrow) → Blood filtration Anatomy of the Respiratory System Respiratory zone of the respiratory system → Consists of alveoli and other gas exchange regions →Upper respiratory tract → In head and neck → Nose through larynx →Lower respiratory tract → Organs of the thorax → Trachea through lungs The Nose →Nose extends from nostrils (nares) to posterior nasal apertures (choanae)—posterior openings →Facial part is shaped by bone and hyaline cartilage → Superior half: nasal bones and maxillae → Inferior half: lateral and alar cartilages → Ala nasi: flared portion at lower end of nose shaped by alar cartilages and dense connective tissue Nasal fossae—right and left halves of nasal cavity → Nasal septum divides nasal cavity → Composed of bone and hyaline cartilage → Vomer forms inferior part → Perpendicular plate of ethmoid forms superior part → Septal cartilage forms anterior part → Roof and floor of nasal cavity → Ethmoid and sphenoid bones form the roof → Hard palate forms floor Separates the nasal cavity from the oral cavity Allows you to breathe while you chew food → Paranasal sinuses and nasolacrimal duct drain into nasal cavity Anatomy of the Nasal Region 1 Figure 22.2a → Joe DeGrandis/McGraw-Hill Education Anatomy of the Nasal Region 2 Figure 22.2b Joe DeGrandis/McGraw-Hill Education The Nose 3 → Vestibule → Beginning of nasal cavity → Small, dilated chamber just inside nostrils → Lined with stratified squamous epithelium → Vibrissae → Stiff guard hairs that block insects and debris from entering nose → Posteriorly the nasal cavity expands into The Nose 4 Chamber behind vestibule is occupied by three folds of tissue, the nasal conchae Superior, middle, and inferior nasal conchae (turbinates) → Project from lateral walls toward septum Meatus → Narrow air passage beneath each concha → Narrowness and turbulence ensure that most air contacts mucous membranes → Cleans, warms, and moistens the air Nasal mucosa Respiratory epithelium → Epithelial layer in most of the mucosa → Ciliated pseudostratified columnar epithelium Goblet cells produce mucus Cilia are motile Propel the mucus posteriorly toward pharynx Mucus swallowed into digestive tract Olfactory epithelium → Sensory—detects odors Immobile cilia bind odorant molecules (don’t propel mucus) → Only covers a small area of the roof of the nasal fossa and adjacent parts of the septum and superior concha The Nose Erectile tissue (swell body) → Extensive venous plexus in epithelium of inferior concha → Every 30 to 60 minutes, tissue on one side swells with blood → Restricts airflow through that fossa, so most air directed through other nostril → Allows engorged side time to recover from drying → Preponderant flow of air shifts between the right and left nostrils once or twice an hour Anatomy of the Upper Respiratory Tract 1 Figure 22.3b Anatomy of the Upper Respiratory Tract 2 Figure 22.3a → a: Rebecca Gray/McGraw-Hill Education Pharynx (throat) → Muscular funnel extending about 5 in. from choanae to larynx Three regions of pharynx: → Nasopharynx → Posterior to nasal apertures and above soft palate → Receives auditory tubes and contains pharyngeal tonsil → 90 downward turn traps large particles (>10 m) → Oropharynx → Space between soft palate and epiglottis → Contains palatine tonsils → Laryngopharynx → Epiglottis to cricoid cartilage → Esophagus begins at that point Anatomy of the Upper Respiratory Tract 3 Figure 22.3c The Pharynx 2 → Nasopharynx passes only air and is lined by pseudostratified columnar epithelium → Oropharynx and laryngopharynx pass air, food, and drink and are lined by stratified squamous epithelium → Muscles of the pharynx assist in swallowing and speech The Larynx 1 → Larynx (voice box) → Cartilaginous chamber about 4 cm (1.5 in.) long → Primary function is to keep food and drink out of airway → In several animals, it has evolved the additional role of phonation—the production of sound The Larynx 2 → Epiglottis → Flap of tissue that guards superior opening of larynx → At rest, stands almost vertically → During swallowing, extrinsic muscles pull larynx upward → Tongue pushes epiglottis down to meet it → Closes airway and directs food to esophagus behind it → Vestibular folds of the larynx play greater role in Nine cartilages make up framework of larynx First three are solitary and relatively large: → Epiglottic cartilage → Most superior → Spoon-shaped supportive plate in epiglottis → Thyroid cartilage → Shield-shaped → Largest laryngeal prominence (Adam’s apple) → Cricoid cartilage → Ring-like → Connects larynx to trachea Anatomy of the Larynx Figure 22.4  The Larynx 4 Three smaller, paired cartilages → Arytenoid cartilages (2) → Posterior to thyroid cartilage → Corniculate cartilages (2) → Attached to arytenoid cartilages like a pair of little horns → Cuneiform cartilages (2) → Support soft tissue between arytenoids and epiglottis The Larynx 5 → Three ligaments suspend larynx from hyoid and hold it together: → Thyrohyoid ligament → Suspends it from hyoid → Cricotracheal ligament → Suspends trachea from larynx → Intrinsic ligaments → Hold laryngeal cartilages together The Larynx 6 → Interior wall has two folds on each side that extend from thyroid cartilage in front to arytenoid cartilages in back → Superior vestibular folds → Play no role in speech → Close the larynx during swallowing → Inferior vocal cords → Produce sound when air passes between them → Contain vocal ligaments → Covered with stratified squamous epithelium → Suited to endure vibration and contact → Glottis—the vocal cords and the opening between them The Larynx 7 → Walls of larynx are quite muscular → Deep intrinsic muscles operate the vocal cords → Superior extrinsic muscles connect larynx to hyoid bone → Elevate the larynx during swallowing → Infrahyoid group The Larynx 8 → Intrinsic muscles control vocal cords → Pull on corniculate and arytenoid cartilages causing cartilages to pivot → Abduct or adduct vocal cords, depending on direction of rotation → Air forced between adducted vocal cords vibrates them producing high-pitched sound when cords are taut The Larynx 9 → Adult male vocal cords, when compared to female cords → Usually longer and thicker → Vibrate more slowly → Produce lower-pitched sound → Loudness: determined by the force of air passing between the vocal cords → Vocal cords produce crude sounds that are formed into words by actions of pharynx, oral cavity, tongue, and lips Endoscopic Views of the Respiratory Tract Figure 22.5 a: CNRI/Science Photo Library; b: BSIP/Newscom Action of Muscles on the Vocal Cords Figure 22.6 The Trachea 1 Trachea (windpipe) → Rigid tube → 12 cm (4.5 in.) long and 2.5 cm (1 in.) in diameter → Anterior to esophagus → 16 to 20 C-shaped rings of hyaline cartilage Reinforce trachea and prevent collapse during inhalation → Opening in C-rings faces posteriorly toward esophagus → Allows esophagus to expand as swallowed food passes by Trachealis muscle spans opening in rings → Contracts or relaxes to adjust airflow The Trachea 2 Trachea lined by ciliated pseudostratified columnar epithelium → Mucus-secreting cells, ciliated cells, and stem cells → Mucociliary escalator → Mechanism for debris removal → Mucus traps inhaled particles → Upward beating cilia moves mucus to pharynx to be swallowed Middle tracheal layer → Connective tissue beneath the tracheal epithelium → Contains lymphatic nodules, mucous and serous glands, and the tracheal cartilages The Trachea 3 Adventitia → Outermost layer of trachea → Fibrous connective tissue that blends into adventitia of other organs of mediastinum Right and left main bronchi → Trachea forks at level of sternal angle → Carina Internal medial ridge in the lowermost tracheal cartilage → Directs the airflow to the right and left Anatomy of the Lower Respiratory Tract Figure 22.7 The Tracheal Epithelium Figure 22.8 Prof. P.M. Motta/Univ. “La Sapienza,” Rome/Science Source Gross Anatomy of the Lungs 1 Figure 22.9a Tracheotomy → Tracheotomy → To make a temporary opening in the trachea and insert a tube to allow airflow → A permanent opening is called a tracheostomy → Prevents asphyxiation due to upper airway obstruction → Potential problems include: → Inhaled air bypasses the nasal cavity and is hot humidified → If left for long, will dry out mucous membranes → Become encrusted and interfere with clearance of mucus from tract, thereby promoting infection Gross Anatomy of the Lungs 1 Figure 22.9a Gross Anatomy of the Lungs 2 Figure 22.9b Cross Section Through the Thoracic Cavity Figure 22.10 Rebecca Gray/Don Kincaid/McGraw-Hill Education The Lungs 1 →Lung → Base: broad concave portion resting on diaphragm → Apex: tip that projects just above the clavicle → Costal surface: pressed against the ribcage → Mediastinal surface: faces medially toward the heart → Hilum—slit through which the lung receives the main bronchus, blood vessels, lymphatics, and nerves → Structures near hilum constitute root of lung  →Lungs are crowded by adjacent organs The Lungs 2 →Do not fill entire ribcage →Not symmetrical → Right lung → Shorter than left because liver rises higher on the right → Has three lobes—superior, middle, and inferior—separated by horizontal and oblique fissure → Left lung → Tall and narrow because the heart tilts toward the left and occupies more space on this side of mediastinum → Has indentation—cardiac impression → Has two lobes—superior and inferior separated by a single oblique fissure The Bronchial Tree Bronchial tree → Branching system of air tubes in each lung → From main bronchus to 65,000 terminal bronchioles Main (primary) bronchi → Arise from fork of trachea → Supported by C-shaped hyaline cartilage rings Right main bronchus is wider and more vertical than left → Left main bronchus is about 5 cm long → Right main bronchus 2 to 3 cm long → Aspirated (inhaled) foreign objects lodge in the right main bronchus more often than in the left  → Lobar and segmental bronchi are The Bronchial Tree supported by crescent-shaped cartilage plates Lobar (secondary) bronchi → Three right lobar (secondary) bronchi: superior, middle, inferior → One to each lobe of the right lung → Two left lobar bronchi: superior and inferior → One to each lobe of the left lung Segmental (tertiary) bronchi → 10 on right, 8 on left → Bronchopulmonary segment → Functionally independent unit of the lung tissue The Bronchial Tree →All bronchi are lined with ciliated pseudostratified columnar epithelium → Cells grow shorter and the epithelium thinner as we progress distally → Lamina propria has abundance of mucous glands and lymphocyte nodules (mucosa-associated lymphoid tissue, MALT) → Positioned to intercept inhaled pathogens → All divisions of bronchial tree have a large amount of elastic connective tissue → Contributes to the recoil that expels air from lungs The Bronchial Tree 4 Mucosa has a well-developed layer of smooth muscle → Muscularis mucosae contracts or relaxes to constrict or dilate the airway, regulating airflow → Pulmonary artery branches closely follow the bronchial tree on their way to the alveoli → Bronchial artery services bronchial tree with systemic blood → Arises from the aorta The Bronchioles → 1 mm or less in diameter → Pulmonary lobule: portion of lung Bronchial → → ventilated by one bronchiole Have ciliated cuboidal epithelium Well-developed layer of smooth muscle Tree 5 → Divides into 50 to 80 terminal bronchioles → Final branches of conducting zone → Measure 0.5 mm or less in diameter → Have no mucous glands or goblet cells → Have cilia that move mucus draining into them back by mucociliary escalator → Each terminal bronchiole gives off two or more smaller respiratory bronchioles The Bronchial Tree Respiratory bronchioles → Have alveoli budding from their walls → Considered the beginning of the respiratory zone since alveoli participate in gas exchange → Divide into 2 to 10 alveolar ducts → End in alveolar sacs → Clusters of alveoli around a central space (atrium) Histology of the Lung Figure 22.11 → a: MICROSCAPE/Science Source; b: Biophoto Associates/Science Source Alveoli There are 150 million alveoli in each lung → 70 m2 of surface for gas exchange Cells of the alveolus → Squamous (type I) alveolar cells → Great (type II) alveolar cells → Alveolar macrophages (dust cells) Squamous (type I) alveolar cells → Thin cells allow rapid gas diffusion between air and blood → Cover 95% of alveolus surface area Alveoli 2 Great (type II) alveolar cells → Round to cuboidal cells that cover the remaining 5% of alveolar surface → Repair the alveolar epithelium when the squamous (type I) cells are damaged → Secrete pulmonary surfactant → A mixture of phospholipids and proteins that coats the alveoli and prevents them from collapsing during exhalation Alveoli 3 Alveolar macrophages (dust cells) → Most numerous of all cells in the lung → Wander lumens of alveoli and connective tissue between them → Keep alveoli free from debris by phagocytizing dust particles → 100 million dust cells die each day as they ride up the mucociliary escalator to be swallowed and digested with their load of debris Pulmonary Alveoli Figure 22.12a Alveoli 4 Each alveolus surrounded by a basket of capillaries supplied by the pulmonary artery → Respiratory membrane → Thin barrier between the alveolar air and blood Consists of three layers: → Squamous alveolar cells → Endothelial cells of blood capillary → Their shared basement membrane Respiratory Membrane Figure 22.12b,c The Pleurae 1 Visceral pleura → Serous membrane that covers lungs → Parietal pleura → Adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm → Pleural cavity → Potential space between pleurae → Normally no room between the membranes, but contains a film of slippery pleural fluid Gross Anatomy of the Lungs 1 Figure 22.9a 22.2 Pulmonary Ventilation → Expected Learning Outcomes: → Name the muscles of respiration and describe their roles. → Describe the brainstem centers that control breathing and the inputs they receive from other levels of the nervous system. → Explain how pressure gradients account for the flow of air into and out of the lungs, and how those gradients are produced. → Identify the sources of resistance to airflow and discuss their relevance to respiration. Pulmonary Ventilation → Breathing (pulmonary ventilation) Repetitive cycle → Inspiration (inhaling) → Expiration (exhaling) Respiratory cycle → One complete inspiration and expiration Quiet respiration → Breathing while at rest, effortless, and automatic Forced respiration → Deep, rapid breathing, such as during exercise The Respiratory Muscles 1 → Flow of air in and out of lung depends on a pressure difference between air within lungs and outside body → Respiratory muscles change lung volumes and create differences in pressure relative to the atmosphere → Diaphragm → Prime mover of respiration → Contraction flattens diaphragm, enlarging thoracic cavity and pulling air into lungs → Relaxation allows diaphragm to bulge upward again, compressing the lungs and expelling air → Accounts for two-thirds of airflow The Respiratory Muscles 2 → Internal and external intercostal muscles → Synergists to diaphragm → Located between ribs → Stiffen the thoracic cage during respiration → Prevent it from caving inward when diaphragm descends → Contribute to enlargement and contraction of thoracic cage → Add about one-third of the air that ventilates the lungs → Scalenes The Respiratory Muscles 3 → Accessory muscles of respiration act mainly in forced respiration → Erector spinae, sternocleidomastoid, pectoralis major, pectoralis minor, and serratus anterior muscles and scalenes → Greatly increase thoracic volume The Respiratory Muscles 4 → Normal quiet expiration → Energy-saving passive process achieved by the elasticity of the lungs and thoracic cage → As muscles relax, structures recoil to original shape and original (smaller) size of thoracic cavity → Results in airflow out of lungs → Forced expiration → Rectus abdominis, internal intercostals, and other lumbar, abdominal, and pelvic muscles → Greatly increased abdominal pressure pushes viscera up against diaphragm increasing thoracic pressure, forcing air out The Respiratory Muscles 5 → Valsalva maneuver → Breathing technique used to help expel contents of certain abdominal organs → Depression of the diaphragm raises abdominal pressure → Consists of taking a deep breath, holding it by closing the glottis, and then contracting the abdominal muscles → Aids in childbirth, urination, defecation, vomiting The Respiratory Muscles 6 Figure 22.13