The Respiratory System part 2-combined.pdf

The Respiratory System Part 1 DES JARDINS Chapter 1 Introduction Primary function of the respiratory system: Absorption of O2 and excretion of CO2 External respiration Gas exchange between the gas of the atmosphere and blood Internal respiration Gas exchange between tissue cells and systemic capilla...

The Respiratory System Part 1 DES JARDINS Chapter 1 Introduction Primary function of the respiratory system: Absorption of O2 and excretion of CO2 External respiration Gas exchange between the gas of the atmosphere and blood Internal respiration Gas exchange between tissue cells and systemic capillary blood The system brings gas into close proximity with the flowing blood in the pulmonary circulatory system 2 Introduction (Cont.) The respiratory system includes: Upper airways, chest wall, respiratory muscles, lower airways, pulmonary blood vessels, support nerves, and lymphatics Also humidifies and warms inspired air while removing inhaled contaminants and filtering out chemicals. 3 Conducting Airways Passageways between ambient environment and alveoli No gas exchange occurs but important to ventilation Upper airways and lower airways 4 Upper Respiratory Tract (URT) Defined as airways starting at the nose, extend to trachea Composed of Nasal cavities and sinuses Oral cavity Pharynx Larynx 5 Upper Respiratory Tract (Cont.) 6 Functions of the Upper Airways Passageway for gas flow Filter Heater Humidification Sense of smell and taste Phonation (vocal cords are located in the larynx) Protection of the lower airways 7 Nasal Cavity External nares give entrance into cavities Vestibules contain gross hairs working as filter Concha or turbinates—three shelf like bones projecting from lateral walls Function: Increase surface area for filtering, warming, and humidifying inhaled gases Contain olfactory cells providing sense of smell Surface fluid is provided by goblet cells and submucosal glands in cavity and sinuses 8 Sinuses Hollow spaces in the facial bones Four sets of sinuses Frontal, ethmoid, sphenoid, maxillary Function of sinuses Reduce weight of head Strengthen skull Modify voice during phonation Copyright © 2017 Elsevier Inc. All Rights Reserved. 9 Sinuses (Cont.) 10 Oral Cavity Vestibule Tongue Intrinsic muscles Extrinsic muscles0 Lingual frenulum Hard palate Soft palate Palatine arches Forms common passage for air, food, and fluids Posterior portion of tongue has nerve endings triggering 11 gag reflex to protect airway Pharynx Oral and nasal cavities open into the pharynx Nasopharynx (from nasal cavity to uvula) Adenoids lie right where many particles impact Eustachian tubes link to middle ear Oropharynx (from uvula to tip of epiglottis) Palatine tonsils (removed in tonsillectomy) Vallecula epiglottica- important landmark for insertion of endotracheal tube Laryngopharynx –hypopharynx (tip epiglottis to larynx) Anatomic location where respiratory and digestive tracts divide Pharyngeal reflex(aka “gag reflex”) 12 Copyright © 2017 Elsevier Inc. All Rights Reserved. 13 Larynx Contains nine cartilages Thyroid (Adam’s apple) Cricoid falls just below thyroid cartilage Epiglottis attaches to thyroid cartilage Vocal folds False- no role in vocalization True- “vocal cords” Glottis- space between vocal cords 14 Larynx (Cont.) 15 Larynx (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 16 Patent Upper Airway Relative positions of oral cavity, pharynx, and larynx are major determinant of patency, particularly in unconscious patient Head tilts forward, partial or total occlusion can occur Extend head into “sniff position” to open airway and facilitate artificial airway insertion Patent = OPEN! 18 Patent Upper Airway (Cont.) 19 Lower Respiratory Tract Everything distal to larynx Made up of conducting and respiratory airways Conducting airways—first 15 generations Purpose: convey gas from URT to area of gas exchange (lung parenchyma) Respiratory airways Microscopic airways distal to conducting zone Participate in gas exchange with blood Copyright © 2017 Elsevier Inc. All Rights Reserved. 20 Histology of Airway Wall Conducting airways (trachea to bronchioles) Walls constructed of three layers Mucosa—inner layer forms mucous membrane Composed of epithelia Pseudostratified, ciliated, goblet cells, columnar epithelia—most numerous cell type Submucosa—composed of connective tissue, bronchial glands, and smooth fibers that wrap around airway Adventitia—outer covering of connective tissue Copyright © 2017 Elsevier Inc. All Rights Reserved. 21 Lobar and Segmental Pulmonary Anatomy (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 22 Histology of Airway Wall (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 23 Cilia Tiny hair like structures Help propel mucus toward the pharynx “mucociliary escalator” Cigarette smoking, O2 and some drugs can impede cilia action! Copyright © 2017 Elsevier Inc. All Rights Reserved. 24 Cartilaginous AirwaysTrachea and Bronchi Trachea: extends below cricoid cartilage to sternal angle “windpipe” 11-13 cm long, 1.5-2.5 cm in diameter Extends to the level of the 5th thoracic vertebrae Divides into right and left main stem bronchi Bifurcated at the carina Anterior and sides supported by 15 to 20 C-shaped cartilage Trachealis muscle connects tips of C-shaped cartilage and forms posterior wall 25 Trachea and Bronchi (Cont.) 26 Trachea and Bronchi (Cont.) Right bronchus branches at about 25 degree angle Due to angle, most foreign aspirate goes to right lower lobe Left bronchus branches at 40-60 degrees Because of angles, respiratory therapists are careful to monitor the depth of an artificial airway 27 Trachea and Bronchi (Cont.) Copyright © 2017 Elsevier Inc. All Rights Reserved. 28 Branches of Bronchi Lobar bronchi- second generation Segmental bronchi- third generation Subsegmental bronchi- fourth-ninth generation Generation continue until bronchi reach diameter of less than 1-mm and connective tissue sheaths disappear Copyright © 2017 Elsevier Inc. All Rights Reserved. 29 Lobar and Segmental Pulmonary Anatomy Each segment is supplied by segmental bronchus These further divide numerous times until conducting airways end in terminal bronchiolessmallest airway! All airways up to this point constitute anatomic deadspace. Meaning: they do NOT participate in gas exchange as the alveoli do! ~2 ml/kg of lean body weight, typically 150 ml 30 Lobar and Segmental Pulmonary Anatomy Each lung is divided into lobes and segments Right lung has 3 lobes and 10 segments Left lung has 2 lobes and 8 or 10 segments Copyright © 2017 Elsevier Inc. All Rights Reserved. 31 Noncartilaginous Airways Bronchioles- tenth to fifteenth generations Cartilage absent Terminal bronchioles- sixteenth to nineteenth generations About 0.5 mm in diameter Cilia and mucous glands disappear Thinner, small channels in terminal bronchioles= canals of Lambert Copyright © 2017 Elsevier Inc. All Rights Reserved. 32 Sites of Gas Exchange Alveoli Primary function is gas exchange 15 to 20 grapelike clusters at the end of the terminal bronchioles Manufacture and storage of surfactant Reduces surface tension and alveolar tendency to collapse Increases compliance and decreases work of breathing Respiratory bronchioles, alveolar ducts and alveolar clusters make up the primary lobule Also known as acinus, lung parenchyma, terminal respiratory unit and functional units 33 Copyright © 2017 Elsevier Inc. All Rights Reserved. 34 Sites of Gas Exchange Alveolar epithelium Two cell types Type I- squamous pneumocyte 95% of alveolar surface Major sites of alveolar gas exchange Unable to reproduce Type II- granular pneumocyte 5% of alveolar surface Primary source of surfactant Pores of Kohn Permit gas to move between alveoli Copyright © 2017 Elsevier Inc. All Rights Reserved. 35 Sites of Gas Exchange Alveolar Macrophages Type III alveolar cells Play major role in removing bacteria and foreign particles that deposit within acini Interstitium Gel like substance that are held together by web-like network of collagen fibers Tight space- between alveolar epithelium and endothelium of pulmonary capillaries Loose space- surrounds bronchioles and primary lobule Copyright © 2017 Elsevier Inc. All Rights Reserved. 36 To Be Continued… Pulmonary Circulation Lymphatics Nervous Control Lungs Thoracic Structures Copyright © 2017 Elsevier Inc. All Rights Reserved. 37 The Respiratory System Part 2 DE S JARDINS CHAPTE R 1 COPYRIGHT © 2017 ELSEVIER INC. ALL RIGHTS RESERVED. Previously in The Respiratory System Part 1… We discussed… ❑ External respiratory vs internal respiration ❑What the respiratory system consists of ❑Conducting vs Noncartilaginous airways ❑The functions of the upper airways ❑The importance of a patent airway ❑Trachea, carina, bronchi, alveoli COPYRIGHT © 2017 ELSEVIER INC. ALL RIGHTS RESERVED. 2 Pulmonary Circulation Supplied with blood from right heart at flow rate equal to entire blood volume each minute at rest ◦ Capillaries cover about 90% of alveolar surface Functions of lungs ◦ Gas exchange at the alveolar-capillary (A/C) membrane (primary function) ◦ Pick up oxygen and drop off CO 2 ◦ A/C membrane controls fluid exchange in lung ◦ Production, processing, and clearance of variety of chemicals and blood clots 3 Pulmonary Circulation (Cont.) 4 Pulmonary Versus Systemic Circulation Hemodynamic values are very different between systems ◦ Pulmonary: low pressure, low resistance ◦ Systemic: high pressure, high resistance 5 Bronchial Circulation Separate arterial supply Supplied with blood from aorta via minor thoracic branches Supplies blood to larger lung structures (1%-2% CO) ◦ Trachea, bronchi Lung metabolic demands are fairly low ◦ Most lung parenchyma gets oxygen directly from inspired gas Bronchial veins drain via various routes ◦ Some drain to pulmonary veins, contributing to anatomic shunt 6 COPYRIGHT © 2017 ELSEVIER INC. ALL RIGHTS RESERVED. 7 Lymphatics Extensive system of lymphatic vessels, lymph nodes, the tonsils, and the thymus gland Primary function is to clear fluid from the interstitial and pleural spaces to help maintain the fluid balance in the lungs Also plays an important role in the specific defenses of the immune system ◦ Removes bacteria, foreign material, and cell debris via the lymph fluid and through the action of various phagocytic cells (e.g., macrophages), providing defense against foreign material and cells that are able to penetrate deep into the lung 8 9 Nervous Control of Lungs Autonomic nerves- regulate involuntary vital functions Sympathetic- accelerates hearts, constricts blood vessels, relaxes bronchial smooth muscles, raises blood pressure Parasympathetic- slows heart rate, constricts bronchial smooth muscles, increases gland activity 10 11 Nervous Control of Lungs (Cont.) 12 Lungs Cone-shaped, spongelike organs Apices extend 1 to 2 cm above clavicles Each lung has two (left) or three (right) lobes—separated by fissures ◦ Left upper and lower lobes divided by oblique fissure ◦ Right lower lobe is also delineated by oblique fissure, while transverse fissure separates upper and middle lobes Lungs’ elasticity results from alveolar surface tension, elastic properties of tissue, and connective tissue 13 Lungs (Cont.) 14 Lungs (Cont.) 15 Mediastinum Contains organs and tissues in the center of thoracic cage between right and lung lungs Contains trachea, heart, great vessels, nerves, portions of esophagus, thymus gland and lymph nodes If compressed or distorted, can severely compromise cardiopulmonary system 16 Components of Thoracic Wall Skin, fat, skeletal muscles, and bony structures form outer portion of wall Pleura- the serous membranes that line the thorax and envelop the lungs. Composed of three layers: Parietal Pleura: inner layer of the thoracic wall Visceral Pleura: innermost layer, covers the lung Intrapleural Space: space between the parietal and visceral layers, contains fluid that helps to minimize friction with movement- pleural fluid!!!!! Airtight seal adhering two pleural membranes together 17 Respiratory System in the Adult (Cont.) 18 Thoracic Wall Cross Section COPYRIGHT © 2017 ELSEVIER INC. ALL RIGHTS RESERVED. 19 Lungs and Heart Together 20 21 Respiratory System in the Adult (Cont.) Chest wall ◦ Cone-shaped cavity contains vital organs ◦ Functions to protect those organs ◦ Ability to change shape facilitates breathing 22 Components of Thoracic Wall (Cont.) Sternum composed of: manubrium, body, and xiphoid process ◦ Sternal angle at joining of body and manubrium ◦ External landmark for tracheal division into mainstem bronchi 12 pairs of ribs Pairs 1 - 7 (true ribs) connect directly to the sternum ◦ Immediately below each rib run artery, vein, and nerves for particular portion of chest wall Pairs 8 – 12 (false ribs) NOT directly nor indirectly attached to the sternum ◦ ◦ 8-10 are attached to sternum by cartilaginous straps 11 and 12 (floating ribs) not attached to anything! 23 Components of Thoracic Wall (Cont.) 24 Rib Movement: Facilitates Breathing Pair 1: raise slightly, pulling sternum up, which increases AP diameter Rib pairs 2 to 7 move in two directions (see Figure 8-20) ◦ Increase AP diameter, “pump action” ◦ Increase lateral space, “bucket handle” Rib pairs 8 to 10 move similar to 2 to 7 ◦ However, slight reduction of AP diameter ◦ While lateral space increases 25 Rib Movement: Facilitates Breathing (Cont.) 26 Muscles of ventilation Diaphragm and intercostals: primary muscles of respiration ◦ Active during resting breathing ◦ 75% of work performed by diaphragm ◦ Muscle relaxation results in passive exhalation 27 Diaphragm Normal diaphragmatic excursion 1 to 2 cm ◦ With maximum inspiration may be 10 cm ◦ 75% of the work Hyperinflation (increased lung volumes) flattens domes ◦ ◦ ◦ ◦ Contraction may decrease AP diameter Decreased efficiency with increased work of breathing Seen in severe asthma and COPD To compensate for this, individuals must recruit other accessory muscles to enlarge the thorax ◦ Result is less efficient breathing and excessive muscle work 28 Diaphragm (Cont.) Innervated by phrenic nerves that arise from C3, C4, and C5 ◦ Passes down between the lungs and heart to reach the diaphragm! Diaphragmatic Paralysis ◦ Spinal cord injuries at or above level of third cervical vertebrae ◦ Loss of all nervous control of respiratory muscles ◦ Unable to breathe 29 Diaphragm (Cont.) Other nonpulmonary diseases can also affect diaphragm function: ◦ Abdominal wall muscle tensioning (splinting) due to pain ◦ Abdominal distention with fluid (ascites) ◦ Any other causes of abdominal wall rigidity can interfere with descent 30 Diaphragm (Cont.) 31 Muscles of ventilation Accessory muscles of inspiration ◦ Muscles recruited to assist diaphragm to enable adequate inspiration ◦ External intercostal, scalenus, sternocleidomastoid, pectoralis major, trapezius ◦ Active only during increased demand Accessory muscles of expiration ◦ Recruited to assist in exhalation when airway resistance becomes significantly elevated ◦ Rectus abdomini, external abdominis obliques, internal abdominis obliques, transversus abdominis, internal intercostal 32 Respiratory Muscles 33 Respiratory Muscles (Cont.) 34 Respiratory Muscles (Cont.) 35 36 Conclusion ▪The respiratory system is a complex system with many functions and landmarks. ▪Every part of the respiratory system is important to each other. ▪As a respiratory therapist, we should be very knowledge of this sytem. What’s next… ▪How does the circulatory system play a part? ▪Why is blood flow important? 37