The Respiratory System A.pptx

Week 2 Lecture 6a The Respiratory System Lecturer: Audrey I. Stephen The Respiratory System This topic relates to: Learning outcome(s) Outline the general functions of the respiratory system Describe the structure of the respiratory system Describe gas exchange in lungs Formative and summative asses...

Week 2 Lecture 6a The Respiratory System Lecturer: Audrey I. Stephen The Respiratory System This topic relates to: Learning outcome(s) Outline the general functions of the respiratory system Describe the structure of the respiratory system Describe gas exchange in lungs Formative and summative assessment Any topic within this module could potentially have a question(s) in the exam paper Links with other topics in the module Links with cardiovascular system, nervous system, homeostasis, muscular system Links with other modules and stages Stages 2 and 3 sciences Links to nursing and paramedic practice Essential knowledge for caring for people with respiratory disease, carrying out CPR, providing airway support. 2 Respirator y Structures and the Flow of Air Frontal sinus Nasal cavity Soft palate Hard palate Pharynx Nostril Epiglottis Oral cavity Esophagus Larynx Trachea Bronchus Right lung Left lung Overview – functions of Oxygen is required by cells to break down nutrients, to respiratory system release energy and produce ATP; carbon dioxide is a product of nutrient breakdown, which has to be excreted from the body Respiratory system: Obtains oxygen from the atmosphere, and removes carbon dioxide from the body cells Consists of tubes that filter, warm, and moisturise incoming air, and transport it into the gas exchange areas, and microscopic air sacs that exchange gases Other functions of the respiratory system: removes particles from incoming air, regulates temperature and water content of the air, provides vocal sounds, regulates blood pH, and helps in sense of smell 4 Summary of Respiratory Structures Respiratory Tract: Oro-laryngopharyngeal airway 6 Respiratory Tract: Trachea and Trachea sits in front of the onwards oesophagus and below larynx C shaped rings of cartilage maintain structure Right and Left bronchi (sing: bronchus) to each lung Branches into each lobe of each lung – 3 in right lung; 2 in left – lobar bronchi Within lobes branch into segmental bronchi and many further branches ending in terminal bronchioles and alveoli 7 Mucus movement in the respiratory tract 8 Respiratory Tract: Trachea and onwards As bronchi branch beyond segmental bronchi there is less cartilage – towards the respiratory bronchioles, terminal bronchioles and alveolar ducts there is none As cartilage diminishes the layer of smooth muscle increases No cartilage and presence of smooth muscle enables these bronchioles to alter in diameter to meet the oxygen demands of the body 9 Characteristics of the Bronchial Cartilage: present in the trachea and bronchi, but Tree lessens in the smaller tubular structures, and is absent in the bronchioles As cartilage lessens, smooth muscle increases in walls of bronchioles, and occurs in all structures until the alveolar ducts Absence of cartilage and presence of smooth muscle allows for changes in diameter of bronchioles: Bronchodilation: increase in diameter of the bronchioles during fight-or-flight or sympathetic stimulation Bronchoconstriction: decrease in diameter of the bronchioles during certain allergic responses or asthma Mucous membranes of bronchial tree filter, warm, and humidify incoming air 10 Respiratory Tract: Alveoli Respiratory bronchioles, terminal bronchioles and alveolar ducts have smooth muscle Bronchodilation occurs when smooth muscle relaxes – more air can enter the bronchioles and alveoli Bronchoconstriction is the reduction in diameter due to smooth muscle contraction – reduces amount of air entering the alveoli Note the branches of the pulmonary artery and pulmonary vein around the 11 alveolus Respiratory Tract: Alveoli Lining of the alveolus is simple squamous epithelium (thin, flattened cells) enabling rapid gas exchange; surfactant secreting cells and local macrophages The alveoli are surrounded by blood vessels Exchange of gases takes place across the blood vessel/alveolar boundary Surfactant secreting cells (Septal cells) form part of the structure of alveoli Surfactant reduces surface tension of fluid in the alveoli & 12 Diffusion across the respiratory membrane In a mixture of gases, each gas accounts for a portion of the total pressure; the amount of pressure exerted by each gas is its partial pressure When the partial pressure of O2(PO2) is higher in alveolar air than in capillary blood, O2 will diffuse into the blood Atmospheric pressure is 760 mm Hg at sea level Air is 21% O2, so the PO2 is 0.21 × 760 = 160 mm Hg When the PCO2 is greater in the blood than in the alveolar air, CO2 will diffuse from the blood and into the alveolus In a gas mixture, each gas diffuses from higher partial pressure to lower partial pressure Several factors favor increased gas diffusion: more surface area, shorter distance, greater solubility of gases, and a steeper partial pressure gradient 13 Partial pressure and gas exchange 14 Respiratory System: Link with Cardiovascular System To achieve the functions the respiratory and cardiovascular system work together Pulmonary artery deoxygenated blood to lungs Pulmonary veins oxygenated blood back to heart Aorta Blood to systemic capillaries and cells of the body 15 Summary This lecture has covered: Respiratory structures and the gas exchange process The functions of the respiratory system and the individual parts of the system in more detail Lecture b will cover: The mechanisms of breathing for inspiration and expiration Respiratory volumes and capacities The control of breathing