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- 2. Functions andOrganization of the Respiratory System Mechanics of breathing VENTILATION‐REPERFUSION RELATIONSHIPS Oxygen and Carbon dioxide Transport Control of breathing Alveolar - Arterial equilibration-1 Effects of low and high gas pressure on the body Effects of exercise on the respiratory system. Learning Objectives
- 3. The Respiratory System •Functions to supply the body w/ O2 and remove CO2 • “Respiration” is actually 4 distinct processes: 1. Ventilation – Movement of air into & out of the lungs 2. External Respiration – Gas exchange btwn blood and air-filled chambers of the lungs 3. Transport of Gases 4. Internal Respiration – Gas exchange btwn systemic blood and the tissue cells
- 4. Functions of theRespiratory System: Overview • Exchange O2 – Air to blood – Blood to cells • Exchange CO2 – Cells to blood – Blood to air • Regulate blood pH • Vocalizations • Protect alveoli Overview of external and cellular respiration
- 5. Functional Anatomy • Organsinclude: nose, nasal cavity, pharynx, trachea, bronchi, bronchioles, and the alveoli. • Divided into respiratory and conducting zones. • Gas exchange with the blood occurs in the respiratory zones. It does NOT occur in the conducting zones. • The conducting zones transport, cleanse, warm and humidify the incoming air.
- 6. The Airways: Conduction ofAir from Outside to Alveoli • Filter, warm & moisten air • Nose, (mouth), trachea, bronchi & bronchioles • Huge increase in cross sectional area Branching of the airways
- 7. The Nose • Onlyexternally visible part of the respiratory system. • Functions include: – Providing an airway for respiration – Moistening and warming air – Filtering inspired air – Serving as a resonating center for speech – Housing the olfactory receptors.
- 8. Pharynx • Funnel-shaped. • Connectsthe nasal cavity and mouth superiorly to the larynx and esophagus inferiorly • 3 regions. From superior to inferior: – Nasopharynx – Oropharynx – Laryngopharynx
- 9. Nasopharynx • Only anair passage. During swallowing, the soft palate and its uvula move superiorly and close it off. • Lined by respiratory epithelium. • High on its posterior wall is the pharyngeal tonsil (a.k.a. adenoids) which traps entering pathogens. • The auditory tubes open into its lateral walls.
- 10. Oropharynx • Lies posteriorto the oral cavity • Extends from the soft palate to the epiglottis and allows passage of food and air • Lined by nonkeratinized stratified squamous epithelium
- 11. Laryngopharynx • Lies posteriorto the epiglottis and extends to the larynx where the respiratory and digestive paths diverge • Common passage for both food and air • Lined by stratified squamous epithelium
- 12. Larynx • Superiorly attachedto the hyoid bone and opens into the laryngopharynx. • Inferiorly, it’s continuous w/ the trachea • Main tasks are: – Provision of a patent airway for air and food. – Routing of air and food to proper pathways. – Voice production. • Consists of an intricate arrangement of 9 cartilages connected by membranes and ligaments.
- 13. • The larynxis closed by the epiglottis during swallowing. • In addition to opening and closing the glottis for speech, the vocal folds can act as a sphincter during conditions such as coughing, sneezing or straining
- 14. Trachea • Descendsfrom the larynx to the mediastinum. • Ends by dividing into the 2 primary bronchi at midthorax. • Contains 3 layers: mucosa, submucosa, and adventitia • Tracheal mucosa contains pseudostratified ciliated epithelium w/ goblet cells. • Smoking destroys respiratory cilia – necessitates coughing for mucus propulsion • Submucosa contains seromucous glands – produce the mucus that lines the trachea
- 15. Bronchi and Subdivisions •Each bronchus runs obliquely into the mediastinum before plunging into the medial depression (hilus) of the lung on its own side. • Inside the lungs, the primary bronchi divide into secondary bronchi – 3 on the right and 2 on the left – each of which supplies one lung lobe. • The secondary bronchi become tertiary bronchi and so on until 23 branchings have occurred. This yields the bronchial tree. • Passages with a diameter of <1mm are bronchioles. • Terminal bronchioles are the last portion of the conducting zone.
- 18. Respiratory Zone • Definedby the presence of thin-walled air sacs called alveoli. • Begins at the transition from terminal bronchioles to respiratory bronchioles – which contain scattered alveoli. • Respiratory bronchioles become alveolar ducts which lead into terminal clusters of alveoli called alveolar sacs.
- 19. • Alveoli aremade of simple squamous epithelium consisting of 2 cell types: Type I and Type II alveolar cells. • Type I alveolar cells – Extremely thin. Occupy most of the alveolar SA. – External surfaces are cobwebbed by pulmonary capillaries. – Together the alveolar and capillary PM’s and their fused basal laminas form the respiratory membrane which has gas on 1 side and blood on the other. – Lung alveoli are surrounded by elastic fibers.
- 20. • Scattered among theType I’s are Type II cells which secrete surfactant. • Alveolar pores connect adjacent alveoli. • Alveolar macrophages (dust cells) crawl along the internal alveolar surfaces
- 21. Lung Gross Anatomy •Occupy all of the thoracic cavity except the mediastinum. • Each lung is w/i its own pleural cavity • Anterior, lateral, and posterior surfaces are costal • Just deep to the clavicle is the superior tip – the apex. • The concave bases sit on the diaphragm. • On the medial surface is an indentation (hilus) where the primary bronchi enter and the blood vessels enter and exit.
- 22. Lung Gross Anatomy •The left lung is smaller than the right and has an indentation (cardiac notch) where the heart sits. • Left lung has an upper and a lower lobe • Right lung has 3 lobes (upper, middle, and lower) • The smallest subdivision of the lung visible to the naked eye is the lobule.
- 23. Innervation - BloodSupply • Pulmonary arteries, capillaries and veins • Bronchial arteries. Most blood that travels to the lungs in the bronchial arteries returns via the pulmonary veins. • Parasympathetic activity causes bronchoconstriction while sympathetic activity causes bronchodilation.
- 24. The Pleurae • Thin,double-walled serosa. • Parietal pleura covers the thoracic wall and superior diaphragm • Visceral pleura covers the external lung surface • Pleurae produce pleural fluid that fills the slit-like pleural cavity btwn them. • Helps affix the lungs to the thorax and causes the lungs to move when thorax does.
- 25. Important Pressures • Atmosphericpressure (Patm) is the pressure exerted by the air surrounding the body. – At sea level, it’s 760 mmHg • Intrapulmonary pressure (Palv) is the pressure w/i the alveoli of the lungs. – It rises and falls during breathing but always equalizes with the atmospheric pressure • Intrapleural pressure (Pip) is the pressure w/i the pleural cavity. – It’s always 4mmHg less than the pressure in the alveoli – Thus it’s always lower than both Palv and Patm