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Respiratory System

This chapter provides an overview of the respiratory system, including its function, organs, and structure. It explores the pathway of air from the nose to the lungs, the structure of the upper and lower respiratory tracts, and the process of gas exchange in the alveoli.

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Respiratory System

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  1. Respiratory System Anatomy & Physiology Chapter 14

  2. I. Overview A. Function: • Brings about the exchange of oxygen and carbon dioxide between the blood, the air, and tissues

  3. B. Organs • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs – alveoli

  4. C. Respiratory tract • Pathway of air from nose to lungs • Air in the respiratory tract are: • Cleansed – by hairs, cilia, and mucus • Warmed – by heat from the blood vessels • Moistened – by the wet surfaces in the passageway • Necessary to keep lung tissue healthy

  5. II. Structure A. Upper Respiratory Tract • Nasal cavities, pharynx, glottis, larynx

  6. 1. Nasal Cavity • Description: Hollow canals separated by a septum of bone and cartilage • Function: Filter, warm, and moisten the air

  7. Paranasal Sinuses – Cavities within bones surrounding the nasal cavity • Function of the sinuses • Lighten the skull • Act as resonance chambers for speech • Produce mucus that drains into the nasal cavity • Mucous membrane lines nasal cavity • Cilia moves mucous and trapped particles to the pharynx

  8. Contains lateral projections called conchae • Increases surface area • Increases air turbulence within the nasal cavity • The nasal cavity is separated from the oral cavity by the palate • Anterior hard palate (bone) • Posterior soft palate (muscle) Hard Palate Soft Palate

  9. 2. Pharynx – Throat • Description: funnel-shaped passageway between the nasal cavity and larynx • Function: Connects nasal and oral cavities to the larynx

  10. Three regions of the pharynx • Nasopharynx – superior region, passageway for air • Oropharynx – where oral cavity joins pharynx, passageway for food and air • Laryngopharynx – inferior region that opens to larynx • Tonsils – located in oropharynx • A lymphatic tissue that protects against inhaled pathogens

  11. 3. Epiglottis • Description: flap of tissue that sits at the base of the tongue • Function: prevents food from entering the trachea, or windpipe, during swallowing

  12. 4. Larynx • Description: Also called the voice box, contains the vocal cords • Function: Produces sound • Vocal cords are elastic tissues that vibrate producing sound as air travels through • The opening or slit in the vocal cords is called the glottis

  13. B. Lower Respiratory Tract • Trachea, bronchi, bronchioles, lungs, alveoli

  14. 1. Trachea • Description: known as the windpipe, flexible tube that connects larynx to bronchi • Function: directs air to bronchi

  15. Cilia Goblet cells Pseudostratified epithelial Basement membrane • Held open by C-shaped hyaline cartilage • Trachea is lined with pseudostratified ciliated columnar epithelial cells • Cilia sweeps mucus loaded with dust and other debris away from lungs

  16. Review • Breakdown the words “pseudostratified ciliated columnar epithelial” to understand the meaning. • “pseudo” – fake • “stratified” – layers • “ciliated” – with hair like projections • “columnar” – cells that are taller than wider

  17. 2. Bronchi • Description: Left and right branched tubes of the trachea • Function: passageway of air to lungs

  18. Bronchi enters the right and left lungs • Bronchi subdivide into smaller and smaller branches called bronchioles • Right bronchus is wider, shorter, and straighter than left

  19. 3. Bronchioles • Description: Smallest branches of the bronchi • Function: Bronchioles lead to the alveoli

  20. 4. Lungs • Description: paired, cone-shaped organ that occupy the thoracic cavity • Function: contains alveolus where gas exchange occurs

  21. Apex (superiorportion) is near the clavicle • Base (inferior portion) rests on the diaphragm • Each lung is divided into lobes by fissures • Left lung – two lobes • Right lung – three lobes

  22. Coverings of the lungs • Visceral pleura covers the lung • Parietal pleura lines the walls of the thoracic cavity • Pleural fluid fills the area between layers of pleura to allow gliding

  23. 5. Alveoli • Description: Structure made up of simple squamous epithelium surrounded by blood capillaries • Function: Exchange of gas

  24. Respiratory membrane – extremely thin membrane that aids in the rapid exchange of gases

  25. Gas crosses the respiratory membrane bydiffusion • Oxygen enters the blood • Carbon dioxide enters the alveoli • Macrophages add protection • Surfactant in alveoli prevents the lung from closing or collapsing

  26. Review • What gases are exchanged in the respiratory membrane? • How are gases moved or transported across the membrane?

  27. Summary • Draw a flow map showing the pathway air travels through the respiratory system starting with the nasal cavity and ending with the alveoli. Underneath each structure (8 total), write down the function. • Ex.

  28. IV. Gas Exchange and Transport • Respiration – process of exchanging gases between the atmosphere and body cells

  29. A. External Respiration • Exchange of gases between air and blood in the lungs • Blood entering the lungs is oxygen-poor and carbon dioxide-rich • Oxygen movement into the blood • The alveoli always has more oxygen than the blood • Oxygen moves by diffusion from an area of high concentration to an area of low concentration

  30. Carbon dioxide movement out of the blood • Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli • Pulmonary capillary blood gives up carbon dioxide • Blood leaving the lungs is oxygen-rich and carbon dioxide-poor

  31. B. Internal Respiration • Exchange of gases between blood and body cells • An opposite reaction to what occurs in the lungs • Carbon dioxide diffuses out of tissue to blood • Oxygen diffuses from blood into tissue

  32. C. Gas Transport • Oxygen transport in the blood • Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) • A small amount is dissolved in the plasma • Carbon dioxide transport in the blood • Most is transported in the plasma as bicarbonate ion (HCO3–) • A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen

  33. III. Mechanism of Breathing • Ventilation – manner in which air enters and exits the lungs • Two phases • Inspiration – flow of air into lung • Expiration – air leaving lung

  34. A. Inspiration • Active phase of ventilation • Diaphragm and intercostal muscles contract • The size of the thoracic cavity increases • External air is pulled into the lungs due to an increase in intrapulmonary volume

  35. B. Expiration • Largely a passive process which depends on natural lung elasticity • Diaphragm and intercostal muscles relax • As muscles relax, air is pushed outof the lungs • Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage

  36. C. Nonrespiratory Air Movements • Can be caused by reflexes or voluntary actions • Examples • Cough and sneeze – clears lungs of debris • Laughing • Crying • Yawn • Hiccup

  37. D. Ventilation Control • Normal breathing rate is 12-20 ventilation per minute • Controlled by the respiratory center in the medulla oblongata (brain) • Factors that influence ventilation • Nervous input • Chemical input

  38. 1. Nervous input • Intercostal and phrenic nerves stimulate muscles to contract for inspiration • Lack of stimulation results in expiration

  39. 2. Chemical input • Level of carbon dioxide in the blood is the main regulatory chemical for respiration • Increased carbon dioxide increases respiration

  40. E. Respiratory Volumes • Normal breathing moves about 500 ml of air with each breath (Tidal Volume [TV]) • Respiratory capacities are measured with a spirometer • Many factors that affect respiratory capacity • A person’s size • Sex • Age • Physical condition

  41. Inspiratory reserve volume (IRV) • Amount of air that can be taken in forcibly over the tidal volume • Usually between 2100 and 3200 ml • Expiratory reserve volume (ERV) • Amount of air that can be forcibly exhaled • Approximately 1200 ml

  42. Residual volume • Air remaining in lung after expiration • About 1200 ml • Vital capacity • The total amount of exchangeable air • Vital capacity = TV + IRV + ERV • Dead space volume • Air that remains in conducting zone and never reaches alveoli • About 150 ml

  43. Functional volume • Air that actually reaches the respiratory zone • Usually about 350 ml

  44. V. Respiratory Disorders • A. Tonsillitis– occurs when tonsils become inflamed and enlarged • Can make breathing difficult • Tonsils are the first line of defense against pathogens that enter the pharynx • B. Laryngitis – infection of larynx • Lead to inability to talk audibly • Disappears with treatment

  45. C. Chronic Obstructive Pulmonary Disease (COPD) • Term used to describe several progressive lung diseases • Third leading cause of death in the U.S. • Example: chronic bronchitis, emphysema, asthma

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