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Respiratory System Overview - Anatomy, Respiration, and Gas Exchange

This chapter provides an overview of the respiratory system, including its anatomy, respiration process, and gas exchange. It covers topics such as oxygen and carbon dioxide transport, respiratory diseases, and the components of the respiratory tract.

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Respiratory System Overview - Anatomy, Respiration, and Gas Exchange

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  1. Chapter 22. Respiratory System

  2. Overview • Respiratory anatomy • Respiration • Respiratory musculature • Ventilation, lung volumes and capacities • Gas exchange and transport • O2 • CO2 • Respiratory centers • Chemoreceptor reflexes • Respiratory Diseases

  3. Oxygen • Is obtained from the air by diffusion across delicate exchange surfaces of lungs • Is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs

  4. Functions of the Respiratory System • Supplies body with oxygen and get rid of carbon dioxide • Provides extensive gas exchange surface area between air and circulating blood • Moves air to and from exchange surfaces of lungs • Protects respiratory surfaces from outside environment • Produces sounds • Participates in olfactory sense

  5. Components of the Respiratory System Figure 23–1

  6. Organization of the Respiratory System • Upper respiratory system • Nose, nasal cavity, sinuses, and pharynx • Lower respiratory system • Larynx, trachea, bronchi and lungs

  7. The Respiratory Tract • Conducting zone: • from nasal cavity to terminal bronchioles • conduits for air to reach the sites of gas exchange • Respiratory zone: • the respiratory bronchioles,alveolar ducts, and alveoli • sites of gas exchange

  8. The Respiratory Epithelium Figure 23–2

  9. Respiratory Epithelia • Changes along respiratory tract • Nose, nasal cavity, nasopharynx = pseudostratified ciliated columnar epithelium • Oropharynx, laryngopharynx = stratified squamous epitheium • Trachea, bronchi = pseudostratified ciliated columnar epithelium • Terminal bronchioles = cuboidal epithelium • Respiratory bronchioles, alveoli = simple squamous epithelium • Think about why each part has the lining that it does • For example, in alveoli • walls must be very thin (< 1 µm) • surface area must be very great (about 35 times the surface area of the body) • In lower pharynx • walls must be tough because food abrades them

  10. The RespiratoryMucosa • Consists of: • epithelial layer • areolar layer • Lines conducting portion of respiratory system • Lamina propria • Areolar tissue in the upper respiratory system, trachea, and bronchi (conducting zone) • Contains mucous glands that secrete onto epithelial surface • In the conducting portion of lower respiratory system, contains smooth muscle cells that encircle lumen of bronchioles

  11. Respiratory Defense System • Series of filtration mechanisms removes particles and pathogens • Hairs in the nasal cavity • Goblet cells and mucus glands: produce mucus that bathes exposed surfaces • Cilia: sweep debris trapped in mucus toward the pharynx (mucus escalator) • Filtration in nasal cavity removes large particles • Alveolar macrophages engulf small particles that reach lungs

  12. Upper Respiratory Tract Figure 23–3

  13. Upper Respiratory Tract • Nose : • Air enters through nostrils or external nares into nasal vestibule • Nasal hairs in vestibule are the first particle filtration system • Nasal Cavity : • Nasal septum divides nasal cavity into left and right • Mucous secretions from paranasal sinus and tears clean and moisten the nasal cavity • Meatuses Constricted passageways in between conchae that produce air turbulence: • Warm (how?) and humidify incoming air (bypassed by mouth breathing) • trap particles • Air flow: from external nares to vestibule to internalnares throughmeatuses, then to nasopharynx

  14. The Pharynx • A chamber shared by digestive and respiratory systems that extends from internal nares to the dual entrances to the larynx and esophagus at the C6 vertebrae • Nasopharynx • Superior portion of the pharynx (above the soft palate) contains pharyngeal tonsils; epithelium? • Oropharynx • Middle portion of the pharynx, from soft palate to epiglottis; contains palatine and lingual tonsils; communicates with oral cavity; epithelium? • Laryngopharynx • Inferior portion of the pharynx, extends from hyoid bone to entrance to larynx and esophagus

  15. Lower Respiratory Tract • Air flow from the pharynx enters the larynx, continues into trachea, bronchial tree, bronchioles, and alveoli

  16. Anatomy of the Larynx Figure 23–4

  17. Cartilages of the Larynx • 3 large, unpaired cartilages form the body of the larynx (voice box) • thyroid cartilage (Adam’s apple) • hyaline cartilage • Forms anterior and lateral walls of larynx • Ligaments attach to hyoid bone, epiglottis, and other laryngeal cartilages • cricoid cartilage • hyaline cartilage • Form posterior portion of larynx • Ligaments attach to first tracheal cartilage • the epiglottis • elastic cartilage • Covers glottis during swallowing • Ligaments attach to thyroid cartilage and hyoid bone

  18. Small Cartilages of the Larynx • 3 pairs of small hyaline cartilages: • arytenoid cartilages • corniculate cartilages • cuneiform cartilages • Corniculate and arytenoid cartilages function in opening and closing the glottis and the production of sound

  19. Larynx Functions • To provide a patent airway • To function in voice production • To act as a switching mechanism to route air and food into the proper channels • Thyroid and cricoid cartilages support and protect the glottis and the entrance to trachea • During swallowing the larynx is elevated and the epiglottis folds back over glottis prevents entry of food and liquids into respiratory tract

  20. Sphincter Functions of Larynx • The larynx is closed during coughing, sneezing, and Valsalva’s maneuver • Valsalva’s maneuver • Air is temporarily held in the lower respiratory tract by closing the glottis • Causes intra-abdominal pressure to rise when abdominal muscles contract • Helps to empty the rectum • Acts as a splint to stabilize the trunk when lifting heavy loads • Glottis also “closed” (covered) by epiglottis during swallowing

  21. The Glottis Figure 23–5

  22. Sound Production • Air passing through glottis: • vibrates vocal folds and produces sound waves • Sound is varied by: • tension on vocal folds • voluntary muscles position cartilages

  23. Anatomy of the Trachea Figure 23–6

  24. The Trachea • Extends from the cricoid cartilage into mediastinum where it branches into right and left bronchi • Has mucosa, submucosa which contains mucous glands, and adventitia • Adventita made up of 15–20 C-shaped tracheal cartilages (hyaline)strengthen and protect airway • Ends of each tracheal cartilage are connected by an elastic ligament and trachealis muscle where trachea contacts esophagus. Why?

  25. The Primary Bronchi • Right and left primary bronchi are separated by an internal ridge (the carina) • Right primary bronchus • larger in diameter than the left • descends at a steeper angle

  26. The Bronchial Tree • Formed by the primary bronchi and their branches • Each primary bronchus (R and L) branches into secondary bronchi, each supplying one lobe of the lungs (5 total) • Secondary Bronchi Branch to form tertiary bronchi • Each tertiary bronchus branches into multiple bronchioles • Bronchioles branch into terminalbronchioles: • 1 tertiary bronchus forms about 6500 terminal bronchioles

  27. Bronchial Tree Figure 23–9

  28. Bronchial Structure • The walls of primary, secondary, and tertiary bronchi: • contain progressively less cartilage and more smooth muscle, increasing muscular effects on airway constriction and resistance • Bronchioles: • Consist of cuboidal epithelium • Lack cartilage support and mucus-producing cells and are dominated by a complete layer of circular smooth muscle

  29. Autonomic Control • Regulates smooth muscle: • controls diameter of bronchioles • controls airflow and resistance in lungs • Bronchodilation of bronchial airways • Caused by sympathetic ANS activation • Reduces resistance • Bronchoconstriction • Caused by parasympathetic ANS activation or • histamine release (allergic reactions)

  30. The Bronchioles Figure 23–10

  31. Conducting Zones Figure 22.7

  32. Lungs Figure 23–7

  33. The Lungs • Left and right lungs: in left and right pleural cavities • The base: • inferior portion of each lung rests on superior surface of diaphragm • Hilus • Where pulmonary nerves, blood vessels, and lymphatics enter lung • Anchored in meshwork of connective tissue

  34. Lung Anatomy • Lungs have lobes separated by deep fissures • Right lung is wider and is displaced upward by liver. Has 3 lobes: • superior, middle, and inferior • separated by horizontal and oblique fissures • Left lung is longer is displaced leftward by the heart forming the cardiac notch. Has2 lobes: • superior and inferior • separated by an oblique fissure

  35. Relationship between Lungs and Heart Figure 23–8

  36. Respiratory Zone • Each terminal bronchiole branches to form several respiratory bronchioles, where gas exchange takes place (Exchange Surfaces) • Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of alveoli • Approximately 300 million alveoli: • Account for most of the lungs’ volume • Provide tremendous surface area for gas exchange

  37. Respiratory Zone

  38. Alveoli • Alveoli Are air-filled pockets within the lungs where all gas exchange takes place • Alveolar epithelium is a very delicate, simple squamous epithelium • Contains scattered and specialized cells • Lines exchange surfaces of alveoli

  39. Alveolar Organization Figure 23–11

  40. Alveolar Organization • Respiratory bronchioles are connected to alveoli along alveolar ducts • Alveolar ducts end at alveolar sacs: common chambers connected to many individual alveoli • Each individual alveolus has an extensive network of capillaries and is surrounded by elastic fibers

  41. Alveolar Epithelium • Consists of simple squamous epithelium (Type I cells) • Patrolled by alveolar macrophages, also called dust cells • Contains septal cells (Type II cells) that produce surfactant: • oily secretion containing phospholipids and proteins • coats alveolar surfaces and reduces surface tension

  42. Alevolar problems • Respiratory Distress: difficult respiration • Can occur when septal cells do not produce enough surfactant • leads to alveolar collapse • Pneumonia: inflammation of the lung tissue • causes fluid to leak into alveoli • compromises function of respiratory membrane

  43. Respiratory Membrane • The thin membrane of alveoli where gas exchange takes place. Consists of: • Squamous epithelial lining of alveolus • Endothelial cells lining an adjacent capillary • Fused basal laminae between alveolar and endothelial cells • Diffusion across respiratory membrane is very rapid because distance is small and gases (O2 and CO2) are lipid soluble

  44. Blood Supply to Respiratory Surfaces • Pulmonary arteries branch into arterioles supplying alveoli with deox. blood • a capillary network surrounds each alveolus as part of the respiratory membrane • blood from alveolar capillaries passes through pulmonary venules and veins, then returns to left atrium with ox. blood

  45. Blood Supply to the Lungs Proper • Bronchial arteries provide systemic circulation bringing oxygen and nutrients to tissues of conducting passageways of lung • Arise from aorta and enter the lungs at the hilus • Supply all lung tissue except the alveoli • Venous blood bypasses the systemic circuit and just flows into pulmonary veins • Blood Pressure in the pulmonary circuit is low (30 mm Hg) • Pulmonary vessels are easily blocked by blood clots, fat, or air bubbles, causing pulmonary embolism

  46. Pleural Cavities and Membranes • 2 pleural cavities are separated by the mediastinum • Each pleural cavity holds a lung and is lined with a serous membrane = the pleura: • Consists of 2 layers: • parietal pleura • visceral pleura • Pleural fluid: a serous transudate thatlubricates space between 2 layers

  47. Respiration • Refers to 4 integrated processes: • Pulmonary ventilation – moving air into and out of the lungs (provides alveolar ventilation) • External respiration – gas exchange between the lungs and the blood • Transport – transport of oxygen and carbon dioxide between the lungs and tissues • Internal respiration – gas exchange between systemic blood vessels and tissues

  48. Gas Pressure and Volume Figure 23–13

  49. Boyle’s Law • Defines the relationship between gas pressure and volume: P 1/V Or P1V1 = P2V2 • In a contained gas: • external pressure forces molecules closer together • movement of gas molecules exerts pressure on container

  50. Pulmonary Ventilation Respiration: Pressure Gradients Figure 23–14

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