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BIOL 121 Chp 23: The Respiratory System
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BIOL 121 Chp 23: The Respiratory System


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This is a lecture presentation for my BIOL 121 Anatomy and Physiology I students on Chapter 23: The Respiratory System (Principles of Anatomy and Physiology, 14th Ed. by Tortora and …

This is a lecture presentation for my BIOL 121 Anatomy and Physiology I students on Chapter 23: The Respiratory System (Principles of Anatomy and Physiology, 14th Ed. by Tortora and Derrickson).

Rob Swatski, Associate Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email:

Please visit my website for more anatomy and biology learning resources:

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  • 1. Chapter 23TheRespiratorySystem Rob Swatski Asst. Prof. Biology HACC – York Campus 1
  • 2. IntroductionThe 2 systems that cooperate to supply O2 & eliminate CO2 are the cardiovascular & the respiratory system Respiratory system provides for gas exchangeCardiovascular system transports the respiratory gases Failure of either system has the same effect on the body: - disruption of homeostasis - rapid death of cells: O2 starvation & buildup of wastes 2
  • 3. Respiration The exchange of gases between the atmosphere, blood, & cells3 basic steps:1. Ventilation (breathing)2. External (pulmonary) respiration3. Internal (tissue) respiration 3
  • 4. 4
  • 5. Respiratory System AnatomyNosePharynx = throatLarynx = voiceboxTrachea = windpipeBronchi = airwaysLungsLocations of infections:- upper respiratory tract is above vocal cords- lower respiratory tract is below vocal cordsConducting system consists of a series of cavities & tubes - nose, pharynx, larynx, trachea, bronchi, bronchiole, & terminal bronchioles - that conduct air into the lungsRespiratory portion consists of the area where gas exchange occurs - respiratory bronchioles, alveolar ducts, alveolar sacs, & alveoli 5
  • 6. 6
  • 7. Pharynx 7
  • 8. Larynx Cartilage & CT tube Anterior to C4 to C6Constructed of 3 single & 3 paired cartilages 8
  • 9. Cartilages of the LarynxEpiglottis: leaf-shaped piece of elastic cartilage – during swallowing, larynx moves upward – epiglottis bends to cover glottisCricoid cartilage: ring of cartilage attached to top of tracheaPair of arytenoid cartilages sit upon cricoid – many muscles responsible for their movement – partially buried in vocal folds (true vocal cords) 9
  • 10. Trachea & Bronchial Tree 10
  • 11. Airway EpitheliumCiliated pseudostratified columnar epithelium with goblet cells produce a moving mass of mucus 11
  • 12. Bronchi The trachea divides into the: right & left pulmonary bronchi The bronchial tree consists of the:trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, & terminal bronchioles Bronchi walls: contain rings of cartilage Bronchiole walls: contain smooth muscle 12
  • 13. Bronchi & Bronchioles Primary bronchi supply each lungSecondary bronchi supply each lobe of the lungs (3 right + 2 left) Tertiary bronchi supply each bronchopulmonary segmentRepeated branchings called bronchioles form the bronchial tree 13
  • 14. Structures Within a Lobule of LungBranchings of single arteriole, venule & bronchiole are wrapped by elastic CT Respiratory bronchiole: simple squamous epithelium Alveolar ducts surrounded by alveolar sacs & alveoli – sac is 2 or more alveoli sharing a common opening 14
  • 15. Cells Types of the AlveoliType I alveolar cells – simple squamous cells where gas exchange occursType II alveolar cells (septal cells) – free surface has microvilli – secrete alveolar fluid containing surfactantAlveolar dust cells (macrophages) – wandering macrophages remove debris 15
  • 16. Details of theRespiratoryMembrane 16
  • 17. Pulmonary Ventilation Respiration occurs in 3 basic steps: pulmonary ventilation, external respiration, & internal respirationInspiration (inhalation) is the process of bringing air into the lungsThe movement of air into & out of the lungs depends on pressure changes governed in part by Boyle’s law, which states that the volume of a gas varies inversely with pressure, assuming that temperature is constant 17
  • 18. Boyle’s Law As the size of a closed container decreases, the pressure inside increasesThe molecules have less wall area to strike so the pressure on each inch of area increases 18
  • 19. Dimensions of the Chest Cavity Inhalation requires muscular contraction & chest size changesContraction of the diaphragm flattens the dome & increases the vertical dimension of the chest 19
  • 20. Quiet InspirationDiaphragm lowers 1 cm & ribs lifted by musclesIntrathoracic pressure falls & 2-3 liters inhaled 20
  • 21. Quiet Expiration Passive process with no muscle actionElastic recoil & surface tension in alveoli pulls inward Alveolar pressure increases & air is pushed out 21
  • 22. Labored BreathingForced inspiration – sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for airForced expiration – abdominal muscles force diaphragm up – internal intercostals depress ribs 22
  • 23. IntrapleuralPressuresAlways subatmospheric (756 mm Hg)As diaphragm contracts intrathoracic pressure decreases even more (754 mm Hg)Helps keep parietal & visceral pleura sticking together 23
  • 24. Summary of BreathingAlveolar pressure decreases & air rushes inAlveolar pressure increases & air rushes out 24