Respiration. Ontogenesis of respiration.

1. Respiration. Ontogenesis of respiration.

2. The Respiratory System • Cells continually use O2 & release CO2 • Respiratory system designed for gas exchange • Cardiovascular system transports gases in blood • Failure of either system • rapid cell death from O2 starvation

3. Respiratory System Anatomy • Nose • Pharynx = throat • Larynx = voicebox • Trachea = windpipe • Bronchi = airways • Lungs - upper respiratory tract is above vocal cords • lower respiratory tract is below vocal cords Shina Alagia

4. External Nasal Structures • Skin, nasal bones, & cartilage lined with mucous membrane • Openings called external nares or nostrils Shina Alagia

5. Nose -- Internal Structures • Large chamber within the skull • Roof is made up of ethmoid and floor is hard palate • Internal nares are openings to pharynx • Nasal septum is composed of bone & cartilage • Bony swelling or conchae on lateral walls Shina Alagia

6. Functions of the Nasal Structures • Olfactory epithelium for sense of smell • Pseudostratified ciliated columnar with goblet cells lines nasal cavity • warms air due to high vascularity • mucous moistens air & traps dust • cilia move mucous towards pharynx • Paranasal sinuses open into nasal cavity • found in ethmoid, sphenoid, frontal & maxillary • lighten skull & resonate voice Shina Alagia

7. Pharynx • Muscular tube (5 inch long) hanging from skull • skeletal muscle & mucous membrane • Extends from internal nares to cricoid cartilage • Functions • passageway for food and air • resonating chamber for speech production • tonsil (lymphatic tissue) in the walls protects entryway into body • Distinct regions -- nasopharynx, oropharynx and laryngopharynx Shina Alagia

8. Nasopharynx From internal nares to soft palate openings of auditory (Eustachian) tubes from middle ear cavity adenoids or pharyngeal tonsil in roof Shina Alagia

9. Oropharynx From soft palate to hyoid bone fauces is opening from mouth into oropharynx palatine tonsils found in side walls, lingual tonsil in tongue Common passageway for food & air Shina Alagia

10. Laryngopharynx Extends from hyoid bone to cricoid cartilage Common passageway for food & air & ends as esophagus inferiorly Shina Alagia

11. Larynx • Cartilage & connective tissue tube • Anterior to C4 to C6 • Constructed of 3 single & 3 paired cartilages Shina Alagia

12. Vocal Cords • False vocal cords (ventricular folds) found above vocal folds (true vocal cords) • True vocal cords attach to arytenoid cartilages Shina Alagia

13. Trachea and Bronchial Tree • Full extent of airways is visible starting at the larynx and trachea Shina Alagia

14. Trachea • Ciliated pseudostratified columnar epithelium • Hyaline cartilage as C-shaped structure closed by trachealis muscle Shina Alagia

15. Bronchi and Bronchioles • Primary bronchi supply each lung • Secondary bronchi supply each lobe of the lungs (3 right + 2 left) • Tertiary bronchi supply each bronchopulmonary segment • Repeated branchings called bronchioles form a bronchial tree Shina Alagia

16. Pleural Membranes & Pleural Cavity • Visceral pleura covers lungs --- parietal pleura lines ribcage & covers upper surface of diaphragm • Pleural cavity is potential space between ribs & lungs Shina Alagia

17. Gross Anatomy of Lungs • Base, apex (cupula), costal surface, cardiac notch • Oblique & horizontal fissure in right lung results in 3 lobes • Oblique fissure only in left lung produces 2 lobes Shina Alagia

18. Mediastinal Surface of Lungs • Blood vessels & airways enter lungs at hilus • Forms root of lungs • Covered with pleura Shina Alagia

19. Structures within a segment of Lung • Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT • Respiratory bronchiole • simple squamous • Alveolar ducts surrounded by alveolar sacs & alveoli • sac is 2 or more alveoli sharing a common opening Shina Alagia

20. Cells Types of the Alveoli • Type I alveolar cells • simple squamous cells where gas exchange occurs • Type II alveolar cells (septal cells) • free surface has microvilli • secrete alveolar fluid containing surfactant • Alveolar dust cells • wandering macrophages remove debris Shina Alagia

21. Alveolar-Capillary Membrane • Respiratory membrane = 1/2 micron thick • Exchange of gas from alveoli to blood • 4 Layers of membrane to cross • alveolar epithelial wall of type I cells • alveolar epithelial basement membrane • capillary basement membrane • endothelial cells of capillary Shina Alagia

22. Details of Respiratory Membrane • Find the 4 layers that comprise the respiratory membrane Shina Alagia

23. Double Blood Supply to the Lungs • Deoxygenated blood arrives through pulmonary trunk from the right ventricle • Bronchial arteries branch off of the aorta to supply oxygenated blood to lung tissue • Venous drainage returns all blood to heart • Pulmonary blood vessels constrict in response to low O2 levels so as not to pick up CO2 on there way through the lungs Shina Alagia

24. Respiration • Respiration is exchange of primarily oxygen and carbon dioxide between atmosphere and human body Shina Alagia

25. Respiration: Steps • Respiration is achieved in four steps • Pulmonary ventilation: Inspiration + Expiration • External respiration: Diffusion across alveolar-capillary membrane • Gas transport: Transport of O2 and CO2 • Internal respiration: Exchange between ICF and tissue capillary Shina Alagia

26. Breathing or Pulmonary Ventilation • Air moves into lungs when pressure inside lungs is less than atmospheric pressure • How is this accomplished? • Air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure • How is this accomplished? • Atmospheric pressure = 1 atm or 760mm Hg Shina Alagia

27. Boyle’s Law • As the size of closed container decreases, pressure inside is increased • The molecules have less wall area to strike so the pressure on each inch of area increases. Shina Alagia

28. Dimensions of the Chest Cavity • Breathing in requires muscular activity & chest size changes • Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest Shina Alagia

29. Quiet Inspiration • Diaphragm moves 1 cm & ribs lifted by external intercostal muscles • Intrathoracic pressure falls and 2-3 liters inhaled Shina Alagia

30. Quiet Expiration • Passive process with no muscle action • Elastic recoil & surface tension in alveoli pulls inward • Alveolar pressure increases & air is pushed out Shina Alagia

31. Intra-pleuralPressures Helps keep parietal & visceral pleura stick together and alveoli inflated • Always subatmospheric (756 mm Hg) • As diaphragm contracts intrapleural pressure decreases even more (754 mm Hg) Shina Alagia

32. Summary of Breathing • Alveolar pressure decreases & air rushes in • Alveolar pressure increases & air rushes out Shina Alagia

33. External Respiration • Exchange of gas between air & blood • Gases diffuse from areas of high partial pressure to areas of low partial pressure • Deoxygenated blood becomes oxygeneted • Compare gas movements in pulmonary capillaries to tissue capillaries Shina Alagia

34. Internal Respiration • Exchange of gases between blood & tissues • Conversion of oxygenated blood into deoxygenated • Observe diffusion of O2 inward • at rest 25% of available O2 enters cells • during exercise more O2 is absorbed • Observe diffusion of CO2 outward Shina Alagia