Explain the gross anatomy and functions of the respiratory system. Discuss the structure and functions of the upper and lower respiratory tracts in detail, including a description of the histology in each region. Identify the pleural cavities, its membranes and the muscles of ventilation.

Respiratory System Function Major Functions Upper respiratory system: 1.Air conditioning 2.Defense against pathogens Lower respiratory system: 1.Speech & other respiratory sounds 2.Gas exchange 3.Maintenance of homeostasis, e.g. pH Fig 24-1

Respiratory Epithelium Structure? Mucus produced by ________ Mucus escalator Defense by means of filtering hairs ciliary escalator sticky mucous

Nasal Conchae Superior, middle and inferior Other name: “Turbinate bones” because they create ______ Advantage ? ! Respirator breathing ! Fig 24.3

Upper Respiratory System 1) Nose  external and internal nares  turbinates or conchae (superior, middle, and inferior)  nasal septum  hard palate 2) Pharynx - shared passageway for respiratory and digestive systems  nasopharynx - part above uvula and posterior to internal nares  oropharynx – portion visible in mirror when mouth is wide open uvula - posterior edge of soft palate  laryngopharynx – between the hyoid bone & the esophagus Fig 24.3c

Lower Respiratory System Anything below Pharynx Larynx: Cartilaginous cylinder (from C 4 - C 7 ) Made up of 9 cartilages – 3 large unpaired (know these!) – 3 small paired (involved in construction of voice box Stabilized by ?? C3 C4 C5 C6 C7 Fig 24.4

Trachea Passageway to lungs (attached via ligament to ?) Lining ? Incomplete cartilage rings (C- shaped) - completed by trachealis muscle. Significance? Annular ligament Fig 24-7

Tracheal Blockage or Heimlich Maneuver or abdominal thrust Tracheostomy

From Bronchi to Lungs  1  bronchi (enter lungs at hilus, complete cartilage rings)  2  bronchi (from now on cartilage plates)  3  bronchi  Bronchioles  Terminal bronchioles  Respiratory bronchioles  Alveolar ducts  Alveolar sacs Conducting portion Respiratory portion Fig 24.9 Fig 24.11

Paired Lungs Situated in _________ Subdivided into lobes (each supplied by 2  bronchus) Right lung: 3 lobes (rel. broad and short) Left lung: 2 lobes (long and narrow) Right and left lung separated by __________ Lung hilus Why? Fig 24-8

Alveolar Organization Alveoli are site of gas exchange Close association with capillaries Lots of elastic fibers in alveolar wall Alveolar cells Type I cells – respiratory epitheliocytes Type II cells – septal cells – produce surfactant Alveolar Macrophages – dust cells – phagocytic Fig Fig 24-12

Respiratory Membrane Different from respiratory epithelium Super thin. Made up of 4 layers: 1.epithelium of alveolus 2.its basement membrane back to back and fused to the 3.basement membrane of capillary endothelium 4.endothelium of capillary

Chronic progressive enlargement of alveoli accompanied by destruction of their wall Due to prolonged exposure to respiratory irritants (??) Emphysema

Pleural Cavities and Membranes Two cavities separated by mediastinum Lining of cavities? pleurisy Pneumothorax Conducting blood supply to the lungs via bronchial arteries. Venous return to pulmonary veins (consequence ?) Fig 24-13

Pulmonary Embolism Causes for development of emboli in veins of legs: Immobilization Trauma Long surgeries Oral contraceptives Obesity Cigarette smoking Hypertension See p. 805

Respiratory Muscles Diaphragm: depresses  inhalation External intercostals: elevate ribs  inhalation Internal intercostals: depress ribs  active exhalation Accessory muscles - serratus anterior, scalenes, pectoralis minor, sternocleidomastoid, internal and external obliques, transverse abdominus, rectus abdominus Fig 24-14