The respiratory system Structure of the respiratory system What is respiration? ventilation gas exchange between ai

1. The respiratory system Structure of the respiratory system What is respiration? ventilation gas exchange between air and blood between blood and cells (oxygen) exchange and transport of carbon dioxide

4. General functions of upper tract Take in, moisten air Trap irritants/infectious particles cilia mucous membranes Paranasal sinuses- resonant chambers Pharynx- passageway for food and air Larynx- breathing and speech

6. Trachea branches into bronchi Trachea is ciliated and woth goblet cells Cartilaginous rings hold it open Bronchial tree branches off into bronchioles, terminating in alveoli

8. What is the mechanism of breathing? Inspiration, expiration thoracic cavity changes in size- how? Phrenic nerve stimulation causes diaphragm to contract (and drop) Thoracic cavity enlarges, air pressure drops and atmospheric pressure forces air in External intercostals may contract, elevate sternum Pleural membranes moves out (and together)

10. Expiration Lots of elastic tissue in lungs and thoracic wall Recoil helps return tissues to original configu- ration Alveoli enlarge during inspiration, contract during expiration

12. What are the respiratory volumes and capacities? Components of normal breathing, at rest and under exertion Capacities will vary with age, sex, body size- and state of health

14. Restrictive disorders- vital capacity is reduced; FEV is normal Obstructive disorders- FEV is reduced, vital capacity is normal, e.g., asthma Bronchoconstriction Inflammation Emphysema- destruction of alveoli COPD- obstructive and restrictive; chronic bronchitis and emphysema

15. Breathing is normally rhythmic and involuntary Respiratory muscles are under voluntary control Respiratory centers in pons and medulla oblongata Dorsal group- basic rhythmicity Ventral group- when deeper breathing is required Both act on diaphragm and respiratory muscles

16. Inflation reflex prevents lungs from over- inflating Stretched lung tissues stimulate stretch receptors in visceral pleura and within lungs Signal ultimately reaches pons (pneumotaxic area) which modulates inspiratory activity

18. What factors affect breathing? Respiratory control centers are sensitive to carbon dioxide and hydrogen levels If those rise (in blood), breathing rate increases Low blood oxygen can also be detected Hyperventilation lowers blood carbon dioxide levels; can lead to blood alkalosis (slows breathing rate)

20. How does gas exchange occur? Both alveoli and capillaries are lined with simple squamous epithelium Respiratory membrane is formed between them; gases diffuse across it Diffusion is due to differential partial pressures of oxygen and carbon dioxide

22. In blood, oxygen is transported by hemoglobin (combines with heme group) In tissues, oxygen is released High temperatures, acidic conditions reduce affinity of oxygen for hemoglobin Carbon dioxide also binds to hemoglobin, but to a different site Only about 23% of carbon dioxide is transported this way

23. Most carbon dioxide is formed into bicarbonate Carbonic anhydrase in red blood cells catalyzes this reaction Chloride ion plays a role, too

26. Disorders of the respiratory system Infections Chronic inflammation (asthma) Degenerative disease, e.g., emphysema Lung cancer Genetic disorders

27. Interaction of respiratory and other systems Loading of oxygen (and carbon dioxide) requires blood transport and specilaized functions of red blood cells Utilization and regulation of voluntary muscles Sensitivity to pH (acidosis, alkalosis) Response to exercise? Response to high altitude?