1. Respiratory System
Chapter 19

2. Functions Exchange of gases- O2 in, CO2 out
Regulation of pH- retain or excrete CO2
Protect from inhaled pathogens/substances
Vocalization

3. Structure of the respiratory system
Assists in ventilation- inspiration/expiration
Muscles of thorax and abdomen
Upper/lower respiratory tract
Alveoli

4. Muscles Creates the force to move air during breathing
Diaphragm- responsible for 45% of air that enters into the lungs

5. Upper respiratory system
Mouth, nasal cavity, pharynx, larynx

6. Lower respiratory system
Trachea, bronchi and branches, lungs
Bronchi, bronchioles, supported by cartilage rings

7. Lower respiratory system
Trachea, bronchi and branches, lungs
Lungs- spongy tissue, occupied by alveoli
Two lungs, surrounded by double walled pleural sac

8. Upper and parts of lower- functions
Warming air- maintain core body temp
Adding water vapor- epithelium doesn’t dry out
Filter out particles- foreign material doesn’t get to alveoli, mucus

9. Filtering out particles
Need two parts- water and mucus
Mucus is secreted by goblet cells

10. Alveoli Hollow sacs, site of gas exchange Surrounded by capillaries
100 m2

11. Ventilation Bulk flow of air between the atmosphere and the alveoli
One respiratory cycle = inspiration followed by expiration (12-20 per minute)

12. Properties of gases
Move down concentration gradient (higher to lower concentration)
Boyle’s law:

13. Air flow during ventilation
Due to pressure gradients
Must decrease pressure in lungs (air moves from high to lower pressure)

14. Involves:
contraction of diaphragm draws lungs down
-muscles contract and pull ribs up and out

15. Adequate ventilation Requires compliance and elastance
Compliance- amount of force exerted to expand lungs, ability to stretch (high compliance = less force to stretch)
Elastance- resistance to being deformed

16. Compliance and elastance
If either are compromised, it affects air flow
Decrease in elastance- elastin fibers

17. Emphysema
Destroys elastin
Compliance? Elastance?

18. Compliance and elastance
If either are compromised, it affects air flow
Decrease in compliance
More work to stretch a stiff lung
Restrictive lung diseases

19. Pulmonary fibrosis Decrease in compliance
Macrophages ingest particles, cannot be digested
Macrophages stimulate production of inelastic collagen (out of control wound healing)
Scarring of lung tissue, irreversible

20. It’s not just elastin the resists stretch…
Surface tension!
Alveoli have thin fluid layer between cells and air, creates surface tension which resists stretch

21. Adequate ventilation Also determined by other factors: Length of tubes
Viscosity
Diameter of tubes

22. Adequate ventilation
Length is constant
Viscosity

23. Adequate ventilation
Diameter of tubes

24. Measuring ventilation
Assess pulmonary function
Spirometer- volume of air moved per breath

25. Measuring ventilation
Four volumes
Tidal volume (quiet breathing)
Inspiratory reserve volume (forced inspiration)
Expiratory reserve volume (forced expiration)
Residual volume (air that doesn’t escape, can’t measure)

27. Dead space
Doesn’t take part in gas exchange

28. Gas Exchange and Transport

30. How does oxygen enter the bloodstream (and CO2 leave)?

31. Concentration gradients
Gases diffuse down concentration gradients

32. Concentration gradients
Gases diffuse down concentration gradients
From air to water, depends on solubility too
Oxygen isn’t very soluble
At equilibrium, same partial pressure, concentration differs

33. Oxygen needs some help because of low solubility

35. Carbon dioxide does a bit better
More soluble in water
But, body produces more than can be dissolved in plasma
Can bind to hemoglobin too, released at lungs

36. CO2 obeys same laws as O2

37. Why remove CO2? Elevated CO2 causes pH disturbance (acidosis)
Can depress CNS function
Toxic to the body, so must be removed

38. What happens at the interface of the capillaries and the cells?
Same thing as the lungs

39. Chemoreceptors in arterial system monitor CO2, O2, and pH levels

40. Non-respiratory air movements
Movement of air for something other than breathing
Clear air passages (cough/sneeze)
Vocalization and express emotion (laughing/crying)