Anatomy and Physiology

1. [Tab 2]Respiratory System Anatomy and Physiology

2. 1910.134(b)(10)Respiratory Protection “Persons should not be assigned to tasks requiring use of respirators unless it has been determined that they are physically able to perform the work and use the equipment.”

3. Conditions which may limit respirator use • any lung disease (e.g., emphysema, COPD, allergies, asthma) • x-ray evidence of pneumoconiosis • reduced pulmonary function • heart disease • cerebral blood vessel disease • hypertension

4. Respiratory System • function: • gas exchange between atmosphere & blood • parts: • upper respiratory system: • mouth, nose, pharynx, larynx • lower respiratory system: • trachea, bronchi, bronchioles, lungs

5. The Lungs very large surface area: 145 M2 in healthy male (or, about 40 times greater than surface area of our external skin) very thin membrane required at gas exchange area: only 1/2 to 1 micron thick in healthy persons micron?

8. Micron • one millionth of a meter • about 1/ 1000th the size of a hair • um

9. The Nose • Warms, cools air • Humidifies air • Filters particulates > 10 microns (nose hairs and turbinate impaction) • Reacts with water soluble gases • Preferred entrance of air

10. The Pharynx • the chamber which collects incoming air and food • passes air to trachea • regulates air pressure and velocity • filters particles (2 to 10 microns) through impaction • reacts with water soluble gases

11. The Trachea • passage from pharynx to lungs • the “windpipe” • largest conduit to lungs • filters particles 2 to 10 microns • very sensitive (cough reflex)

13. The Bronchi • two subdivisions of the trachea • one for each lung • further subdivide into segmental bronchi • filters particles 2 to 10 microns

14. The Bronchioles • smaller subdivisions of bronchi • lower velocity = settling • flow less turbulent • removes particles from 2 to 0.5 microns • smooth muscle layer constricts

15. The Alveoli (Air Exchange) • respiratory bronchioles and alveolar ducts • small air sacs • covered with capillaries • immunologic protection (macrophage)

16. Factors Determining Deposition • size • density • shape (fiber, aspect ratio) • solubility (water vs lipid) • chemical composition (toxic vs inert)

17. The following slides are not for the class to see, but rather just instructor notes

18. Types of Pulmonary Disease • Obstructive- larger airways: asthma, bronchitis, COPD, emphysema • Restrictive- lung cannot expand fully or oxygen transfer inhibited: hypersensitivity pneumonitis, asbestosis, silicosis, black lung, berylliosis

19. Emphysema --occurs when adjacent walls in alveoli break through, causing a reduction in the number of air sacs --this decreases the total gas exchange surface that is available --over time, the lung becomes less elastic, and the outflow of air is obstructed

20. Chronic bronchitis -- inhaled irritants cause excessive production of mucous in lower respiratory passages --they also cause inflammation & fibrosis (hardening) of the skin surface (mucosa) --the result: airway obstruction, poor ventilation of lungs, & interference with the gas exchange process --also, bacteria thrive in the mucous, & so pulmonary infections often occur

21. Types of Defense • nose hairs/ turbinates • impaction / centrifugal / cyclonic • cough reflex, sneeze reflex • mucus blanket, ciliated cells • bronchioconstriction • settling, Brownian motion • immune response

22. Protective Measures Many of these defense mechanisms can deteriorate with age, or be compromised as a result of illness, tobacco smoking, or exposure to chemical irritants. So, choose & control your exposures wisely!