1. Respiratory System

2. September 11, 2001
More than a million tons of dust and debris fell on lower Manhattan
Human respiratory tract easily ejects particles greater than 10 micrometers
>95% were large particulates
WTC cough developed by many workers caused by fiberglass lodged in throats and noses
By October 2001, air quality had returned to normal

3. Functions Obtain oxygen Remove carbon dioxide
Entrap particles from incoming air
Help control temp. and water content of air
Produce vocal sounds
Participate in sense of smell
Helps regulate blood pH
Respiration – entire process of gas exchange between the atmosphere and cells

4. Upper Respiratory Tract
Nose – contain openings through which air passes; internal hairs prevent entry of large particles
Nasal cavity – hollow space behind the nose; epithelial lining produces mucous which traps dust; blood vessels warm the air passing through; incoming air is moistened; cilia move particles to pharynx where it is swallowed
Pharynx (throat) – behind oral cavity and the larynx; passageway for food and air; helps produce the sounds of speech

5. Lower Respiratory Tract
Larynx – enlargement in the airway at the top of the trachea and below the pharynx; conducts air in and out of trachea; houses the vocal cords; composed of muscle, cartilage, and elastic tissue
Trachea (windpipe) – flexible, cylindrical tube 12.5 cm long; extends anterior to the esophagus and into the thoracic cavity, where it splits into right and left bronchi; ciliate mucous membrane with many goblet cells lines the inner wall; 20 C-shaped rings of cartilage

6. Bronchial tree divides into tertiary bronchi
branched airways leading from the trachea to the microscopic air sacs in the lungs
primary bronchi arise at the 5th thoracic vertebra
divides into secondary bronchi
divides into tertiary bronchi
then finer and finer tubes
bronchioles divide giving rise to other bronchioles and alveolar ducts
ducts lead to alveoli sacs of alveoli

7. Lungs Soft, spongy, cone-shaped organs in the thoracic cavity
Mediastinum separates the right and left lungs
Visceral pleura is a layer of serous membrane that attaches to each lung surface
Right lung is larger than left
Right lung has 3 lobes, left lung has 2 lobes

8. Inspiration
Atmospheric pressure due to the weight of air is the force that moves air into the lungs
At sea level, this pressure is sufficient to support a column of mercury about 760 mm high in a tube
During normal inspiration, pressure inside the lungs and alveoli decreases and atmospheric pressure pushes outside air into the airways

9. Steps of Inspiration
Nervous impulse stimulate muscle fibers in the diaphragm to contract
Diaphragm moves downward
Thoracic cavity enlarges
Pressure within the alveoli falls to about 2 mm Hg below that of atmospheric pressure
Air is forced into the airways
Pressure and volume are inversely related
1st breath is the toughest

11. Steps of Expiration
Diaphragm and external intercostal muscles relax following inspiration
Abdominal organs push the diaphragm upward
Surface tension develops between the surfaces of the alveolar linings and decreases the diameters of the alveoli
Alveolar pressure increases to 1 mm Hg above atmospheric pressure
Air inside of lungs is forced out through respiratory passages

13. High elevation respiration

14. Emphysema
Progressive, degenerative disease that destroys alveolar wall
Clusters of small air sacs merge to form larger chambers, which drastically decreases the surface area of the respiratory membrane
Reduced volume of gases can be exchanged
Affected person must exert abnormal muscular effort to exhale

15. Lung Cancer
Uncontrolled division of abnormal cells that rob normal cells of nutrients and oxygen
Some cancer growths in lungs result from cells that have metastasized from other parts of the body
Treated with surgery, ionizing radiation, and drugs, but the survival rate is low

17. Cystic fibrosis
A defect in channels leading to certain glands which causes formation of extremely thick, sticky mucus
Encouragement of infections by microorganisms in lungs
Also impairs absorption of nutrients

18. Respiratory Air Volumes and Capacities
Spirometry – measures volumes of air in or out of the lungs
Tidal volume –volume of air that enters or leaves during a single respiratory cycle (500 mL)
Inspiratory reserve volume – volume that can be inhaled during forced breathing in addition to tidal volume (3000 mL)
Expiratory reserve volume – volume that can be exhaled during forced breathing in addition to tidal volume (1100 mL)
Residual volume – volume that remains in lungs even after maximal expiration
Total lung capacity – total volume of air that the lungs can hold

19. Control of Breathing Respiratory center in brain Voluntarily
Medullary rhythmicity area (control movement)
Pneumotaxic area (control rate)
Chemosensitive areas sense changes in CSF concentrations of CO2 and H+
Voluntarily
Stop breathing for short time, but changes in blood concentration stimulate the respiratory center
Can increase breath-holding time by breathing rapidly and deeply in advance (hyperventilation)

20. Gas Transport Binds to hemoglobin or dissolves in plasma
Less active cells receive less oxygen
Hypoxia – deficiency of O2 reaching the tissues