1. Chapter 15
Respiratory System

2. 15-1: The Respiratory System
Functions of the Respiratory System
Five functions:
Gas exchange between air & circulating blood
Moving air within lungs
Protect respiratory surfaces; defend against pathogens
Produce sounds & speech
Aid in sense of smell

3. Components of the Respiratory System
Respiratory tract—passageways that carry air to & from the lungs
Upper conducting portion
Lower respiratory portion (bronchioles & alveoli)
Respiratory mucosa lines respiratory tract
Secrete mucus; trap debris & pathogens

5. 15-1 Checkpoint Identify the five functions of the respiratory system.
What membrane lines the conducting portion of the respiratory tract?

6. 15-2: Conducting Portion The Nose
External nares open into nasal cavity
Hairs guard nasal entry from large airborne particles
Bony hard palate forms floor of nose
Nasopharynx extends from nose to soft palate
Nasal conchae create nasal air turbulence

8. The Pharynx Three divisions:
Nasopharynx—internal nares to soft palate
Oropharynx—soft palate to back of tongue
Laryngopharynx—back of tongue to entrance of esophagus/trachea
Materials in laryngopharynx can go either in esophagus or trachea

9. The Larynx
Air leaves the pharynx & enters the larynx through the glottis
Epiglottis folds over the glottis to prevent entry of liquids or foods into trachea
True vocal cords produce speech
Food/liquids touching the vocal cords trigger coughing reflex

10. Visualization of Vocal Cords

11. The Trachea (windpipe)
Extends from larynx to branches of bronchi
Walls of trachea supported by tracheal cartilages (C-shaped rings)
Prevent collapse or overexpansion of trachea

13. The Bronchi Trachea branches into right & left primary bronchi
Primary bronchi branch into smaller airways that form the bronchial tree
Primary bronchi  secondary bronchi  tertiary bronchi
Bronchi end in bronchioles
Bronchodilation & bronchoconstriction change size of bronchioles

14. Bronchoscopy Video

15. 15-2 Checkpoint
The pharynx is a passageway for which two body systems?
What are the vocal cords used for?
Why are C-shaped cartilages in the tracheal wall better than completely circular cartilages?

16. 15-3: Respiratory Tract The Bronchioles
Each terminal bronchiole supplies air to a lobule of the lung
Respiratory bronchioles open into alveolar ducts that end at alveolar sacs
Surfactant on alveolar surfaces keep alveoli open

18. The Respiratory Membrane
Gas exchange occurs at the respiratory membrane on alveolar surface
Gas exchange process:
Respiratory membranes receive blood from the pulmonary arteries
Oxygen enters respiratory capillaries on alveoli
Arterioles meet capillaries, drop off CO2 & pick up O2,
Venules return oxygenated blood to the heart

19. The Lungs The Pleural Cavity
Right lung has 3 lobes, left lung has 2 lobes
The Pleural Cavity
Each lung surrounded by a pleural cavity
Lined by parietal pleura on inside of body wall
Visceral pleura covers surface of lungs
Pleural fluid reduces friction between pleural surfaces
A break in the pleural cavity causes a pneumothorax (collapsed lung)

20. 15-3 Checkpoint
Trace the path of airflow from the glottis to the respiratory membrane.
What would happen to the alveoli if surfactant were not produced?
What are the functions of the pleural surfaces?

21. 15-4: Respiration Processes
External respiration—exchange of CO2 & O2 between body & external environment
Involves breathing, gas diffusion, & transport of CO2 & O2
Internal respiration—absorb O2 & release CO2 by cells
Hypoxia—low tissue O2 levels
Anoxia—supply of O2 cut off

22. 15-4 Checkpoint Define external respiration & internal respiration.
Name the steps involved in external respiration.
How does hypoxia differ from anoxia?

23. 15-5: Pulmonary Ventilation
Pulmonary ventilation—movement of air into & out of respiratory tract
Single breath (respiratory cycle) = inhalation + exhalation
Respiratory rate—number of breaths per minute
Breathing maintains adequate alveolar ventilation—air movement into & out of alveoli

24. Pressure & Airflow to the Lungs
Air moves from high pressure to low pressure
Diaphragm actions:
Contraction—drops diaphragm & increases thoracic cavity volume
Relaxation—raises diaphragm & decreases thoracic cavity volume

25. Rib cage actions: Inhalation: Exhalation:
Elevation—raises rib cage & increases thoracic cavity volume
Depression—lowers rib cage & decreases thoracic cavity volume
Inhalation:
Diaphragm contracts  rib cage elevates  internal pressure drops  air rushes in
Exhalation:
Diaphragm relaxes  rib cage depresses  internal pressure rises  air rushes out

27. Lung Volumes & Lung Capacities
Tidal volume—amount of air moved into & out of lungs in one respiratory cycle

28. Expiratory reserve volume (ERV)—amount of air that could be forcibly expelled

29. Inspiratory reserve volume (IRV)—amount of air that can be taken in above the tidal volume

30. Vital capacity—maximum amount of air that can be moved into & out of lungs
IRV + ERV + tidal volume

31. Residual volume—amount of air that remains in lungs even after maximum exhalation

32. Typical inhalation brings in 500 mL of air
350 mL travels along conducting passageways
150 mL does not take part in gas exchange (composes anatomical dead space)

33. 15-5 Checkpoint
Explain how the diaphragm and rib cage cause air to move into and out of the lungs.
What is tidal volume?
Mark breaks a rib and it punctures the chest wall on his left side. What will happen to his left lung?
How would fluid accumulation around the alveoli affect vital capacity?

34. 15-6: Gas Exchange
Incoming air in alveoli mixes with air in anatomical dead space; some is exhaled
Blood in pulmonary arteries has higher CO2 & lower O2 than blood in the alveoli
Difference in gases cause CO2 to enter alveoli & O2 to enter bloodstream
O2 diffuses from bloodstream into body tissues
Blood returns to heart to complete cycle

35. 15-6 Checkpoint What happens to air in the alveoli?
Compare the oxygen and carbon dioxide content of the alveoli, blood in the heart, and blood in the tissues.

36. 15-7: O2 & CO2 Transport Oxygen Transport
O2 molecules carried in the blood by hemoglobin molecules
Lower O2 content = more O2 release by hemoglobin
O2 release also due to low pH & high body temp
Carbon monoxide (CO) poisoning—CO binds to hemoglobin & blocks O2 from binding

37. Carbon Dioxide Transport
CO2 transported:
Dissolved in plasma
Bound to hemoglobin—forms carbaminohemoglobin
Transported as bicarbonate ions (70% of CO2 transport)
Excess CO2 molecules act as an acid in the bloodstream & lower blood pH

38. 15-7 Checkpoint
Identify the three ways that carbon dioxide is transported in the bloodstream.
As you exercise, hemoglobin releases more oxygen to active skeletal muscles than it does when the muscles are at rest. Why?
How would blockage of the trachea affect blood pH?

39. 15-8: Control of Respiration
Local Control of Respiration
Active tissues increase difference in CO2 & O2 levels causing more delivery of O2
Respiratory Centers of the Brain
Medulla oblongata & pons regulate respiratory muscles
Control rate & depth of breathing

40. Reflex Control of Respiration
Mechanoreceptors—respond to changes in lung volume
Inflation reflex—prevents lungs from overexpanding
Deflation reflex—stimulates inhalation when lungs are collapsing
Chemoreceptors respond to chemical changes in the blood
CO2 levels are responsible for regulating respiratory activity

41. Control by Higher Centers
Portions of the brain can override respiratory centers
Control respirations during talking/singing
Hyperventilation increases rate & depth of breathing; raises blood pH
Hypoventilation decreases rate & depth of breathing; decreases blood pH

42. 15-8 Checkpoint
Are chemoreceptors more sensitive to carbon dioxide or to oxygen?
Strenuous exercise stimulates which set of respiratory reflexes?
Little Johnny tells his mother he will hold his breath until he turns blue and dies. Should she worry?