1. Biology 212 Anatomy & Physiology
Respiratory System

2. Functions of Respiratory System
Ventilation: Movement of air to and from sites of gas
exchange
Gas Exchange: Movement of specific gases such as
oxygen & carbon dioxide between air and
blood (in lung) or between blood and
extracellular fluids (in other tissues)
Gas Transport: Movement of oxygen (in blood) away
from lung and of carbon dioxide (also in
blood) back toward lung.
Obviously: Closely linked with circulatory system

3. Organs of Respiratory System
Nasal Cavity
Pharynx
Larynx
Trachea
Bronchi
Lungs
Air Blood
Smaller bronchi Branches of pulmonary arteries
Bronchioles Arterioles
Alveolar ducts Capillaries
Alveoli Venules
Branches of pulmonary veins

6. Nasal Cavity:
Removes dust & other debris
Warms inhaled air
Humidifies inhaled air

7. Right & left sides of nasal cavity separated by nasal septum; nasal cavity separated from oral cavity by palate

8. Inhaled air passes from nasal cavity into pharynx.

9. Inhaled air passes from nasal cavity into pharynx.
Three regions:
Nasopharynx

10. Inhaled air passes from nasal cavity into pharynx.
Three regions:
Nasopharynx
Oropharynx

11. Inhaled air passes from nasal cavity into pharynx.
Three regions:
Nasopharynx
Oropharynx
Laryngopharynx
Inhaled air passes from laryngopharynx into larynx

12. Inhaled air passes from nasal
cavity into pharynx.
Three regions:
Nasopharynx – Pseudostratified columnar epithelium
Oropharynx Mixture of pseudostratified columnar
Laryngopharynx and stratified squamous epithelia

13. Functions of Larynx:
- Keeps airway open even with negative pressure
- Keeps food / liquids from entering trachea
- Vocalization

14. Structure of Larynx:
Nine cartilages connected by muscles & ligaments

15. 3 large unpaired: Thyroid Cricoid Epiglottis
Structure of Larynx:
Nine cartilages:
3 large unpaired: Thyroid
Cricoid
Epiglottis
6 smaller paired: Arytenoid
Corniculate
Cuneiform
Anterior View
Posterior View

16. Anterior Posterior Midsagittal (Section)
Superior

17. Vocal cords (also called vocal folds or vocal ligaments) are strands of dense regular connective tissue running anteriorly from arytenoid cartilages to thyroid cartilage.
If they are adducted (close together) air moving between the cords causes them to vibrate.

18. Vocal cords (also called vocal folds or vocal ligaments) are strands of dense regular connective tissue running anteriorly from arytenoid cartilages to thyroid cartilage.
Air moving between them cause them to vibrate.
Intrinsic muscles of larynx (no, you don’t need to know their names) move the vocal cords by moving the arytenoid cartilage
Opening between vocal cords = glottis

19. Begins at bottom of larynx (cricoid cartilage)
Trachea:
Begins at bottom of larynx (cricoid cartilage)
Ends by dividing into two primary bronchi.
Cricoid Cartilage
Primary Bronchus

20. Trachea:
Held open by cartilages
which form incomplete
rings around it.
Lumen lined by
pseudostratified
columnar epithelium.
Many mucous glands
in wall; cilia on surface

21. Trachea:
Cross section of neck at level of vertebra cervical 6

22. Lungs:
Occupy most of thoracic cavity

23. Lungs:
Primary bronchus, pulmonary artery, and pulmonary veins enter/leave lung together at hilum (or hilus or root) of each lung

24. Lungs:
Surrounded by double-layered pleura
with
pleural cavity between parietal and visceral layers

25. Primary bronchus
Pulmonary artery
Pulmonary vein

26. Lungs:
Each lung divided into lobes by deep grooves or fissures
Right lung has 3 lobes:
Superior lobe
Middle lobe
Inferior lobe

27. Lungs:
Each lung divided into lobes by deep grooves or fissures
Right lung has 3 lobes:
Superior lobe
Middle lobe
Inferior lobe
Separated by 2 fissures:
Horizontal fissure
Oblique fissure

28. Lungs:
Each lung divided into lobes by deep grooves or fissures
Left lung has 2 lobes:
Superior lobe
Inferior lobe

29. Lungs:
Each lung divided into lobes by deep grooves or fissures
Left lung has 2 lobes:
Superior
Inferior
Separated by 1 fissure:
Oblique fissure

30. Lungs:
Each lung divided into lobes by deep grooves or fissures
Each lobe has is own
secondary bronchus,
its own branch of the
pulmonary artery, and
pulmonary vein

31. Lungs:
Each lobe consists of bronchopulmonary segments
Each segment has is own
tertiary bronchus, its own
branch of the pulmonary
artery, and its own branch
of the pulmonary vein

32. Trachea
Primary bronchi
Secondary bronchi
Tertiary bronchi
(smaller branches)
(bronchioles)
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli

33. Trachea
Primary bronchi
Secondary bronchi
Tertiary bronchi
(smaller branches)
(bronchioles)
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli
Conducting Zone
Respiratory Zone

34. Alveoli:
Microscopic air sacs
Diameter um
Wall = simple squamous
epithelium called
Type I Alveolar cells
Other cells:
Type II alveolar cells
(secrete surfactant)
Dust cells (macrophages)

35. As the bronchi branch and divide, so do the pulmonary arteries and pulmonary veins which accompany them.
At the end, each alveolus is
surrounded by many capillaries
for the exchange of gasses
between air (in the alveolus)
and blood (in the capillaries).

36. This air (in the alveolus) and blood (in the capillaries) are separated by a very thin wall, called the respiratory membrane, through which gasses can easily diffuse.

37. Let’s return to ventilation:
Humans inhale by creating a negative pressure (or suction) in the lungs.
Movement of the diaphragm and intercostal muscles cause the thoracic cavity to get larger.
The lung expands to fill this larger space, which lowers the pressure of the air within the alveoli.
Since the pressure of the air in alveoli is now lower than the pressure of atmospheric air, it gets pushed from the mouth and nose through the pharynx, larynx, trachea, bronchi, bronchioles, and alveolar ducts into the alveoli.

38. Air pressure is measured according to how hard it can push on other substances.
The most common way is to measure how far it can push mercury (a liquid metal with the chemical symbol Hg) up a tube.
If it can push mercury 750 millimeters (ml) up a tube, we say the air pressure is “750 millimeters of mercury”, abbreviated “750 mm Hg”.

39. Air pressure is measured according to how hard it can push on other substances.
The most common way is to measure how far it can push mercury (a liquid metal with the chemical symbol Hg) up a tube.
If it can push mercury 750 millimeters (ml) up a tube, we say the air pressure is “750 millimeters of mercury”, abbreviated “750 mm Hg”.
Here’s why this is important:
Air will always move from the place with higher pressure to the place with lower pressure

40. Terminology you need to know:
Atmospheric pressure
Intrapulmonary pressure (pressure of air in alveoli)
Intrapleural pressure (pressure of air in pleural cavity)
Difference between intrapleural pressure
and
intrapulmonary pressure
is called
transpulmonary pressure

42. Proper ventilation requires that the lungs also expand each time the thoracic cavity expands.
This can not happen if air enters the pleural cavity (pneumothorax) or if blood enters the pleural cavity (hemothorax). These cause the lung (covered by visceral pleura) to collapse and pull away from the chest wall (lined by parietal pleura).
Called atalectasis.

43. Respiratory Volumes:
TIDAL VOLUME: The volume of air which moves in and out of the lungs with a normal breath (normal = ml)

44. Respiratory Volumes:
EXPIRATORY RESERVE VOLUME: The volume of air, beyond tidal volume, which can be forcibly expired (normal = + 1,200 ml)

45. Respiratory Volumes:
INSPIRATORY RESERVE VOLUME: The volume of air, beyond tidal volume, which can be forcibly inhaled (normal = + 3,000 ml)

46. Respiratory Volumes:
RESIDUAL VOLUME: The volume of air which remains in the lungs after forcible expiration (normal = + 1,200 ml)

47. Respiratory Volumes:
VITAL CAPACITY: = Sum of Tidal volume
+ Inspiratory reserve volume
+ Expiratory reserve volume

48. Respiratory Volumes:
TOTAL LUNG CAPACITY: = Tidal volume
+ Inspiratory reserve volume
+ Expiratory reserve volume
+ Residual volume

49. Note that all of the air which enters your nose does not reach your alveoli.
Approximately 150 ml of air remains in the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.
This = Anatomical dead space.

50. Gas Exchange: Movement of specific gases:
a) From a mixture of gases into a liquid
(e.g. oxygen moves from air in the alveoli into blood in the capillaries)
b) From a liquid into a mixture of gases
(e.g. carbon dioxide moves from blood in the capillaries
into air in the alveoli)
From one liquid into another liquid
(e.g. oxygen leaves the blood and diffuses into extracellular fluid, while carbon dioxide moves from the extracellular fluids into the blood.

52. These movements of gasses follow certain laws of physics:
Dalton’s Law
Henry’s Law

53. Dalton’s Law:
Each individual gas in air contributes to the total air pressure in proportion to its concentration
and
Each individual gas is said to have a partial pressure in proportion to its concentration in the air.

54. Atmospheric Air:
Nitrogen = 78%
Oxygen = 21%
Water = 0.5%
Carbon dioxide = 0.04%
Other gases = 0.46%
Total = 100%
This mixture of gases exerts a total pressure of approximately 760 mm Hg
Nitrogen contributes 78% of the total pressure
so its partial pressure = 760 mm Hg x 78% = mm Hg
Partial pressure of oxygen: 760 mm Hg x 21% = mm Hg
Partial pressure of water: 760 mm Hg x 0.5% = 3.8 mm Hg
Partial pressure of CO2: 760 mm Hg x 0.04% = 0.3 mm Hg
Partial pressure of others: 760 mm Hg x 0.46% = 3.5 mm Hg

55. Henry’s Law:
When a mixture of gases (such as air) is in contact with a liquid, each gas will dissolve in the liquid in proportion to both its solubility and its partial pressure
The solubility of any gas is a “constant” which never changes, so
How much of a gas dissolves in a liquid (such a blood) can only be changed by changing its partial pressure, which (according to Dalton’s law) can only be changed by changing its concentration.

56. (How much of a gas dissolves in a liquid can only be changed by changing its partial pressure, which can only be changed by changing its concentration.)
Thus:
For any gas moving back and forth between air and blood:
Increasing the concentration of that gas in the air will cause
more of the gas to move from air to blood
Decreasing the concentration of that gas in the air will cause
less of the gas to move from air to blood

57. Example #1:
Suppose you have air which is
78% Nitrogen
20% Oxygen
1% Water
1% Carbon dioxide
and you measure how rapidly oxygen diffuses from this air to blood
Then, you change the composition of the air to
75% Nitrogen
14% Oxygen
5% Water
6% Carbon dioxide
How will this affect how much oxygen diffused from the air to the blood?

58. Example #2:
Suppose you have air which is
78% Nitrogen
20% Oxygen
1% Water
1% Carbon dioxide
and you measure how rapidly oxygen diffuses from this air to blood
Then, you change the composition of the air to
69% Nitrogen
20% Oxygen
5% Water
6% Carbon dioxide
How will this affect how much oxygen diffused from the air to the blood?

59. Realize:
The composition of air in alveoli does not equal the composition of air in the atmosphere.
Incoming air humidified in nose
Thus: Higher water concentration in alveoli
b) Oxygen is constantly diffusing out of alveolar air into the blood, and carbon dioxide is constantly diffusing from the blood to the alveolar air
Thus: oxygen and CO2 concentrations in alveoli
c) Each breath (+500 ml tidal volume) mixes new air with air remaining in alveoli (+1,200 ml residual volume)

60. Inspired air: Alveolar air:
78.6% Nitrogen % Nitrogen
20.8% Oxygen % Oxygen
0.5% Water % Water
0.04% Carbon dioxide % Carbon dioxide

61. Recall:
Gas exchange has four parts:
Oxygen moves from air to blood in lung
Carbon dioxide moves from blood to air in lung
Oxygen moves from blood to extracellular fluids in
consumer tissues
Carbon dioxide moves from extracellular fluids to blood
in consumer tissues
Fortunately: All of these gas movements are governed by the same laws of physics (Dalton’s and Henry’s laws).
That is: movement of a gas from one place to another depends on its concentrations in the two places and on its solubility.