1. The Respiratory System
The respiratory system works with the cardiovascular system to exchange gases between the air and blood (external respiration) and between blood and tissue fluids (internal respiration).
Inspiration and expiration move air in and out of the lungs during breathing.
Cellular respiration is the final destination where ATP is produced in cells.

2. Oxygen Transport How is oxygen transported throughout the body?
Red Blood Cells attach oxygen to hemoglobin proteins
As hemoglobin and oxygen combine the blood turns bright red; the blood is NEVER blue

4. Inspiration
During inspiration, the thoracic cavity and lungs expand so that air is drawn in.

5. Cilia in the Trachea

7. Alveoli

8. Gas Exchanges in the Body
External Respiration
External respiration is the diffusion of CO2 from pulmonary capillaries into alveolar sacs and O2 from alveolar sacs into pulmonary capillaries.
The principles of diffusion alone govern whether O2 or CO2 enters or leaves the blood in the lungs and in the tissues.

10. Placement of the Vocal Cords
a. Frontal section of the larynx shows the location of the vocal cords inside. b. Viewed from above, it can be seen that the vocal cords are stretched across the glottis. When air passes through the glottis, the vocal cords vibrate, producing sound. The glottis is narrow when we produce a high-pitched sound (top), and it widens as the pitch deepens (bottom).

11. The Path of Air
This drawing shows the path of air from the nose to the trachea.

12. Gas Exchange in the Lungs
The lungs consist of alveoli surrounded by an extensive capillary network. Notice that the pulmonary artery carries O2-poor blood (colored blue), and the pulmonary venule carries O2-rich blood (colored red).

13. Expiration
During expiration, the thoracic cavity and lungs resume their original positions and pressures. Now air is forced out.

14. During external respiration in the lungs, CO2 leaves the blood and O2 enters the blood. During internal respiration in the tissues, O2 leaves the blood and CO2 enters the blood.
External Respiration: At the pulmonary capillaries, O2 enters red blood cells where it combines with hemoglobin (Hb) to form oxyhemoglobin (HbO2). Also, bicarbonate (HCO3-) is converted inside red blood cells to H2O and CO2. CO2 leaves red blood cells and capillaries and diffuses into the lungs to be exhaled.
Internal Respiration: At the systemic capillaries, oxyhemoglobin (HbO2) inside red blood cells gives up its oxygen and becomes Hb and O2. Hemoglobin (Hb) now combines with H+ to form reduced hemoglobin (HHb). O2 leaves red blood cells and capillaries and enters tissue cells. At the same time, CO2 enters red blood cells. Some combines with Hb to form carbaminohemoglobin (HbCO2). Most CO2 is converted to bicarbonate (HCO3-), which is carried in the plasma.

15. Sites of Upper Respiratory Infections
A nasal infection, more commonly called rhinitis, is the usual symptom of a common cold due to a viral infection, but rhinitis can also be due to a bacterial infection. Secondary to an URI, the sinuses, middle ear, tonsils, and vocal cords can become infected. Allergies also cause runny nose, blocked sinuses, and laryngitis.

16. Lower Respiratory Tract Disorders
Exposure to infectious pathogens and/or air pollutants, including cigarette and cigar smoke, can cause the diseases and disorders shown here.
Pneumonia: Alveoli fill with thick fluid, making gas exchange difficult.
Pulmonary fibrosis: Fibrous connective tissue build up in the lungs, reducing lung elasticity.
Pulmonary tuberculosis: Tubercles encapsulate bacteria, and the elasticity of the lungs is reduced.
Emphysema: Alveoli burst and fuse into enlarged air spaces. Surface area for gas exchange is greatly reduced.
Asthma: Airways are inflamed due to irritation, and bronchioles constrict due to muscle spasms.
Bronchitis: Airways are inflamed due to infection (acute) or an irritant (chronic). Coughing brings up mucus and pus.

17. Normal Lung versus Cancerous Lung
On the left is a normal lung with the heart in place. Note the healthy red color. On the right are the lungs of a heavy smoker. Notice how black the lungs are except where cancerous tumors have formed.

18. Trace a molecule of oxygen from your mouth to the heart including all
Review Question:
Trace a molecule of oxygen from your
mouth to the heart including all
sections of the respiratory system
involved and the proper circulatory
vessels.

19. Diversity in the structure of gills, external body surfaces functioning in gas exchange

20. The Structure and Function of Fish Gills
Each arch has two rows of gill filaments,
composed of flattened plates called lamellae.

21. Countercurrent Exchange
O2 diffuses into the blood over the entire
length of a capillary

22. Tracheal Systems Air enters the tracheae through spiracles and
passes into tracheoles.

23. The Avian Respiratory System
During inhalation stale air from the lungs enters the anterior air sacs and fresh air enters the posterior air sacs.

24. The Avian Respiratory System
During exhalation stale air from the posterior air sacs enters the lungs and air from the anterior air sacs exits.

25. Automatic Control of Breathing

26. Loading and Unloading of Respiratory Gases

27. Oxygen Dissociation Curves for Hemoglobin

28. Dissociation Curves for Two Hemoglobins

29. List the structures that a molecule of air
would go through starting with the mouth and ending with the lungs.
What part of the brain controls breathing?