1. RESPIRATION

2. Respiration
The function of the respiratory system is to exchange gases with the cardiovascular system.
The respiratory system involves both external respiration and internal respiration. .
External respiration is the exchange of gases between the atmosphere and the blood.
Internal respiration is the exchange of gases between the blood and the cells of the body

3. The Lungs
The lungs are the central organs of the respiratory system in which gases are exchanged.
The lungs are located inside the thoracic cavity, which is bound by the rib cage and the diaphragm.
In order to decrease friction from movement of the lungs during breathing, the entire cavity and the lungs are coated with a slippery fluid secreted by membranes, called pleura.

4. The Lungs The Path of Air
External respiration begins at the mouth and at the nose.
Air is filtered and moistened by various parts of the nose and mouth and them moves into the throat.
The throat is also called the pharynx and is a tube at the back of the nasal cavity and the mouth.

5. The Lungs The Path of Air
Air then moves from the pharynx through the epiglottis into a cartilaginous tube, called the trachea.
The epiglottis is a flap of cartilage that hangs at the entrance of the larynx and directs food and air to the correct places.

6. The Lungs The Path of Air
At the end of the trachea, the air moves into the two bronchi.
Each of the bronchi lead from the trachea to the lungs.
The air moves through the bronchi and then into the smaller tubes called the bronchioles that branch from the bronchi.

7. The Lungs The Path of Air
Air finally makes its way through the bronchioles to the place where gas exchange takes place—alveoli.
Capillaries surround the alveoli, where the gasses pass into/out of
Gas exchange is facilitated by the enormous amount of surface area in the lungs.

8. Gas Exchange in the Lungs: Alveoli
When air enters the lungs, the oxygen in the air crosses the thin alveolar membranes and the capillary walls and dissolves into the blood by diffusion.
Carbon dioxide moves in the opposite direction, also by diffusion, and crosses the capillary walls and thin alveolar membranes to enter the alveoli.

9. Gas Exchange and Transport
Transport of Oxygen
Most of the oxygen absorbed into the blood combines with hemoglobin, which distributes the blood to cells.

10. Gas Exchange and Transport
Transport of Carbon Dioxide
Carbon dioxide diffuses into the blood and either stays in the plasma, binds to hemoglobin, or reacts with water to produce bicarbonate ions.
Bicarbonate ions combine with hydrogen ions to form carbonic acid, which in turn forms carbon dioxide and water. The carbon dioxide diffuses out of the capillaries into the alveoli and is exhaled into the atmosphere.

11. Oxygen-Hemoglobin Dissociation Curve
This curve relates oxygen saturation and the partial pressure of oxygen in the blood (PO2)
This is determined by “hemoglobin’s affinity for oxygen”, which is how readily hemoglobin binds to and releases oxygen from/to the surrounding fluid

12. Mechanism of Breathing
Breathing is the process of moving air into and out of the lungs.
Inspiration is the process of taking air into the lungs.
When a deep breath is taken, the chest and ribs expand.

13. Mechanism of Breathing
The expansion of the chest and ribs occurs with help from the diaphragm, which is a large skeletal muscle that separates the thoracic cavity from the abdominal cavity and the abdominal wall.
Expiration is the process of releasing air from the lungs. When this happens, the diaphragm and rib muscles relax, which forces the lungs to deflate.

14. Mechanism of Breathing
Regulation of Breathing
Both rate and depth of breathing change in order to provide oxygen and eliminate carbon dioxide from cells.
The rate of breathing is controlled by the brain and brain stem by monitoring the concentration of carbon dioxide in the blood.
All the activities used to regulate breathing are controlled subconsciously by the brain.

15. Video Clips Path of Air and Gas Exchange
Gas Exchange During Respiration
Tension Pneumothorax – Three Kings Clip (START AT 35s…NSFW!)