1. The Respiratory System

2. Respiratory System
Consists of the trachea, bronchi, lungs, and alveoli.
Gas exchange is vital here.

3. Breathing through your nose
When you breathe in through your nose, air mixing in the nasal cavity, warming up the air in the nose before it enters the lungs.
The mucus and hairs in the nose are designed to trap particles in the air to prevent them from depositing in the lungs.

4. The path that air follows
After entering the nose, air passes down a muscular tube called the pharynx (food also passes through here).
Air then passes through the larynx (voice box) which is located in the neck.

5. From the larynx, air travels down the trachea, which is a long tube that runs down to the bronchi.
The first division of the trachea is called the bronchi, which subdivides in the lungs into smaller and smaller tubes.
Bronchi and the trachea can secrete mucus to trap foreign particles, just like the nasal cavity.

6. These smaller tubes, now called bronchioles, subdivide even further into the alveoli.
The alveoli are small sacs that line the inside of the lungs, and are the places where gas exchange occurs.

7. The lungs
The lungs are held in place by the ribs and the diaphragm, which is a large organ that is designed to aid the lung in respiration.
The lungs work by creating a pressure differential. This causes air to rush in or out depending on the diaphragm.
When the diaphragm relaxes, the pressure in the lungs is greater than the atmosphere, which cause air to exit the lungs.

8. Factors that affect breathing
The body does not monitor O2 levels in the body. It actually monitors carbon dioxide levels in the body. As long as you have little carbon dioxide in your lungs, you breathe normally, but if the amount of carbon dioxide in the lungs increases, then you begin to breathe heavier to increase O2 levels.

9. Oxygen and carbon dioxide transport
Oxygen is carried by the RBCs by binding with the iron in the blood. This oxygen can then be released at any point.
Oxygen transport:
1. oxygen reaches the lungs.
2. oxygen diffuses through the capillaries.
3. oxygen rich blood travels to the heart.
4. oxygen diffuses through the cells in aerobic respiration.
5. carbon dioxide causes a pH change in the blood, which in turn causes the RBCs to change shape to receive oxygen easily. Carbon dioxide leaves the blood.
6. carbon dioxide travels as bicarbonate ions.
7. heart pumps blood to lungs.
8. Carbon dioxide is kicked out of the body.

10. Why carbon dioxide travels as bicarbonate.
Carbon dioxide travels as -HCO3- or bicarbonate, in the blood to act as a buffer for the blood.
Buffers act to prevent extreme pH changes, thus preventing the blood from becoming too acidic or basic.

11. Diseases of the lungs
Asthma- causes the bronchioles to constrict making it difficult to breathe. Can be deadly if untreated.
Emphysema- alveoli lose elasticity, making it hard to breathe, causing fatigue and breathlessness. Usually caused by cigarette smoking.
Lung cancer- leading cause of death in the world today. Cancer is caused by abnormal cell growth. Around 1 in 3 people with lung cancer die from it. Usually caused by cigarette smoking.

12. Healthy lungs

13. Not so healthy lungs