1. Breathing and the Lungs
Chapter 14, Section 2

2. Objectives Identify the main structures of the Respiratory System
Explain how air is inhaled and exhaled
Describe gas exchange in the lungs and the rest of the body
Explain how the body regulates breathing

3. Key Terms Respiratory system Trachea Bronchus Alveoli Gas exchange
Diaphragm
Tidal volume
Vital capacity
Breathing rate

4. How the Respiratory System Works
Humans must have oxygen to survive
Oxygen helps us “burn” food
Carbon Dioxide and water are products from the burn
The cells of our body each require this service provided by the respiratory system
Oxygen is brought in as we breath in, (inhale)
Carbon Dioxide is removed as we breath out, (exhale)

5. Parts of the Respiratory System
Trace the path of air from the mouth to the smallest area of the lung.
It appears as a system of branching passages.
The “purple” areas show the capillaries where red and blue are mixed

6. Gas Exchange The top figure shows a small section of the lung
Notice the capillaries that surround the “air sac” or alveoli
The bottom figure shows how the gases “leak” back and forth
The RBC “releases” CO2 and can then “receive” O2

7. How Does the Body Get O2?
The cells of your body have small “holes” that allow the oxygen and Carbon Dioxide to pass in and pass out of the cell
Capillaries surround every cell and allow for the “drop off” and “pick up” to occur
Every cell has this “service” and would die without it

8. Breathing In and Out The lungs hold a maximum volume of air
This known as your Vital Capacity
When you are breathing normally, this is the Tidal Volume
The image shows a fancy gadget called a Spirometer, (for testing these amounts)

9. Automatic Breathing
Your brain sends signals to the muscles of your rib cage and diaphragm causing them too contract
Control is both conscious and subconscious
Sensors in several arteries can detect oxygen levels
When levels are low, the brain sends messages to “speed up” your breathing

10. Definitions
Respiratory system is the system that brings oxygen to the body and removes Carbon Dioxide
Trachea is the tube that brings air between the throat and the chest
Bronchus is one of two large tubes that carry air between the trachea and the lungs
Alveoli is a small sac in the lung where oxygen and carbon dioxide are exchanged between the air and the lungs

11. Definitions
Gas exchange is the exchange of oxygen and carbon dioxide between the body and the air
Diaphragm is a sheet of muscles below the chest cavity that functions in breathing
Tidal volume is the volume of air that is exchanged during normal breathing
Vital capacity is the maximum amount of air a person can exhale
Breathing rate is the number of times a person breathes in and out in a minute

12. Summary
The nose, mouth, throat, trachea, and bronchi are part of the respiratory system
Air is taken in when the diaphragm and the muscles between the ribs contract; Air is released when these muscles relax
Gas exchange occurs in the lungs and in the body’s tissues
The brain controls breathing

13. Questions 1. In the respiratory system, gas exchange occurs in the
A. Alveoli
B. Throat
C. Trachea
D. Bronchus
E. all of the answers are correct

14. Questions True or false?
2. The brain regulates breathing automatically.
3. The brain regulates breathing consciously.
4. The brain senses O2 and CO2 when it regulates breathing
5. the heart is part of the respiratory system

15. Answers #1 the correct answer is A, alveoli #2 is true #3 is true
#5 is false