Breathing and the LungsChapter 14, Section 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

Key Terms

•Respiratory system•Trachea•Bronchus•Alveoli•Gas exchange•Diaphragm•Tidal volume•Vital capacity•Breathing rate

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)

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

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

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

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)

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

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

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

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

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

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

Answers

•#1 the correct answer is A, alveoli•#2 is true•#3 is true•#4 is true•#5 is false