The Respiratory System Chapter 18, Section 1 Monday, April 12, 2010 Pages 566 -- 575

Objectives Understand the functions of the respiratory system. Describe the structures that are involved with the passage of air as it travels to the lungs. Understand the role of oxygen, carbon dioxide, and water as they move in the lungs. Explain the process of breathing and speaking.

Vocabulary Words Respiration Cilia Pharynx Trachea Bronchi Lungs Alveoli Diaphragm Larynx Vocal cords

Respiratory System Functions of the respiratory system: Move oxygen from the outside environment into the body. Removes carbon dioxide and water from the body.

Respiration It is the process in which oxygen and glucose undergo complex chemical reactions inside cells. These chemical reactions release energy that your body needs to function properly. This process also produces carbon dioxide and water.

Respiration vs. Breathing In respiration, the oxygen and glucose in your body’s cells undergo a complex series of chemical reactions. The chemical reactions release energy that aid in growth and regular cell function. Respiration also gets rid of carbon dioxide and a small of water through your lungs. All of these things are processes that take place as a chemical reaction inside cells.

Respiration vs. Breathing It is the movement of air into and out of the lungs that is referred to as breathing.

Respiration Path Air from the outside environment ---> nose ---> pharynx ---> trachea ---> bronchi ---> the lungs.

The Nose The nose is the first organ the air from the outside environment travels through. The inside of the nose is coated with mucus. Mucus cleans, warms, and moistens the air that we breathe. The inside of the nose is lined with cilia.

The Nose -- cont’d Cilia in your nose are tiny hairlike extensions that can move together. They sweep the mucus into the throat where it is swallowed.

The Pharynx The pharynx is the next organ after the nose. The pharynx is also known as simply, the top of the throat.

The Trachea The trachea is also known as the windpipe. The trachea leads from the pharynx to the lungs. Walls of the trachea are made up of rings of cartilage that prevents it from collapsing. The trachea is lined with cilia and mucus.

Bronchi Air from the trachea move into the right and left bronchi (singular is bronchus). Bronchi are passages that direct air into the lungs.

The Lungs The lungs are the main organs of the respiratory system. Inside the lungs, each bronchus divides into smaller and smaller tubes. At the end of the smallest tubes are bunches of alveoli.

Alveoli (singular alveolus) Alveoli are tiny sacs of lung tissues. These tiny sacs are specialized for the movement of gases between air and blood. Alveoli are surrounded by capillaries.

Gas Exchange Air enters an alveolus ---> oxygen passes through the wall of the alveolus ---> capillary wall into the blood ---> carbon dioxide and water pass from the blood into the alveoli. This process is called gas exchange.

The Diaphragm The diaphragm is a large dome-shaped muscle at the base of the lungs. The diaphragm and rib muscles make the chest cavity expand when you inhale and contract when you exhale.

The Process of Breathing You inhale or breathe in. Rib muscles contract and lifts the chest wall upward and outward. The diaphragm contacts and moves downward. When the rib muscles and diaphragm contract, it lifts the chest wall and provides more space for the lungs to expand.

The Process of Breathing -- Cont’d At this time, that space is fully occupied and no extra air can fill it. This causes the pressure of the air inside the lungs to decrease. The pressure of the air inside the chest cavity is lower than that of the surrounding atmosphere pushing on the body.

The Process of Breathing -- Cont’d This difference in air pressure causes the air to rush into your chest. (Think vacuum cleaner!) This describes inhalation. When you exhale or breathe out, the rib muscles and diaphragm relaxes. The relaxation causes the chest cavity to become smaller, squeezing the air out of the lungs.

The Larynx The larynx is also known as your voicebox. It is located at the top of the trachea. The vocal cords are folds of connective tissue that stretch across the opening of the larynx. Vocal cords vibrate when air passes over them. This vibration is what produces the sound of your voice.

High and Low Tones The high and low pitch tones in your voices depend on the length of the vocal cords. High pitch voices are produced by the contraction and shortening of the vocal cords. Low pitch voices are produced by the relaxation of the vocal cords. Vocal cord length changes over a person’s lifetime.

Review What is the function of the respiratory system? Trace the path of oxygen in the respiratory system (air to alveoli). What is the difference between respiration and breathing?

Homework Workbook 18.1 (4/14) Vocabulary quiz 18.1 (4/14) Worksheet 18.1 (4/14) Current Science -- Free Range (4/13) Bring in one clean water bottle. Make sure it has a narrow neck. Remove the label.