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The Respiratory System

Life Science - Middle School

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The Respiratory System © C opyright NewPath Learning. All Rights Reserved. 94-4906 www.newpathlearning.com The respiratory system consists of the airways, the lungs, and the respiratory muscles that assist the movement of air into and out of the body. The primary function of the respiratory system is to supply the blood with oxygen and to remove carbon dioxide. Structures of Respiration The air starts its journey to the lungs through one of the two nostrils of the nose. The nasal cavity is lined with cilia and mucus that trap and eliminate particles. Blood vessels in the nose begin to warm the air entering the body while the mucus moistens the air. The air then enters the throat or pharynx. Once through the pharynx, the air enters the trachea. The trachea is the airway that leads from the pharynx to the lungs and is also called the windpipe. The trachea has rings of cartilage that help it to stay open and are lined with cilia and mucus to trap invading particles. The lungs are the key organs of the respiratory system. The left bronchus leads into the left lung and the right bronchus leads into the right lung. The bronchi branch off into smaller and smaller passageways. At the very end of each branch are structures called alveoli. Process of Gas Exchange When air enters the alveoli in the lungs, oxygen passes through the walls of the alveoli and then the walls of the capillaries and into the blood. Carbon dioxide passes from the blood, through the capillary walls and into the alveoli. This is the process of gas exchange. The alveoli are small sacs within the lungs that specialize in the exchange of gas between the blood and air. The Mechanics of Breathing The diaphragm plays an important role in the breathing process. When a person inhales, the rib muscles contract which cause the chest to move up and out. At the same time, the diaphragm also contracts moving downward. This action allows the lungs to expand and take in air. When a person exhales, the diaphragm and rib muscles relax. This decreases the size of the chest and lungs and forces the air to exit the lungs. diaphram exhale inhale CO2 out O2 in alveoli wall sinuses trachea larynx lung bronchus diaphram pharynx RBC carbon dioxide wall of alveoli capillary nose alveoli oxygen bronchioles

The Respiratory System © C opyright NewPath Learning. All Rights Reserved. 94-4906 www.newpathlearning.com • alveoli • larynx • bronchioles • lungs • bronchus • mucus • capillary • nasal cavity • carbon dioxide • nose • cilia • oxygen • diaphram • pharynx • exhale • sinuses • inhale • trachea Key Vocabulary Terms What is the primary function of the respiratory system? __________________ __________________________________________________________________ __________________________________________________________________ Structures of Respiration Describe the major structures of respiration: Lungs ____________________________________________________ __________________________________________________________ Trachea ___________________________________________________ ___________________________________________________________ Bronchi ___________________________________________________ _____________________________ Alveoli ________________ _____________________ _____________________ _____________________ Process of Gas Exchange Describe the process of gas exchange. ___________________ ________________________ ________________________ ________________________ ________________________ ________________________ The Mechanics of Breathing Describe the mechanics of breathing. ______________________ ______________________ ______________________ ______________________ ______________________ ______________________ ______________________ \|xiBAHBDy01785rzu

The Respiratory System

Life Science - Middle School

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