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Respiratory System Objectives • Identify the function of the respiratory system • Identify the parts of the respiratory system in order, starting with inhalation • Describe gas exchange Introduction • The respiratory system brings about the exchange of oxygen and carbon dioxide between the blood, the air, and tissues • Two Types of Respiration – External respiration – exchange of gases between the atmosphere and the blood – Internal respiration – exchange of gases between the blood and the cells Parts of Human Respiratory System • • • • • • Nose Pharynx (throat) Larynx (voice box) Trachea (windpipe) Bronchi Lungs Human Respiration • Nose – Air is warmed, moistened, and filtered before entering the lungs – Hairs throughout the nasal cavity trap and filter out large dust particles – Mucus moistens the air and traps dust and smoke Human Respiration • Pharynx (throat) – Passageway for air and food • Larynx (voice box) – Contains two elastic folds of tissue called vocal chords – Muscles pull and tighten the vocal chords and air passing through causes them to vibrate, producing sound Human Respiration • Trachea (windpipe) – Epiglottis – flap of tissue that covers the entrance of the trachea when you swallow – Cilia sweep the trapped particles and mucus away from the lungs – Particles will be either swallowed or spit out – Trachea branches into bronchioles at the lungs Human Respiration • Bronchi – Two large passageways in the chest cavity – Lined with cilia and mucus – Each bronchus leads to a lung Human Respiration • In the lung, each bronchus branches into smaller bronchioles • Bronchioles further divide into millions of tiny air sacs called alveoli • Alveoli is arranged in clusters similar to grapes • Capillaries surround each alveolus Gas Exchange • The average healthy human lung contains 150 million alveoli • Oxygen dissolves in the moisture on the inner surface of alveoli and then diffuses across the capillaries and into the blood • Carbon dioxide diffuses in the opposite direction Gas Exchange • The air you inhale usually contains 21% oxygen and 0.04% carbon dioxide • Exhaled air usually contains less than 15% oxygen and 4% carbon dioxide • 97% of the oxygen moves into the red blood cells • Hemoglobin increases the amount of oxygen blood can hold more than 60 times Breathing • Breathing is the movement of air into and out of the lungs • There are no muscles which move the lungs • Air pressure is the force that drives air into the lungs • The lungs are sealed in two sacs in the chest cavity called the pleural membranes • At the bottom of the chest cavity is a large flat muscle called the diaphragm Breathing • When you inhale, the diaphragm contracts and the rib cage rises up, expanding the volume of the chest cavity • This creates a partial vacuum inside the cavity, and atmospheric pressure forces air into the lungs • Inspiration - taking air into the lungs • Expiration - releasing air out of the lungs How Breathing is Controlled • Breathing is too important for you to have complete control • The nervous system controls the involuntary portion • Breathing is controlled in the brain by the medulla oblongata • Cells in its breathing center monitor the amount of carbon dioxide in the blood • As the carbon dioxide level increases, nerve impulses from the breathing center cause the diaphragm to contract Notes Review • What is the function of the respiratory system? – The respiratory system brings about the exchange of oxygen and carbon dioxide between the blood, the air, and tissues Notes Review • List the 6 parts of the respiratory system. – Nose – Pharynx (throat) – Larynx (voice box) – Trachea (windpipe) – Bronchi – Lungs Notes Review • Describe the process of gas exchange. – Oxygen dissolves in the moisture on the inner surface of alveoli and then diffuses across the capillaries and into the blood – Carbon dioxide diffuses in the opposite direction Notes Review • Describe the process of breathing. – Breathing is controlled by a muscle called the diaphragm. – When you inhale, the diaphragm contracts and the rib cage rises up, expanding the volume of the chest cavity. – This creates a partial vacuum inside the cavity, and atmospheric pressure forces air into the lungs.
