Respiratory System

What is Respiration? Cellular respiration = producing energy (ATP) from the breakdown of molecules in food in the presence of oxygen Respiration = oxygen and carbon dioxide are exchanged between cells, blood, and air in the lungs What does CPR stand for?-- cardiopulmonary resuscitation (rescue breathing combined with chest compressions

Human Respiratory System Function: exchange oxygen and carbon dioxide Structures: Nose: filters air as it enters the body Pharynx: tube in the back of the mouth (throat) passes air and food Larynx: “voice box” = vocal cords (two folds of elastic tissue) Trachea: “windpipe” Epiglottis covers entrance of trachea when you swallow Bronchi: large passageways leading air to each lung Bronchioles are branches from bronchi in each lung Lungs: gas exchange Alveoli = tiny air sacs clustered at the end of the bronchioles and wrapped in capillaries

Figure 37-14 The Respiratory System Section 37-3 Pharynx Nose Larynx Trachea Mouth Lung Bronchiole Epiglottis Bronchus Alveoli Bronchioles Diaphragm Capillaries Edge of pleural membrane

Gas Exchange 350 million alveoli in a healthy lung Increase surface area for gas exchange across capillaries Oxygen in alveoli diffuses across capillaries into blood Carbon dioxide in blood diffuses across capillaries into alveoli Very efficient gas exchange Inhaled air contains 21% oxygen and 0.04% carbon dioxide Exhaled air contains 15% oxygen and 4% carbon dioxide

Figure 37-15 Gas Exchange in the Lungs Alveoli Section 37-3 Bronchiole Capillary

Breathing The movement of air into and out of the lungs At the bottom of the chest cavity is a large flat muscle = diaphragm The lungs are sealed in two sacs = pleural membranes When you breathe in (inhale), the diaphragm contracts and expands the volume of the chest cavity, creating a partial vacuum in the pleural membranes, allowing atmospheric pressure to fill the lungs with air When you breathe out (exhale), the diaphragm relaxes and decreases the volume of the chest cavity, increasing the pressure in the chest cavity and forcing air out of the pleural membranes

Figure 37-16 The Mechanics of Breathing Section 37-3 Air exhaled Air inhaled Rib cage descends Rib cage rises Diaphragm Diaphragm Inhalation Exhalation

How breathing is controlled Although you can voluntarily hold your breath, eventually your body will “force” you to breathe Breathing is controlled in the medulla oblongata in the brain, which is part of the autonomic nervous system Cells monitor the amount of carbon dioxide in the blood and as it increases, nerve impulses cause the diaphragm to contract bringing air into the lungs

Tobacco creates problems Smoking tobacco damages and eventually destroys the protective system by paralyzing cilia and trapping mucus in airways Tobacco contains: Nicotine = addictive, stimulate drug that increases the heart rate and blood pressure Carbon monoxide = poisonous gas that blocks the transport of oxygen by hemoglobin in the blood Tar = carcinogen (causes cancer)

Respiratory diseases caused by smoking Chronic bronchitis = bronchi become swollen and clogged with mucus, so constant coughing to try and force the particles out Emphysema = respiratory disease due to loss of elasticity of lung tissue making breathing very difficult Lung cancer = deadly because it spreads to other parts of body Heart disease = narrowing of blood vessels increases blood pressure and makes the heart work harder