T HE R ESPIRATORY S YSTEM Chapter 2, Section 2.1

Y OUR B ODY N EEDS O XYGEN ! The body can store food, but it is unable to store a lot of oxygen. Respiratory system functions: to get oxygen from the environment remove carbon dioxide and other waste The continuous process of moving and using oxygen involves mechanical movement and chemical reactions. Air is transported into your lungs by mechanical movements. Oxygen is used during chemical reactions that release energy in your cells.

E XCHANGING O XYGEN AND C ARBON D IOXIDE Most living things must have oxygen to survive. Oxygen (along with other gases) enters your body when you inhale. Oxygen is transported to cells throughout the body. The air you breathe contains only about 20% oxygen and less than 1% CO2. It is important to exhale CO2 because high levels of it will damage and destroy cells. Proper levels of CO2 and oxygen are required for our body to maintain homeostasis. If levels of oxygen or CO2 change, your brain signals the body to breathe faster or slower.

C ELLULAR R ESPIRATION Cellular respiration occurs in your cells as they use oxygen in chemical reactions to release energy. The respiratory system works with the circulatory system and digestive system to make cellular respiration possible. CR requires glucose (from food) and oxygen (from breathing) to release energy. CO2 is a waste product of the process and must be removed. Remember: glucose + oxygen  carbon dioxide + water + energy

R ESPIRATORY S TRUCTURE AND F UNCTION Nose, Throat and Trachea When you inhale, air enters your body through your nose or mouth. Inside your nose, tiny hairs called cilia filter dirt and other particles out of the air. Mucus, a sticky liquid in your nasal cavity, also filters the air by trapping particles like dirt and pollen as air passes by. The nasal cavity warms the air slightly before it moves down your windpipe or trachea. The trachea is surrounded by rings of cartilage to keep the tube open. The epiglottis keeps air, food, and liquids from entering your stomach.

R ESPIRATORY S TRUCTURE AND F UNCTION Lungs The lungs are two large organs located on either side of the heart. When you breathe, air enters the throat, passes through the trachea, and moves to the lungs through structures called bronchial tubes. The bronchial tubes which carry air into each lung) branch throughout the lungs into smaller and smaller tubes. At the end of the smallest tubes, air enters tiny air sacs called alveoli. The walls of alveoli are only 1 cell thick (this is thinner than a piece of paper). Oxygen passes from the inside of the alveoli into the blood and CO2 waste is passed from the blood to the alveoli.

R ESPIRATORY S TRUCTURE AND F UNCTION Ribs and Diaphragm The rib cage encloses a space inside your body called the thoracic cavity. Some ribs are connected by cartilage to the breastbone or to each other, making the rib cage flexible. This allows the rib cage to expand when you breathe and make room for the lungs to expand and fill with air. The diaphragm is a large muscle that stretches across the floor of the thoracic cavity. When you inhale, your diaphragm contracts and pulls downward, making the lungs expand. Air rushes into the lungs and inhalation is complete. When the diaphragm and other muscles relax, the process reverses and you exhale.

O THER F UNCTIONS OF R ESPIRATION Speech and Other Respiratory Movements Air moving through your vocal cords allows you to produce sound The muscles in your throat, mouth, cheeks and lips allow you to form that sound into words. The larynx, or voice box, is a 2 inch tube shaped organ the size your thumb located at the top of your trachea. The vocal chords are folds of tissue located in the larynx. When you speak, air causes vocal chords to vibrate and produce sound.

O THER F UNCTIONS OF R ESPIRATION Speech and Other Respiratory Movements Expressing Emotion Coughing/sneezing Crying Sighing Yawning Laughing Hiccups- sudden inhalations that make your diaphragm contract. When the diaphragm contracts, the air passageway between the vocal cords closes, creating the sound of a hiccup. Hiccups can be caused by eating too fast, stress, and sudden temperature change.

O THER F UNCTIONS OF R ESPIRATION Water Removal Most respiratory movements including hiccups, yawning, coughs, breathing and speaking involve releasing water from your body to the environment. Water is lost through sweat, urine, and exhalations of air. When it’s cold enough outside, you can see your breath because the water vapor you exhale condenses into larger droplets when it moves from your warm body to the cold air.