Respiratory System PDF - Biology

THE RESPIRATORY SYSTEM  The Respiratory System The respiratory system is responsible for taking in oxygen and removing removing carbon dioxide from the body. Nasal cavity Mouth Trachea Bronchus...

THE RESPIRATORY SYSTEM  The Respiratory System The respiratory system is responsible for taking in oxygen and removing removing carbon dioxide from the body. Nasal cavity Mouth Trachea Bronchus Bronchus Lung Lung  The Respiratory System ➔ When we inhale , air enters through our nose and mouth. ➔ The air then travels down the trachea (strong, rings of cartilage ) ➔ Just before the lungs, the trachea is divided into two branches called bronchus (plural: bronchi) The Lungs These are the organs that allow gas exchange trachea (has rings of cartilage) bronchi (bronchus) bronchioles alveoli (alveolus) To help keep the air that reaches our lungs clean , the bronchi are lined with cells covered in cilia The cilia are covered in mucus a thick layer of mucus cilia which helps trap cells bacteria and dirt before they reach the lungs As the air enters our lungs, the bronchus branches into smaller and smaller tubes At the end of these tubes are tiny sacs called alveoli  The Alveoli The alveoli are surrounded by tiny capillaries The oxygen from the air diffuses into the capillaries and the carbon dioxide in our blood diffuses into the air sacs Alveoli (air sacs) Provide large surface area for gas exchange The surface area (using the alveoli) of both lungs is equivalent to the surface of a tennis court !  Features of Alveoli for Efficient Gas Exchange Alveoli have… ➔ large surface area to absorb oxygen. ➔ moist surface to allow oxygen to dissolve. ➔ thin lining to allow easy diffusion of gases. ➔ dense network of blood capillaries for easy gas exchange.  Breathing… Your lungs do not contain any muscle tissue To breathe, our body uses the muscles in our rib cage and our diaphragm to change the space inside your chest cavity. As you inhale, your diaphragm contracts and moves down. The rib cage expands as the muscles between your ribs contract. This increases the space (but lowers the pressure) in our lungs and air rushes in. To exhale, the diaphragm and the muscles of the rib cage relax. The diaphragm moves up, decreasing the space (but increasing the pressure) and the air moves out of our lungs. How The Diaphragm Works…