10.1 Lungs

• What are the main parts of the respiratory system?

  The main parts of the respiratory system are the lungs, trachea (windpipe), bronchi, bronchioles, diaphragm, and alveoli.
• Describe the structure and basic function of alveoli

  Alveoli are tiny air sacs in the lungs where gas exchange occurs. They have thin walls, allowing oxygen to pass into the bloodstream and carbon dioxide to exit the body when we breathe.
• Understand how we inhale and exhale.

  When we inhale, the diaphragm contracts and moves downward, while the rib muscles lift the ribs up and out. This increases the volume of the chest cavity, causing air to rush into the lungs. When we exhale, the diaphragm relaxes and moves upward, while the rib muscles relax, reducing the chest cavity's volume and pushing air out of the lungs.
• State the main function of each part of the respiratory system.

  1.Lungs: Exchange oxygen and carbon dioxide with the blood.

  2. Trachea (windpipe): Conducts air to and from the lungs.

  3. Bronchi: Branches of the trachea that carry air to each lung.

  4. Bronchioles: Smaller branches of the bronchi that distribute air within the lungs.

  5. Diaphragm: Muscle beneath the lungs that controls breathing by contracting and relaxing.

  6. Alveoli: Tiny air sacs in the lungs where gas exchange occurs.
• Describe the passage of air through the respiratory system

  Air enters the respiratory system through the nostrils or mouth, travels down the trachea (windpipe), branches into bronchi, then bronchioles, reaching the alveoli in the lungs where gas exchange occurs. After oxygen is absorbed into the bloodstream and carbon dioxide is released, air exits the lungs following the reverse path.
• State how the specialised structure of the alveoli helps them function.

  The thin walls of alveoli help oxygen and carbon dioxide move between the lungs and the blood. This allows oxygen to enter the bloodstream and carbon dioxide to leave it, making breathing efficient.
• Describe how oxygenated blood is different to deoxygenated blood.

  Oxygenated blood has oxygen, giving it a bright red color, while deoxygenated blood lacks oxygen and appears darker red
• Describe what occurs to allow us to exhale.

  During exhalation, the diaphragm and rib muscles relax, reducing the volume of the chest cavity. This increase in pressure forces air out of the lungs.
• Describe what occurs to allow us to inhale .

  During inhalation, the diaphragm contracts and moves downward while the rib muscles lift the ribs up and out, expanding the chest cavity and drawing air into the lungs.