Biology paper 2

• What is the primary function of the human lungs?

  To provide an exchange surface for gas exchange
• What is absorbed by the lungs from the air?

  Oxygen needed for respiration
• What is transferred from the blood into the lungs?

  Carbon dioxide produced by respiration
• Where are the human lungs located?

  Within the chest
• What is the process called that brings air into contact with the gas exchange surface?

  Ventilation
• What adaptations does the human respiratory system have for gas exchange?

  • Allows air to pass in and out of the body
  • Efficient gas exchange occurs in the alveoli
• What protects the lungs in the thorax?

  12 pairs of ribs
• What muscles are involved in moving the ribs?

  Two sets of intercostal muscles
• What is located below the lungs?

  A muscular diaphragm
• What encloses the lungs?

  Two aligning pleural membranes
• How do the pleural membranes function in relation to the lungs?

  They wrap around the lungs and line the rib cage
• What is the main organ in the circulatory system?

  The heart
• What is the primary function of the heart?

  To transport oxygen and nutrients to the body's tissues
• Where does deoxygenated blood flow from the body first?

  To the right atrium
• What is the next step after blood flows from the right atrium?

  It flows to the right ventricle
• What happens to blood in the lungs?

  It becomes oxygenated
• Where does oxygenated blood flow after the lungs?

  To the left atrium
• What is the final destination of oxygenated blood before it goes to the body?

  Left ventricle
• What is the path blood takes as it passes through the heart?

  1. Blood flows from the body via the vena cava and from the pulmonary vein.
  2. It enters the right atrium and then the right ventricle.
  3. Blood travels to the lungs via the pulmonary artery.
  4. Blood returns from the lungs to the pulmonary vein.
  5. Blood travels around the body to be re-oxygenated.
• What do waste products leave the tissues as?

  Carbon dioxide and waste from muscle tissues and various organs
• How does blood travel to the tissues?

  Via the arteries
• What happens to carbon dioxide in the blood?

  It leaves the body in its bodily form via the veins
• What happens to blood after it is re-oxygenated?

  The whole process continues
• What does the trachea branch into?

  Two bronchi
• What is the function of the rings of cartilage in the trachea?

  They help to keep the trachea open as air is drawn in
• What do the bronchi split into?

  Smaller branches called bronchioles
• What are bronchioles?

  They are smaller tubes that branch from the bronchi
• What do bronchioles end in?

  A cluster of microscopic air sacs called alveoli
• Where does gaseous exchange occur?

  Between the alveoli and blood in the capillaries
• What supplies the lungs with blood?

  The pulmonary artery
• What is the role of capillaries in the lungs?

  They supply blood to the alveoli for gas exchange
• What happens to the air breathed in and out?

  It passes through the bronchioles
• What happens to blood after it passes through the capillaries in the lungs?

  It goes to the pulmonary vein
• What is the pathway of air from the trachea to the alveoli?

  • Trachea branches into bronchi
  • Bronchi split into bronchioles
  • Bronchioles end in alveoli
• Describe the process of gaseous exchange in the lungs.

  • Occurs between alveoli and capillary blood
  • Oxygen enters the blood, carbon dioxide exits
  • Facilitated by the thin walls of alveoli and capillaries
• What is the approximate diameter of each alveolus?

  About 300 µm
• Why do alveoli have a large surface area to volume ratio?

  Because of their small spherical size
• How many alveoli are there approximately in one lung?

  About 350 million
• What is the total surface area of the alveoli?

  About 70 m²
• What percentage of the alveoli's surface is covered by capillaries?

  70 percent