the lungs

• What is the trachea commonly known as?


  Windpipe
• What muscle is responsible for breathing by contracting and relaxing?

  Diaphragm
• What is the primary function of the trachea?


  To carry air to and from the lungs
• What are the main branches of the trachea that lead into the lungs called?

  Bronchi
• What are bronchioles?


  Smaller branches of the bronchi within the lungs
• Where does gas exchange occur in the lungs?


  In the alveoli
• What is the role of alveoli in the respiratory system?


  To carry out gas exchange
• What is necessary for effective gas exchange in the alveoli?


  A good blood supply
• How does a steep concentration gradient benefit gas exchange?


  It enhances the diffusion of gases
• Why are there many alveoli in the lungs?


  To create a large surface area for gas exchange
• What is the primary function of the small intestine?


  To absorb digested food
• What are villi in the small intestine?


  Finger-like projections that increase surface area
• How do villi assist in digestion?


  By increasing surface area for absorption
• What do villi contain that aids in nutrient absorption?


  A network of capillaries
• Why is a good blood supply important for villi?


  It increases absorption of nutrients
• What are the key features of villi that enhance absorption in the small intestine?


  • Single layer of cells
  • Good blood supply
  • Increase surface area
• key structures of the lungs

  • Trachea
  • Bronchi
  • Alveoli
  • Capillary network surrounding the alveoli