KA 7: Absorbtion of Materials

• What must be absorbed into the bloodstream for respiration?

  Oxygen and nutrients from food
• Why must waste materials be removed from cells?

  To prevent toxicity and maintain homeostasis
• What do tissues contain to allow material exchange?

  Capillary networks
• What features do surfaces involved in absorption share?

  Large surface area, thin walls, extensive blood supply
• How does breathing facilitate gas exchange?

  Oxygen is absorbed, carbon dioxide is released
• How do oxygen and carbon dioxide enter and leave the bloodstream?

  By diffusion
• What are the gas exchange organs in the body?

  Lungs
• What provides a large surface area in the lungs?

  A large number of alveoli
• How does gas exchange occur in the alveoli?

  Through thin alveolar walls to blood capillaries
• What structural feature keeps the air passages open?

  Cartilage in the trachea and bronchi
• Why is gas exchange efficient in the alveoli?

  Large surface area, thin lining, good blood supply
• What role does moisture play in gas exchange?

  It helps gases dissolve into liquid
• How does a good blood supply affect gas exchange?

  Ensures immediate transport of gases
• What enzymes digest food in the digestive system?

  Amylase, protease, and lipase
• What happens to food by the time it reaches the small intestine?

  It is broken down into smaller molecules
• What features make the small intestine suitable for absorption?

  • Long and folded structure
  • Many small finger-like projections (villi)
  • Very thin walls for rapid diffusion
  • Good blood supply for efficient transport
• What is the function of villi in the small intestine?

  Increase surface area for absorption
• How does an individual villus aid in absorption?

  Contains blood capillaries and lacteals
• What do lacteals do in the villi?

  Collect fats and drain into bloodstream
• Why are epithelial cells in villi one cell thick?

  To allow rapid diffusion of nutrients
• What nutrients are absorbed into blood capillaries from villi?

  Glucose and amino acids
• How do fatty acids and glycerol get transported in the body?

  Combined into fats and collected by lacteals
• Label this diagram.

  Villus.

  A) Epithelium

  B) Capillary network

  C) Lacteal

  D) Nerve

  
• Label this diagram.

  Structure of the lungs.

  A) rings of cartilage

  B) trachea

  C) ribs

  D) bronchus

  E) heart