7. absorption of materials

Question 1

describe the alveoli

Answer 1

• main function is exchange of gases
• thin walls
• walls are very close to blood capillaries
• surrounded by a network of blood capillaries so that gases can be easily transported to and from lungs

Question 2

describe the lungs

Answer 2

• they are gas exchange organs
• consist of a large number of alveoli providing a large surface area
• oxygen and CO2 are absorbed through the thin alveolar walls to or from the many blood capillaries

Question 3

describe the villus

Answer 3

each villus contains a network of capillaries to absorb glucose and amino acids

the lacteal absorbs the products of fat digestion (glycerol and fatty acids)

Question 4

features all absorption surfaces have:

Answer 4

large surface area - for diffusion of gases

thin walls - allows fast diffusion of oxygen into blood and carbon dioxide into the alveoli

surrounded by large capillary network - so gases can be easily transported to and from the lungs