The Human Gas-exchange System

• Why are the volumes of oxygen and carbon dioxide large in mammals?

  They are large organisms with a large volume of living cells, and they have high metabolic and respiratory rates.
• What are the features of a human gas-exchange system?

  Nasal cavity, nostril, trachea, bronchus, bronchioles, alveoli, and lungs.
• What blood vessels branch over the alveoli?

  Pulmonary veins with oxygenated blood flowing out and pulmonary arteries with deoxygenated blood flowing in.
• What is the site of gas exchange in a mammal?

  The lungs.
• Why are the lungs located inside the bond?

  Air is not dense enough to support and protect the delicate structures, and the body would otherwise lose a great deal of water.
• What are the lungs supported and protected by?

  The ribcage.
• What can move ribs?


  The muscles in-between them.
• What is the trachea supported by?

  Rings of cartilage.
• What do the rings of cartilage do for the trachea?

  Prevents the trachea from collapsing as the air pressure inside falls then breathing in.
• What do both the trachea and bronchi produce and have?

  Mucus and cilia.
• Why does the trachea and bronchus produced mucus and have cilia?

  To trap dirt particles and cilia move the dirt mucus towards the throat.
• What do alveoli have?

  Collagen and elastic fibres.
• What do the elastic fibre allow the alveoli to do?

  Stretch as they fill up with air when breathing in and spring back during breathing out to expel the carbon dioxide rich air.
• What is the gas-exchange surface?

  The alveolar membrane.