Chapter 7 - Exchange surfaces

Question 1

Why is diffusion alone is not suitable to supply oxygen to cell in larger multicellular organisms?

Answer 1

• They have a small SA:V so there is a larger diffusion distance
• High metabolic demands and high CO2 production which needs to be released in due time

Question 2

What are some features of a specialised exchange surface?

Answer 2

• Increased surface area
• Shorter diffusion pathways (thin layers/ membranes)
• Good blood supply for a steeper conc. gradient
• Higher ventilation by exchange systems

Question 3

What are some main components of the human gaseous exchange system?

Answer 3

Mouth, nose, trachea, alveoli, lungs, diaphragm, intercoastal muscles and ribs

Question 4

What are the specialised cells in the trachea and what do they do?

Answer 4

• Ciliated epithelium and goblet cells
• Cilia help to move mucus along the trachea walls away from the lungs
• Goblet cells release mucus which trap unwanted microorganisms and particles

Question 5

What are some specialities of alveoli?

Answer 5

• Single layer of elasticated epithelium cells for a short diffusion pathway
• Elasticity allows for recoil so air that moves into the alveoli is pushed back out again
• Surrounded by capillaries for a good blood supply to maintain blood concentration levels

Question 6

What happens during inhalation?

Answer 6

External intercoastal muscles contracts, ribs move up and out and the diaphragm contracts downwards leading the lungs decreasing in pressure so air is drawn in

Question 7

What happens during exhalation?

Answer 7

Internal intercoastal muscles relax, ribs move down and in and the diaphragm relaxes upwards leading to the pressure within the lungs to increase and so air is forced out

Question 8

What are some ways of measuring the capacity of the lungs?

Answer 8

• Peak flow meter (measures the rate of exhalation)
• Vitalographs (measures the speed of exhale)
• Spirometer (measures the different aspects of lung volume and breathing patterns)