Exchange surfaces and breathing

Question 1

Why do larger organisms need exchange surfaces?

Answer 1

• Large diffusion distance
• Small SA-V ratio
• Very active so higher demand

Question 2

As size increases

Answer 2

Surface area to volume ratio decreases

Question 3

What is an ‘Exchange surface’ ?

Answer 3

A specialised area that is adapted to make it easier for molecules to cross from one side to another- efficient diffusion.

Question 4

Features of exchange surfaces: Why? + Examples
Increased surface area - 
Thin layers -
Good blood supply - 
Ventilation -

Answer 4

• Provides area ended for gas exchange increases SA:V ratio
• Provides a short diffusion distance speeds up rate of diffusion
• Constant delivery and removal of substances to/from exchange surface - maintains a steep concentration gradient.
• Breathing in and out maintains steep concentration gradient.

Question 5

What is the risk for moist exchange surfaces?

Answer 5

Water loss via evaporation

Question 6

Structure of airways: trachea and bronchus:

• Differ in ____
• Inner surface covered with ________ epithelium
  - Rhythmic wave like movement moves ____ to top of trachea where then swallowed microbes are then destroyed by _____ _____
• ______ cells
  - Secrete sticky ____ containing glycoprotein
  - Prevents ______ and traps _____
  - _____ also present causes bacterial lysis.
• _____ : Strong and durable prevents airway collapse.
  - Trachea in incomplete rings allows some expansion
  - Bronchi in irregular patterns
• Smooth _____ contacts and relaxes altering the diameter.
• ________ fibres stretch during inhalation and relaxes during exhalation.

Answer 6

• Size
• Ciliated
• Mucus
• Stomach acid
• Goblet
• Mucus
• Dehydration
• Microbes
• Lysozyme
• Cartilage
• Muscle
• Elastic

Question 7

Features of Bronchioles:

• Smaller
• Have no _____
• Lined with flattened ______
• Wall contains smooth _____
• Contains _____ fibres

Answer 7

• Cartilage
• Epithelium
• Muscle
• Elastic

Question 8

Structure of Alveoli:

• Air spaces divided by ______ walls
• Single layer _____ epithelium cells
• Adjacent blood _____ also S epithelium
• C______ and ____ fibres present for recoil prevents _____ and help ____ air.
• Moist film into which gases _____ before ______

Answer 8

• Alveolar
• Squamous
• Capillaries
• Collagen
• Elastic
• Bursting
• Expel
• Dissolve
• Diffusion

Question 9

Emphysema is a chronic lung disease. Caused by smoking and atmospheric pollution. The elastic fibres in the alveoli are broken causing the alveoli burst. What effect does this have on breathing?

Answer 9

• Smaller surface area
• Lack of elastic tissue means lungs do not stretch or recoil as much -air is trapped + increased pressure further bursting

Question 10

Mechanism of breathing …

• Movement of ribcage and diaphragm ventilate the lungs.
• Air is moved as a result of ______ changes
• ______ brings fresh air into the lungs maintaining the O2 concentration gradient
• _______ removes CO2 to maintain CO2 concentration gradient
• Increase in volume = increase in _______

Answer 10

• Pressure
• Inspiration
• Expiration
• Pressure

Question 11

What does MMVP stand for?

What should you use this to answer?

Answer 11

Muscle
Muscle
Volume
Pressure

Inspiration is and active process

Question 12

Expand on MMVP …

• Intercostal muscles …
• Diaphragm …
• Volume …
• Pressure …
• Air enters down …

Answer 12

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