Unit 3 - Mammalian gas exchange and ventilation

Question 1

What are the 4 features of efficient exchange surfaces?

Answer 1

-Increased surface area
-Thin layers
-Good blood supply
-Ventilation to maintain a diffusion gradient

Question 2

Why does an increased surface area make an exchange surface efficient?

Answer 2

Provides the area needed for exchange overcomes limitations of low SA:V ratio

Question 3

Why do thin layers make an exchange surface efficient?

Answer 3

the distances that substances have to diffuse across is short making it fast and efficient

Question 4

Why does a good supply make an exchange surface efficient?

Answer 4

the greater the difference in concentration the greater the rate of diffusion. A good supply means substances are constantly being delivered and removed, maintaining the steep concentration gradient

Question 5

Why does ventilation make an exchange surface efficient?

Answer 5

For gases ventilation helps to maintain concentration gradients

Question 6

How is the trachea adapted for the gas exchange system?

Answer 6

-supported by incomplete rings of strong, flexible cartilage to allow for movement and prevent the trachea from collapsing
-lined with ciliated epithelium and goblet cells

Question 7

How are bronchioles adapted for the gas exchange system?

Answer 7

-contain no cartilage
-contain smooth muscle
-smooth muscle contracts when bronchioles constrict and relaxes when they dilate

Question 8

How are the alveoli adapted for the gas exchange system?

Answer 8

-very thin walls
-contain elastic fibres which allow alveoli to stretch as air is drawn n and when they return to size help squeeze air out
-good capillary blood supply
-coated in surfactant

Question 9

Does inspiration/inhalation require energy?

Answer 9

Yes

Question 10

Does expiration/exhalation require energy?

Answer 10

No, it is a passive process