Exchange and transport

Question 1

What is the function of lung surfactant?

Answer 1

-Decreases surface tension which prevents alveoli from sticking together and collapsing
-It is made up of a mixture of lipids and proteins

Question 2

What do goblet cells and ciliated epithelial cells do?

Answer 2

-Goblet cells secrete mucus which traps dust and pathogens
-Ciliated epithelial cells beat in a synchronised pattern to waft mucus to the pharynx where it is coughed up or swallowed

Question 3

What is the process of inspiration?

Answer 3

-External intercostal muscles contract
-Ribs move up and out
-Diaphragm contracts and flattens so it moves down
-This increases the volume in the thorax and decreases the pressure so air is forced in

Question 4

What is the process of expiration?

Answer 4

-External intercostal muscles relax
- Ribs move down and in
-Diaphragm relaxes so goes to a dome shape, this decreases the volume of the thorax and increases the pressure so air moves out

Question 5

Three main factors that affect the need for an exchange system

Answer 5

-Size
-Metabolic rate
-SA:VOL ratio

Question 6

Why do smaller organisms have lower demand for oxygen than larger organisms?

Answer 6

Smaller organisms have larger SA:Vol so simple diffusion is sufficient

Question 7

What makes a good exchange surface?

Answer 7

-Large SA:Vol
-Thin permiable walls
-Good blood supply (maintain high conc gradient)