Module 3: Exchange surfaces

Question 1

Why do larger animals need specialised exchange surfaces

Answer 1

Low SA:V
Diffusion is too slow to supply enough oxygen
They are more active so need good supplies of nutrients and oxygen

Question 2

Features of an efficient exchange surface

Answer 2

Large surface area to provide more space for molecules to pass through
Good blood supply-keeps concentration high
Thin barrier to reduce diffusion distance

Question 3

Function of cartilage

Answer 3

Prevents collapse during inspiration

Question 4

Function of ciliated epithelium

Answer 4

Waft away mucus from the epithelial surface in the nasal cavities, bronchial tubes and trachea
have cilia that move in a wave-like motion

Question 5

Function of Goblet cells

Answer 5

Secrete mucus

Question 6

Function of smooth muscle

Answer 6

Contracts to constrict the airway which narrows the lumen

Question 7

Function of elastic tissue

Answer 7

Recoils to its original shape after the smooth muscle contracts

Question 8

Events during Inspiration

Answer 8

Diaphragm contracts to move down
External intercostal muscles contract
Volume of chest cavity increases 
Pressure in chest cavity drops below atmospheric pressure
Air moved into lungs

Question 9

Events during expiration

Answer 9

Diaphragm relaxes
External intercostal muscles relax
Volume of chest cavity decreases 
Pressure in chest cavity rises above pressure in surrounding atmosphere
Air is moved out of lungs

Question 10

Vital capacity

Answer 10

The greatest volume of air that can be expelled from the lungs after taking the deepest breath possible

Question 11

Tidal volume

Answer 11

Volume of air inhaled or exhaled in one breath, usually measured at rest

Question 12

Breathing rate

Answer 12

The number of breaths per minute

Question 13

Oxygen uptake

Answer 13

Volume of oxygen absorbed by the lungs in one minute

Question 14

Gas exchange in insects

Answer 14

1. Air enters the system via spiracles
2. The air is then transported into the body through tracheae
3. These divide into smaller tube called tracheoles and at the end is tracheal fluid.
4. Gas exchange occurs between air in tracheal and tracheal fluid

Question 15

Gas exchange in Fish

Answer 15

Use gills to absorb oxygen from surrounding water
Gills are also the site where carbon dioxide is released into the water
Operculum is a bony plate covering the gills
Each gill has 2 rows of filaments
Each filament is folded into lamellae to increase their surface area
Lamellae enables a counter-current which increases rate of diffusion