Exchange surfaces

Question 1

Why do larger organisms require exchange surfaces

Answer 1

Diffusion is:
- Too slow
- The distance is too great for cells far from the
surface
- Small surface area to volume ratio

Larger organisms have a higher metabolic demand

Question 2

What makes an efficient exchange surface

Answer 2

Large surface area
Thin barrier to reduce diffusion distance
Steep concentration gradient

Question 3

How are the lungs adapted for gas exchanger

Answer 3

Contain many alveoli which create a large surface area for for gas exchange

Alveolar walls are one cell thick which provide a thin barrier to reduce diffusion distance

Lots of capillaries which provide a blood supply to maintain a steep concentration gradient

Moist, which allows gases to dissolve

Question 4

What happens during Inhalation

Answer 4

Diaphragm contracts and moves down

External intercostal muscles contract and move ribs up and out
Internal intercostal muscles relax

Volume of chest increases

Pressure in the lungs decrease

Question 5

What happens during exhalation

Answer 5

Diaphragm relaxes and moves upwards

External intercostal muscles relax so ribs move down and in

Volume in chest decreases

Pressure in the lungs increase

Question 6

What tissues are found in the lungs

Answer 6

Cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliated cells
Squamous epithelium

Question 7

What is the function of cartilage in the lungs

Answer 7

Prevents the collapse and bursting of the trachea during pressure changes in ventilation
Flexible so you can move your neck

Question 8

What is the function of smooth muscle in the lungs

Answer 8

Can stretch and recoil to maintain the diameter of the airways

Question 9

What is the function of elastic fibres in the lungs

Answer 9

Stretches when breathing in to prevent bursting
Recoils when breathing out to help push air out of the lungs

Question 10

What is the function of goblet cells in the lungs

Answer 10

Secrete mucus which is sticky and collects particles of dust and bacteria

Question 11

What is the function of the ciliated epithelium in the lungs

Answer 11

wafts mucus up the airways towards the mouth

Question 12

What is the function of the squamous epithelium in the lungs

Answer 12

provides a short diffusion distance for oxygen and carbon dioxide to diffuse across

Question 13

What is the vital capacity

Answer 13

Maximum volume of air that can be inhaled or exhaled in one breath

Question 14

What is tidal volume

Answer 14

Volume of air that is exhaled or inhaled in one breath at rest

Question 15

what is residual volume

Answer 15

Volume of air left in the lungs after hardest possible exhalation

Question 16

What is oxygen uptake

Answer 16

Rate of oxygen consumption

Question 17

What is breathing rate

Answer 17

number of breaths per unit of time

Question 18

What precautions should you take when using a spirometer

Answer 18

Have enough oxygen in the chamber

Disinfect the mouthpiece

Use a nose clip

Have a counterbalance

Question 19

Why should the student use a nose clip when using the spirometer

Answer 19

To ensure that all the air breathed in and out is from the chamber
Which allows for accurate results

Question 20

What chemical should be used to remove the CO2

Answer 20

Soda lime

Question 21

How does ventilation occur in bony fish

Answer 21

The fish opens its mouth and lowers the floor of the buccal cavity

Volume of buccal cavity increases, pressure decreases and water enters the mouth

Fish closes its mouth, floor of buccal cavity rises, volume decreases, pressure increase and water is forced out across gill filaments

Operculum forced to open and water leaves the gills

Question 22

How are the gills adapted for gas exchange

Answer 22

Each gill is made up of many gill filaments which provide a large surface area.

each gill filament is covered with many gill plates which provide a large surface area

Gill plates have lots of capillaries which provide blood to maintain a steep concentration gradient

Thin cell walls to provide a short diffusion distance

Counter current system which ensures that a steep concentration gradient is maintained

Question 23

How to dissect the gills of a fish

Answer 23

Push back the operculum and use scissors to carefully remove the gills

Cut each gill arch through the bone at the top and bottom