3.1 Exchange Surfaces (lungs)

Question 1

What is gaseous exchange?

Answer 1

The movements of gases by diffusion between an organism and its environment

Question 2

How do alveoli help with gas exchange?

Answer 2

There are lots of them creating a large surface area

Question 3

How is the distance shortened for diffusion in the lungs?

Answer 3

Alveoli and capillary walls are only one cell thick
Made of squamous epithelium which is half width of usual cells
Close contact between alveoli and capillaries
Capillaries are narrow

Question 4

How is a steep diffusion gradient maintained in the lungs?

Answer 4

Permeable ventilation and a good blood supply coming from a constant stream of deoxygenated blood

Question 5

What are the features of the trachea?

Answer 5

• C shaped cartilage which prevents collapse
• Elastic fibres- Recoil to return airway to original state
• Smooth muscle- Constricts airway
• Blood vessels- Supplies cells with oxygen and removes waste products
• Inner most lining contains epithelium (ciliated and goblet cells)

Question 6

What are the features of the bronchi?

Answer 6

Same as trachea just smaller in size

Question 7

What are the features of the bronchioles?

Answer 7

• Larger ones may have some cartilage
• Mainly smooth muscle and elastic fibres

Question 8

What are the features of Alveoli?

Answer 8

• Walls made of squamous epithelium
• Elastic fibres- Recoil after exhalation to prevent bursting

Question 9

What is the mechanism of breathing of inhalation?

Answer 9

1. Diaphragm contracts to become flatter
2. Digestive organs pushed down
3. INtercostal muscles (between ribs) contract
4. Rib cage rises
5. Volume of thorax increases
6. Pressure inside the thorax decreases below atm establishing pressure gradient \
7. Air is forced in

Question 10

What is a spirometer used for?

Answer 10

Measuring tidal volume,breathing rate and vital capacity

Question 11

How is validity increased using a spirometer?

Answer 11

• Nose clip so all air inhaled and exhaled goes into spirometer

Question 12

How are spirometers kept safe for the use of the subject?

Answer 12

• Mouthpiece is disinfected/replaced
• Air in spirometer is medical grade oxygen
• CO2 absorber so there is no rebreathing of CO2

Question 13

How do spirometers work?

Answer 13

• As subject inhales oxygen is removed from chamber causing it to fall creating a downward line on kymograph
• As subject exhales air is returned and chamber rises again creating a upward line on kymograph

Question 14

What effect do the contraction of muscles due to allergens have on ventilation?

Answer 14

• Diameter of bronchi and bronchioles reduce
• More air remains in lungs

Question 15

What chemical could be used in a CO2 absorber to absorb CO2?

Answer 15

• Sodaline

Question 16

What is tidal volume?

Answer 16

• The volume of air that moves in and out of the lungs with each resting breath

Question 17

What is vital capacity?

Answer 17

• The volume of air that can be breathed in when the strongest possible exhalation followed by the strongest possible intake.

Question 18

What is inspiratory reserve volume?

Answer 18

Maximum volume of air you can breathe over normal tidal volume

Question 19

What is expiratory reserve volume?

Answer 19

• Extra amount of air you can force out of your lungs over normal tidal volume

Question 20

What is residual volume?

Answer 20

The volume air left in your lungs when you have exhaled as hard as possible

Question 21

What is the total lung capacity?

Answer 21

The sum of the vital capacity and residual volume

Question 22

How do you calculate rate of oxygen uptake?

Answer 22

Measure volume of oxygen used
Measure time taken
Divide volume by time

Question 23

Why can’t lungs fully expel all air?

Answer 23

• Because thorax cannot flatten fully so there is no pressure gradient