Exchange Surfaces

Question 1

Why is diffusion alone enough to supply the needs of single-called organisms?

Answer 1

1- Metabolic activity of a single-celled organism is usually low, so O2 demands and CO2 production are relatively low
2- SA:V ratio of organism is large

Question 2

Give 4 features of effective gaseous exchange surfaces

Answer 2

1- Increased SA; provides area needed for exchange
2- Thin layers; diffusion distance is shorter
3- Good blood supply; ensures a steeper conc gradient for more diffusion, substances are constantly delivered and removed
4- Ventilation; maintains diffusion gradient

Question 3

Give 3 important features of the nasal cavity

Answer 3

1- Large SA with good blood supply; warms air to body temperature
2- Hairy lining; secretes mucus to trap dust/bacteria, protecting lungs from irritation/infection
3- Moist surfaces; increase humidity of incoming air, reducing evaporation from exchange surfaces

Question 4

What does the trachea do?

Answer 4

The main airway carrying clean, warm, moist air from the nose down into the chest

Question 5

What are the adaptations of the trachea?

Answer 5

• Incomplete rings of cartilage

- Lined with ciliated epithelium

Question 6

What is the advantage of having incomplete rings of cartilage in the trachea?

Answer 6

Stop the trachea from collapsing

Question 7

What is the advantage of the trachea being lined with ciliated epithelium?

Answer 7

• Have goblet cells to secrete mucus to trap dust and microorganisms
• Have cilia to beat and move mucus/dirt/microorganisms away from lungs

Question 8

What are bronchi?

Answer 8

Where the chest cavity divides to form a left and right bronchus, similar in structure to the trachea but are smaller

Question 9

What are the bronchioles?

Answer 9

Where the bronchi divide

Question 10

What are the adaptations of bronchioles?

Answer 10

• No cartilage rings
• Walls contain smooth muscle
• Lined with a thin layer of flattened epithelium

Question 11

What is the advantage of bronchioles having a wall containing smooth muscle?

Answer 11

• Allows contraction (constrict)
• Allows relaxation (dilate)
• Changes amount of air reaching lungs

Question 12

What is the advantage of bronchioles being lined with flattened epithelium?

Answer 12

Makes some gaseous exchanges possible

Question 13

What are alveoli?

Answer 13

Tiny air sacs, which are the main gas exchange surfaces of the body

Question 14

What are the alveoli made of?

Answer 14

• A layer of thin, flattened epithelial cells

- Collagen and elastic fibres

Question 15

What is the advantage of the alveoli consisting of elastic fibres?

Answer 15

• Allow the alveoli to stretch as air is drawn in

- Allow elastic recoil; helps squeeze air out when they return to resting size

Question 16

Give 4 main adaptations of the alveoli

Answer 16

1- Large SA
2- Thin layers
3- Good blood supply
4- Good ventilation

Question 17

What is the advantage of the alveoli having a large SA?

Answer 17

For increased rate of diffusion

Question 18

What is the advantage of the alveoli having thin layers?

Answer 18

Single epithelial cell thick for short diffusion distance

Question 19

What is the advantage of the alveoli having a good blood supply?

Answer 19

Maintains a steep concentration gradient for more diffusion

Question 20

What is the advantage of the alveoli having good ventilation?

Answer 20

Maintains a steep diffusion gradient for O2 and CO2 between blood and air in the lungs

Question 21

What is ventilation?

Answer 21

Air moving in and out of the lungs as a result of pressure changes in the thorax brought about by breathing movements

Question 22

What is the thorax?

Answer 22

Chest cavity

Question 23

What is the diaphragm?

Answer 23

A broad, domed sheet of muscle, which forms the floor of the thorax

Question 24

What is inspiration?

Answer 24

Breathing in

Question 25

What happens to the diaphragm during inspiration?

Answer 25

Contracts
Flattens
Lowers

Question 26

What happens to the external intercostal muscles during inspiration?

Answer 26

Contract

Ribs move upwards + outwards

Question 27

What happens to the volume of the thorax during inspiration?

Answer 27

Increases

Question 28

What happens to the pressure of the thorax during inspiration?

Answer 28

Decreases so is lower than the pressure of the atmospheric air

Question 29

What is expiration?

Answer 29

Breathing out

Question 30

What happens to the diaphragm during expiration?

Answer 30

Relaxes

Moves up

Question 31

What happens to the external intercostal muscles during expiration?

Answer 31

Relax

Ribs move down + inwards

Question 32

What happens to the volume of the thorax during expiration?

Answer 32

Decreases

Question 33

What happens to the pressure of the thorax during inspiration?

Answer 33

Increases so is higher than the pressure of the atmospheric air

Question 34

What is a spirometer used to measure?

Answer 34

• Different aspects of the lung volume

- Investigate breathing patterns

Question 35

What is tidal volume?

Answer 35

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

Question 36

What is vital capacity?

Answer 36

The volume of air that can be breathed in when the strongest possible exhalation is followed by the strongest possible inhalation

Question 37

What is residual volume?

Answer 37

The volume of air left in your lungs when you exhale as hard as possible

Question 38

What is total lung capacity?

Answer 38

Sum of vital capacity and residual volume

Question 39

What is breathing rate?

Answer 39

The number of breaths taken per minute

Question 40

What is ventilation rate?

Answer 40

The total volume of air inhaled in one minute

Question 41

How do you calculate ventilation rate?

Answer 41

Tidal volume x breathing rate