Lesson 1: Gas Exchange

Question 1

Why do larger multi-cellular organisms need exchange systems?

Answer 1

• small surface area to volume ratio
• cells in the centre of the organisms would not receive anything using only diffusion.
• higher metabolic rate

Question 2

what are five characteristics of specialised exchange surfaces in animals?

Answer 2

• concentration gradient
• Large Surface Area
• Thin layers
• Moist surface
• Permeability

Question 3

How is having a large surface area an adaptation for efficient gas exchange?

Answer 3

a large area that gas exchange can occur over.

Question 4

How is having thin layers an adaptation for efficient gas exchange?

Answer 4

short diffusion path

Question 5

How is having a good blood supply an adaptation for efficient gas exchange?

Answer 5

maintain a large diffusion gradient, constant diffusion

Question 6

How is having a moist surface an adaptation for efficient gas exchange?

Answer 6

dissolves gas

Question 6

How is ventilation an adaptation for efficient gas exchange?

Answer 6

maintains diffusion gradient

Question 7

How is permeability an adaptation for efficient gas exchange?

Answer 7

pores and openings

Question 8

What adaptations do animals have to maintain a steep concentration gradient at exchange surfaces?

Answer 8

• A dense network of blood vessels
• Continuous blood flow
• Ventilation

Question 9

describe the nasal cavity

Answer 9

• large SA & good blood supply = warms air to body temperature
• hairy lining = traps bacteria and dust
• moist = increases humidity and reduces evaporation

Question 10

describe the trachea

Answer 10

• c shape cartilage rings = prevents collapse and allows food down oesophagus
• mucus membrane lining produces mucus to trap dust and bacteria
• smooth muscle to regulate air flow

Question 11

describe the bronchioles

Answer 11

• small diameter slows air flow = more time for gas exchange in the alveoli.
• high degree of branching also ensures that air is distributed throughout the lungs.

Question 12

describe alveoli

Answer 12

• made up of collagen, elastic fibres and flattened epithelial cells.
• elastic fibers recoil removing air from alveoli

Question 13

describe surfactant

Answer 13

• dissolves gasses
• reduces surface tension, preventing collapse

Question 14

What are the adaptations of alveolis for efficient gas exchange?

Answer 14

• Large surface area: numerous + folded
• Short diffusion distance: one cell thin
• Large concentration gradient: surround by an extensive network of capillaries and regular ventilation

Question 15

What is the difference between type 1 and 2 pneumocytes in structure and coverage %?

Answer 15

type 1:
* covers 95% of alveoli SA
* thin + flat cells
type 2:
- cuboidal cells
- 5%

Question 16

What is the difference between type 1 and 2 pneumocytes in function?

Answer 16

type 1: gas exchange
type 2: produces surfactant + differentiate into type 1 (when damaged).

Question 17

summarise ‘inspiration’

Answer 17

• Diaphragm contract – Moves Down
• External Intercostal Muscles contract – move up and out
• Thoracic Volume – Increases
• Thoracic Pressure – Decreases
• Air Flow – In to lungs (to equalise the pressure difference)

Question 18

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summarise ‘expiration’

Answer 18

• Diaphragm – Moves up
• External Intercostal Muscles – move down and in
• Thoracic Volume – decreases
• Thoracic Pressure – increases
• Air Flow – out the lungs (to equalise the pressure difference)

Question 19

what are external intercostal muscles used for?

Answer 19

forced expiration

Question 20

what does tidal volume mean?

Answer 20

the volume of air in each breath

Question 21

what does vital capacity mean?

Answer 21

The maximum volume of air that can be breathed in and out

Question 22

what does breathing rate mean?

Answer 22

The number of breaths per minute

Question 23

what does oxygen uptake mean?

Answer 23

The rate at which a person uses up oxygen (dm3 min-1)

Question 24

What device is used to measure lung volume?

Answer 24

spirometer

Question 25

What happens to lung volume after exercise?

Answer 25

tidal volume and **rate of breathing **increases due to taking in more oxygen and removing more carbon dioxide.

Question 26

What factors can affect your lung capacity?

Answer 26

• age
• body composition
• biological sex
• respiratory disease
• level of physical activity

Question 27

what is haemoglobin?

Answer 27

protein molecule found within red blood cells

Question 28

what is the function of haemoglobin?

Answer 28

carries oxygen

Question 29

what can haemoglobin bind to?

Answer 29

oxygen and carbon dioxide

Question 30

what is the structure of haemoglobin?

Answer 30

• quaternary structure
• 4 polypeptides
• each polypeptide has a haem group
• each haem group has an iron molecule

Question 31

what is saturated haemoglobin?

Answer 31

haemoglobin bounded to oxygen molecule(s)

Question 32

What is cooperative binding of oxygen to haemoglobin?

Answer 32

as oxygen binds to haemoglobin, the affinity for oxygen increases due to shape change making it easier for other oxygen molecules to bind

Question 33

how many oxygens can a haemoglobin bind to?

Answer 33

8

Question 34

what does affinity mean?

Answer 34

attraction (for)

Question 35

How does foetal haemoglobin differ from adult?

Answer 35

higher affinity for oxygen

Question 36

what happens when a carbon dioxide attaches to a haemoglobin?

Answer 36

oxygen is released and affinity decreases