3.1.1 Exchange surfaces

Question 1

Name two substances that are absorbed across an exchange surface.

Answer 1

Oxygen and glucose

Question 2

Do multicellular organisms have a large or small surface area to volume ratio?

Answer 2

Small

Question 3

What are three adaptations of the alveoli for efficient gas exchange?

Answer 3

• Walls are one cell thick, to create short diffusion distance
• Good blood supply, which maintains a steep concentration gradient
• Many alveoli which are very small, creating a large surface area

Question 4

Name the process by which oxygen passes from the alveolus in the lungs and into the blood.

Answer 4

(Simple) diffusion

Question 5

Name the flap under which you find the gills.

Answer 5

Operculum

Question 6

What are three adaptations in the gills for efficient gas exchange?

Answer 6

• Many folds called lamellae, creating a large surface area
• Walls of gill filaments are one cell thick, creating a short diffusion distance
• Counter-current flow between water and blood in capillaries creates a steep concentration gradient

Question 7

What are four common features of an efficient exchange surface?

Answer 7

Large surface area
Short diffusion distance
Good blood supply
Ventilation mechanism

Question 8

What is the purpose of cartilage in the trachea?

Answer 8

Keeps airways open

Prevents trachea from collapsing when you breathe in and pressure drops

Question 9

In which tissues in the mammalian gas exchange system is the ciliated epithelium found?

Answer 9

• Trachea
• Bronchi

Question 10

What is the purpose of mucus in the trachea and bronchi?

Answer 10

Traps pathogens

Question 11

What is the purpose of cilia in the trachea and bronchi?

Answer 11

Wafts mucus up and out of the airway

Question 12

In which tissues in the mammalian gas exchange system is smooth muscle found?

Answer 12

• Bronchi
• Bronchioles

Question 13

In which tissues in the mammalian gas exchange system are elastic tissues found?

Answer 13

In ALL lung tissues

(Trachea, bronchi, bronchioles, alveoli)

Question 14

What is the function of smooth muscle in the bronchi and bronchioles?

Answer 14

Dilates to increase air flow

Constricts to reduce air flow

Question 15

What is the purpose of elastic fibres in the mammalian gas exchange system?

Answer 15

Fibres recoli to help push air out when exhaling

Question 16

What shape are the rings of cartilage in the trachea?

Answer 16

C-shaped rings

Question 17

What happens to the internal and external intercostal muscles during inspiration (inhalation)?

Answer 17

• External intercostal muscles contract
• Internal intercostal muscles relax

Question 18

What happens to the internal and external intercostal muscles during expiration (exhalation)?

Answer 18

• External intercostal muscles relax
• Internal intercostal muscles relax during passive expiration (but contact during forced expiration)

Question 19

Describe what happens inside the chest cavity during inspiration.
Talk about the changes in muscles, volume and pressure.

Answer 19

Diaphragm contracts and pulls
down
External intercostal muscles
contract
Ribcage moves upwards and
outwards
Volume inside chest cavity increases
Pressure inside chest cavity decreases
There is more pressure outside the lungs
Air particles are drawn in to balance the pressure difference

Question 20

Is inspiration an active or passive process?

Answer 20

Active (because it requires energy)

Question 21

Describe what happens inside the chest cavity during expiration.
Talk about the changes in muscles, volume and pressure.

Answer 21

Diaphragm relaxes
External intercostal muscles relax
Ribcage moves downwards and inwards
Volume in thorax (chest cavity) decreases
Pressure inside thorax increases
Air is forced out of the lungs

Question 22

What is the role of elastic fibres in expiration?

Answer 22

Elastic fibres are stretched during inspiration
During expiration, elastic fibres recoil
This helps to reduce the volume inside the thorax
Air is therefore expelled

Question 23

Is expiration an active or passive process?

Answer 23

Passive (does NOT require energy)

Question 24

When the rubber sheet of a bell jar is pulled down the balloons expand.
Explain why the balloons expand.

Answer 24

volume inside of jar increases

pressure inside jar / balloons decreases

to below pressure in atmosphere

(therefore) air moves / is pushed into / is forced into balloons / glass tube

Question 25

Name this piece of equipment.

Answer 25

Spirometer

Question 26

Name four readings that you can obtain using a spirometer.

Answer 26

Tidal volume Vital capacity Breathing rate Oxygen uptake

Question 27

Describe how a 'spirometer trace' is formed.

Answer 27

Person breathes through tube connected to oxygen chamber Lid of oxygen chamber moves up and down Movements are recorded by the pen

Question 28

What is the purpose of soda lime in a spirometer?

Answer 28

It absorbs carbon dioxide from a person's exhaled air

Question 29

Why does the volume of gas in the oxygen chamber decrease over time as a person uses a spirometer?

Answer 29

The air that is exhaled is a mixture of oxygen and carbon dioxide Carbon dioxide is absorbed by the soda lime There is only oxygen in the chamber which the patient inhales from As oxygen is inhaled and used up in respiration, the total volume decreases

Question 30

What is 'breathing rate'?

Answer 30

The number of breaths taken per minute

Question 31

What is 'tidal volume'?

Answer 31

The volume of air that is breathed in or out during normal breathing (at rest).

Question 32

What is 'vital capacity'?

Answer 32

The maximum volume of air that can be breathed in or out in one breath.

Question 33

What is 'oxygen uptake'?

Answer 33

The volume of oxygen used up in a given time.

Question 34

Which letter shows the residual volume?

Answer 34

H

Question 35

What is 'residual volume'?

Answer 35

The amount of air left in the lungs after fully exhaling.

Question 36

What is 'total lung capacity'?

Answer 36

The maximum amount of air that the lungs can hold after taking the deepest breath possible.

Question 37

Which letter shows the total lung capacity?

Answer 37

D

Question 38

Which letter shows the tidal volume?

Answer 38

F

Question 39

Which letter shows the vital capacity?

Answer 39

C

Question 40

Describe what happens during inspiration in bony fish. Include information about changes in pressure and volume.

Answer 40

Fish opens mouth Lower the floor of the buccal cavity Increased volume inside buccal cavity Decreased pressure inside buccal cavity Pressure is higher outside the mouth Water flows into buccal cavity

Question 41

Describe what happens during expiration in bony fish. Include information about changes in pressure and volume.

Answer 41

Fish closes mouth Raises the floor of the buccal cavity Decreased volume inside buccal cavity Increased pressure inside buccal cavity Pressure is higher inside the mouth Operculum is forced to open Water exits through the operculum

Question 42

Name the structure that increases the surface area in fish gills.

Answer 42

Lamellae

Question 43

Name the pore found in the exoskeleton of an insect.

Answer 43

Spiracle

Question 44

What are three adaptations of the tracheal system in insects?

Answer 44

Tracheoles have thin walls (up to one cell thick) Creates a short diffusion distance Tracheoles contain fluid Allows oxygen to dissolve for faster diffusion Trachea are supported by circles of chitin Prevents trachea from collapsing

Question 45

What is the purpose of valves in the insects' trachea?

Answer 45

Prevents water loss