7 Exchange surfaces and breathing

Question 1

What features do effective exchange surfaces have in common?

Answer 1

1) Increased surface area
2) Thin layers
3) Good blood supply
4) Ventilation to maintain diffusion gradient

Question 2

What structures are there in the gaseous exchange system?

Answer 2

• Goblet cells
• Cilia
• Elastic fibres
• Smooth muscle
• Rings of cartilage

Question 3

What do goblet cells do?

Answer 3

• Goblet cells secrete mucus onto the lining of the trachea.

- Mucus traps microorganisms and dust particles in the inhaled air, stopping them from reaching the alveoli.

Question 4

What does cilia do?

Answer 4

• Cilia beat the mucus, along with any trapped dirt and microorganisms.
• This moves the mucus upward away from the alveoli towards the throat, where its swallowed.
• This helps prevent lung infections.

Question 5

What do elastic fibres do?

Answer 5

• Elastic fibres in the walls of the trachea, bronchi and bronchioles and alveoli help the process of breathing out.
• On breathing in, the lungs inflate and the elastic fibres are stretched.
• Then, the fibres recoil to help push the air out when exhaling.

Question 6

What does smooth muscle do?

Answer 6

• Smooth muscle in the walls of the trachea,bronchi and bronchioles allows their diameter to be controlled.
• During exercise the smooth muscle relaxes, making the tubes wider.
• This means there’s less resistance to airflow and air can move in and out of the lungs more easily.

Question 7

What do rings of cartilage do?

Answer 7

• Rings of cartilage in the walls of trachea and bronchi provide support.
• They’re strong but flexible
• Stops the trachea and bronchi collapsing when you breathe in and the pressure drops.

Question 8

What is inspiration?

Answer 8

Taking air in/inhalation

Question 9

Is inspiration an active or passive process?

Answer 9

Inspiration is an active process- it requires energy.

Question 10

What happens during inspiration?

Answer 10

1) The external intercostal and diaphragm muscles contract.
2) This causes the ribcage to move upwards and outwards, and the diaphragm to flatten, increasing the volume of the thorax.
3) As the volume of the thorax increases, the lung pressure decreases to below atmospheric pressure.
4) This causes air to flow into the lungs.
5) The pressure inside and outside of the chest is equalised.

Question 11

What is expiration?

Answer 11

Breathing out/exhalation

Question 12

Is expiration an active or passive process?

Answer 12

Expiration is a passive process.

Question 13

What happens during expiration?

Answer 13

1) The external intercostal and diaphragm muscles relax.
2) The ribcage moves downwards and inwards, and diaphragm becomes curved again.
3) The thorax volume decreases, causing the pressure to be above atmosphere pressure.
4) Air moves out of the lungs.
5) The pressure inside and out is equal again.

Question 14

Can you exhale forcibly?

Answer 14

• Yes, you can exhale forcibly using energy.
• The internal intercostal muscles contract, pulling the ribs down hard and fast.
• The abdominal muscles contract forcing the diaphragm up to increase the pressure in the lungs rapidly.

Question 15

What different ways are used to measure the volume of air drawn in and out of lungs?

Answer 15

1) Peak flow meter
2) Vitalographs
3) Spirometer

Question 16

What is a peak flow meter?

Answer 16

A peak flow meter is a simple device that measures the rate at which air can be expelled from the lungs.

Question 17

What are vitalographs?

Answer 17

• The patient being tested breathes out as quickly as they can through a mouthpiece.
• The instrument produces a graph of the amount of air they breathe out and how quickly it is breathed out.
• This volume of air is called the forced expiratory volume in 1 second.

Question 18

What is tidal volume?

Answer 18

The volume of air in each breath, usually about 500cm3.

Question 19

What is vital capacity?

Answer 19

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

Question 20

What is oxygen consumption?

Answer 20

The rate at which an organism uses up oxygen.

Question 21

What is residual volume?

Answer 21

The volume of air that is left in your lungs when you have exhaled as hard as possible.

Question 22

What is a spirometer?

Answer 22

A spirometer is a machine that can give readings of tidal volume, tidal capacity, breathing rate and oxygen uptake.

Question 23

How does a spirometer function?

Answer 23

1) It has an oxygen-filled chamber with a moveable lid.
2) The person breathes through a tube connected to the oxygen chamber.
3) As the person breathes in and out, the lid of the chamber moves up and down.
4) These movements can be recorded by a pen attached to the lid of the chamber-this writes on the rotating drum, creating a spirometer trace.

Question 24

What is the ventilation rate?

Answer 24

The ventilation rate is the total volume of air inhaled in one minute.

Question 25

How do you calculate ventilation rate?

Answer 25

Tidal volume* breathing rate

Question 26

What do insects use to exchange gases?

Answer 26

Trachea

Question 27

What are spiracles?

Answer 27

Small openings along the thorax and abdomen of an insect that open and close control the amount of air moving in and out of the gas exchange system.

Question 28

What is tracheal fluid?

Answer 28

Fluid found at the ends of the tracheoles in insects that helps control the surface area available for gas exchange.

Question 29

Oxygen dissolves in the tracheal fluid…

Answer 29

and diffuses into body cells

Question 30

How do insects use abdominal movements?

Answer 30

• Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of the spiracles.
• Larger insects use their wing movements to pump their thoraxes.

Question 31

Adaptations of fish to get enough oxygen:

Answer 31

1) Water containing oxygen enters the fish through its mouth and passes out through the gills.
2) Each gill is made of thin branches called gill filaments or primary lamellae, which give a big surface area for exchange of gases.
- The gill filaments are covered in lots of tiny structures called gill plates or secondary lamellae, which increase the surface area even more.
3) The gill plates have lots of blood capillaries and thin surface layer of cells to speed up diffusion.
4) Blood flows through the gill plates in one direction and water flows over in the opposite direction.
- This is called a counter-current system.
- It maintains a large concentration gradient between the water and the blood.
- The concentration of oxygen in the water is always higher than that in the blood, so as much oxygen as possible diffuses from the water into the blood.

Question 32

What system do fish use for gas exchange?

Answer 32

Counter-current system

Question 33

How are gills ventilated in bony fish?

Answer 33

1) The fish opens its mouth, which lowers the floor of the buccal cavity (the space inside the mouth).
- The volume of the buccal cavity increases, decreasing the pressure inside the cavity.
- Water is sucked in to the cavity.
2) When the fish closes its mouth, the floor of the buccal cavity is raised again.
- The volume inside the cavity decreases, the pressure increases, and water is forced out of the cavity across the gill filaments.
3) Each gill is covered by a bony flap called the operculum (which protects the gills).
- The increase in pressure forces the operculum on each side of the head to open, allowing water to leave the gills.