2 Breathing and gas exchange, page 39 - 51

Question 1

What is in the thorax?

Answer 1

• Ribs.
• Intercostal muscles.
• Diaphragm.
• Trachea.
• Bronchi.
• Bronchioles.
• Alveoli.
• Pleural membranes.

Question 2

What do the ribs do?

Answer 2

Protects the lungs.
Inhalation = move up and out.
Exhalation = down and in.

Question 3

What do the external intercostal muscles do?

Answer 3

They contract pulling the ribs up and out.

Question 4

What do the internal intercostal muscles do?

Answer 4

They contract pulling the ribs down and in.

Question 5

What does the diaphragm do?

Answer 5

Inhalation = Contracts so the diaphragm flattens.
(Pressure decreases)
(Volume increases)
Exhalation = Diaphragm becomes dome-shaped.
(Pressure increases)
(Volume decreases)

Question 6

What does the trachea do?

Answer 6

The trachea splits into two tubes called the bronchi, which lead into each lung.
Contains cartilage to keep it open.

Question 7

What are the bronchi and what do they do?

Answer 7

They divide up into smaller and smaller bronchioles. Contain cartilage to keep them open.

Question 8

What are the bronchioles and what do they do?

Answer 8

They lead to the alveoli.

Question 9

What are the alveoli and what do they do?

Answer 9

Gas exchange takes place in the alveoli

Question 10

What are the pleural membranes and what do they do?

Answer 10

They are two thin, moist membranes which make up a continuous envelope around the lungs, forming an airtight seal.

Question 11

What is between the pleural membranes?

Answer 11

Pleural cavity.

Question 12

What is the pleural cavity?

Answer 12

It is filled with a thin layer of liquid called pleural fluid, this is so the surfaces of the lungs don’t stick together when we breathe.

Question 13

What is gas exchange?

Answer 13

It is a process that is done in the alveoli, the lungs absorb oxygen into the blood and remove carbon dioxide from it.

Question 14

How does gas exchange take place in the alveoli?

Answer 14

The de-oxygenated blood is brought around the alveoli through capillaries.
There is carbon dioxide in this Blood so the carbon dioxide diffuses into the alveoli. Likewise, the oxygen diffuses from the alveoli into the bloodstream. The heart then brings this Blood to the cells in order for them to respire.

Question 15

What are the adaptations of the alveoli?

Answer 15

• Large surface area - many alveoli are present in the lungs with a shape that further increases surface area.
  Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance.
• Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface.
• Permeable walls - allow gases to pass through.
  Good blood supply - ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.
• A large diffusion gradient - breathing ensures that the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves from the alveoli to the blood. Carbon dioxide diffuses in the opposite direction.

Question 16

How does the trachea keep the airways clean?

Answer 16

• Lined with a layer of cells called mucus.
• The mucus traps particles of dirt or bacteria that are breathed in.
• Other structures are covered by cilia.
• The cilia wafts the mucus with the trapped particles out towards the mouth so dirt and bacteria are prevented from entering the lungs.

Question 17

What are some effects of smoking on the lining of the air passage?

Answer 17

• The cilia are destroyed by the chemicals in cigarette smoke.
• This means that mucus is not swept away and can block the airways, smoke irritates your throat and causes more mucus to be produced.
• Causes lung disease called bronchitis.

Question 18

What is emphysema and how does smoking cause it?

Answer 18

• The smoke damages the walls of the alveoli, which break down and fuse together.
• This decreases the surface area making gas exchange extremely inefficient.
• Their blood carries much less oxygen and emphysema patients often have to have a supply of oxygen close to them at all times.

Question 19

What are the carcinogens found in cigarettes?

Answer 19

• Nicotine.
• Tar.
• Carbon monoxide.
• Other toxic components.

Question 20

What is nicotine?

Answer 20

It is a highly addictive substance and is a stimulant so it makes the heartbeat faster and narrows blood vessels. The narrowing of blood vessels create blood clots which eventually stops the blood flow towards the heart therefore causing a heart attack.

Question 21

What is tar

Answer 21

A sticky, black chemical that accumulates in the lungs. It can break down alveoli and can damage the DNA of lung cells.

Question 22

What is carbon monoxide?

Answer 22

A poisonous gas that binds to haemoglobin instead of oxygen this is a problem as oxygen is needed for developing babies, so when they are deprived of this and the given carbon monoxide this could cause complications. The compound is called carboxyhaeomoglobin.

Question 23

What does carbon monoxide do to unborn babies?

Answer 23

The mother will deprive her unborn fetus of oxygen.
- Leads to lower birth mass.