B8.1 - Gas exchange

Question 1

list the adaptations for an exchange surface, Alveoli

Answer 1

Ventilation, Kept clear, Thin membrane, Large surface area, Blood supply

Question 2

From alveoli’s adaptation, what does ventilation mean?.

Answer 2

if a gas is exchanged, the surface is ventilated (through breathing) to maintain a high concentration gradient and increase the rate of exchange.

Question 3

From alveoli’s adaptation, what does Kept clear mean?

Answer 3

Any particles of dust for example will block an exchange surface and reduce the rate of exchange. So Goblet cells and Cililia cells prevent this.

Question 4

How does the Cillia cells and Goblet cells help the airway kept clear?

Answer 4

Goblet cells produce sticky mucus that traps particles and cilia cells waft the mucus up and out of the airway up to the mouth where it can be swallowed. This prevents dirt and microorganisms entering the lungs causing damage and infection.

Question 5

From alveoli’s adaptation, what does thin membrane mean?

Answer 5

Alveoli has a thin permeable membrane increasing the rate of diffusion because of the distance. Alveoli are one cell thick.

Question 6

From alveoli’s adaptation, what does large surface area mean?

Answer 6

Allows more substance to diffuse at the same time.

Question 7

From alveoli’s adaptation, what does Blood supply mean?

Answer 7

Alveoli are densely packed with blood vessels. The blood vessels replenish the blood supply to maintain a high concentration gradient by bringing in new blood as diffusion starts to even out the concentrations.

Question 8

The pathway of oxygen into blood.

Answer 8

1. Air is entered through mouths and nose and then into the lungs through the trachea
2. Trachea divides into Bronchi
3. Then to bronchioles
4. Then alveoli (There’s millions of alveolus)
5. Alveoli are surrounded by capillaries, allowing gas exchange.

Question 9

How does inspiration work?

Answer 9

• The diaphragm contracts and becomes flattens
• The internal intercostal muscles relax and the external intercostal muscles contract moving the rib cage up and out.
• The thorax volume increases, forcing air into the lungs because of decreased internal pressure

Question 10

How does expiration work?

Answer 10

• The diaphragm relaxes and becomes dome-shaped.
• The internal intercostal muscles contract and the external intercostal muscles relax, moving the ribcage downwards and in.
• The thorax volume decreases, increasing internal pressure.
• Air is forced out of the lungs.

Question 11

Inspired air percentage of Oxygen, Carbon dioxide and Water vapour.

Answer 11

Oxygen: 21%
Carbon dioixde: 0.04%
Water vapour: variable

Question 12

Expired air percentage of oxygen, Carbon dioxide and Water vapour.

Answer 12

Oxygen: 16%
Carbon dioxide: 4.5%
Water vapour: high

Question 13

How do you test for Carbon dioxide?

Answer 13

lime water becomes cloudy is Carbon dioxide is present.

Question 14

What does exercise do?

Answer 14

Increase the rate of respiration in muscle cells. Causing the rate and depth of breathing to increase.

Question 15

Explain why exercise increases the rate and depth of breathing.

Answer 15

• The increased rate of respiration in cells creates a higher concentration of carbon dioxide in the blood.
• The brain detects this and causes breathing to become deeper and faster.
• This means more carbon dioxide can be breathed out at a quicker rate (and more oxygen is also breathed in).

Question 16

What happens to air passages when you smoke?

Answer 16

Tar damages these the cilia cells leading to a build-up of mucus. Smoke irritates the bronchi, causing bronchitis.

Question 17

What happens to alveoli when you smoke?

Answer 17

Tar damages the walls of the alveoli. The alveoli walls break down and join together, forming larger air spaces than normal. This reduces the efficiency of gas exchange, so people with the lung disease emphysema (a type of COPD) carry less oxygen in their blood and find even mild exercise difficult.

Question 18

List Tobaccos chemicals that’s inside.

Answer 18

Carbon monoxide, Nicotine, Tar, Smoke particles.

Question 19

What does Tobacco do to you, in terms of Carbon monoxide?

Answer 19

It takes the place of oxygen in haemoglobin, reducing the capacity of blood to carry oxygen. This puts more strain on the circulatory system and also increases the risk of coronary heart disease and strokes

Question 20

What does Tobacco do to you, in terms of Nicotine?

Answer 20

It narrows blood vessels so will put more strain on the circulatory system and increase blood pressure. Narrow blood vessels are more likely to become clogged with fat. If this happens in the coronary artery, this causes coronary heart disease. This means the heart muscle cells do not get sufficient oxygen and so less aerobic respiration takes place. To compensate the cells respire anaerobically, producing lactic acid which cannot be removed (due to lack of blood supply). This creates a low pH environment in the cells causing enzymes to denature and eventually heart muscle cells will die. If enough heart muscles die this can cause a heart attack

Question 21

What does Tobacco do to you from Tar?

Answer 21

Its sticky substance that coats the cells of the trachea, bronchi and bronchioles, leading to coughing and cell damage. This gives a decrease in the rate of gas exchange and can lead to cancer of the lungs, mouth and throat.

Question 22

What does Tobacco do to you from Smoke particles?

Answer 22

It will kill white blood cells and trigger asthma.