Gas exchange in humans

Question 1

Where is the gas exchange system located?

Answer 1

In the thorax

Question 2

What path does air take when we breathe it in

Answer 2

Breath in, air flows through the trachea, down the bronchi, further into the lungs through the bronchioles, into the alveoli where they diffuse into the blood

Question 3

What is the trachea, what does it do

Answer 3

The trachea is another name for the windpipe. connects the larynx (or voice box) to the bronchi of the lungs. It is an integral part of the body’s airway and has the vital function of providing air flow to and from the lungs for respiration.

Question 4

What is the thorax

Answer 4

The thorax is the upper part of the body

Question 5

What are the bronchioles, what do they do

Answer 5

They are small branches leading to everywhere in the lungs. They transfer gases to and from the lungs

Question 6

What are alveoli, what do they do

Answer 6

Microscopic air sacs which are optimised for gas exchange in lungs

Question 7

What is the pleural membrane, what does it do

Answer 7

this forms a double layer between the lungs and the thorax walls. In between the membranes, there is a thin layer of pleural fluid. Together they form an airtight seal and prevent the lungs from sticking to the thorax wall as the inflate and deflate.

Question 8

What are intercostal muscles, what do they do

Answer 8

Intercostal muscles between the ribs

help to connect the bones and are important in moving air into and out of the lungs.

Question 9

What is the diaphragm, what does it do

Answer 9

This domed sheet of muscle and fibrous tissue is also important in moving
air into and out of the lungs

Question 10

What is ventilation

Answer 10

Ventilation is the process of moving air into and out of the lungs (inhalation and
exhalation). Moving air relies on differences in air pressure between the lungs and the atmosphere

Question 11

What happens during inhalation

Answer 11

Diaphragm contracts, moving down and flattening. Intercostal muscles contract, moving rib cage up and out. This causes the volume of the thorax to increase
and air pressure in the thorax to fall. Air pressure in the thorax is now less than
atmospheric pressure, causing air to move into the lungs.

Question 12

What happens during exhalation

Answer 12

Diaphragm relaxes, moving up and doming. Intercostal muscles relax, moving rib cage down and in. This causes the volume of the thorax to decrease and air pressure in the thorax to rise. Air pressure in the thorax is now more than atmospheric pressure, causing air to move out of the lungs.

Question 13

Why are the alveoli suited for gas exchange

Answer 13

Large surface area (60m^2), surrounded by a network of capillaries which maintains a high CG, each alveolus is one cell thick

Question 14

Where does gas exchange occur in the lungs

Answer 14

In the alveoli. Oxygen diffuses from alveoli into RBC, carbon dioxide diffuses another way round

Question 15

How does exercise affect our breathing rate

Answer 15

During exercise our breathing rate increases, as well as the depth of each breath. This is in response to the increased concentration of carbon dioxide in the blood. Because of our breathing rate increases, we excrete carbon dioxide more rapidly. Oxygen can also diffuse into the blood at a faster rate (as there is a higher concentration gradient).

Question 16

How do we measure breath rate

Answer 16

we simply count the number of breaths a

person takes each minute.

Question 17

How do we measure breath depth

Answer 17

use a device called a spirometer to measure the volume of air inhaled and exhaled.

Question 18

How many chemicals do cigarettes have

Answer 18

4000 chemicals

Question 19

What addictive drug is present in cigarettes/tobacco smoke

Answer 19

Nicotine. Many anti-smoking products contain nicotine, which gradually decreases to help a person get rid of their smoking habit

Question 20

How many carcinogens are in a cigarette/tobacco smoke

Answer 20

There are at least 17 carcinogens. These carcinogens alter DNA and increase the risk of cancer

Question 21

Name 5 carcinogens in tobacco smoke and what they do

Answer 21

Arsenic results in high levels of skin cancer, bladder cancer and lung cancer
Formaldehyde irritates the eyes, nose and throat
Acetaldehyde can increase chance of getting digestive tract cancers
Lead can damage almost every organ system, damages nervous system
Benzene causes irreversible damage to the bone marrow, may cause anaemia

Question 22

What disease is closely linked with smoking

Answer 22

Lung cancer, but also bronchitis, emphysema, atherosclerosis, myocardial infection, larynx cancer, oesophagus cancer

Question 23

What does carbon monoxide do to your body

Answer 23

This irreversibly (permanently) binds to the
haemoglobin forming carboxyhaemoglobin, and so reducing the amount of oxygen transported by the blood. If a pregnant woman smokes, the baby will receive less oxygen and as a result is likely to weigh less at birth. This can cause other problems.

Question 24

How are cilia affected by chemicals in tobacco

Answer 24

Chemicals in tobacco smoke destroy cilia, reducing their number. At the same time, mucus production will increase; this is in response to the smoke. The mucus cannot be moved out of the airways quickly. This causes smoker’s cough and increases the risk of infections.

Question 25

How are alveoli affected by tobacco smoke

Answer 25

Smoke can also reach the alveoli, damaging them. The alveoli walls break down in places and fuse together, forming larger irregular air spaces. This decreases the surface area for gas exchange, so less oxygen diffuses into the blood. Causes emphysema

Question 26

What are bronchi, what do they do

Answer 26

Bronchi are the main passageway into the lungs.