Gas Exchange in Humans

Question 1

Where is the gas exchange system located in the body?

Answer 1

Thorax

Question 2

When we breathe in what pipe does the air pass down?

Answer 2

Trachea (windpipe)

Question 3

What is the trachea (windpipe) surrounded by that keeps it open but makes swallowing easier?

Answer 3

C - shaped rings of cartilage

Question 4

What does the trachea split into?

These are tubes that lead to the lungs and are also surrounded by cartilage rings.

Answer 4

Bronchi

Question 5

What do the bronchi divide, or branch, into?

They are tubes which carry air deep into the thorax.

Answer 5

Bronchioles

Question 6

At the end of each bronchiole there are microscopic air sacs. These are the sites of gas exchange. What are they called?

Answer 6

Alveoli

Question 7

The lungs are surrounded by a double layer which is between them and the thorax walls. What is this layer called?

Answer 7

The floral membrane.

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

Question 8

What helps to protect the organs in the thorax?

Answer 8

The ribs help to protect the organs in the thorax. Intercostal muscles between the ribs help to connect the bones.

Question 9

What is found between the ribs to help connect the bones and are also important in moving air into and out of the lungs?

Answer 9

Intercostal muscles

Question 10

What is found below the lungs, separating the organs of the thorax and the abdomen?

Answer 10

The diaphragm. It is a domed sheet of muscle and fibrous tissue, it’s also important in moving air into and out of the lungs.

Question 11

What is the name of the process for moving air into and out of the lungs?

Answer 11

Ventilation

Question 12

What happens for inhalation?

Answer 12

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

Question 13

What happens for exhalation?

Answer 13

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

Question 14

Where does gas exchange occur?

They are air sacs with a specialised structure for efficient gas exchange.

Answer 14

Alveoli

Question 15

What gas defuses from the air into the red blood cells, and what does it bind with for transport?

Answer 15

Oxygen, which binds with haemoglobin

Question 16

What gas, when dissolved in the plasma, defuses from the blood into the alveoli?

Answer 16

Carbon dioxide

Question 17

What happens to the oxygen and carbon dioxide content of air, from entering the lungs to when it leaves the lungs?

Answer 17

Air leaving the lungs contains about 4% less oxygen 4% more carbon dioxide

Question 18

There are an enormous number of alveoli in the lungs, giving a total surface area around 16m². What does this large surface area increase the rate of?

Answer 18

Diffusion

Question 19

What is each alviolus surrounded by?

They form a network which constantly carries deoxygenated blood to the alveolus and moves oxygenated blood away.

Answer 19

Capillaries

Question 20

How thick are the walls of the alveoli? Why?

Answer 20

The walls of the alveoli are one cell thick

This means that gases only need to move very small distances, speeding up diffusion

Question 21

During exercise what happens to our breathing?

Answer 21

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.

Question 22

When our breathing rate increases what do we excrete more rapidly?

Answer 22

Carbon dioxide

Question 23

During exercise, why can oxygen defuse into the blood at a faster rate?

Answer 23

Because there is a higher concentration gradient

Question 24

During exercise an increased breathing rate and heart rate supplies more oxygen to the muscles for what type of respiration?

Answer 24

Aerobic respiration

Question 25

During exercise, if there isn’t enough oxygen supplied to the muscles then they will respire anaerobically. If this happens the breathing rate will remain high after exercise finishes, supplying the extra oxygen needed to oxidise what?

Answer 25

Lactic acid

Question 26

How do we measure the breathing rate?

Answer 26

We count the number of breaths a person takes each minute. If we measure breathing rate at rest and after exercise we can work out the difference.

Question 27

How do we measure breathing depth?

Answer 27

You can use a device called a spirometer to measure the volume of air inhaled and exhaled, which can be done at rest and during exercise to find a difference.

Question 28

In healthy lungs what prevents dirt and bacteria entering the lungs?

Answer 28

The lining of the trachea and bronchi are specialised to prevent dirt and bacteria entering the lungs

Question 29

What do goblet cells produce and what does it trap?

Answer 29

Goblet cells produce mucus, which traps dust and pathogens

Question 30

Why do the cilia of the lining cells move?

Answer 30

The cells move to transport the mucus up the airways where it is then swallowed