Structure of the Human Gas-Exchange System

Question 1

What do all aerobic organisms require in order to release energy in the form of ATP?

Answer 1

A constant supply of oxygen

Question 2

Why does the carbon dioxide produced as a result of respiration have to be removed?

Answer 2

Build up can be harmful to the body

Question 3

Why is the volume of oxygen that has to be absorbed and the volume of carbon dioxide that has to be removed large in mammals?

Answer 3

• they are relatively large organisms with a large volume of living cells
• they maintain a high body temperature which is related to them having high metabolic and respiratory rates

Question 4

What do mammals use to ensure efficient gas exchange between the air and their blood?

Answer 4

Lungs

Question 5

What is the site of gas exchange in mammals?

Answer 5

The lungs

Question 6

Why are the lungs located inside the body?

Answer 6

• air is not dense enough to support and protect the delicate structures
• the body as a whole would otherwise lose a great deal of water and dry out

Question 7

How are the lungs supported and protected?

Answer 7

By the rib cage

Question 8

How are the ribs moved to allow for breathing?

Answer 8

By the internal intercostal muscles and the external intercostal muscles

Question 9

What does ventilation within the lungs allow for?

Answer 9

The air within them to be constantly replenished

Question 10

What are the lungs and what do they consist of?

Answer 10

A pair of lobed structures made up of a series of highly branched tubules, called bronchioles, which end in tiny air sacs called alveoli

Question 11

What is the trachea and what does it consist of?

Answer 11

It is a flexible airway that is supported by rings of cartilage, the cartilage prevent the trachea from collapsing as air pressure falls when breathing in. The tracheal walls are made up of muscle, lined with ciliated epithelial and globlet cells

Question 12

What are the the bronchi and what do they consist of?

Answer 12

The bronchi are two divisions of the trachea, each leading to one lung. They are similar in structure to the trachea and they produce mucus like the trachea to trap dirt particles, which the cilia move upwards towards the throat. Larger bronchi are supported by cartilage but cartilage is reduced as bronchi get smaller

Question 13

What are the bronchioles and what do they consist of?

Answer 13

A series of branching subdivisions of the bronchi. Their walls are made of muscle lined with epithelial cells. This muscle allows them to constrict so that they can control the flow of air in and out of the alveoli

Question 14

What are the alveoli and what do they consist of?

Answer 14

Minute air-sacs with a diameter of between 100um and 300um, at the end of the bronchioles. Between the alveoli there are elastic and collagen fibres which allow the alveoli to stretch as they fill with air when breathing in. They can then spring back during breathing out in order to expel the carbon dioxide-rich air. The alveolar membrane is the gas-exchange Surface Arbilla gets

Question 15

What supports the trachea?what does cartilage prevent?

Answer 15

The trachea from collapsing when pressure drops during breathing in

Question 16

What are the muscular walls of the trachea lined with?

Answer 16

Ciliated epithelium and goblet cells

Question 17

What is the role of ciliated epithelium in the trachea and bronchi?

Answer 17

They waft the mucus they produce (which contains trapped dust and dirt) out of the lungs towards the throat

Question 18

What are the two divisions of the trachea?

Answer 18

The bronchi

Question 19

What are larger bronchi supported by?

Answer 19

Cartilage

Question 20

What does the muscle within the bronchioles allow?

Answer 20

It allows them to control the air flow in and out of the alveoli

Question 21

Where are the alveoli?

Answer 21

At the end of the bronchioles

Question 22

What are found between the alveoli?

Answer 22

Collagen and elastic fibres

Question 23

What are the alveoli lined with?

Answer 23

Epithelium

Question 24

What do elastic fibres allow the alveoli to do?

Answer 24

Stretch as they will with air and as they spring back during breathing out they expel carbon dioxide-rich air

Question 25

What is the gas exchange in the lungs?

Answer 25

The alveolar membrane

Question 26

State two reasons why humans need to absorb large volumes of oxygen from the lungs

Answer 26

• humans are large
• humans have a large volume of cells
• humans have a high metabolic rate
• humans have a high body temperature

Question 27

List in the correct sequence all the structures that air passes through on its journey from the gas-exchange surface of the lungs to the nose

Answer 27

Alveoli - bronchioles - bronchus - trachea - nose

Question 28

Explain how the cells lining the trachea and bronchus protect the alveoli from damage

Answer 28

• The cells produce mucus that traps particles of dirt and bacteria in the air breathed in. The cilia on these cells move this debris up the trachea and into the stomach
• the dirt can damage and cause infection in the alveoli