Gas Exchange

Question 1

Describe the structure of the trachea

Answer 1

The trachea is lined with mucus-secreting goblet cells and cilia. The cilia sweep microorganisms and dust away from the lungs. Regular arrangement of C-shaped cartilage rings

Question 2

Describe the structure of the lungs

Answer 2

It is where gas exchange occurs

Question 3

Describe the structure of the bronchi

Answer 3

Similar in structure to trachea. Irregular blocks of cartilage

Question 4

Describe the structure of the bronchioles

Answer 4

These are narrow tubes that carry air from the bronchi to the alveoli. They have no supporting cartilage and so can collapse

Question 5

Describe the structure of alveoli

Answer 5

They are tiny sacs with many structural adaptations to enable efficient gas exchange

Question 6

Describe the structure of the capillary network

Answer 6

An extensive network of capillaries surrounds the alveoli and are on the exchange surface between the lungs and blood

Question 7

Use of cartilage in trachea and bronchi

Answer 7

It keeps these airways open and air resistance low, it prevents them from collapsing as air pressure changes during breathing. The cartilages is strong but flexible and is able to move as we breathe

Question 8

Ciliated epithelium

Answer 8

It is found along the trachea down to the bronchi. Each cell has cilia which sweep mucus, dust and bacteria upwards and away from the lungs. Goblet cells can be found scattered throughout the ciliated epithelium in the trachea

Question 9

Function of goblet cells

Answer 9

They are mucus producing cells, mucus traps dust, bacteria and other microorganisms from reaching the lungs

Question 10

Squamous epithelium

Answer 10

The alveoli have a thin lining of thin squamous epithelium. It forms the structure of the alveolus wall and so is very thin and permeable for easy diffusion of gases

Question 11

Smooth muscle

Answer 11

It can be found throughout the walls of the bronchi and bronchioles. It helps regulate the flow of air into the lungs by dilating when more air is needed and constricting when less air is needed

Question 12

Network of capillaries

Answer 12

Each alveolus is surrounded by an extensive network of capillaries. CO2 diffuses out of the capillaries and into the alveoli to be exhaled, wile O2 diffuses from alveoli and into the capillaries to be carried around the body

Question 13

Function of mucous glands

Answer 13

They work with goblet cells in the trachea and bronchi to produce mucus

Question 14

Function of elastic fibres

Answer 14

Found in the squamous epithelium of the alveolar walls. They allow the tiny alveoli to stretch as they fill with air and recoil to help force air out. It is the elastic abilities which enable them to have such a large surface area

Question 15

Describe the gas exchange process

Answer 15

O2 and CO2 are exchanged in a process of simple diffusion. The air in the alveoli contains a high concentration of O2. The O2 diffuses from the alveoli and into the blood capillaries, before being carried away to the rest of the body. The blood in the capillaries has a relatively low concentration of O2 and high concentration of CO2. The CO2 diffuses from the blood and into the alveoli and is then exhaled

Question 16

Features of the alveoli and its importance

Answer 16

1) Large surface area. The average human has millions of alveoli. This enormous surface area increases the space available for O2 and CO2 to diffuse.
2) Thin walls. The cells are only one cell thick. Gases have a very short diffusion distance and so gas exchange is quick and efficient