The human gas exchange system

Question 1

What is the trachea

Answer 1

The airway that leads from the mouth and nose to the bronchi

Question 2

What is the trachea lined with and what is this important for

Answer 2

Mucus - secreting Goblet cells and ciliated cells (Also known as cilia and 3-4µm long) . The cilia sweep microorganisms and dust away from the lungs

Question 3

What happens at the lungs

Answer 3

Where gas exchange takes place. (Lungs are a central part of the respiratory system)

Question 4

What are bronchi

Answer 4

The left and right bronchi (Bronchus plural) are at the bottom of the trachea and are similar in structure, but narrower.

Question 5

What do the bronchi lead to

Answer 5

Bronchioles

Question 6

What are bronchioles

Answer 6

Narrow tubes (less than 1mm) which carry air from the bronchi to the alveoli. Since they are so narrow, they have no supporting cartilage and so can collapse

Question 7

What are alveoli

Answer 7

The main site of gas exchange in the lungs. These are tiny sacs with many structural adaptations to enable efficient gas exchange, such as their thin walls and large surface area to volume ratio

Question 8

What role does the capillary network have in human gas exchange and where is the network found

Answer 8

An extensive network of capillaries surrounds the alveoli and are an exchange surface between the lungs and the blood. During gas exchange oxygen diffuses from the alveoli into the capillaries, while carbon dioxide diffuses the other way and is exhaled.

Question 9

Look at a diagram of the human gas exchange system to improve understanding

Answer 9

Look at a diagram of the human gas exchange system to improve understanding

Question 10

What does the trachea and both bronchi have around them to support them and stop them from collapsing

Answer 10

Rings of cartilage

Question 11

What moves mucus to the top of trachea

Answer 11

Rhythmic wavelike movement

Question 12

What happens when mucus reaches the top of the trachea and what happens as a result of this

Answer 12

The mucus is swallowed and so microbes trapped in the mucus are destroyed by stomach acid

Question 13

What do goblet cells do

Answer 13

Secrete sticky mucus containing glycoprotein

Question 14

What does mucus secreted by goblet cells do

Answer 14

Protects from dehydration and traps microbes and dust.​ lysozyme also present which causes bacterial lysis (breaking down of cell)

Question 15

What does the cartilage do on trachea and bronchi

Answer 15

Holds airways open during inhalation. (Cartilage is strong and flexible)

Question 16

What is the advantage of the trachea having incomplete c-shaped rings of cartilage

Answer 16

Allow food to pass down the oesophagus. ​
Allows the neck to move without blocking airway- flexibility

Question 17

Describe bronchi cartilage formation

Answer 17

In irregular blocks

Question 18

What does the loose tissue / smooth muscle on the inside of the cartilage allow for

Answer 18

contract or relax to alter diameter ​

Question 19

What is one reason asthma makes breathing harder

Answer 19

It causes constriction and so narrows airways.​

Question 20

What do elastic fibres do during exhalation

Answer 20

Recoil to dilate the airway

Question 21

What ‘loose tissue’ is in the inside of the cartilage

Answer 21

Smooth Muscle, Elastic Fibres, Glandular Tissue (secretes tissue), Blood Vessels

Question 22

What parts of the gas exchange system contain cilia / goblet cells

Answer 22

Trachea, Bronchi, Bronchioles (Not alveoli)

Question 23

What parts of the gas exchange system contain elastic fibres

Answer 23

Trachea, Bronchi, Bronchioles and alveoli

Question 24

What parts of the gas exchange system contain smooth muscle

Answer 24

Trachea, Bronchi, Bronchioles (Not alveoli)

Question 25

What occurs during inspiration (inhalation)

Answer 25

External intercostal muscles contract, pulling the ribcage upwards and outwards.​ Diaphragm contracts, pulling it from a domed to a flattened shape. (See Image)

Question 26

What is the effect of inspiration

Answer 26

volume of the thorax and lungs increase​ pressure is reduced​ air enters, goes down the pressure gradient.​

Question 27

What occurs during expiration - relaxed

Answer 27

External intercostal muscles relax and the ribcage falls under its own weight.​ Diaphragm relaxes and gut pressure pushes it back into its domed shape. Elastic recoil of lung tissue.

Question 28

What is the effect of relaxed expiration

Answer 28

volume of the thorax and lungs decrease​ pressure is increased​ air is forced out.​

Question 29

What occurs during forced expiration

Answer 29

Internal intercostal muscles contract, pulling the ribcage down and in.​ Abdominal muscle contracts pushing the diaphragm upwards.

Question 30

What is the effect of forced exhalation

Answer 30

volume of the thorax and lungs decrease​ pressure is increased​ air is forced out.

Question 31

When does forced exhalation occur

Answer 31

During Exercise, singing, playing a wind instrument.

Question 32

List the factors affecting the rate of diffusion

Answer 32

Concentration gradient, surface area, membrane thickness

Question 33

How does concentration gradient affect the rate of diffusion across membranes

Answer 33

The bigger the difference, the faster the rate

Question 34

How does surface area affect the rate of diffusion across membranes

Answer 34

The larger the area for diffusion, the faster the rate

Question 35

How does membrane thickness affect the rate of diffusion across membranes

Answer 35

the longer the diffusion path across a membrane, the slower the rate of diffusion. Distance halved = rate of diffusion doubles​

Question 36

Whats the equation for rate of diffusion (Fick's Law)

Answer 36

Surface Area X Difference in concentration / Length of diffusion path

Question 37

What is alveolar wall made from

Answer 37

squamous epithelium (<0.5 µm thick)

Question 38

What are walls of capillaries surrounding alveoli made from

Answer 38

squamous epithelium​

Question 39

What is the total diffusion path for gases between alveoli and capillaries

Answer 39

<1µm

Question 40

What are alveoli covered in

Answer 40

A thin film of moisture : Gases dissolve in this before diffusing through the alveolar wall.

Question 41

What happens to red blood cells to allow more time for diffusion

Answer 41

Red blood cells are slowed as they pass through the pulmonary capillaries

Question 42

What happens to red blood cells to reduce diffusion distance

Answer 42

Red blood cells are flattened against the wall of the capillary