Gas Exchange In Humans

Question 1

What does air enter as you breathe in?

Answer 1

The trachea

Question 2

What does the trachea split into? Where do these lead to?

Answer 2

2 bronchi, one bronchus leading to each lung.

Question 3

What do bronchi branch off into?

Answer 3

Bronchioles - smaller tubes

Question 4

What do Bronchioles end in?

Answer 4

Air sacs called alveoli

Question 5

Where does gas exchange occur in humans?

Answer 5

At the alveoli

Question 6

Where are the intercostal muscles found?

Answer 6

Between the ribs.

Question 7

What are the 2 types of intercostal muscles?

Answer 7

Internal and external intercostal muscles

Question 8

How is a large surface area achieved for efficient gas exchange in mammals?

Answer 8

Highly branched bronchioles leading to alveoli

Question 9

Now is air moved across the exchange surface in mammals?

Answer 9

Tidal flow - flows in opposite directions in and out

Question 10

How is the required gas delivered to respiring cells?

Answer 10

Red blood cells in blood vessels

Question 11

What lines the alveoli?

Answer 11

A single layer of flattened epithelial cells and a network of pulmonary capillaries

Question 12

What are the capillaries surrounding the alveoli lined with?

Answer 12

A single layer of endothelial cells

Question 13

How thick are the capillaries surrounding the alveoli?

Answer 13

Very thin-one cell thick

Question 14

Why is it beneficial for the capillaries to be narrow as the red blood cells pass through?

Answer 14

The capillaries are narrow so that red blood are flattened and squeezed through. This slows them down and increases surface area for diffusion.

Question 15

Where are squamous epithelia found?

Answer 15

On the outer layer of the alveoli, lining the cheeks, inside blood vessels, lining the chambers of the heart

Question 16

What are the adaptations of squamous epithelia?

Answer 16

Smooth, flat, very thin, packed closely together, single layer of flattened cells

Question 17

Why are squamous epithelia important?

Answer 17

The layer of cells forms a thin cross-section which reduces the distance that substances have to move to pass through - it shortens the diffusion pathway
It is permeable, allowing for the easy diffusion of gases

Question 18

Why is it important that the surface of the squamous epithelia is a low friction surface?

Answer 18

Low friction decreases the chance of clots forming

Question 19

What 5 factors increase the rate of diffusion in mammals?

Answer 19

1. The RBC’s are slowed as they pass through the pulmonary capillaries
2. The RBC’s are flattened against the capillary walls
3. The walls of capillaries and alveoli are very thin
4. Alveoli have folds and there are many capillaries
5. ventilation and circulation

Question 20

Why does the slowing down of RBC’s as they pass through capillaries increase the rate of diffusion?

Answer 20

More time for efficient exchange of oxygen.

Question 21

Why does the flattening of RBC’s against the capillary wall increase the rate of diffusion?

Answer 21

Reduces the distance between the alveoli and capillary therefore a shorter diffusion pathway

Question 22

Why do thin walls increase rate of diffusion?

Answer 22

Shorter diffusion pathway

Question 23

Why do folds in alveoli and many capillaries increase the rate of diffusion?

Answer 23

Increases the surface area

Question 24

Why do ventilation and circulation increase rate of diffusion?

Answer 24

Ensure a concentration gradient is maintained

Question 25

Define the term ventilation

Answer 25

The process by which air is constantly moved into and out of the lungs

Question 26

What is inspiration (inhalation)?

Answer 26

When arr is forced into the alveoli because the pressure of the atmosphere is greater than the pressure inside the lungs

Question 27

What happens during inspiration?

Answer 27

The external intercostal muscles and the diaphragm contract which causes the ribcage to move upwards and outwards and me diaphragm to flatten. The volume of the thorax increases as the diaphragm flattens. The pressure in the thorax decreases as volume increases. The pressure of air in the atmosphere is higher than the pressure inside the thorax. Air is drawn into the lungs. This is an active process and requires energy.

Question 28

What happens during expiration?

Answer 28

The external intercostal muscles and the diaphragm relax (the internal ones remain relaxed unless expiration is forced). The volume of the thorax decreases as the diaphragm becomes domed. The pressure in the thorax increases as volume decreases. The pressure 'of air in the atmosphere is lower than the pressure inside the thorax. Air is forced out of the lungs.

Question 29

Is normal expiration active or passive?

Answer 29

It is passive as it doesn't require energy.

Question 30

What is the equation for pulmonary ventilation?

Answer 30

Pulmonary ventilation= tidal volume x ventilation rate

Question 31

What is ventilation rate?

Answer 31

The breaths taken in one minute

Question 32

What is pulmonary ventilation?

Answer 32

The measure of the amount of air that is moved into the lungs in one minute

Question 33

Name the process by which oxygen passes from an alveolus in the lungs into the blood

Answer 33

Diffusion

Question 34

Describe now oxygen in the air in the alveoli enters the capillaries

Answer 34

Diffusion across the alveoli epithelium

Question 35

What is tidal volume?

Answer 35

The volume of air normally taken in at each breath when the body is at rest

Question 36

What is forced expiratory volume (fev 1)

Answer 36

The maximum volume of air breathed out in one second

Question 37

What is forced vital capacity? (Fvc)

Answer 37

The maximum volume of air that can be forced out of the lungs after a deep breath in

Question 38

What is ventilation rate?

Answer 38

Number of breaths per minute

Question 39

What is a spirometer? What's it used for?

Answer 39

Amachine used to record measurements such as tidal volumes vital capacity etc.

Question 40

What is residual volume?

Answer 40

Volume of air left in the lungs after forcibly breathing out

Question 41

What is expiratory reserve volume?

Answer 41

The max volume of air that can be expelled from the lungs after normal expiration

Question 42

What is inspiratory reserve volume?

Answer 42

The max volume of air that can be inhaled after a normal inspiration

Question 43

Now do you work out % change in FEV1?

Answer 43

Final value - original value x100 Original value

Question 44

What is a correlation?

Answer 44

A link/ relationship between 2 things that happen

Question 45

What are the walls of the alveoli made from?

Answer 45

A single layer of thin, flat cells called alveolar epithelium

Question 46

What protein can be found in the walls of the alveoli?

Answer 46

Elastin. It helps the alveoli return to their normal shape after inhaling or exhaling

Question 47

Describe the route that air takes to get to alveoli

Answer 47

Moves down the trachea, bronchi and bronchioles into the alveoli this is down a pressure gradient

Question 48

Describe the route oxygen takes to get into the blood

Answer 48

Alveoli, alveolar epithelium, capillary endothelium, blood

Question 49

What 2 features do alveoli have that speed up diffusion+ gas exchange?

Answer 49

- A thin exchange surface: the alveolar epithelium is only one cell thick which means there is a short diffusion pathway - a large surface area:more gas exchange can take place

Question 50

Explain how gas exchange occurs at the alveoli

Answer 50

Air moves in and out of the alveolus. Blood enters the capillary from the rest of the body. It has a high concentration of carbon dioxide and a low concentration of oxygen. The alveolus has a high concentration of oxygen and a lower concentration of carbon dioxide. There is a net movement of carbon dioxide into the alveolus and a net movement of oxygen out of the alveolus. Blood goes to the rest of the body with A lower concentration of carbon dioxide and a higher concentration of oxygen