Respiration and Gas Exchange in Humans

Question 1

What does the gas exchange system do?

Answer 1

Supplies oxygen and removes carbon dioxide

Question 2

What does the gas exchange system do?

Answer 2

Supplies oxygen for respiration and removes carbon dioxide

Question 3

What is the process by which energy is released from food in your cells?

Answer 3

Cellular respiration

Question 4

What is the function of mucus and cilia?

Answer 4

Mucus is a sticky liquid that traps particles of dirt or bacteria that are breathed in.
The cilia sweep mucus and trapped particles towards the mouth protecting the lungs where they might cause an infection.

Question 5

Function of alveoli

Answer 5

Tiny air sacs adapted for gaseous exchange

Question 6

Function of the bronchus and bronchioles

Answer 6

Carries air to lungs

Question 7

Description and function of diaphragm

Answer 7

Sheet of muscle with a fibrous middle part which is domed. Aids breathing movements and ventilation

Question 8

Function of diaphragm

Answer 8

Aids breathing movements and ventilation

Question 9

What does ventilating the lungs do?

Answer 9

Ventilation means moving air in and out of the lungs, it brings in rich oxygenated blood and removes blood containing carbon dioxide.

Question 10

Function of intercostal muscles?

Answer 10

Controls rib movement

Question 11

What are the adaptations of alveoli?

Answer 11

Large surface area
Rich blood supply (steep diffusion gradient)
Short diffusion distances between the air and the blood

Question 12

How are alveoli adapted for gas exchange?

Answer 12

The huge number of microscopic alveoli gives the lungs a very large surface area
There is a moist lining for gases to dissolve in
The alveoli have very thin walls - only one cell thick, so the gas doesn’t have far to diffuse
They have a great blood supply to maintain a high concentration gradient
The walls are permeable so gases can diffuse across easily
Short diffusion distance as the blood around the alveolus is separated by only two layers; the cells making up the wall of the alveolus and the capillary wall itself.

Question 13

What is the waste product of respiration?

Answer 13

Carbon dioxide

Question 14

How thick are the walls of capillaries and alveoli?

Answer 14

One cell

Question 15

What is the difference between respiration and breathing?

Answer 15

Respiration is the oxidation reaction that releases energy from foods, such as glucose where as breathing is the process of ventilation.

Question 16

What is the diaphragm?

Answer 16

A muscular sheet of tissue under the lungs.

Question 17

What is the bronchial tree?

Answer 17

The air passages of the lungs are a highly branching network so it is sometimes called a bronchial tree.

Question 18

What does each bronchus split into?

Answer 18

Smaller and smaller tubes called the bronchioles, each ending at the alveoli.

Question 19

What is the trachea?

Answer 19

The windpipe throughout which air enters our lungs when we breath in.
The trachea splits into two tubes called the bronchi, one leading to each lung.
Lined with cells making mucus, and cells with cilia which move the mucus away from the lungs

Question 20

What are the walls of the trachea made up of?

Answer 20

Cartilage that supports the airways and keep them open when we breathe in.

Question 21

What are pleural membranes?

Answer 21

Thin, moist membranes forming an airtight seal around lungs and separating the inside thorax from the lungs.

Question 22

Experiment to show effect of exercise on heart rate:

Answer 22

Get three people to sit still for 5 minutes
Count the number of breaths they take in one minute and put it in a table.
Then do 4 minutes of exercise (e.g. running) and as soon as you stop, count the number of breaths you take in a minute
Control variables: same gender and age of people, do exercise for the same amount of time at the same temperature

Question 23

Why does the air movement in the lungs remains a steep concentration gradient?

Answer 23

For the diffusion of oxygen and carbon dioxide between the blood and the lungs.

Question 24

What does gas exchange depend on?

Answer 24

Efficient diffusion of gases.

Question 25

What do the walls of bronchi and the trachea contain and why?

Answer 25

Cartilage to keep them open when we breathe in (otherwise they would squash flat)

Question 26

What does cigarette smoke contain?

Answer 26

Nicotine, carbon monoxide, tar and carcinogens

Question 27

Explain fully what happens when we breathe in

Answer 27

The ribs move out and upwards.
The intercostal muscles contract
The diaphragm contracts and is no longer dome shaped but rather flat.
Therefore, the thorax volume increases
This decreases the pressure, drawing air in

Question 28

Explain how diffusion occurs at the alveoli in detail (long, sorry Issi).

Answer 28

Blood is pumped from the heart to the lungs and passes through the capillaries surrounding the alveoli.
The blood around the alveolus is seperated by only two layers; the cells making up the wall of the alveolus and the capillary wall itself. The blood has come from respiring tissues of the body where it has given up some of its oxygen and gained carbon dioxide.
The alveolus has a higher oxygen concentration so it diffuses across the wall of the alveolus to the blood. Vice versa for carbon dioxide. The blood that leaves the capillaries that flows back to the heart gains oxygen and lost carbon dioxide.
The heart pumps this to respiring cells.

Question 29

Explain why excess mucus can cause lung infections

Answer 29

Mucus traps dust and bacteria. The bacteria will reproduce rapidly as mucus has ideal breeding conditions

Question 30

Describe the structure of the thorax

Answer 30

The thorax is separated from the lower part of the body by the diaphragm
The lungs are organs which are surrounded by pleural membranes and protected by the ribcage
The air that you breathe in goes through the trachea - this splits into two tubes called bronchi, one going to each lung
The bronchi split into progressively smaller tubes called bronchioles
The bronchioles finally end at small bags called alveoli where the gas exchange takes place

Question 31

What is the thorax

Answer 31

The top part of your body

Question 32

How can smoking cause emphysema?

Answer 32

The smoke damages the walls inside the alveoli, which beak down and fuse together again, forming enlarged, iregular air spaces.
This greatly reducing the surface area for gas exchange, making it very inefficient - the blood of a person with emphysema carries less oxygen

Question 33

What can the tar in cigarette smoke cause?

Answer 33

Tar damages the cilia in your lungs and trachea.
These hairs, along with mucus, catch dust and bacteria before they reach the lungs.
The cilia also help to keep the trachea clear by sweeping mucus back towards the mouth - when these cilia are damaged, chest infections are more likely
Tar also irritates the bronchi and bronchioles, encouraging mucus to be produced which can’t be cleared very well by damaged cilia - this causes smoker’s cough and chronic bronchitis

Question 34

How can the carbon monoxide in cigarette smoke lead to coronary heart disease?

Answer 34

The carbon monoxide in cigarette smoke reduces the amount of oxygen the blood can carry.
To make up for this, heart rate increases - which leads to an increase in blood pressure
High blood pressure damages the artery walls, making the formation of blood clots more likely - this increase the risk of coronary heart disease (heart attacks)

Question 35

What are carcinogens?

Answer 35

Chemicals that can lead to cancer

Question 36

Why does exercise increase breathing rate?

Answer 36

Your muscles respire more during exercise, therefore they use up more oxygen and produce more CO2
Therefore, they have to be supplied with more oxygen and have more carbon dioxide removed so your breathing rate increases