5.3 Lungs & Gas Exchange

Question 1

How do our cells get the energy needed to function?

Answer 1

They must carry out cellular respiration.

Question 2

Describe how oxygen travels from our mouths to our alveoli.

Answer 2

Whenever we breathe in, air passes through our mouth or nose and then down our trachea. From there, it divides between our two bronchi. It then further divides between branch-like structures which we call bronchioles. Once the air has made its way through all these branches, it reaches these small sacs which are called alveoli.

Question 3

What is a single alveoli called?

Answer 3

Alveolus

Question 4

In a digram showing alveoli, why might the red blood cells appear blue?

Answer 4

To show that the blood has been passed around the body, so the haemoglobin within the red blood cells will have already given up lots of its oxygen to the tissues, meaning there won’t be much left.

Question 5

Describe in detail how gas exchange in the alveoli works

Answer 5

• When the blood in the capillaries have just returned to the lungs from being passed around the body, the haemoglobin within the red blood cells will have already given up lots of oxygen to the tissues, meaning that there won’t be much left. (This is why they may be shown as blue in diagrams). As the alveoli are full of fresh oxygen, we have the perfect concentration gradient by which the oxygen in the alveoli can diffuse down that gradient into the blood and then our oxygenated blood can start the cycle all over again
• The carbon dioxide will be at a higher concentration in the blood (it is dissolved in the blood) than the alveoli so it can easily diffuse across. Once in the alveoli, we can just breathe it out.

Question 6

How do you calculate ‘breathing rate’ into breaths per minute?

Answer 6

no. of breaths taken/no. of minutes

Question 7

Which organ system are the lungs part of?

Answer 7

Respiratory system