1During exercise
Working muscles respire faster. They need more oxygen and make more carbon dioxide, so you breathe faster and more deeply, and your heart beats faster.
exercise
Lesson 7.4 notes
Exercise, asthma, smoking and stomata
See how exercise changes your breathing, what happens in an asthma attack, what smoking does to your lungs, and how leaves exchange gases.
2An asthma attack
In an asthma attack the bronchioles narrow: the muscle around them tightens, the lining swells and extra mucus is made. Less air can get through, so breathing is hard.
asthma
3Inhalers
A reliever inhaler contains a drug that relaxes the muscle around the bronchioles. The airways widen again, so air can flow in and out more easily.
reliever inhaler
4What's in cigarette smoke
Tar is sticky and causes cancer. Carbon monoxide takes the place of oxygen in red blood cells, so the blood carries less oxygen. Nicotine is addictive.
tarcarbon monoxidenicotine
5Smoker's cough
Tar damages the cilia, so they can't sweep mucus away. The mucus builds up and has to be coughed up. Microbes trapped in it can cause chest infections.
smoker's cough
6Damaged alveoli
Smoking can break down the walls between alveoli (emphysema). Fewer, bigger air sacs have much less surface area, so less oxygen gets into the blood and people get out of breath easily.
emphysema
7Gas exchange in leaves
Leaves exchange gases through pores called stomata. In the light, carbon dioxide diffuses in for photosynthesis; oxygen and water vapour diffuse out. Guard cells close them in the dark or when water is short.
stomataguard cells
Explore: Exercise lab
Pick an activity and watch the breathing trace: how many breaths a minute, how big each breath is, and how much air goes in each minute.
Common mistake: Leaves don't breathe like lungs
Plants have no lungs and make no breathing movements. Gases simply diffuse in and out through the stomata, and guard cells control how open they are.
Remember
- Exercise: muscles respire faster, so you breathe faster and deeper to bring in more oxygen and remove carbon dioxide.
- Asthma: the airways narrow as the muscle tightens, the lining swells and more mucus is made. A reliever inhaler relaxes the muscle.
- Smoking: tar damages cilia and causes cancer; carbon monoxide cuts the oxygen blood carries. Leaves exchange gases through stomata.
Going further at GCSE
GCSE: How the body responds to exercise → GCSE: Leaf tissues and stomata →