Chapter 8 Respiratory system

1. The respiratory system

2. Respiration: the release of energy
from food inside living cells
Respiration
Aerobic Anaerobic
Requires O2 Does not require O2
Examples:
Plants , animals and humans respire aerobically
Yeast (fungus) respire anaerobically

3. Releasing energy
• Cells use this energy for:
• muscle …………..
• maintaining body ……………... (in mammals and birds)
• building new large ……...……. for cell growth
• nerve …………. .
• Active transport
+ +
Cells release energy from sugars by respiration
contraction
temperature
molecules
impulses

4. Finding out if respiration takes place
• What could you do to test a sample of soil
whether it contains living organisms or not?
• Test it if the sample respires it will produce:
• 1. carbon dioxide
• 2. heat

5. To test if a sample produces carbon dioxide
• Bubble the gas produced through lime water
• Lime water will change from clear to cloudy/ milky

6. To test if a sample is producing heat
A B

7. Measuring respiration in germinating seeds
• A respirometer is an apparatus that measures
the rate of respiration in plants or small animals.
• Germinating seeds use up oxygen and release
carbon dioxide, a chemical in the tube absorbs
CO2 and thus the amount of air in the tube
decreases.
• This causes the red liquid in the capillary tube
move towards the left.

8. Respiratory system
bronchiole
left lung
diaphragm
ribs
Intercostal
muscle
trachea
bronchus
alveoli
heart

9. Gas exchange in alveoli

10. How are alveoli adapted to increase
gas exchange
Feature How it increases the efficiency of gas exchange
1. Have thin walls Decrease distance for diffusion, increase diffusion rate
2. Have moist walls Gasses can dissolve in water and diffuse easier
3. Are numerous To increase surface area

11. How air differs when we breathe?
constituent Inhaled air Exhaled air Reason for difference
Oxygen 20% 18% O2 is carried away by RBCs
Carbon dioxide 0.04% 4% CO2 is released by respiring cells
Nitrogen 78% 78% It is not used by the body
Temperature variable Higher Air is warmed by body tissues
Humidity variable greater Air is moistened by body tissues

12. Comparing inhaled and exhaled air
• Precaution: The volunteer
should breath gently in and
out to prevent splashing of the
liquid.
• What change do you expect?
• In which tube would lime
water change first?

13. Breathing in(inhalation) 10

14. Breathing out(exhalation) 10

15. Lung volume
• This apparatus can be used to measure lung
capacity

16. Effect of exercise on breathing rate
• Design and carry out an experiment to show how
exercise affects the rate of breathing.
• How are you going to make your experiment:
1. fair
2. reliable
3. accurate
• Plot your results on graph paper.