1. 1 earoicb 2 esptniirrao 3 xogney 4 lcguoes 5 reitabhng 6 gidsteeiv 7 arcbno oexiidd 8 gneery 9 ritoonmdhica
1 Aerobic
2Respiration
3 Oxygen
4 Glucose
5 Breathing
6 Digestive
7 Carbon dioxide
8 Energy
9 Mitochondria

2. Anaerobic respiration
Learning objectives
Write the equation for anaerobic respiration in animal cells.
Explain the effect of lactic acid build up on muscle activity.
Explain why anaerobic respiration is less efficient than aerobic respiration.
Define the term oxygen debt.
Write the equation for the Breakdown of lactic acid into carbon dioxide and water.

3. Aerobic respiration carbon dioxide glucose + oxygen  + water (energy)
You know that……
carbon
dioxide
glucose +
oxygen  +
water
(energy) +

4. Aerobic respiration Glucose + Oxygen Carbon Dioxide + Water + Energy
Aerobic – ‘with oxygen’
Plenty of oxygen
Efficient
When able to completely digest food
…but what happens when we are using energy faster than oxygen can
be supplied?

5. Anaerobic respiration
Glucose Lactic Acid + (some) Energy
from the digestive system
waste product
not as much energy as with aerobic respiration
Anaerobic – ‘without oxygen’
Not efficient
Harmful waste product – causes cramp
For short periods of time

6. Lactic acid can stop muscles within the body from contracting and relaxing. This can lead to fatigue and cramp.
relaxation
The lactic acid soaks the muscle cells and prevents the muscle cell from doing its job.
contraction

7. This leaves us with a problem...
If you want to consider the full impact of damage caused by the presence of lactic acid, just remember that the heart is made of muscle cells!
This leaves us with a problem...
if we want to do exercise
YES NO
We want the energy that anaerobic respiration produces
But we don’t want the lactic acid waste product
So the answer is for anaerobic respiration to be a ‘gap-fill’ during periods of very low / no oxygen availability.

8. Oxygen debt oxygen levels time
rest
aerobic
exercise stops
anaerobic
exercise
oxygen levels
time
Anaerobic respiration keeps our bodies going until we can breathe in more oxygen again.
Whilst we are performing anaerobic respiration, our bodies are building up a ‘debt’ of oxygen.

9. The oxygen debt will have to be repaid when the exercise stops.
Whilst we are performing anaerobic respiration, our bodies are building up a ‘debt’ of oxygen
The oxygen debt will have to be repaid when the exercise stops.
The oxygen breaks down (oxidises) the lactic acid into carbon dioxide and water.
The process of anaerobic respiration which can then turn back into...
In this way, the process of aerobic respiration can be converted into
Respiration in exercise

10. Changes during a triathlon
Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114

11. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
Before the race starts Helen tries to relax as much as possible. Her heart rate is low but the excitement of the coming race has already started to get adrenalin pumping around her body. This natural hormone is preparing her body for the race to come.

12. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
As the swim starts Helen’s body reacts to the cold water and exercise, notice the slight drop in temperature but the increase in heart and breathing rates. Why has the blood sugar dropped slightly?

13. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
She’s well into her swim now. Helen’s heart rate and breathing rate have both increased. Why? And what has caused the increase in her blood sugar level?

14. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
Out of the water and onto her bike. This is a long slog to the next part of the race – the 40 km bike ride. Helen needs to pace herself to leave energy for the road race.

15. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
The 10 km road race has started! Helen’s leg muscles are really beginning to ache now as lactic acid from anaerobic respiration begins to build up. Her breathing and heart rates increase even further but she must be careful not to push herself too far – or she won’t be able to finish.

16. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
The end is in sight! Now its time to sprint to the finish line. Helen’s body cannot take this sort of strain for much longer – the last few hundred metres will be the hardest of the whole triathlon! Her heart rate is now higher than at any previous time in the race.

17. Before
Start of swim
Into swim
Cycling
Running
Sprint finish
After
Body temperature (oC)
36.3
36.0
36.7
37.4
Heart rate
(beats per min) 85
135
145
155
142
159
133
Breathing
(litres per min)
3.2
6.9
7.2
7.6
7.9
8.3
Blood sugar
(mg per 100 cm3)
100 80
120
106 94 83
114
And its over! Helen’s time was 2 hours 53 minutes! She’ll continue to breathe heavily for another 10 minutes or more as the lactic acid in her muscles is broken down. She’ll cool down slowly to help to prevent muscle pain.