Extra bits on respiration, aerobic vs anaerobicWatch
I've been asked to cover extra info on respiration, stuff that might not be in textbooks or obvious, etc.
1. Why has aerobic respiration evolved to override anaerobic respiration?
2. When does anaerobic respiration occur in humans?
3. What is the link between breathing, heart rate and respiration?
2) When your cells are using up oxygen faster than the blood can supply it - usually in muscle cells during exercise. Aching muscles during intense exercise are actually caused by the build up of lactic acid in muscles.
3) Respiration uses up oxygen, which needs to be replenished, and produces CO2, which needs to be removed. Blood flow, which is linked to heart rate, is the method by which O2 can diffuse into cells and CO2 can diffuse into blood. Breathing then expels CO2 and takes in O2.
I don't really remember the details of heart and lungs (it's been about 3 years since I did that stuff), but I hope this helps.