Answer:
Firstly, when we exercise, or do some activity (in this case football), we use more energy than usual...
The reason some of her body systems work faster than normal, is to keep the body working and in the equilibrium, so that she won’t get tired too fast.
Related to circulation, her blood flow increases, since she needs more oxygen to reach the muscles faster, due to the exercise/activity (Lactic acid builds up, so more oxygen is required.)
Her breathing increases to take in more oxygen(O2), and give out more carbon dioxide(CO2).
Her body respires more(respiration), both aerobically(with oxygen), and anaerobically(without oxygen), lactic acid builds up due to anaerobic respiration.
(Here, energy is released from glucose to generate a substance called lactic acid. ... Therefore anaerobic respiration cannot be used for a prolonged period of time without having damaging effects on a cell.)
When she inhales (Oxygen), it goes to the lungs, to the alveoli ( Alveoli are tiny air sacs in your lungs that take up the oxygen you breathe in and keep your body going)
In the Alveoli, diffusion takes place, this is where oxygen is diffused into the blood, and carbon dioxide is diffused (taken into) into the lungs.
Then we exhale, which gives out the carbon dioxide(CO2), this happens really fast, we also breathe so fast, this process happens within seconds.
Red blood cells contain something called haemoglobin, this combines with oxygen To form oxyhaemoglobin, then when the red blood cell reaches the muscle, it gives the oxygen, converting oxyhaemoglobin back to haemoglobin.
Heart: pumps blood faster (as I said before), to ensure oxygen gets distributed faster to where it’s needed
