More biology+caffeine fun

Last night I tried to explain to Sayer some of the effects of caffeine on the body. I did this because I was using caffeine to stay alert, and suffering the 'side effects' of really really needing to pee. She seemed to be listening in between her giggles.

Today as we drove home I showed her the bottle of soda I was drinking and asked her if she could tell me what was in it. Her first answer was cola. Well, yes. :) What else? What is in the cola that is helping me to stay awake? She couldn't come up with the name, but when I told it to her and asked what it did for me she was able to tell me that it stimulated my brain to keep me awake and made me need to pee.

So we elaborated on that today. I talked with her about the circulatory system and how the arteries take blood away from the heart and get progressively smaller as they go farther out into the body. And veins take blood back to the heart, getting progressively bigger. But in between the arteries and the veins, where the vessels are really small ... those are the capillaries. And caffeine affects them by dilating them - opening them up wider - which allows more blood to flow through them, which allows for more delivery of oxygen ... And when the capillaries in the brain get flooded with oxygen it makes the brain more alert ... which is not necessarily more awake, but anyway ...

And we went over, again, that caffeine makes the kidneys work harder and therefore extract more water from the blood and body tissues. At that point Sayer chimed in that the body stored that water in the bladder, which gets really full, which leads to mommy singing/howling about how badly she has to pee.

So. Does that count as biology? Chemistry? Humor?