Thread: Some questions on the human digestive system

Have alot of different questions and though ive read the answer to many by searching the net there are some left id like more input on.

How effective is our digestive system compared to animals and insects? What are the major differences?

How long does it take for nutrition entering the stomach to entering the bloodstream?

How long does it take for nutrition entering the bloodstream to be consumed by the body entirely?

If you neglect to chew your food proparly will it affect the energy gain of the food, or cause your body to have to work harder to digest it?

Food goes to the blood, and so the blood gives energy and mass to the body. Does this mean that scientifically we literally are what we eat?

Is there a huge difference in eating food in forms of real food or powder/pills?


If a person is fed lots of food and the blood of this person is drawn and injected into the bloodstream of a person that is halfway to die from starvation, will the recipents body be able to benefit from his blood/nutrition considering they have the same blood type?

Ive heared one of the reasons human ancestors got smarter was beginning to cook their meat with fire/heat, is this a myth? If it is true why does it matter for the body if the meat is cooked or raw and how does this affect intelligence?

Is it true calorie intake and age are related?

From wiki:

Severe caloric restriction has been found to reduce reactive oxidative species and to increase the life-span of rodents, possibly by promoting mitohormesis. Studies have shown that both calorie restriction and reduced meal frequency or intermittent fasting can suppress the development of various diseases and can increase life span in rodents by 30-40%

Does this seem to indicate eating food damages the body over time due to the "bad" stuff in the food in addition to the nutritions we need? Are digestion and age related somehow? and...

Are there any PURE food sources that have little to none "bad stuff"?

Are there any modernday alternatives to giving the body nutrition without using our digestive system?

Is it scientifically possible in theory to make the human body get its energy from somewhere else, or will the body still need food to apply mass?

Sorry for long post, hopefully somene is bored enough to answer some of them.

Okay, where to start? first of all i think your first question was about the differences between human and animal digestive systems, from what I can gather mamalian digestive systems all work on the same principle... food goes into stomach, to large and small intestines to colon. However different animals can produce different enzymes that can break down structures in food to make them useful for that animal. The gastrointestinal system's symbiotic relationship between commensal flora will also differ between animals. Major changes in the physiology from certain animals dependent on evolution etc such as you may have heard that cows have four stomachs, in fact they don't have four separate stomachs, it is more like four separate compartments to the stomach to help break down the cellulose in grass for energy. The list would be endless to describe the differences between each animal, as for insect as you can imagine, the less evolutionary beings have more primative digestive systems comprising of direct capillaries from which energy is gained. I couldnt really comment further on that.

You are right, digestion begins the mouth from chewing, amylase enzyme starts to break down the food as soon as you chew. You can test this by keeping a small piece of bread in your mouth, the amylase will break down the complex carbohydrate starch into smaller monosaccharides, and it will taste sweet. But its a wonder why humans have evolved to do this, because it is not until the large intestine when absorption of the food begins, so why break down food in the mouth apart from the fact that it tastes good? So no, absorption is not affected by chewing (that doesnt mean you shouldnt chew your food).

You are what you eat, if you dont eat, you will break down your own muscle, organs, fatty tissue for energy until you die. And although nutritional substitutes can be a good source of vitamins and minerals simple carbohydrates etc, it doesnt cover the dietary requirements such as lipids, complex carbs, proteins and most of all fibre.

I think the real reason for human becoming more intelligent is the millions of years of evolution and probably has little to do with meat whether it be cooked or not. But if its true, does that make vegetarians vegetables? The only possible way to gain energy directly elsewhere than food, would be to starve yourself, at first you body will turn glycogen into glucose then it will break down fatty tissues into smaller molecules then it will break down muscle fibre and other tissues and organs for energy in cell respiration in the brain, eventually leading to death. But its all stores that are absorbed by ... guess what... food!

Hope that helps :-D