Water and Food

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Last Updated: Thursday, 25 May 2023 23:38

Published: Thursday, 25 May 2023 23:29

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Water and Food:

Water and Food are consumed by us, and are needed to keep the body alive. Water provides hydration to cells, while food provides important nutrients needed by the body's cells, which eventually provide energy to body.

Water and food (all food have some water content) are taken in by mouth. We smash and grind it up in the mouth. From the mouth, there's a pipe called esophagus which takes it to the stomach. The stomach mixes it all up with chemicals that start to dissolve it. Bile is added a little later to dissolve fats. The bile also gives the food mass its color brown.

Small/Large Intestine:

This mass of mixed solids and liquids moves through the intestines. Everything that can be broken down is broken down into individual molecules. The whole mass is now considered a liquid with larger solids suspended in it. Even though we drink 2-3 litres of water a day, saliva, gastric juice, bile, etc secreted to the this whole mass makes up like 9 litres of liquid. The individual molecules (good and bad) then are absorbed from the intestines into your bloodstream by actually “soaking” through the intestine wall and through the blood vessel walls waiting on the other side. Some of these molecules are chemically pushed or pulled across into the blood vessels. What is left in the intestines gets drier and drier as more and more water is pulled out and absorbed into the bloodstream.

Food needs to be broken up into smaller molecules. Water, on the other hand, is a very simple molecule, so our body doesn’t have to break it down into smaller, simpler molecules. As a matter of fact, water molecules are so small that they have no problem diffusing through the phospholipid bilayer that forms the cell membrane of human tissues. This cell membrane (presumably) consists of small channels or pores through which water or water-soluble substances can enter, meaning that water is directly absorbed through the epithelial cells that cover humans’ intestinal tract. Small intestine tract has villi which are finger like projections, which are made of epithelial cells. These epithelial cells have brush like border called microvilli, which further increase the surface area for absorption. In short, this means that the small intestine is responsible for the absorption of most of the water that we consume. 90% of the fluid is absorbed in small intestine, and only 10% in large intestine. Blood capillaries are inside the villi, so anything absorbed via these epithelial cells  is passed on to the blood, which carries to all the places in human body.

The kidneys are constantly monitoring the amount of water and other by products and waste products in the bloodstream, such as uric acid, and pull or push them into the urinary tract, to keep the concentration in the blood just right. This all collects in the bladder. It is a mixture of mostly excess, unneeded water and other chemicals such as ammonia. When the bladder is full, we urinate (called urine because of the uric acid).

Meanwhile, the soon-to-be stool keeps moving along and at different parts of the intestine, different molecules are absorbed. It is held in the end of the large intestine. When it is full, we defecate.

Water's Journey thru body: