Day 6 - Absorption

On Monday, I talked about digestion, one of the processes our body goes through when we ingest food. Today I want to talk about the second process: Absorption.

Absorption takes place in three different ways in our body depending on the kinds of substances being absorbed. In the first, passive diffusion, substances are absorbed through membranes in order to equal out the concentration gradient. This means that if the amount of water on one side of the membrane is higher than the amount of water on the other side, water from the higher side will pass over into the side with the lower amount in order to make the sides equal. In this way, water, most fats, and some minerals are absorbed into our bodies. Through facilitated diffusion, the nutrients being absorbed also needs another substance, or a carrier molecule, to help facilitate it through the membrane. The amount of the substance absorbed, like passive diffusion, also depend on the concentrations on either side of the membrane, with substances moving from the higher concentration into the area with lower concentration. Substances such as Fructose (a type of sugar) are absorbed through facilitated diffusion. Finally, through active transport, nutrients we ingest have to combine with another substance and require energy (known as ATP) in order to move across the cell membrane. Many of the nutrients that must undergo active transport are proteins. Interestingly enough, through active transport, nutrients can be absorbed from the area of lower concentration into the area of higher concentration.

Here is a picture to help you visualize the three processes:

The majority of absorption takes place in both the small and the large intestines. The Villi that I talked about on Monday provide a HUGE absorptive area in the small intestines! Most of the nutrients in food are absorbed in the small intestine; including iron, vitamin B-12, water, lipids (fats), sodium, glucose and fructose (types of sugars). Then the remaining nutrients are sent into the large intestine. In the large intestine, part of the remaining water, salt, and vitamins are absorbed. Finally, the remenants are excreted as urine or feces.  By this time, almost all the nutritional value has been sucked out of the foods; however, the non-absorbed remains of digestion, water, bacteria, and dead mucosal cells can be found in feces.

So there you have it! Through these two simultaneous processes, digestion and absorption, our body takes the different foods that we eat, breaks them down, absorbs the nutrients, and excretes what is left over! For the rest of this month, I want to look at the nutrients our body requires and talk about them individually.

Today's Workout: Yet another swim workout! Tomorrow will be an out of water workout I promise! Going to buy my new running shoes then :)

Do five sets of the following:

50 freestyle swim

50 pull freestyle

50 kick freestyle

50 freestyle swim

TOTAL: 1000 yards/meters

Today's Food Tip: Black beans are full of anthocyanins which are antioxidants that help improve overall brain function. In fact, they are on the top ten brain foods list! So today, make black beans a part of one of your meals! Toss them in with a breakfast burrito or make a black bean dip to eat with whole grain tortilla chips!

Today's Relaxation Activity: After five days of working out, spend some time stretching today. Make sure to concentrate on your breathing and open up your muscles.