Diet & Nutrition, Digestive System: Anatomy 3.1.2. The Digestive System: How does it work?

Your digestive system is uniquely designed to turn the food you eat into nutrients, which the body uses for energy, growth and cell repair. Here's how it works.

Mouth

The mouth is the beginning of the digestive tract. In fact, digestion starts here as soon as you take the first bite of a meal. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

Throat

Also called the pharynx, the throat is the next destination for food you've eaten. From here, food travels to the esophagus or swallowing tube.

Esophagus

The esophagus is a muscular tube extending from the pharynx to the stomach. By means of a series of contractions, called peristalsis, the esophagus delivers food to the stomach. Just before the connection to the stomach there is a "zone of high pressure," called the lower esophageal sphincter; this is a "valve" meant to keep food from passing backwards into the esophagus.

Stomach

The stomach is a sac-like organ with strong muscular walls. In addition to holding the food, it's also a mixer and grinder. The stomach secretes acid and powerful enzymes that continue the process of breaking down the food. When it leaves the stomach, food is the consistency of a liquid or paste. From there the food moves to the small intestines.

Small Intestine

Made up of three segments, the duodenum, jejunum, and ileum, the small intestine is a long tube loosely coiled in the abdomen(spread out, it would be more than 20 feet long). The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile from the livers. Bile is a compound that aids in the digestion of fat and eliminates waste products from the blood. Peristalsis (contractions) is also at work in this organ, moving food through and mixing it up with digestive secretions. The duodenum is largely responsible for continuing the process of breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

Why is digestion important?

Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body. The body breaks down nutrients from food and drink into carbohydrates, protein, fats, and vitamins.

Carbohydrates. Carbohydrates are the sugars, starches, and fiber found in many foods. Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products, as well as sugars added during food processing. Complex carbohydrates are starches and fiber found in whole-grain breads and cereals, starchy vegetables, and legumes. The Dietary Guidelines for Americans, 2010, recommends that 45 to 65 percent of total daily calories come from carbohydrates.1

Protein. Foods such as meat, eggs, and beans consist of large molecules of protein that the body digests into smaller molecules called amino acids. The body absorbs amino acids through the small intestine into the blood, which then carries them throughout the body. The Dietary Guidelines for Americans, 2010, recommends that 10 to 35 percent of total daily calories come from protein.1

Fats. Fat molecules are a rich source of energy for the body and help the body absorb vitamins. Oils, such as corn, canola, olive, safflower, soybean, and sunflower, are examples of healthy fats. Butter, shortening, and snack foods are examples of less healthy fats. During digestion, the body breaks down fat molecules into fatty acids and glycerol. The Dietary Guidelines for Americans, 2010, recommends that 20 to 35 percent of total daily calories come from fat.1

Vitamins. Scientists classify vitamins by the fluid in which they dissolve. Water-soluble vitamins include all the B vitamins and vitamin C. Fat-soluble vitamins include vitamins A, D, E, and K. Each vitamin has a different role in the body’s growth and health. The body stores fat-soluble vitamins in the liver and fatty tissues, whereas the body does not easily store water-soluble vitamins and flushes out the extra in the urine. Read more about vitamins on the Office of Dietary Supplements website at www.ods.od.nih.govExternal NIH Link.

1U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th ed. Washington, D.C.: U.S. Government Printing Office; 2010.

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How does digestion work?

Digestion works by moving food through the GI tract. Digestion begins in the mouth with chewing and ends in the small intestine. As food passes through the GI tract, it mixes with digestive juices, causing large molecules of food to break down into smaller molecules. The body then absorbs these smaller molecules through the walls of the small intestine into the bloodstream, which delivers them to the rest of the body. Waste products of digestion pass through the large intestine and out of the body as a solid matter called stool.

Video: Biologist who coined biodiversity. (Biodiversity is related to ecosystem & when the ecosystem is productive topic.)

How little we understand our species. Related to biodiversity and ecosystem/ When the ecosystem is productive, every species has a function.
5.400 new amphibians species were found, Distinct kinds of Gorilla's were found 1.5 million species were estimated to be, but not studied.
Life on Earth may depend on the activities going on underwater.

16.000 discovered but there could be 100.000 of em..! 1 million worldwide bacteria.
In 1 tonne of sterile soil(normal clean planting soil), there are about 4 million species of unknown bacteria witch no one know's what there roles are?
We don't know...! We live on a planet witch is based on guess and faith alone. There are 500 species of friendly bacteria in our mouth and throat that would be helpful if you developed some kind of infection. with the antibiotics and these bacteria, there are more chances of overcoming the infection.
Modern Biology: The variety of genes on the planet in viruses exceeds that in all of life combined. Explorers launched into the ocean will be relatively easier to comprehend with new technologies by getting bacteria samples underwater. Already what we thought were bacteria have been found to compose instead 2 great domains of microorganisms. The true bacteria and the one cell organisms, there we are, chaos. Witch are closer then are the bacteria we belong to. Some serious Scientologist have begone to wonder that among the enormous and still unknown diversity of microorganisms, 1 might just might find aliens among us true aliens arrived from other space, they've had millions of years to do it! But especially during the earliest period of biological evolution on the planet.
We do know that some bacterial species are capable of almost unimaginable, extremes of temperatures, and or other harsh changes in our environmental including radiation strong enough to maintain long enough to crack the pyrex vessels around the growing population of bacteria.

Copying nature in the lab Ted talk video feedback's

In the video i remember the lady speaking saying we are what we eat, well we are what our cell's eat really.It could be easily described as  we are what our cells eat because in a study, in the case of the Flora we have in our gut, these cells may not even be human..? Cells mediate our experience of life. Behind every sound, site, touch, taste, and smell.
A corresponding set of cells that receive that info and then interprets it for us!
This is an interesting video because i never seen our self's like this until really i seen this video and, well u learn something new everyday..!

Note: These are my opinions about the video and feedback's. not professional.

The power of plants movements (Ted-Talk Video feedback's)

Even tho plants can't literally move as in pick up it's roots and just go for a stroll. But, this also doesn't mean they can't move... People don't generally see plants as living things as they do when they see a , let's say a dog or cat, bird Etc. But, in deed, plants do live kind of like all living things or beings do. They can sleep, play, move and pull toward sources of light like the sun or U.V lamps and can also communicate within each other by insects and birds sucking the pollen and sweet out of the flowers, the plant then has moved plenty but just not like we do like walking or driving but by using the natural elements around itself. so really it's adapted to nature to live and uses it to keep living. The roots are the part of the plant witch literally moves but underground(we don't see it) But they still move.

Just a fact: the total number of roots in a single RYE plant is approximately 13.815.672=Total length of 622 kilometers long

My feedback's from (Ted-talk) Video about plants movements (power of plant movements)

Genetic variability and adaptive evolution in parthenogenetic root-knot nematodes

Root-knot nematodes RKN" of the genus. Meloidogyne are biotrophic plant parasites of major agricultural importance, which exhibit very variable modes of reproduction, from classical amphimixis to mitotic parthenogenesis. This review focuses on those RKN species that reproduce exclusively by mitotic parthenogenesis (apomixis), in contrast to those that have meiotic/amphimitic events in their life cycle. Although populations of clonal organisms are often represented as being ecologically isolated and evolutionary inert, a considerable volume of literature provides evidence that asexual RKN are neither: they are widely distributed, extremely polyphagous, and amenable to selection and adaptive variation. The ancestors of the genus are unknown, but it is assumed that the parthenogenetic RKN have evolved from amphimictic species through hybridization and subsequent aneuploidization and polyploidization events. Molecular studies have indeed confirmed that the phylogenetic divergence between meiotic and mitotic RKN lineages occurred early, and have revealed an unexpected level of clonal diversity among populations within apomictic species. Laboratory experiments have shown that asexual RKN can rapidly adapt to new environmental constraints (EG' host resistance), although with some fitness costs. Lastly, the molecular and chromosomal mechanisms that could contribute to genome plasticity leading to persistent genetic variation and adaptive evolution in apomictic RKN are discussed. It is concluded that RKN provide an excellent model system in which to study the dynamic nature and adaptive potential of clonal genomes.

Then importance of the cells. What role do they play within us?... Let's see...

Each of us is the result of a handful of tiny stem cells that multiplied to produce the 200 types of specialized cells in our body.

Our stem cells continue to be active to keep us healthy -- without them, we wouldn’t survive more than a few days! The exhibition We are surrounded by millions of bacteria, viruses and other microbes (germs) that have the potential to enter our bodies and cause harm. The immune system is the body's defense against pathogens (disease-causing microbes). The immune system is made up of non-specialised defences such as skin and the acidic juice produced by your stomach. But it also has some highly specialized defences which give you immunity against (resistance to) particular pathogens. These defences are special white blood cells called lymphocytes. Other types of white blood cells play an important part in defending your body against infection.

 The immune system is generally divided into two parts. The first part is the defences you are born with. These form what are known as the innate system.

The second part of your immune system, known as immunity, develops as you grow. Your immunity gives you protection against specific pathogens. Not only can this system recognize particular pathogens, it also has a memory of this. This means that if you encounter a certain pathogen twice, your immune system recognizes it the second time around. This usually means your body responds quicker to fight off the infection.

 The innate system is found in many different places around the body. First line of defense is your skin. Skin forms a waterproof barrier that prevents pathogens from entering the body. Your body cavities, such as the nose and mouth, are lined with mucous membranes. Mucous membranes produce sticky mucus which can trap bacteria and other pathogens. Other fluids produced by the body help to protect your internal layers from invasion by pathogens. Gastric juice produced by the stomach has high acidity which helps to kill off many of the bacteria in food. Saliva washes pathogens off your teeth and helps to reduce the amount of bacteria and other pathogens in your mouth.

Biodiversity types. Genetic Diversity| Species Diversity | Ecosystem Diversity.

Researchers generally accept three levels of biodiversity:1- genetic Biodiversity., 2-species Biodiversity., and 3-ecosystem Biodiversity. These levels are all interrelated yet distinct enough that they can be studied as three separate components. Some researchers believe that there are fewer or more levels than these, but the consensus is that three levels is a good number to work with. Most studies, either theoretical or experimental, focus on the species level, as it is the easiest to work on both conceptually and in practice. The following parts will cover all levels of diversity, though examples will generally use the species level.

1- Genetic diversity is the variety present at the level of genes. Genes, made of DNA (right), are the building blocks that determine how an organism will develop and what its traits and abilities will be. This level of diversity can differ by alleles (different variants of the same gene, such as blue or brown eyes), by entire genes (which determine traits, such as the ability to metabolize a particular substance), or by units larger than genes such as chromosomal structure. 

 Genetic diversity can be measured at many different levels, including population, species, community, and biome. Which level is used depends upon what is being examined and why, but genetic diversity is important at each of these levels. 

2- Species Diversity. Species are well known and are distinct units of diversity. Each species can be considered to have a particular "role" in the ecosystem, so the addition or loss of single species may have consequences for the system as a whole. Conservation efforts often begin with the recognition that a species is endangered in some way, and a change in the number of species in an ecosystem is a readily obtainable and easily comprehensible measure of how healthy the ecosystem is.  Biodiversity studies typically focus on species. They do so not because species diversity is more important than the other two

 3-Ecosystems Diversity: Ecosystem-level theory deals with species distributions and community patterns, the role and function of key species, and combines species functions and interactions. The term "ecosystem" here represents all levels greater than species: associations, communities, ecosystems, and the like. Different names are used for this level and it is sometimes divided into several different levels, such as community and ecosystem levels; all these levels are included in this overview. This is the least-understood level of the three described here due to the complexity of the interactions. Trying to understand all the species in an ecosystem and how they affect each other and their surroundings while at the same time being affected themselves, is extremely complex.
One of the difficulties in examining communities is that the transitions between them are usually not very sharp. A lake may have a very sharp boundary between it and the deciduous forest it is in, but the deciduous forest will shift much more gradually to grasslands or to a coniferous forest. This lack of sharp boundaries is known as "open communities" (as opposed to "closed communities," which would have sudden transitions) and makes studying ecosystems difficult, since even defining and delimiting them can be problematic.
Some researchers think of communities as simply the sum of their species and processes, and don't think that any of the properties found in communities are special to that level. Many others disagree, claiming that many of the characteristics of communities are unique and cannot be extrapolated from the species level. Examples of these characteristics include the levels of the food chain and the species at each of those levels, guilds (species in a community that are functionally similar), and other interactions.