How Nutrients Get in, and Wastes Out

How Nutrients Get in, and Wastes Out.

In a human being, nutrients are necessary for survival. But how are these

nutrients obtained? This report will go into depth on how the food we eat gets

into our cells, and how the waste products that we produce get out of the body.

Also, the unicellular organism Paramecium will be compared with a human being,

in terms of all of the above factors.

Dietary Nutrients

The chief nutrients in a diet are classified chemically in four groups:

carbohydrates, proteins, vitamins (Which do not require digestion) and fats.

Carbohydrates in the diet occour mainly in the form of starches. These are

converted by the digestive process to glucose, one of the main nutrients needed

for cellular respiration to occour. Starch is a large molecule, a polymer of

glucose. Dextrin and maltose are intermediate products in the digestion of

starch. Some foods contain carbohydrates in the form of sugars. These are the

simple sugars, such as sucrose (cane sugar) or lactose (milk sugar), that must

be processed into smaller units. Occasionally, the simplest form of sugar, a

monosaccharide such as glucose, is present in food. These monosaccharides do

not require digestion.

Proteins are polymers composed of one or more amino acids. When they are

digested, they produce free amino acids and ammonia.

Vitamins are a vital part of our food that are absorbed through the small

intestine. There are two different types of vitamins, water-soluble (All the B

vitamins, and vitamin C) and fat-soluble (vitamins A, D and K).

Neutral fats, or triglycerides, are the principal form of dietary fat. They are

simple compounds, and within digestion are broken down into glycerol and fatty

acids, their component parts.

Ingestion

Intake of food in the Paramecium is controlled by the needs of the cell. When

food is sensed, the organism guides itself towards the food, and guides it into

the oral groove, then enclosing it in a vacuole. Enzymes are then secreted to

digest the food, which is then absorbed into the cytoplasm and made available to

the various organelles. But, a Paramecium has to be able to move to its food

source, while a human cell has his food brought to it through the circulatory

system. In man, a much more complicated system exists than that of a

unicellular organism, for the size of the animal and the fact that all of the

cells within the animal must be able to absorb food and get rid of wastes, just

like the Paramecium does.

Digestion in the Mouth

Upon entering the mouth, the food is mixed by mastication with saliva, which