Nutrients

All living organisms need to interact with their environment to get the needed nutrients and be able to expel the waste products.  

All organisms need several basic requirements for their survival.  These include the ability to:

  • Intake of nutrients

  • Exchange of gases

  • Expel waste

  • Move materials


We need 6 essential nutrients to stay healthy: Carbohydrates (sugars), proteins, lipids (fats), water, vitamins, and minerals. Without them, cells stop working properly


Food contains the nutrients we need but not in the form our bodies can use directly. The food we eat must be broken down into nutrients that can be absorbed into the blood and carried to the cells of the body. This is called digestion. 


Our digestive system is a collection of organs working together to carry out digestion. 

There are four main steps in digestion;

  1. Ingestion - the taking in of nutrients

  2. Digestion - the physical and chemical breakdown of complex food molecules into smaller molecules)

  3. Absorption (the transfer of digested nutrients from the digestive system to the bloodstream

  4. Egestion - the removal of waste food materials from the body


Organisms need to intake nutrients to provide their cells with:

  • The sugars needed for cellular respiration and the production of energy.

  • The proteins essential for building and repairing tissue, regulating body functions and providing energy and heat.

  • The fats used to build and maintain cell membranes; maintain body temperature by providing insulation; cushion organs and bones; aid in absorption of fat-soluble vitamins


Nutrients: Chemicals that an organism needs to grow, build and repair tissues, and to produce energy


In order for organisms to absorb and use these macromolecules, they must be in the smallest units possible.


Sugar (carbohydrates)


  • Main source of energy for humans

  • Composed of carbon, hydrogen and oxygen

  • Three main types of carbohydrates: monosaccharides, disaccharides, polysaccharides

  • Monosaccharides

    • Most basic form of carbohydrates

    • Sugars are absorbed as monosaccharides 

      • Fructose, Glucose and Galactose

  • Disaccharides

    • Two sugars joined

    • Ex. Table sugar and milk

  • Polysaccharides

    • Starch, cellulose (plants)

  • Carbs are stored in the liver and muscle tissue in the form of glycogen

    • Glycogen is a polysaccharide

    • Excess is stored as lipids


Proteins 

  • One of the key building blocks of cells and perform a wide range of functions

  • Involved in metabolic activities and used to generate motion

  • Some are hormones

    • Hormones: A chemical signal or messenger molecule, circulated through the body and used to coordinate cellular functions

  • Most complex of all nutrients

  • Are made up of long chains of amino acids

    • Proteins are found as amino acids

    • We use 20 different amino acids to build protein, we make 12 and need to consume the other 8

      • Essential amino acids - the ones we obtain from food sources


Fats (lipids)

  • They provide a concentrated source of chemical energy for the body

  • The help in the absorption of vitamins, are the main components of cell membranes, and serve as insulation of the body

  • Sex hormones are lipids

  • Are found as triglycerides - three fatty acids bonded to a glycerol molecule

    • Can be either saturated (bad) or unsaturated (good)

    • Fatty acids contain long chains of carbon and hydrogen atoms

  • Some fatty acids are essential - Omega-3

  • Excess leads to heart disease and obesity