Bio 104 5/17/96

• Food is broken down in compartments of the digestive tract by enzymes and is reabsorbed
• Mouth
  • mechanical break down of food
    1. teeth
    2. saliva
    3. salivary amylase breaks down starch into maltose
• Stomach
  • glands secret gastric juice (containing pepsin and lipase)
    1. lipase breaks down lipids
    2. pepsin breaks down proteins
  • HCL hydrolyses the chemical bonds in food (acid hydrolysis)
    • some fatty acids and amino acids can be taken up directly, but not much
• Small Intestine
  • 2 accessory glands which aid in digestion
    1. gall bladder
    2. pancreas
    • bile from the gall bladder elmusifies fats
    • the pancreas has an enzyme to break down every food monomer possible
• In the small intestine, final break downs of starches, fats, and proteins occur.
  • Amino acids and sugars are taken up by epithelial cells and go directly into the capillaries. Fatty acids and glycerol go into the lymph vessels
• Structure
  • circular folds
    • have villi, which contain both lymph vessels and capillaries
      • cells themselves have micro-villi
    • thus creating a huge amount of surface area
• Colon -It takes up water and storage of feces -makes vitamins

• # of calories in carbohydrates is about 1/3 of the amount in fats
  • we have too much fat in our diet
• Food pyramid
  • In essence, eat breads, then fruits and vegetables, limit the amount of meats and fats, and stay away from Lay's Potato Chips!

At this point we had a class discussion, and I figured out I am going to die fat and very unhealthy.

• molecules that are produced in one place, but produce specific effects in another place
  • regulatory molecules
  • we have glands that produce hormones

• series of 9 organs plus 3 specialized tissues that produce hormones
  • release hormones directly into the blood steam
  • place they effect is called the target cell
• Classes of Hormones:
  1. Steroids: carbon, hydrogen, and some oxygen in a ring structure.
     • soluble in fat
     • examples are:
       • progesterone
       • testosterone
       • estrogen
       • aldosterone
     • cell membranes have bilayer of fat and steroids can go in easily and bind with receptor proteins. Then this steroid/protein conglomeration binds to the nucleus and effects protein synthesis.
     • testosterone used to build protein and muscle
     • anabolic steroids build up muscle, but they are really a form of testosterone. See figure 37.4
     How steroid hormones work. Figure 37.4
  2. Peptides and proteins
     • 9-80 amino acids long
       1. Growth Hormone (GH)
          • produced by pituitary gland
          • not enough leads to dwarfism
       2. ADH
       3. insulin
          • 51 amino acids long
       4. FST glucagon
          • 29 amino acids long. See figure 37.5.
       How peptide hormones work. Figure 37.5
     • target cells have receptors, unlike steroids, they act as a second messenger, which causes a chemical change in the cell. This change is done by the receptor not the hormone

3. Modified Amino Acids
   • thyroxin
   • adrenaline
   • histamine
   • The pituitary gland is connected to the hypothalamus.
     1. anterior pituitary gland produces trophic hormones which effect other endocrine glands.

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