NUTRIENT PROCUREMENT
     Macronutrients = needed in "parts per thousand: Micronutrients: needed in "parts per million"

1.  performs some vital function, i.e., needed for either growth & maintenance and/or reproduction
2.  cannot be substituted for by other elements
3.  function is a direct one (structural component/enzyme or cofactor)

Plants - Autotrophs
         Can basically live in an inorganic environment and make organic nutrients
    Nutrients Required = CO₂ & H₂O for PS
        Many other elements (besides C, H, O) also necessary; most dissolved as ions in H₂O

Heterotrophs - Bacteria, Some Protists, Fungi, Animals 
            Herbivores, Omnivores, Carnivores

Essential Nutrients
    Organic Molecules

• all heterotrophs require some preformed carbohydrates
• most need some preformed amino acids (A. A.'s) B 9 of 20 essential for humans; some bacteria can fix nitrogen (make virtually all A.A.=s)
• two fatty acids are essential for humans (linoleic & linolenic acids)

    Vitamins/Minerals (Table 45-3 and 45-4, pages 1005 and 1006)
        Vitamins - many (particularly water-soluble) function as coenzymes
               1.  water-soluble: C, B-complex
               2.  lipid-soluble (vertebrates only): A, D, E, K (not used as coenzymes)
             D, K and some B not essential in the diet for humans, for reasons discussed in class
        Minerals (elements) -- All essential 
                (C, H, O, N, S, some P from prots./carbos./lipids -- organic molecules)
                 Macronutrients: Na, Cl, K, P, Mg, Ca, Fe             Know function for each of macros
                 Micronutrients: Cu, Mn, Zn, Mo, I, Se                     and for I and Zn 

            These are for humans; plants and other heterotrophs may require some different minerals

• Bacteria B most parasitic, nutrients obtained by (extracellular digestion followed by) absorption
• Fungi B Saprophytic (some parasitic); extracellular digestion followed by absorption
• Animals, Protozoans B ingestion, which is then followed by intracellular digestion (protozoans), or extracelluar digestion followed by absorption (animals); in most animals allows intake of Alarge@ prey, though some aquatic animals are filter feeders (including the biggest B Baleen Whales)

DIGESTION B two types:

1. physical (mechanical: chewing/muscular mashing) 
2. chemical (enzymatic, mainly hydrolytic)

Specializations in different groups:

        I.  Incomplete Digestive System B One-opening/two-way
                Cnidarians, Flatworms

        II.  Complete Digestive System B Two-opening/one-way; with specialized organs and 
                numerous digestive enzymes; roundworms and all higher animal groups. 
             Advantages?
                1. Longer Transit Time B more complete digestion and absorption
                2. Specialization of organs for specific digestive functions
                3. Continuous feeding possible, though some organs used for storage

                Some organs in you should know from other animals: Crop, gizzard

I. Oral Cavity B
      Lips/Cheeks
        Teeth (incisors, canines, premolars, molars) -- functions of each?
        Tongue -- for physical digestion and taste
        Salivary glands -- Saliva has salivary amylase, which begins chemical digestion of carbohydrates, 
                as well as lysozyme
II. Pharynx (throat)/Esophagus B Swallowing -- Peristalsis
III. Stomach B storage (discontinuous feeding), many folds for expansion
        Chief (zymogenic) cells release pepsinogen (inactive --WHY?)
        Parietal cells release HCl and intrinsic factor (intrinsic factor vital as aid in absorbing vit. B-12)
                HCl activates the pepsinogen to form pepsin -- begins chemical digestion of protein
IV. Small intestine B most digestion, absorption takes place here through the surfaces of the 
        villi/microvilli; bile from liver/gall bladder and tremendous numbers of digestive enzymes are 
        dumped into small intestine from pancreas; [see handout on digestive enzymes]

            Note: bile does *not* contain enzymes -- only bile salts/phospholipids for emulsifying fats

V. Large intestine/rectum/anus

Know function of bile and function of the indicated (discussed in lecture) enzymes from the handout.

See also Table 45-1, page 998.