Chapter 15

 

  1. Digestion is the act of breaking down foods for absorption. The body taking up nutrients from the alimentary canal is an example of absorption. Assimilation is the action of making digested food part of you. Nutrition- pizza and cheeseburgers.
  2. Bernoulli’s effect is significant to the functioning of a sponge. This occurs as the water flows over the osculum of the sponge. As water flows over the pressure is reduced at the osculum. This leads to the increase if flow as water exits the osculum and enters the rest of the sponge.
  3. Pepsin is a protein produced exclusively for digesting proteins in the stomach. Enteroglucagon is a hormone that inhibits intestinal motility.
  4. An essential amino acid is one that must come from a dietary source because the body cannot produce it from other sources.
  5. Doing so would reduce the amount of energy cells could get from breaking down these compounds. This is true because the body oxidizes these compounds to gain energy. Once the compounds are in smaller units they will basically be farther through one of the energy producing pathways.
  6. A protective coat of mucous covers these cells and thus protects them.
  7. Microorganisms in the alimentary canal benefit the host by making things such as essential vitamins. Specific examples are in the book.
  8. This is discussed on page 639.
  9. Bile emulsifies fats and helps make neutralize acidity in the intestines. Bile also contains some waste products from red blood cell metabolism. The first to functions are important to digestion. Emulsifying the fats allows them to be digested and changing the pH allows the intestinal enzymes to activate.
  10. The alimentary canal has two major nervous bundles, the myenteric plexus and the submucosal plexus. These are both innervated by the sympathetic system. The parasympathetic system innervates the myenteric plexus. See page 647.
  11. An ATP dependent ion exchanger drives the production of HCl in the stomach. Here H is kicked out as K is brought in. There is a misprint ion the textbook. Look at fig 15-32 on page 655. They have H coming back into the cell at the active transporter that expels the H ion. That is a misprint because K is the ion that is transported into the cell. Cl leaves the cell via a channel to keep the charge balanced.
  12. These two systems must both secrete substances based on the requirements of the host. The main difference is what is secreted and where it goes. Well, the cells are set up differently too (based on what they secrete).
  13. Secondary modification is what happens to a exocrine secretion as it travels down a duct past other secretory cells. That is to say that on the trip the cells will modify what was already secreted. See figure 15-28 on page 649.
  14. Page 652.
  15. One example, VIP (vasoactive intestinal peptide), is both a neuropeptide and an intestinal peptide. It is classified like this because the peptide is produced in the CNS and the intestines. Thus far there is no functional connection between the two. That is to say that the VIP in the brain doesn’t effect the intestines.
  16. Read the chapter.
  17. Those that go down their concentration gradient into the cell do so be facilitated diffusion. Those that go against the concentration gradient use the Na gradient as a source of energy.
  18. Pg 659
  19. Pg661