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Gastroesophageal sphincter

IPHY 3430 9-6-11 REVIEW SESSION THIS THURSDAY, 7:15 Location of Exam: Duane G1B30 Sept. 22, 8 am. Digestive System Purpose: Obtain energy-containing substrates, water, vitamins, and ions from outside body into circulation. Gastroesophageal sphincter. Liver. Stomach. Gallbladder.

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Gastroesophageal sphincter

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  1. IPHY 3430 9-6-11REVIEW SESSION THIS THURSDAY, 7:15Location of Exam: Duane G1B30Sept. 22, 8 am.

  2. Digestive SystemPurpose:Obtain energy-containing substrates, water, vitamins, and ions from outside body into circulation.

  3. Gastroesophageal sphincter Liver Stomach Gallbladder Pancreas Duodenum Descending colon Transverse colon Ascending colon Jejunum Cecum lleum Appendix Sigmoid colon Rectum Anus Table 16-1, pp. 582-583

  4. Mouth1. Mastication2. Moisten3. Enzymatic breakdown

  5. Formation of saliva1. Ptyalin or  amylase2. Mucus 3. Water4. Thiocyanate, proteolytic enzymes, and antibodies. Salivary gland containing secretory granule.

  6. Mucuscomposed of glycoproteins (polysaccharides and protein)1. Adherent qualities2. Coats wall of gut, mouth, etc.3. Allows particles to slide without resistance4. Resistant to digestion5. Can help buffer small amounts of acid

  7. Process of saliva secretion1. Parasympathetic nervous system stimulation causes release of acetylcholine (ACH) on surface of salivary gland cells.2. ACH causes increase in membrane permeability to Ca++.3. Ca++ causes secretory vesicles to fuse with cell membrane and break open on outer surface, emptying contents into lumen of salivary gland (exocytosis).

  8. Process, cont.4. ACH stimulation causes Na+ transport out of salivary cells by active transport (with ATP), Cl- follows passively, water moves by osmosis.5. As water containing ions and other secretions moves toward mouth, K+ actively exchanged for Na+, HCO3- actively exchanged for Cl-.6. Role of SNS--vary blood flow, esp. decrease blood flow

  9. Rates of secretion0.5 ml per minute all the time except during sleep, when it drops below that value.Just prior to or during eating--8-10x higher than normal valueTotals/day = 1-1.5 liters/day (cows = 250 liters/day)

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