Peter Mitchell: Diffusion is the answer!

Paul Boyer: I think it actually twists!

Masasuke Yoshida “check this out.”

Which of the following enzymes work most effectively at a very low pH? A. Salivary amylase B. Trypsin C. Pepsin D. Pancreatic amylase E. Pancreatic lipase

Which of the following organs is incorrectly paired with its function? A. Stomach –protein digestion B. Oral cavity -starch digestion C. Large intestine –bile production D. Small intestine –nutrient absorption E. Pancreas –enzyme production

In zero gravity environment of space, how does food swallowed by an astronaut reach her stomach? A. Swallowing hard B. Running around wheel creates -> artificial gravity C. Involuntary muscle contractions D. IV administration of nutrients

Salivary glands Secretes enzymes that digest carbohydrates Liver Secretes molecules required for digestion of fats Gall bladder Stores secretions from liver; empties into small intestine Pancreas Secretes enzymes and other materials into small intestine 1. Mouth Mechanical and chemical processing (chewing reduces size of food; saliva digests carbohydrates) 2. Esophagus Transports food 3. Stomach Mechanical and chemical processing (digestion of proteins) 4. Small intestine Chemical processing and absorption (digestion of proteins, fats, carbohydrates; absorption of nutrients and water) 5. Large intestine Water absorption and feces formation

End of esophagus Sphincter seals off stomach from esophagus Sphincter seals off stomach from small intestine Lumen (interior) Beginning of small intestine Layers of muscle Stomach

Canal empties to lumen Parietal cells (secrete HCl) Chief cells (secrete pepsinogen) Stomach lining

CO 2 + H 2 O H 2 CO 3 Canal empties to lumen Parietal cell Secretion of HCI by parietal cells CA

HCO 3 – H 2 CO 3 H+H+ H+H+ Canal empties to lumen Parietal cell Secretion of HCI by parietal cells CO 2 + H 2 O ATP

HCO 3 – Cl – To blood From blood H 2 CO 3 H+H+ Cl – Chloride channel Cl – H+H+ HCl to lumen Canal empties to lumen Parietal cell Secretion of HCI by parietal cells CO 2 + H 2 O ATP

Stomach -Enzymes, Hormones, other? Enzymes: pepsinogen (inactive)-> pepsin (protease) from chief cells Other: HCl -> denature ECM bacteria, from parietal cells, activator of pepsin Other: Mucins/mucus protective from goblet or mucus cells Other: mechanical churning -> acid chyme Hormones: Gastrin (+), CCK/secretin (-), enterogastrone (-- pyloric sphinct)

Enzymes, Hormones, other? Your turn enzymes? -> Protocol Expert (PE) hormones? -> Data Recorder (DR) other -> Laboratory Technician (LT) poem -> (if have one) Primary Investigator (PI)

Absorption