1.  Why eat?  We are _________ because we need to obtain food from an outside source. What are the three kinds of these?  Are we locked into this label  3 Reasons to eat! What are they?

2. BG rises after eating BG falls below set point Homeostasis

3.  Bad choices (or no choices) make it hard to maintain ___________.  You’re kind of unbalanced.  In terms of what?  Undernourishment (not enough calories) usually caused by war, drought, or some other crisis (and some eating disorders).  Overnourishment – Obesity, a problem for the haves (as opposed to the have nots).  Can you be overnourished and malnourished at the same time?

4.  Some of the nutrients you can’t make yourself and must come preassembled through ingestion.  How many amino acids are known in living things? How many can you make and how many essential amino acids must you obtain preassembled in your diet?  Missing essential nutrients results in malnutrition.  Essential fatty acids, vitamins, and minerals are other examples of essential nutrients.

5.  The terms herbivore, carnivore and omnivore describe the type of food an animal USUALLY ingests. Animals are opportunistic feeders.  How we eat includes suspension, substrate, fluid, and bulk-feeders (oh no, my python got out and ate your bull mastiff…sorry neighbor).

6.  Ingestion  Digestion (includes enzymatic hydrolysis)  Absorption (surface area…yes!)  Elimination

7.  Two kinds of digestion in the animal kingdom – intracellular and extracellular.  Intracellular similar to heterotrophic protists (seen in sponges and hydras).  Extracellular digestion is seen in all animals with complete digestive tracts (or alimentary canals ) as opposed to gastrovascular cavities in the simpler organisms.  Advantage – you can eat another Big Mac™ while the previous one is still making its way through.

8.  Our digestive system consists of an alimentary canal (mouth to anus – quite a journey) and some glands that secrete digestive juices through ducts into the canal at different locations.  Food pushed along by peristalsis.  My sphincters are all puckered (which is a good thing).  Glands include salivary, pancreas, liver, and gall bladder.

9.  In the mouth (oral cavity).  Presence of food triggers a salivating reflex (Dude, a liter a day?!?)  Saliva contains mucin and amylase.  A bolus forms, enters the pharynx by way of the epiglottis and makes it’s way down the esophagus to “El Estomago”

10.  It stores food (up to 2L).  Churns food together with gastric juice secreted by cells lining stomach.  Gastric juice is mostly HCl acid (stomach has a pH of 2 – if you really want to eat nails…)  Gastric juice also has pepsin that starts breaking down proteins by breaking ______ bonds between amino acids.  Why doesn’t the acid and pepsin break down the cells lining the stomach?  Acid chyme empties from the stomach into the small intestine over 2 to 6 hours through the pyloric sphincter.

11.  Majority of digestion and absorption happen here.  First portion called the duodenum – acid chyme mixes with all digestive juices secreted by pancreas, liver, gall bladder and gland cells within the wall of the SI.  Several hydrolytic enzymes and bicarbonate buffer released by pancreas.  Liver produces bile (contains bile salts – no enzymes) that is stored in gall bladder until needed – acts as detergent to break down fats. Also secretes stuff that makes your poopy dark.

12.  All the macromolecules…  Carbohydrates  Proteins  Fats (bile salts help here by emulsifying )  Nucleic acids

14.  Absorb it!  Each of the monomers absorbed has a different fate before being made available for biosynthesis within cells.  Some are absorbed by diffusion, others by active transport.  Check it out…

16.  Hormones regulate the release of gastric juices using feedback mechanisms.  Ones to know:  Gastrin  Enterogastrones are a group of hormones an example of which is secretin.  Cholecystokinin (CCK)

17.  Major function of the large intestine is water absorption.  If you have diarrhea, the LI isn’t doing what it should – you are ill. This is a great opportunity to tell the story of my bout with bacterial dysentery (better than amoebic).  Our old friend E. coli takes up the rear.  How many times a day does your colon call out to you?