Lecture #3: Digestive System Flashcards
How does the ancestral diet compare to a modern diet?
Ancestral diet had:
- less sugar
- more protein
- more natural food (less added preservatives)
- less salt
- more fiber
Catabolism
Breakdown of structure by enzymatic hydrolysis
• enzymatic hydrolysis: enzymes and water
Anabolism
Build up of structure
Calorie containing molecular
Proteins, carbohydrates, lipids
Proteins break down into?
Polypeptides, then animo acids
Carbohydrates break down into?
Polysaccharides, then monosaccharides (ex: glucose, fructose)
Lipids break down into?
Glycerol + 3 fatty acid chains
What does saliva do?
- Moistens food
- Antimicrobials
- Begin carb digestion
- amylase = enzyme for breaking down starch
What is the stomach and what does it do in the digestion process?
Acidic (PH (~ 2))
1. Begin protein breakdown
- Pepsin : enzyme for protein breakdown (works at a low ph)
• Cells store and release pepsinogen (less degrading)
• cells also release hydrochloric acid (HCl)
- turns pepsinogen into pepsin (active form of enzyme)
peptic ulcer - break in epithelial lining of stomach
• cause is bacteria infection
Acid reflux : Burning of lining of esophagus (heartburn)
What is the small intestine and what does it do in the digestion process?
3 parts of small intestine:
- durdeum (start of small intestine, more breakdown here, less adsorption)
- jejunun (middle of small intestine)
- ileum (end of small intestine, less breakdown here, more adsorption)
What is at the Junction of stomach + small intestine?
- pyloric sphinctur - controls release of material into small intestine
- Pancreas: produces bicarbonate to neutralize acid
- PH ~7
What is trypsin?
Trypsin is an enzyme that helps break down protein, works at a ph of ~ 7
8 essential amino acids
- must be in diet
- other 12 can be manufactured by body
- no plant food has all 8
- mix grain and legume (green peas, lentils, beans) and get all 3
How is digestion finished?
More amylases are added such as lactase
What is lactase?
Enzyme that breaks down lactose
- lactose = milk sugar
- produced in large quantities in juveniles (humans)
What is emulsification?
Liver produces bile (contains bile salts)
• stored in gall bladder
Bile salts
physical seperation of fat droplets
Lipase
Enzyme that breaks down lipids
Hepatic portal system
Small intestine —————-> Liver
Begins and ends at capillary system
- does not go through heart
Small intestine — liver — heart —body
Capillary system
- detoxification
- removes sugar from blood and stores it as glycogen
Large intestine
Absorb water + minerals as needed
Feces
Undigested material + water + coliform bacteria (fiber)
What does the large intestine do when you’re dehydrated?
large intestine will take water and circulate it back into the body
What causes constipation?
Lack of fiber, water, and/or exercise
What are vitamins?
organic molecules needed in small amounts
• not that many calories
water soluble vitamins
Excess is excreted in urine
Ex: vitamin C
- advantage: can get rid of easily in urine
- disadvantage: need to consume daily
Fat soluble vitamins
Excess is stored in fat
Ex: vitamin A
- advantage: not needed everyday, can be taken from body
- disadvantage: can store too much and build up to a toxic level (not likely)
Minerals
Inorganic (no calories)
- ex: calcium
Osteoporosis
weak bones due to lack of calcium and exercise (resistance exercise)
- women with lower levels of estrogen (after menopause) are more at risk
Order of the parts for the passage of food
Mouth -> esophagus -> stomach -> sphincter -> small intestine-> large intestine
what are the primary sections of the digestive system where the following nutrients are digested?
Lipids —> small intestine
Carbohydrates —> mouth (amalases)
Protein —> stomach (pepsin)
