Chapter 22: Nutrition and Digestion (mostly human)
Farabee, show examples of gastrointestinal tracts, Kimball
many organ system anim, some bad links
Biology and Society: Eating Disorders
The causes (unclear, psychological), symptoms, & treatments (counseling, anti-depressants) of bulimia & anorexia.

Overview of Animal Nutrition: Animal Diets:
herbivores eat plants, carnivores eat meat, & omnivores eat both: fig 2,
Earthworms are both omnivores &, decomposers/detritovores

The Four Steps of Food Processing: fig 3
1) ingestion & 2) digestion of food, 3) absorption of nutrients, & 4) elimination of wastes.
Show Fig 16 for overview
GI tract produces motility (like chewing, swallowing) & secretions (like saliva, stomach acid) along entire length
The motility & secretions are determined by presence of food / chyme
The food stimulates nervous, autonomic, & endocrine (hormone) reflexes, until it leaves!

Digestion a Closer Look
The digestive dismantling of large food molecules into small is "essential" for absorption
Digestion is both mechanical, like chewing & churning; & chemical, stomach acid & enzymes:
Hydrolases: split polymers (starch, protein, fat, & nucleic acids) into smaller molecules, fig 4, e.g.
amylase in saliva splits starch into maltose
pepsin in stomach splits proteins into peptides
lipase from pancreas splits fat into two fatty acids & monoglyceride
Enzymes from stomach & pancreas are not active until in stomach or duodenum
Pancreas  is largest & most comprehensive source of  digestive enzymes

Digestive Compartments/Tracts
Sponge cells, choanocytes, feed like an amoeba, or a colonial protist choanoflagellate
Cnidaria & Flatworms have gastrovascular cavity: only one opening
Rest have digestive tube, a great variety of feeding models
 
REVIEW p 489
1. order? absorption, digestion, elimination, ingestion
2. food polymers > monomers (mostly) due ? enzymes,
3. main difference btw gastrovascular cavities & alimentary canals?

A Tour of the Human Digestive System  fig 6.
= Alimentary canal ("tube") & Accessory organs = salivary glands, liver, gallbladder & pancreas
Anatomy: The original is still the best, see next, NOT THIS!

Mouth: oral cavity, includes oral pharynx (in airway too), dentition, fig 7, tooth, saliva,
Palpitate: submandibular salivary glands, hard palate (mostly maxilla),
Pharynx: swallowing, fig 8, tongue shoves food into pharynx, epiglottis closes airway, UES relaxes

Esophagus: entry: striated muscle, gradually changes to smooth at exit into stomach: peristalsis, requires intact nerves

Stomach: anatomy: cardia (entry) > fundus (top) > body (most) > pylorus (exit), rugae (ridges)
    histology: 4 layers: mucosa, submucosa, muscularis externa, serosa which links to mesentery
    secretions from gastric pits: enzymes, acid, mucus protects, intrinsic factor: Alexis St. Martin, Pavlov, dog,
    motility: eating: receptive relaxation, then contract to mix, control, includes nerves & hormones:
    Trouble: ulcer (duodenal is more likely) due to H. pylori, so use antibiotic
    LES, can be compromised: pregnancy heartburn (really esophagus), hernia, GERD

Small Intestine: neutralizes acid chyme from stomach, & digests it, & absorbs nutrients,
    ~7m or 21' long, duodenum, jejunum, ileum, villi,
    Wall has same 4 layers as stomach: wall glands: secrete secrete bicarbonate - neutralize acid &
    motility: segmentation mostly, peristalsis as chyme volume reduces or if feeding
    fig 13: (liver), gall bladder, (stomach), pancreas & duodenum, wiki,
    pancreas: secretes inactive enzymes & bicarbonate, enzymes activate in intestine
    liver: secretes bile: alkaline & bile acids/salts, soapy, emulsify fat, so it can be digested
    gall bladder: stores & concentrates bile, releases it into duodenum when chyme enters from stomach
    control of gastric emptying, & gall bladder & pancreas is by hormones
    Absorption: most nutrients enter blood capillaries, but fatty acids & monoglycerides enter lacteals
    A few problems: gall stones, wiki, duodenal ulcer, treatment,

Large Intestine: 5' or so, entry: cecum & appendix, absorb water, minerals & B & K vitamins (E. coli).
Elimination: nerve reflex arc, usually voluntary

REVIEW p 495
1. chewing is ?? digestion, amylase is ?? digestion of  ??  to  ?
2. if food goes wrong way, where is that ?
3. weightless astronauts are ok when feeding why?
4. antibiotics treat ulcers, why? previously: antihistamines!
5. major organ for nutrient absorption?
6. amylase is to ? , as ? is to fats
7. functions of large intestine?
8. long term treatment with antibiotics may lead to ? vitamin deficiency & why, leads to disease?

Human Nutritional Requirements
Activity: Analyzing Food Labels
Nutritional Disorders
Activity: Case Studies of Nutritional Disorders
Evolution Connection: Fat Cravings
Chapter Review
  1. Animals digest their food without digesting their own cells & tissues by
  2.   - mucus & cellular integrity in stomach,
  3.   - secrete inactive enzymes, stomach & pancreas, which only activate when in the food area

  5. Compare digestive compartments in animals, fig 5: Paramecium, hydra, earthworm: invertebrates & rabbit
  6. livestock .ppt download includes ruminants
REVIEW. 
1. Which phyla have digestive sacs & which have tubes?
2. Why do earthworms have gizzards? 
3. What vertebrate group has a gizzard, why?
4. What do big whales eat?  whale bone is not bone.  Killer whales are also carnivores but what do they eat?
5. How many chambers has a cow's stomach?  ruminant digestion

A Tour of the Human Digestive System:  Kimball,  Wiki,  Also Wiki,  both normal & disease 
  1. The secretions & motility of almost everything below are controlled by nerve reflexes and/or hormones
  2. food stimulates nerve reflexes: long loop via Central NS and/or short loop = in gut wall: enteric & more,
  3. & the secretion of 3 major hormones: gastrin,  secretin,  cholecystokinin
  4. Review:
  5. the main components of the human digestive tract: list names & functions, scroll for answers
  6. Saliva: mucus & water lubricate & dissolve food, amylase digests starch, role of tongue? and of teeth?
  7. Pavlov: conditioned reflex: dog salivates in response to bell
  8. Swallowing is a complex reflex, food is directed away from the trachea by the epiglottis
  9. Stomach
  10. Dr. Beaumont experimented on the stomach of St. Martin after a gunshot wound left access to his stomach contents.
  11. Most agriculture colleges have a cow like this: Idaho
  12. The structure of the stomach fits its functions, fig 10: store & digest food.  
  13. Motility is peristalsis: but only a little liquid moves into the duodenum with each contraction
  14. Gastric juice: acid kills & digests, pepsin digests protein, mucus protects, intrinsic factor for B12 absorption.
  15. Heartburn is due to acid regurgitation into the esophagus, GERD, one cause is hiatal hernia
  16. The stomach does not digest itself for reasons given above.
  17. Common cause of duodenal & stomach ulcers is a bacterium so treatment = antibiotics, and drugs that block acid secretion.
  18. Chemical digestion in the small intestine:
  19. The pancreas is source of most enzymes,
  20. Bile salts/acids from liver emulsify fat (bile is stored in gall bladder)
  21.    starch, polysaccharide > disaccharide > monosaccharide > absorbed > blood
  22.    triglyceride (fat) > monoglyceride & fatty acids > both absorbed > lacteal/lymph > blood
  23.    proteins > amino acids > absorbed > blood,  breast milk & passive immunity
  24.    DNA/RNA to > nucleotides > absorbed > blood

  26. The structure of the small intestine promotes nutrient absorption by folds, villi, microvilli
  27. four layer wall: mucosa, submucosa, muscularis & serosa...
  28. Structure and functions of the large intestine and rectum: remove water & salts, store,
  29. Causes of constipation include dehydration & too little dietary fiber, and much else
  30. Causes of diarrhea include symptom of infection, allergy, food intolerance, foodborne illnes, laxative or irritant food
Human Nutritional Requirements  Kimball is complete,
Calories in food: foodcals,  fast food,  all foods,  all foods if scroll, 
Exercise (aerobic: heart, exercises etc: muscles & joints),
Eat a nutritious balanced diet: NOT fig 16  food pyramid, nutritious foods,  nutritious fast foods,  detailed.
  1. Calories on food packages are really kilocalories = the energy in food.  SI unit is Joule
  2. The first nutritional requirement is enough calories - eat just as many calories as you use
  3. Your metabolism uses oxygen, & produces heat, carbon dioxide & some nitrogen waste in urine

  5. Basal metabolic rate (BMR): lying down, awake & fasting = your minimum calorie requirement
    6. measure by heat production (direct calorimetry) or by oxygen consumption (indirect calorimetry)
     
  6. It can also be extimated using weight, height, & age - done in lab ex
  7. Basal & Metabolic Rate Calculator.   surface area & body mass index: measures fatness but also muscle

  9. More Nutritional Requirements:
  10. Eight amino acids are essential to make protein, the other 12 can be synthesized in the liver
  11. A vegetarian diet is ok: eat legumes and cereals for all eight
  12. Three fatty acids are essential,  but trans fats are a problem , omega-3 fats are in fish oil: cod liver oil
  13. Most Vitamins are co-factors for enzymes,
  14. important minerals (ions): calcium, iron, iodine, fluoride, zinc, & others: usually not an issue

  16. Information found on food labels: cereals often add/include more vitamins & minerals
Nutritional Disorders
  1. Distinguish among malnutrition: missing something, can be calories; undernutrition: calories, & obesity.
Evolution Connection: Fat Cravings
  1. Explain how fat cravings in humans might have evolved (scroll to "a biological drive").
REVIEW: 
Ch 17
How do you decide which phylum and organism belongs to, fig 17.6?
Is anyone a strict, vegetarian?
How can upright posture and larger brain be related?  Human Evolution was messy
Ch 21
Even though they are small many insects "thermoregulate": dragonfly & butterfly?, tent caterpillar, moth, bees & more
What must your body know & have in order to control the amount of any one thing in your blood? Kimball?
What tissue? muscle, nerve, epithelial includes verbal link, detailed, connective includes verbal link,
Ch 22
Calorie counting & using food labels to get enough/not too much of everything are too time consuming to do,
So what should you do to live long & healthy?
Problems of gastic bypass surgery?  also here

Resources
The Green Guide
Organic food  link from source
shade tree coffee, must display bird friendly logo, from Smithsonian migratory bird council source
Marine Stewardship Council: if their logo is on fish pack then sustainable fishing
Cage-free & Free Range - not a reliable verification
Grass fed but also unreliable - union of concerned scientists
antibiotic free - unclear
natural - also unclear