sign in sign up
<<
Home , Digestion, Lumen (anatomy)

Figure 37.2 from Notes page 613 of your text Emma’s lower heart rate Question: Why do fit athletes have lower heart Functional Connections rates? , water intake oxygen intake • Conditioned athletes build a stronger, more efficient heart with greater capacity. To maintain the required oxygen supply the heart does not need to pump as often to distribute the same amount of oxygen as a DIGESTIVE RESPIRATORY elimination SYSTEM SYSTEM of carbon normal heart. dioxide nutrients, Liz’s question about cholesterol and Sam’s comment about avocados: water, oxygen carbon salts dioxide

• Cholesterol in the diet comes exclusively from sources, CIRCULATORY URINARY particularly meats and dairy products. Eggs are probably the best-known SYSTEM SYSTEM source, containing a whopping 213 milligrams of cholesterol per yolk water, (more than two-thirds of the recommended daily allowance of solutes cholesterol). In contrast, of plant origin contain no cholesterol, elimination rapid transport elimination of including avocados. In fact, there are several studies that have shown a of food to and from all excess water, steady diet of avocados actually reduces LDL cholesterol. residues living cells salts, wastes

Digestion and Types of Guts

Sac-like Gut Tube-like Gut

Mouth

Single opening for Complete gut with ingesting food and and anus. Food travels one- excreting wastes. way through the .

5 Tasks for a Digestive System Two Types of Systems 1. Mechanical processing and motility – break-up, mixing, and propelling food 1. Incomplete digestive system • One-way, saclike 2. – release of digestive digestive cavity 3. Digestion – breakdown of food into particles 2. Complete digestive system small enough (soluble) for absorption • A tube with an opening at 4. Absorption – passage of digested nutrients and each end fluid across tube wall and into body fluids 5. Elimination – expulsion of undigested, unabsorbed residues from the end of gut Digestive Specialization

1. Digestive system is often subdivided into functional regions 2. Specialization reflects feeding behavior

cloaca

Digestive Tract Structures and Functions Digestive System Adaptations Adaptations of digestive systems reflect diet 1. Teeth (or gizzard) – physical breakdown. and omnivores 2. Crop – storage - longer alimentary canal compared 3. – chemical breakdown to body size. - more time to digest vegetation 4. Intestine – absorption and breakdown in small - more surface area for uptake of intestine; water absorption in . nutrients 5. / – ceca -very long 6. – water removal, storage - -digesting microbes 7. Various glands/organs for enzymes and which aid digestion. - short alimentary canal - high [nutrient] in meat AFig. 21.12A

Herbivores, Omnivores, Carnivores Dentition 1. Carnivores have a high diet and eat meat. (sheep) Herbivores eat plants. Omnivores eat both. Herbivores and Diet and omnivores have longer guts than carnivores. flat Vegetation has more time to be digested and there is a greater surface area for absorption. Herbivores have molars cellulose digesting in their guts. 2. Teeth – Herbivores have large, flat teeth with lots of surface area for grinding plant . Carnivores have (dog) sharp canines for grasping and tearing flesh. Carnivore molars are pointed. 3. Examples: Carnivores – cheetah, fox, bat, lion; large Herbivores – sheep, deer, , gopher canines Omnivores – man, bear, rat, opossum Foregut and Hindgut Fermentation Specialized Teeth 1. (foregut fermenters) – hoofed, usually horned, herbivorous with a stomach divided into 4 compartments. Examples: cattle, sheep, goats, deer, and giraffes. 1. Structure of teeth ANTELOPE HUMAN reflects feeding MOLAR MOLAR First two stomach compartments contain bacterial symbionts to behavior crown breakdown cellulose. Food is regurgitated for additional (). Food is swallowed a second time and moves to the third and 2. Antelope brush crown root fourth stomachs before passing to intestine. teeth against dirt as 2. Hindgut fermenters – bacterial symbionts in colon or cecum (after they eat; wear the stomach) breakdown cellulose. Examples: termites, elephants, down crowns root horses, zebras, manatees, guinea pigs, rats, porcupines, beaver, , iguana, red howler monkey, , and some .

Digestive System Adaptations Coprophagy – eating mammals have an elaborate system for cellulose digestion Two types of feces - four-chambered stomach soft & hard - prokaryotes and protists in rumen and reticulum break down cellulose fresh cecal pellets - animal periodically regurgitates meal to soften the material(cud) Extract vitamin B

AFig. 21.12B both types

Termite Digestion of Cellulose Silverfish digest Trichonympha unicellular protist wood with cellulase symbiont

termites Longhorned beetles digest wood with cellulase Shipworms digest wood with cellulase

Teredo navalis wood bored by shipworm shipworm shipworm (bivalve)

Vertebrate Digestive System: Common Elements B= C=Cecum Cr=Crop E= G=Gall Bladder L= LI=Large Intestine P= PA=Pyloric Appendices SG= SI= St=Stomach

Accessory organs Human Major components Salivary glands 1. Mouth Secretes enzymes Mechanical and chemical that digest processing (chewing Human Teeth reduces size of food; digests carbohydrates) Liver Secretes 2. Esophagus enamel molars molecules Transports food Lower jaw required for dentin 3. Stomach digestion of fats premolars Mechanical and chemical Gall bladder processing (digestion of canines Stores secretions ) incisors from liver; 4. Small intestine Chemical empties into processing and absorption small intestine (digestion of proteins, fats, 1. Normal adult Pancreas carbohydrates; absorption Secretes enzymes of nutrients and water) number is 32 and other 5. Large intestine materials into Water absorption small intestine and feces formation Saliva

1. Skeletal muscle 1. Produced by salivary glands at back of sensory 2. Functions in speech, receptor mouth and under tongue positioning food, 2. Saliva includes • Salivary () • (buffer) 3. Taste buds contain • Mucins (bind food into ) sensory receptors • Water

Swallowing Structure of the Stomach

1. Complex reflex 1. J-shaped lies below the diaphragm 2. Tongue forces food into serosa 2. Sphincters at both ends muscle 3. Epiglottis and vocal cords close off 3. Outer serosa covers smooth ; breathing temporarily ceases muscle layers 4. Bolus moves into esophagus, then through mucosa 4. Inner layer of glandular esophageal into stomach faces lumen

Stomach Secretions Mixing

1. Secreted into lumen (gastric fluid) 1. A thick mixture of food • Hydrochloric (HCl) and gastric fluid • (protective) 2. High acidity kills many • Pepsinogen (inactive form of a protein- digesting enzyme) 3. Mixed and moved by 2. Stomach cells also secrete the waves of stomach into the bloodstream contractions () Protein Digestion in Stomach Ulcer

1. High acidity of gastric fluid denatures proteins 1. An erosion of the wall of the stomach or small intestine and exposes bonds 2. Can result from undersecretion of mucus and 2. Pepsinogen secreted by stomach lining is buffers, or oversecretion of activated to pepsin by HCl 3. Most ulcers involve Helicobacter pylori and can be treated with antibiotics 3. Pepsin breaks proteins into fragments

Into the Small Intestine Intestinal Secretions

1. Movement into 1. Wall of the duodenum secretes controlled by pyloric • Disaccharidases - digest to sphincter

2. Duodenum receives pyloric sphincter secretions from pancreas, • Peptidases - break protein fragments down to liver, and ; amino continues process of • - digest down to nucleic digestion duodenum acids and monosaccharides

Pancreatic Enzymes Fat Digestion

1. Secreted into duodenum 1. Liver produces 2. Bile is stored in gallbladder, then secreted 2. Pancreatic amylase into duodenum 3. and 3. Bile emulsifies fats; breaks them into small 4. droplets 4. This gives enzymes a greater surface area 5. to work on 6. Pancreatic nucleases and Digestion Small Intestines

1. Gastrin Duodenum Jejunum • Stimulation of • absorption of secretion. carbohydrates and 2. (CCK) proteins. • the principle for delivery of pancreatic enzymes and bile into the small intestine. - larger channels Small intestines • absorption of fats, 3. water, B12, bile • pH control salts.

Lymph One villus Walls of Small Intestine - microvilli vessel mucus secretion absorption ()

1. Projections into the

intestinal lumen increase One villus the surface area available for absorption

hormone secretion blood lysozyme secretion

Lymph One villus vessel mucus secretion absorption (goblet cell) Animation of Absorption starting with absorption cell surface

hormone secretion phagocytosis blood lysozyme secretion absorption capillaries Absorption of Nutrients Absorption Mechanisms INTESTINAL LUMEN 1. Passage of molecules into internal 1. Monosaccharides and amino environment acids are actively transported carbohydrates proteins amino acids 2. Occurs mainly in jejunum and ileum of across plasma membrane of small intestine epithelial cells, then from cell into internal environment 3. Segmentation mixes the lumen contents EPITHELIAL against wall and enhances absorption CELL

INTERNAL ENVIRONMENT

Fat Absorption bile salts Into the Blood + MICELLES FAT GLOBULES EMULSIFICATION free fatty acids, DROPLETS () monoglycerides 1. and amino acids enter blood triglycerides + proteins vessels directly 2. Triglycerides enter lymph vessels, which

1. Bile salts and enzymed bind fat droplets – fatty acids. eventually drain into blood vessels 2. Bile salts bind to fatty acids to form micelles, which create a gradient across cell membranes. 3. Micelles diffuse into cells. Chylomicrons leave epithelial cells by exocytosis and enter internal environment.

Pathways of Organic Large Intestine (Colon)

ascending Food intake 1. Concentrates and stores feces. portion of large intestine dietary carbohydrates, lipids dietary proteins, amino acids 2. Sodium ions are actively

POOL OF CARBOHYDRATES AND FATS POOL OF AMINO ACIDS transported out of lumen and (carbohydrates fats) NH3 water follows. cecum specialized used as nitrogen-containing components of structural appendix storage derivatives (e.g., cellular derivatives structural components of urea 3. Lining secretes mucus and forms steroids, energy (e.g., hormones, proteins, cells ) source nucleotides) enzymes bicarbonate to protect lumen some surface cell activities excreted as excreted in cell some cell lining and provide lubrication. secretion, cell CO2 via urine activities sloughing sloughing Bacteria in Colon Movement through Colon

1. Slow movement of material through colon 1. During a meal, gastrin and autonomic allows growth of bacteria. signals trigger contraction of ascending and 2. Harmless--unless they escape into transverse colon abdominal cavity. 2. Material moves along to make room for 3. Some produce , which is incoming food absorbed through intestinal wall. 3. Feces is stored in last part of colon

Food Pyramid Colon Malfunction ADDED FATS AND SIMPLE SUGARS 1. Appendicitis

2. Constipation , YOGURT, LEGUME, NUT, POULTRY, CHEESE GROUP , MEAT GROUP 3. Colon cancer • Symptoms include blood in feces • Can be caused by a genetic defect FRUIT GROUP VEGETABLE GROUP • Low-fiber diet is a predisposing factor BREAD, CEREAL, RICE, PASTA GROUP

Carbohydrates Lipids

1. Body’s main energy source. 1. Most fats can be synthesized from proteins 2. Foods high in complex carbohydrates are and carbohydrates. usually high in fiber; promote colon health. 2. Essential diets cannot; must be obtained from food. 3. Simple sugars lack fiber, as well as minerals 3. Fats should be about 30 percent of diet. and vitamins of whole foods; intake should be minimized. 4. Excess saturated fats can raise cholesterol level and contribute to heart disease. Essential amino acids Proteins & vegetarians 1. Body cannot build eight of the twenty amino acids. The proteins found in milk, eggs, meat, fish, and cheese are the most complete sources of essential 2. These essential amino acids must be amino acids. Proteins are also found in foods from obtained from diet. plants, but no one plant food has all of the essential 3. Animal proteins are complete; supply all amino acids in the correct amounts. To get all the essential amino acids. essential amino acids the body needs for growth and good health, eat a variety of foods. 4. Plant proteins are incomplete; must be combined.

Sources of essential amino acids Dietary Essentials 1. *Histidine: Apples, pomogranates, alfalfa, beets, carrots, celery, cucumber, dandelion, endive, garlic, radish, spinach, turnip greens. 2. *Arginine: Alfalfa, beets, carrots, celery, cucumbers, green vegetables, leeks, lettuce, potatoes, radishes, parsnips, nutritional . 1. Vitamins 3. Valine: Apples, almonds, pomegranates, beets, carrots, celery, dandelion greens, lettuce, okra, parsley, parsnips, squash, tomatoes, turnips, nutritional yeast. 4. Tryptophan: Alfalfa, brussel sprouts, carrots, celery, chives, dandelion greens, endive, • Essential organic substances fennel, snap beans, spinach, turnips, nutritional yeast. 5. Threnoine: Papayas, alfalfa sprouts, carrots, green leafy vegetables such as celery, collards, kale, and lettuce (especially iceberg), lima beans, laver (Nori -- a sea 2. Minerals vegetable). 6. Phenylalanine: Apples, pineapples, beets, carrots, parsley, spinach, tomatoes, nutritional yeast. • Essential inorganic substances 7. Methionine: Apples, pineapples, Brazil nuts, filberts, brussels sprouts, , cauliflower, chives, dock (sorrel), garlic, horseradish, kale, watercress. 8. Lysine: Apples, apricots, grapes, papayas, pears, alfalfa, beets, carrots, celery, cucumber, dandelion greens, parsley, spinach, turnip greens. 9. Leucine: Avocados, papayas, olives, coconut, sunflower . 10. Isoleucine: Avocados, papayas, olives, coconut, sunflower seeds. A balanced diet provides all of the essential vitamins and minerals. Vitamin and mineral supplements are only required by strict vegetarians and people who are ill. * Essential for children

Vitamins • Vitamins and minerals are important for a vegan diet. If the Essential organic substance lactovegetarian and the ovo-lactovegetarian diets are planned well, they will contain all the vitamins and minerals the body needs for good health. Vitamins and minerals that may be lacking in the vegan diet are Fat soluble Fat insoluble vitamin B-12, , riboflavin, calcium, zinc, and iron. Soybeans and soy bean milk and dark green leafy vegetables are good sources of 1. Excess 1. B vitamins calcium and iron, but spinach, chard, and beet greens should be eaten in accumulates in smaller amounts because they contain oxalic acid. Oxalic acid may 2. Pantothenic acid interfere with the absorption of calcium. tissue 3. 2. Vitamins A, D, • Since vitamin B-12 is not found in plants, it is necessary for strict 4. vegetarians to get it another way. Commercially prepared foods and E, K 5. Vitamin C meat substitutes are sometimes fortified with vitamin B-12. Check the special foods sections of the supermarket or health food store for these items. The health care provider may prescribe a vitamin B-12 supplement. Major Minerals Essential inorganic substances Obesity 1. Increasing numbers of Americans are obese Calcium Magnesium 2. Obesity-related conditions Chloride Phosphorus Copper Potassium Type 2 diabetes Breast cancer Fluorine Sodium Heart disease Colon cancer Iodine Sulfur Hypertension Gout Iron Zinc Gallstones Osteoarthritis

Anorexia All-American Diet

Heaviest Human Heaviest Man

Carol Yager Jon Brower Minnoch (1941-1983) (1960 - 1994) 1400 lbs. 1,600 lbs. He lost 1,000 lbs after a 16 month hospital stay and a 1,200 calorie/day diet. After his release form the hospital he gained 200 lbs in 7 days. He died at 800lbs. X-Ray of Human Stomach

Another sad story Francis John Lang What’s in here? (1934-?) 1187 lbs.

X-Ray of Human Stomach X-Ray of Dog Stomach

What’s in here? Dog ate a knife $650 worth of coins, assorted necklaces and needles.

X-Ray coin X-Ray of Dog Stomach

Girl ate coin Dog ate a knife II X-Ray of Dog Stomach X-Ray of Dog Stomach

Crocodile swallowed Woman swallowed fish hook or fish with fork a hook.