Food Pyramid
Water-Soluble Vitamins Chart
Fat-Soluble Vitamins Chart
Minerals Chart
Large Intestine 2
Large Intestine 1
Liver
Villi and Microvilli
Small Intestine
Stomach Anatomy
Pharynx and Esophagus
Gastrointestinal Tract
I. Overview of Digestion
II. First Part of Digestive Tract
III. Stomach and Small Intestine
IV. Three Accessory Organs and Regulation of Secretions
V. The Large Intestine and Defacation
VI. Nutrition and Weight Control
I. Overview of Digestion
A. Organs are in gatrointestinal tract.
(Insert gastrointestinal tract picture / www.psych.upenn.edu / http://www.psych.upenn.edu/courses/psych127_Spring2002/notes.html)
B. Purpose of Digestion: To hydrolyze macromolecules (carbs, fats, and proteins) to their unit molecules (mainly sugars, amino acids, fatty acids, and glycerol) so they can pas through plasma membranes. These nutrients are carried by the blood to our cells. (Mader 144)
C. What do our cells need?
1c. Oxygen for cell respiration to make ATP. ATP is used for cell metabolism.
- "Glucose is the main substrate, or chemical that gets “burned” or combined with oxygen in cellular respiration." (Frolich PowerPoint Slide 4)
- Glucose diffuses through a special protein pore on the cell membrane
- Insulin is a protein secreted by the pancreas into the blood, usually following a meal.
- Insulin stimulates cells to take up glucose and either store it (as glycogen in liver and muscle) or use it in cellular metabolism
(Frolich PowerPoint Slide 6)
D. Processes Necessary to the Digestive Process:
1d. Ingestion: Mouth takes in food.
2d. Digestion: Mechanical or chemical.
- Mechanical: Occurs when food is divided into pieces that can be digested by enzymes. (Cutting up our food helps mechanical digestion. Occurs in mouth and stomach.
- Chemical: Digestive enzymes hydrolyze particular foods to molecular nutrients. Begins in mouth and is not complete until food reaches small intestine.
- Chyme: Thick, semifluid mass of partly digested food that goes from stomach to small intestine.
3d. Movement of GI tract contents alone digestive tract.
4d. Absorption: Unit molecules made by digestion go theough the wall of the GI tract and enter the cells that line the tract. From there, nutrients enter blood so they can be brought to cells.
5d. Elimination: Molecules that are not digested are removed from body through anus. (Mader 144-145)
E. Wall of Digestive Tract
1e. Lumen: Central space that contains water (food being digested). (The hose)
2e. Wall of tract has 4 layers:
- First layer, next to lumen: Mucosa (AKA Mucous Membrane): Produces mucus that protects the wall from digestive enzymes inside the lumen.
* Possible disorder: Diverticulosis: Portions of mucosa have pushed through the layers and formed pouches, where food has the ability to collect. Pouches can become infected or inflamed.
- Second layer: Submucosa: Broad band of loose connective tissue that contains blood vessels, lymphatic vessels, and nerves. These vessels carry the nutrients absorbed by mucosa.
* Possible disorder: Inflammatory bowel disease: Because the submucosa contains blood vessels, inflammatory response may occur, leading to inflammatory bowel disease. Symptoms: chronic diarrhea, fever, weight loss, and abdominal pain.
- Third layer: Muscularis: Two layers of smooth muscle. These muscles contract to move food from the esophagus to the anus.
* Possible disorder: Irritable bowel syndrome: Contractions of wall cause pain in the abdomen, constipation and / or diarrhea.
- Fourth layer: Serosa: A serous membrane that secretes a serous fluid. Part of the peritoneum, the internal lining of the abdominal cavity.
* Possible disorder: Appendicitis: Inflamed appendix. Peritonitis: Life-threatening infection of peritoneum. (Mader 145)
II. First Part of the Digestive Tract
A. Mouth, pharyns, and esophagus.
1a. Mouth: Receives food and beegins mechanical and chemical digestion.
- Roof of mouth separates the nasal cavities from the oral cavity. Has two parts: Anterior (toward front)hard palate (bone), and Posterior (toward back) soft palate (muscle).
2a. Three pairs of salivary glands: 1st: Lies at side of face just below and in front of ears. These are the ones that swell when someone is sick. 2nd: Beneath the tongue. 3rd: Beneath floor of oral cavity.
3a. Salivary Amylase: Enzyme in saliva that begins process of digesting starch.
B. Teeth and Tongue: Chewing = mechanical digestion.
1b. Teeth have two divisions: crown and root.
* Dental Caries: Tooth decay / cavities. Bacteria within mouth metabolize sugar and produce acids, which erode teeth. Gum disease is linked to cardiovascular disease!
2b. Tongue: Covered by mucous membrane, which contains sensory receptors called taste buds. When a person eats, the food activates nerve impulses to travel through nerves to the brain.
- Tongue is skeletal muscle.
- Bolus: the mass of food that is formed by the tongue for swallowing.
C. Pharynx and Esophagus: Both mouth and nasal passages lead to a cavity called the pharynx.
1c. Trachea is anterior to (in front of) the esophagus, a long tube whose purpose it only to move food to the stomach.
(Insert pharynx and esophagus picture / www.discovercreation.org / http://www.discovercreation.org/newlet/autumn%202004.htm)
2c. Swallowing: voluntary phase. Food enters esophagus, soft palate moves back to close off nasal passages, and the trachea moves up under the epiglottis to cover the glottis (and opening to the larynx, and therefore, air passage).
3c. Peristalsis: Rhythmic contraction that pushes food along esophagus and in all organs of the digestive tract.
4c. Sphincters: Muscles that are around tubes and act as valves; when sphincters contract, tubes close, and open when sphincters relax again. When something is swallowed, the sphincter relaxes to allow food to pass from the esophagus into the stomach before closing again.
* Heartburn: Stomach's contents escape into esophagus. (Mader 146-147)
III. Stomach and Small Intestine: Complete the digestion of food.
A. Stomach: Thick-walled, j-shaped organ that lies on left side of body under the diaphragm (a muscle that separates the thoracic and abdominal cavities).
1a. Linked with esophagus above and duodenum of small intestine below.
2a. Stores food, initiates digestion of protein, and controls the movement of chyme into the small intestine.
3a. Has four layers: Muscularis: Has three layers of smooth muscle: circular, longitudinal, and a layer of smooth muscle that runs obliquely to the other two.
- Oblique layer: Allows stomach to stretch and mechanically break down food to mix with gastric juice.
4a. Mucosa of Stomach: deep folds. Rugae: disappears when stomach capacity is full.
5a. Gastric glands: Produce gastric juice, containing enzyme called pepsin, which digests protein, hydrochloric acid, and mucus.
6a. Food leaves stomach when chyme enters the small intestine in squirts. (Mader 148-149)
(Insert stomach anatomy picture /www.rivm.nl / http://www.rivm.nl/interspeciesinfo/intra/human/stomach)
B. Small Intestine: Named for its small diameter, but is very long! Approx. 18 ft in length.
(Insert small intestine picture / instruct.westvalley.edu / http://instruct.westvalley.edu/granieri/biology15coursepage.html)
1b. Digestion is completed in the small intestine.
2b. Contains enzymes to digest all types of foods. Enzymes are secreted by pancreas and enter via a duct at the duodenum, the first 25 cm of small intestine.
3b. Bile: Mechanically breaks down fact by emulsifying it, which causes fat droplets to disperse in water. A duct brings bile from the liver and gallbladder into the duodenum.
4b. Lipase: Present in pancreatic juice. Hydrolicizes fat to glycerol and fatty acids.
5b. Pancreatic amylase begins and an intestinal enzyme finishes the digestion of carbohydrates to glucose.
6b. Pancreatic trypsin begins and an intestinal enzyme finishes the digestion of proteins to amino acids.
C. Nutrients are absorbed in the small intestine. The products of the digestive process are absorbed in the wall of the small intestine: sugars, amino acids (only additional nutrients that body can’t produce) (Frolich PowerPoint Slide 9)
, fatty acids, and glycerol.
1c. Villi: Fingerlike projections in the mucosa of the small intestine. Microvilli: The cells in the outer layer of the villus are columnar epithelial cells, and each one has thousandss of microscopic extensions. Microvilli greatly increase the surface area of the villus for absorption of nutrients.
(Insert villi and microvilli picture / www.prmgcentral.com / http://www.prmgcentral.com/info/CellularNutrition.htm)
2c. Nutrients are absorbed in the vessels of a villus, which contains blood capillaries and a small lymphatic capillary called a lacteal.
- Sugars (digested from carbohydrates) and animo acids (digested from proteins) enter the blood capillaries of a villus. Glycerol and fatty acids (digested from fats) enter the epithelial cells of the villi, are packaged as lipoprotein droplets (chylomicrons), which enter a lacteal.
3c. After nutrients are absorved, they are carried to all cells of the body by the bloodstream.
D. Lactose Intolerance: Lactose: primary sugar in milk. Those who do not have the enzyme lactase cannot digest lactose, = lactose intolerance.
* Symptoms: diarrhea, gas, bloating, and abdominal cramps.
E. Obesity: Dibetes Type 2 and Cardiovascular Disease: Nutrients absorbed at the small intsetine have a serious effect on body.
1e. Too much saugar and fat can result in obesity, which is associated with both Type 2 diabetes and cardiovascular disease.
2e. Healthy diet and physcial activity improves the ability of the hormone insulin to function properly in Type 2 diabetes. (Mader 151)
IV. Three Accessory Organs and Regulation of Secretions
A. Pancreas: fish-shaped, spongy, grayish pink orgain that stretches across the back of the abdomen behind the stomach.
1a. Pancreatic juice (produced from pancreatic cells) enters the duodenum by way of the pancreatic duct. This juice has digestive enzymes for all types of food.
- Pancreatic Amylase: digests starch.
- Trypsin: digests protein.
- Lipase: Digests fat.
- Pancreas is also an endocrine gland that secretes hormone (substance made by one set of cells that affects the target cells) insulin into blood.
B. Liver: Largest, most metabolic gland in body. Lies mostly in the upper-right section of the abdominal cavity, under the diphragm. "The liver receives blood via the hepatic portal vein from the capillry bed of GI tract and filters blood in the capillaries of the lobules. Removes poisonous substances from blood and detoxifies them.
- Also stores iron and vitamins A, D, E, K, and B12.
- As amino acids are changed into glucose, the liver combines their amino groups with CO2 and forms urea.
- Also makes plasma proteins and regulates the amount of cholesterol in the blood. (Mader 152-153)
(Insert liver picture / www.bupa.co.uk / http://www.bupa.co.uk/health_information/html/organ/liver.html )
- Feedback mechanism between liver and pancreas insure constant blood glucose level.
(Frolich PowerPoint Slide 7)
C. Bile is stored in gallbladder, which is located just below the liver.
* Gallstones: Form when liquid stored in gallbladder hardens into pieces of stonelike material.
* Liver Disorders:
- Jaundice: Bile pigments leak into blood.
- Hepatitis: Inflammation of the liver.
- Cirrhosis: Liver becomes fatty, and then liver tissue is replaced by inactive fibrous scar tissue. (Often seen in alcoholics.)
D. Regulation of Digestive Secretions: Controlled by nervous system and digestive hormones. (Mader 152-153)
V. The Large Intestine and Defecation
A. Large intestine: cecum, colon, rectum, and anal canal. Larger in diameter than small intestine, shorter in length.
1a. Cecum: Lies below the junction with the small intestine.
2a. Veriform Appendix: Small projection of cecum.
3a. Colon: Includes the ascending colon, the transvere colon, and the descending colon, and the sigmoid colon (enters the rectum). Rectum opens at anus = defecation.
B. Functions of Large Intestine: Absorbs water, preventing dehydration. Does NOT produce digestive enzymes and does NOT absorb nutrients.
1b. Absorbs vitamins produced by bacteria called the intestinal flora.
2b. Bacteria in large intestine break down indigestible material, and produce B complex vitamins and most of the vitamin K.
3b. Forms feces, and allows for defecation. This helps regulate homeostasis.
C. Disorders of the Colon and Rectum:
* Diarrhea, constipation, diverticulosis, irritable bowel syndrome, inflammatory disease, and polyps and cancer. (Mader 154-155)
(Insert large intestine picture / www.uco.es / http://www.uco.es/investiga/grupos/eatco/automatica/ihm/ejemplosvrml/Anatomia/HTML/largeIntestine.html)
VI. Nutrition and Weight Control
A. Obesity: Being grossly overweight. Doubled in the US in 20 years. Great concern, because body fat is associated with higher risk for premature death, deabetes type 2, hypertension, cardiovascular disease, stroke, gallbladder disease, repiratory disfunction, osteoarthrities, and certain types of cancers.
- To reverse it, eat fewer calories, be more active, and make wise food choices.
B. Classes of Nutrients: Nutrients: A component of food that performs a physiological funcion of the body. Provide us with energy, promote growth and development, and regulate cellular metabolism.
1b. Carbohydrates: Either simple or complex.
- Glucose: Simple sugar preferred by body as an energy source. Brain cells require glucose.
- Products made from refined grains should be minimized, because during refinement, fiber and vitamins and minerals are removed, leaving mostly starch. Believed to be a major cause of obesity. Also have a high glycemic index, because the blood glucose response the these foods is high.
C. Proteins: Digested to amino acids, needed by cells to synthesize hundreds of cellular proteins.
- Essential Amino Acids: 8 of the 20. Found in eggs, milk products, meat, poultry, and most other foods derived from animals. 2 servings of meat / day is usually plenty.
- Proteins can be harmful if the the diet is severely limited, or if there is an overabundance.
D. Lipids: Fats, oils, and cholesterol.
- Plaque buildup in arteries is known to cause blockages and thus, cardiovascular disease.
E. Minerals: Divided into major minerals and trace minerals.
- Calcium: Major mineral needed to construction of bones and teeth, and for nerve conduction and muscle contraction.
* Osteoporosis: Degenerative bone disease.
- Sodium: Regulates the body's water balance.
(Insert minerals chart Frolich PowerPoint Slide 16)
- Complex carbohydrates: (beans, peas, nuts, fruits, and whole grain products) are recommended as a good source of vitamins, minerals, and fiber.
F. Vitamins: Organic compounds that the body uses for metabolic purposes but is unable to produce in enough quantity.
- many are portions of coenzymes, or enzyme helpers.
- Antioxidants: Vitamins C, E, and A are believed to defend the body against free radicals, and are termed antioxidants.
- Vitamin D: Vtiamin D leaves the skin and is modified first in the kidneys and then in the liver until if finally becomes calcitriol, which promotes the absorption of calcium by the large intestine. (Mader 160-162)
(Insert charts / water and fat-soluble vitamins / Frolich PowerPoint Slides 17-18)
G. Planning Nutritious Meals: A person needs calories for their basal metabolism, and for exercise.
- Limit the amount of calories to what you will use up each day.
- Eat a variety of foods each day.
- Foods from all food groups.
- Eat more vegetables, fruits, whole grains, and low-fat milk products.
- Eat less foods high in saturated fats, added sugars, cholesterol, salt, and alcohol.
- Be physically active everyday.
H. Eating Disorders
1h. Anorexia Nervosa: Severe psychological disorder characterized by an irrational fear of getting fat that causes one to refuse to eat.
2h. Bulimia Nervosa: A person binge-eats, and then purges to avoid gaining the weight.
3h. Muscle Dysmorphia: A person thinks his body is underdeveloped, There is a preoccupation with diest and body forming. (Mader 164-165)
I. What is healthy? Non-packaged; local; home-cooked; culturally-based; spiritually satisfying. (Frolich PowerPoint Slide 24)
1i. How is food raised?
- Most food is no longer farmed, but factory-produced.
- Factory food production looks for maximum short and medium-term profit.
= Factory food production is unconcerned with long-term health of the consumer, or long-term productivity of the land.
- Factory food production is responsive only to government regulations, not to local prestige. Many people in the U.S. no long know where their food comes from, or even how food is grown and raised, or how to do it themselves.
- Small farmers survive by growing local prestige which comes from their concern for long-term health and satisfaction of the consumer and long-term productivity of the land. It is increasingly difficult for them to make a profit. (Frolich PowerPoint Slide 27)
(Insert food pyramid picture / www.tqnyc.org / http://www.tqnyc.org/NYC063564)/nutrition.html
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