Digestion and Nutrition Introduction Digestion mechanical and chemical

Digestion and Nutrition

Introduction Digestion: mechanical and chemical breakdown of food into forms the cell membrane can absorb Alimentary canals: extends from the mouth to the anus Mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anal canal Several accessory organs: release secretions into the canal Salivary glands, liver, gallbladder, and pancreas

General Characteristics 9 -meter muscular tube Structure of the Wall Mucosa: mucous membrane Inner most layer Protects the underlying tissue Carries out secretion and absorption Epithelium, connective tissue, and smooth muscle Tiny folds and projection in the lumen, passageway Increase absorption through increased surface area Glands: secrete mucus and digestive enzymes

Structure of the Wall �Submucosa Loose connective tissue, glands, blood vessels, lymphatic vessels, and nerves organized into plexus Vessels nourish surrounding tissue and carry away absorbed nutrients away �Muscular Layer Moves the tube Smooth muscle tissue and some nerves organized into a plexus �Serosa: serous layer Visceral peritoneum: outer covering of the tube Protect underlying tissue Secrete serous fluid � Moistens and lubricates the tube’s outer surface

Layer of Digestive Tract

Tube Movement Mixing Movement smooth muscles in small segments of the tube contract rhythmically Full stomach: movement mixes the food and digestive juices Propelling Movement Peristalsis: wave-like motion Ring of contraction Push food along the tube

Mouth Receives food Begins digestion mechanically reducing the size of solid particles mixing particles with saliva Oral Cavity: chamber between palate and tongue Vestibule: narrow space between the teeth, cheeks, and lips

Cheeks and Lips Cheeks outer layers of skin pads of subcutaneous fat muscles associated with expression and chewing inner linings of moist stratifies squamous epithelium Lips: highly mobile structures that surround the mouth opening Skeletal muscles Sensory receptors: temperature and texture Red color: due to abundance of blood vessels near their surface

Tongue Covered with mucous membranes Frenulum: connects the midline of the tongue to floor of the mouth Skeletal Muscle Mix food particles with saliva Move food toward the pharynx Papillae: rough projections on surface Provides friction to handle food Contain taste buds Root: posterior region Connected to hyoid bone Lingual tonsils: rounded masses of lymphatic tissue

Palate Roof of oral cavity Hard plate: anterior part Soft plate: muscular arch, which extends downward to coneshaped projection, the uvula During swallowing, drawn upwards Action closes the opening between the nasal cavity and pharynx Palatine Tonsils: back of mouth, on either side Tonsils of tonsillectomy Pharyngeal Tonsils: adenoids Posterior wall of pharynx

Tonsils and Adenoids

Teeth Primary Teeth: 20 deciduous teeth 6 months to 2 or 4 years Secondary Teeth: 32 permanent teeth 6 years to 17 or 25 years Break pieces of food into smaller pieces Increases surface area digestive enzymes

Teeth Crown: projects beyond the gum Enamel: covers the crown Ca salts; hardest substance in the body Dentin: beneath the enamel; bone like Root: anchored to the jaw

Teeth Incisors: chisel-shaped Bit off large pieces of food Cuspids: cone-shaped Grasp food and tear Bicuspids and Molars somewhat flattened surface Grinding food particles

Salivary Gland Secrete saliva Moistens food particles, helps bind them, and begins the chemical digestion of carbohydrates Solvent allowing food to be tasted Helps cleanse the mouth and teeth

Salivary Secretions Serous Cells: water fluid that contains amylase Splits starch and glycogen molecules Mucous Cells: thick liquid called mucus Binds food particles Lubricated during swallowing Parasympathetic Nerves secrete watery saliva see, smell, taste, or think about food Food that looks, smells, or tastes unpleasant inhibits this

Major Salivary Glands Parotid Glands: largest, anterior to each ear Secrete a clear, watery fluid rich in amylase Submandibular Gland: floor of the mouth on the inside surface of the jaw Predominantly serous and some mucous Sublingual Gland: floor of the mouth, inferior to the tongue Smallest Primarily mucous

Pharynx, Esophagus, Stomach, and Pancreas

Pharynx Cavity posterior to the mouth from which the tubular esophagus leads to the stomach Pharynx nor esophagus digests food

Pharynx Structure of Pharynx: connects the nasal and oral cavities with larynx and esophagus Nasopharynx: provides a passage way for air during breathing Oropharynx: passageway for food moving downward from mouth and for air moving to and from the nasal cavity Laryngopharynx: passageway to esophagus

Swallowing Mechanism 1 st stage: voluntary food is chewed and mixed with saliva Tongue rolls mixture into a mass, bolus and forces it into the pharynx 2 nd stage: food stimulates sensory receptors around the pharyngeal opening Triggers swallowing reflex Epiglottis: flap-like structure that closes the tops of the trachea 3 rd stage: peristalsis transports the food in the esophagus to the stomach

Epiglottis

Esophagus Straight, collapsible tube about 25 cm long Food passageway from the pharynx to the stomach Mucous Glands: secretions moisten and lubricate the tube’s inner lining Lower esophageal sphincter: close the entrance to the stomach Prevents regurgitation of stomach contents

Stomach J-shaped, pouch-like organ inferior to the diaphragm upper left portion of abdominal cavity 1 L capacity Functions: Receives food from the esophagus Mixes food with gastric juices Initiates protein digestion Carries limited absorption Move food into small intestine

Parts of the Stomach Cardiac: small area near the esophageal opening Fundic: balloons above the cardiac portion Temporary storage area Body: main part Pyloric: narrows as it approaches the sm. Intestine Pyloric sphincter: muscle valve controlling gastric emptying

Gastric Secretions Mucous Membrane of stomach contains many gastric pits, ends of gastric glands Mucous cells: large quantities of thin mucus Chief cells: digestive enzymes Parietal cells: HCl

Gastric Secretions Digestive Enzymes Pepsin: protein Mucus and other alkaline secretions prevent pepsin from digesting the stomach itself Intrinsic Factor: need for B 12 absorption

Regulation of Gastric Secretions and Absorption Gastric juices are continuously produced, but the rate varies Parasympathetic impulses and the hormone gastrin enhance gastric secretion Food moving into the sm. intestines inhibits secretions Gastric absorption: only a few substances in small quantities Water, certain salts, alcohol, and some lipid-soluble drugs

Mixing and Empting Actions Chyme: mixture of food particles and gastric juices Production aided by movement of stomach Peristaltic waves push chyme toward pyloric sphincter Stomach relax with accumulation of chyme, a little at a time, is pushed into the small intestines

Mixing and Empting Actions Liquid pass quite rapidly Solid remain until they are well mixed Fatty foods remain 3 -6 hours Proteins: quicker Carbohydrates: faster than protein and fats As food enters the duodenum, accessory organs add their secretions Pancreas, liver and gallbladder

Pancreas Secretes pancreatic juice into the duodenum Contains enzymes to digest carbohydrates, fats, nucleic acids, and proteins Pancreatic amylase: carbohydrate digesting enzyme Pancreatic lipase: fat digesting enzyme Nucleases: nucleic acid digestion enzyme Trypsin, chymotrypsin, and carboxypeptidase: protein digesting enzymes

Pancreas Regulation Stimulation the release of pancreatic juices Nervous and endocrine system Food in duodenum Pancreatic juices are high in bicarbonate ions Neutralizes chyme Intestinal contents to be alkaline

Liver, Small Intestines, and Large Intestines

Liver Located in the upper right quadrant of the abdominal cavity Fibrous capsule encloses the liver Connective tissue divides the organ into a large right lobe and a smaller left lobe Each lobe is separated into tiny hepatic lobules Liver’s functional units Bile canals carry bile from hepatic lobules to hepatic ducts

Liver Function Metabolizes carbohydrates, lipids, and proteins Stores some substances Filters blood Destroys toxins Secretes bile Important in digestion

Bile salts, bile pigments, cholesterol, and electrolytes Only bile salts have digestive functions Bile salts emulsify fats and aid in the absorption of fatty acids, cholesterol, and certain vitamins Gallbladder stores bile between meals Cholecystokinin from the small intestine stimulates bile’s release Enters the duodenum

Small Intestine Receives secretions from the pancreas and liver Completes nutrient digestion Absorbs the products of digestion Transports the residues to the large intestine Parts Duodenum Jejunum Ileum

Small Intestine The wall is lined with villi Increase in surface area Aid in mixing and absorption Intestinal glands are located between the villi Secretions of the small intestine Mucus and digestive enzymes Digestive enzymes split sugars, proteins, and fats Gastric juice, chyme, and reflexes stimulated by distention of the small intestine wall stimulate secretion

Absorption Microvilli: absorb monosaccharides, amino acids, fatty acids, and glycerol Fat molecules with long chains enter the lacteals of the villi Fatty acids with short chains enter blood capillaries in villi

Movement Mixing and peristalsis Ileocecal sphincter: controls movement between small and large intestines

Large Intestines Parts Cecum, colon, rectum, and anal canal Colon is divided into ascending, transverse, descending, and sigmoid portions Unique layer of longitudinal muscle fibers arranged in distinct bands

Large Intestines Functions: Little or no digestive function Secretes mucus Absorbs water and electrolytes Forms and stores feces Movement: similar to small intestine Mass movement occurs two to three times a day Feces: water, undigested material, electrolytes, mucus, and bacteria Color is due to bile salts that have been altered by bacteria

Nutrition

Nutrition Process of ingestion and utilization of necessary food substances, or nutrients Carbohydrates: organic compounds that primarily supply cellular energy Sources: starch, glycogen, disaccharides, and monosaccharides Cellulose: polysaccharide that humans cannot breakdown

Carbohydrates Utilized for: Oxidation energy release from glucose Excess glucose is stored as glycogen or converted to fat Most carbohydrates supply energy Some cells require a continuous supply Requirements: humans can survive with a wide range of carbohydrate intake

Lipids Supply energy and used to build cell structure Sources: triglycerides from plants and animals Animals: most cholesterol

Lipids Lipid Utilization Liver and adipose tissue control triglyceride metabolism Linoleic acid: essential fatty acid Corn, cotton seed, and soy oil Lipid Requirements: amounts and types are unknown Fat intake must be sufficient to carry fat soluble vitamins A, D, E, K

Proteins Serve as structural materials, function as enzymes, and provide energy Sources: meats, dairy products, cereals, legumes Requirements Supply essential amino acids and nitrogen for the synthesis of nitrogen containing molecules

Vitamins Essential for normal metabolic processes Body cells cannot synthesize adequate amounts Fat soluble: A, D, E, K Carried by lipids and affected by the same factors that influence lipid absorption Resist the effects of heat; cooking has no effect Water-soluble: B and C vitamins B vitamins: oxidizes carbohydrates, lipids, and proteins Cooking or food processing destroys some water-soluble vitamins

Minerals Elements other than carbon that are essential Most minerals are in the bone and teeth Usually in organic compounds Some are in inorganic compounds or free ions Functions: structural material, enzymes, and vital roles in metabolic processes Major Minerals: Ca, P, K, S, Na, Cl, and Mg Trace Elements: Fe, Mn, Cu, I, Co, Zn, F, Se, Cr

Adequate Diet Provides sufficient energy and essential nutrients to support optimal growth, maintenance, and repair of tissue Impossible to design a diet adequate for everyone Malnutrition: poor nutrition due to the lack of foods or failure to make the use of the available foods

Eating Disorders

Eating Order Statics 8 million Americans have an eating disorder 7 million women and 1 million men 1 in 200 American women suffers from anorexia 2 to 3 in 100 American women suffers from bulimia Nearly half of all Americans personally know someone with an eating disorder (Note: One in five Americans suffers from mental illnesses. ) An estimated 10 – 15% of people with anorexia or bulimia are males ADOLESCENTS Anorexia is the 3 rd most common chronic illness among adolescents 95% of those who have eating disorders are between the ages of 12 -25 50% of girls between the ages of 11 -13 see themselves as overweight 80% of 13 -year-olds have attempted to lose weight

MORTALITY RATES Eating disorders have the highest mortality rate of any mental illness A study by the National Association of Anorexia Nervosa and Associated Disorders reported that 5 – 10% of anorexics die within 10 years after contracting the disease; 18 -20% of anorexics will be dead after 20 years only 30 – 40% ever fully recover The mortality rate associated with anorexia nervosa is 12 times higher than the death rate of ALL causes of death for females 15 – 24 years old. 20% of people suffering from anorexia will prematurely die from complications related to their eating disorder, including suicide and heart problems

Treatment Only 1 in 10 people with eating disorders receive treatment About 80% of the girls/women who have accessed care for their eating disorders do not get the intensity of treatment they need to stay in recovery – they are often sent home weeks earlier than the recommended stay Treatment of an eating disorder in the US ranges from $500 per day to $2, 000 per day. The average cost for a month of inpatient treatment is $30, 000. It is estimated that individuals with eating disorders need anywhere from 3 – 6 months of inpatient care. Health insurance companies for several reasons do not typically cover the cost of treating disorders The cost of outpatient treatment, including therapy and medical monitoring, can extend to $100, 000 or more http: //www. huffingtonpost. com/2010/12/29/isabelle-caro-dead-anorexicmodel_n_802424. html

Amputation Diet Procedure Clip finger and toenails Haircut Drastic Haircut / Headshave Trim Body Hair Remove a wart Take a diuretic Take a laxative Colon Therapy / Take an Enema Poop Run a marathon on a hot day Amputate your arm Amputate your leg Vascetomy Take a big pee. Take a big dump Estimated Immediate Weight Loss 1 ounce maximum 2 -6 ounces 4 -12 ounces 1 oz. (ladies) 3 oz. (men) 24 lbs (Greek men) 1 oz. 1 -3 pounds (temporary) 1 -2 pounds (temporary) 2 -3 pounds (temporary) 0 -2 pounds (temporary) 3 lbs (women), 5 lbs (men) (temporary) 10 -25 lbs (way too permanent) 15 -45 lbs (again, not advised) none. up to 1. 5 pounds up to 2. 5 pounds

Amputation Diet Procedure Go barefoot Go Naked Contact lenses vs. Glasses No liquids all day No food all day No salt all day Don't wear underwear Exfoliating face wash Liposuction Donate a kidney Breast Reduction Surgery Estimated Immediate Weight Loss 1 -2 pounds 1 -8 pounds (summer vs. winter) 0. 3 pounds 1 -2 pounds 2 -3 pounds 0 -1 pound 1 oz. (thong)-2 lbs. (granny panties) nothing. 10 lbs maximum per surgery 3 pounds. 5 -15 pounds typically

Things that Remind Me of My Grandmother 1. If you eat something and no one sees you eat it, it has no calories. 2. If you drink a diet soda with a candy bar, the calories in the candy bar are cancelled out by the diet soda. 3. When you eat with someone else, calories don't count if you don't eat more than they do. 4. Food used for medicinal purposes NEVER count, such as hot chocolate, brandy, toast and Sara Lee Cheesecake. 5. If you fatten up everyone else around you, then you look thinner. 6. Movie related foods (Milk Duds, Buttered Popcorn, Junior Mints, Red Hots, Tootsie Rolls, etc. ) do not have additional calories because they are part of the entertainment package and not part of one's personal fuel. 7. Cookie pieces contain no fat-- the process of breaking causes fat leakage. 8. Things licked off knives and spoons have no calories if you are in the process of preparing something. Examples are peanut butter on a knife making a sandwich and ice cream on a spoon making a sundae.

Things that Remind Me of My Grandmother 9. Foods that have the same color have the same number of calories. Examples are: spinach and pistachio ice cream; mushrooms and white chocolate. NOTE: Chocolate is a universal color and may be substituted for any other food color. 10. Foods that are frozen have no calories because calories are units of heat. Examples are ice cream, frozen pies, and Popsicles. 11. Foods eaten while watching a major event on television do not count. Major events include: Superbowl, Hockey Finals, Indy 500. 12. Powerbars and other type energy bars make you thinner. In all my years of exercising (at least three times a year) I have only seen thin people eating energy bars. Ergo (therefore) they must make you thin. 13. Snickers is the same as an energy bar (see #12) 14. Tasting other people's food does not add to your calorie count. 15. Containers of food that list the number of servings as greater one are lying. Every container includes one serving. Half gallon of ice cream, box of cereal, bottle of soda, bag of chips are all one serving.