THE DIGESTIVE SYSTEMmmmmmm! FUNCTIONS OF THE DIGESTIVE SYSTEM 1.INGESTS FOOD- takes in food 2.DIGESTS FOOD-breaks it down physically and chemically 3.ABSORBS NUTRIENTS- into the bloodstream 4.DEFECATES WASTE- rids body of indigestible items DIGESTIVE SYSTEM 2 MAIN GROUPS OF THE DIGESTIVE SYSTEM 1.ALIMENTARY CANAL- (GASTROINTESTINAL TRACT)- does all the functions of the digestive system 2.ACCESSORY ORGANS- assist in breaking down food in a variety of ways (physically and chemically) ALIMENTARY CANAL - ( aliment means" to nourish) 1Continuous hollow coiled muscular tube which is open to the environment at both ends. MOUTH-PHARYNX- ESOPHAGUS-STOMACH- SMALL INTESTINE-LARGE INTESTINE-ANUS 2.approx. 30 feet long in cadavers 3.Inner lining of each organ is epithelial cells 4.Surrounded by smooth muscle tissue INCLUDES THE FOLLOWING ACCESSORY ORGANS-SALIVARY GLANDS- TEETH- PANCREAS- LIVER- GALL BLADDER- ACCESSORY ORGANS-SALIVARY GLANDS- TEETH- PANCREAS- LIVER- GALL BLADDER- LIPSCHEEKS HARD PALATE- palatine bone (front of mouth) SOFT PALATE- fleshy- located behind UVULA- tiny projection on soft palate that aids in swallowing TONGUE-muscle which helps maneuver food around and involved in swallowing LINGUAL FRENULUM- membrane which secures the tongue to the floor of the mouth MOUTH- mucous membrane lining of epithelium DIGESTIVE ACTIVITIES OF THE MOUTH DIGESTIVE ACTIVITIES OF THE MOUTH INGESTION of food, physically broken down by teeth, starch is chemically broken down by SALIVARY AMYLASE INGESTION of food, physically broken down by teeth, starch is chemically broken down by SALIVARY AMYLASE SWALLOWING- food is forced by the tongue back into the pharynx- once in the pharynx it is out of our control SWALLOWING- food is forced by the tongue back into the pharynx- once in the pharynx it is out of our control posterior to the mouth where food canals and air canals become separated- posterior to the mouth where food canals and air canals become separated- Contains two skeletal muscles which are used in swallowing Contains two skeletal muscles which are used in swallowing EPIGLOTTIS- connective tissue fold that covers the trachea prevents choking PHARYNX- ACTIVITIES OF THE PHARYNX tongue blocks of the mouth, soft palate closes off the nasal passages, epiglottis covers the trachea passage food (BOLUS) enters esophagus 4 LAYERS of TISSUE 1. MUCOSA OF EPITHELIAL CELLS- mostly simple columnar cells used for absorption except for the esophagus which has stratified squamous used for protection 2. SUB-MUCOSA- connective tissue supplies blood and nerves 3. MUSCULARIS EXTERNA- 2 layers of muscles INNER LAYER IS CIRCULAR, OUTER LAYER IS LONGITUDINAL 4.SEROSA- slippery and protects the organ from friction (VISCERAL PERITONEUM) ACTIVITIES OF THE ESOPHAGUS PERISTALSIS- moves food toward stomach by first contracting longitudinal muscles then by contracting circular muscles- this occurs even without the use of gravity- PERISTALSIS- moves food toward stomach by first contracting longitudinal muscles then by contracting circular muscles- this occurs even without the use of gravity- ESOPHAGUS- Runs from the pharynx through the diaphragm down to the stomach (approx 10 inches long) contains smooth muscle both circular and longitudinal to force food through the canal. Runs from the pharynx through the diaphragm down to the stomach (approx 10 inches long) contains smooth muscle both circular and longitudinal to force food through the canal. STOMACH FACTS large C shape- located on the left side of your body -storage tank and site for food breakdown -approximately 25 cm (10 inches) long -when full it can hold about 4 liters (1 gallon) of food 3 MUSCLE LAYERS has a third layer of muscle that allows it to churn and mix food has a third layer of muscle that allows it to churn and mix food LONGITUDINAL LONGITUDINAL CIRCULAR CIRCULAR OBLIQUE OBLIQUE 2-3 liters of gastric juice are produced daily 2-3 liters of gastric juice are produced daily 3 muscle layers of the stomach break food apart physically and mix it with enzymes- forms CHYME 3 muscle layers of the stomach break food apart physically and mix it with enzymes- forms CHYME Gastric juice has a pH of 2 which along with the protein digesting enzymes would eat away the stomach lining (ULCER) Gastric juice has a pH of 2 which along with the protein digesting enzymes would eat away the stomach lining (ULCER) MUCUS- lines the stomach to protect it MUCUS- lines the stomach to protect it Activities that occur in the Stomach Only protein digestion occurs in the stomach Only protein digestion occurs in the stomach NO ABSORPTION OCCURS- except alcohol and aspirin NO ABSORPTION OCCURS- except alcohol and aspirin Typically takes a meal 4 hours to completely empty from the stomach Typically takes a meal 4 hours to completely empty from the stomach Chyme exits the stomach about 3 ml at a time. Chyme exits the stomach about 3 ml at a time. STOMACH- REGIONS OF THE STOMACH 1. CARDIAC- closest to the esophagus 2. FUNDUS- located above the cardiac 3BODY- large base 4. PYLORUS- last part of the stomach PARTS OF THE STOMACH PYLORIC SPHINCTER (VALVE)- controls the opening to the small intestine RUGAE- large folds on the inner lining of the stomach GREATER CURVATURE- lateral curve of the stomach LESSER CURVATURE- medial curve of the stomach PARTS OF THE STOMACH GREATER AND LESSER OMENTUM- double layer of peritoneum which covers all abdominal organs and attaches them to the body wall - filled with fat - insulates, cushions and protects organs - many lymph nodules of the immune system for protection HEART BURN Food and digestive juices move back through the cardioesophageal sphincter and burn the esophagus Food and digestive juices move back through the cardioesophageal sphincter and burn the esophagus Activities of the Stomach- GASTRIC PITS- ESSAY 1. GASTRIC PITS -special cells found in the lining of the stomach are activated by nervous system (sight, smell, and taste of food) 2. STOMACH- Cardioesophageal sphincter opens in the presence of food and allows it in. 3. Presence of food causes the release of the hormone GASTRIN- Gastrin causes the production of GASTRIC JUICES: PEPSINOGEN, HCL, and mucus. 4. HCL bonds with PEPSINOGEN to make PEPSIN. PEPSIN is the major protein digesting enzyme. Also RENNIN an enzyme to digest protein in milk is produced. VOMITING is a reverse peristalsis of the stomach along with contraction of the diaphragm and abdominal muscles is a reverse peristalsis of the stomach along with contraction of the diaphragm and abdominal muscles Does not occur once substances leave the stomach and enter the small intestine Does not occur once substances leave the stomach and enter the small intestine SMALL INTESTINE SMALL INTESTINE- longest organ (up to 20 feet) SMALL INTESTINE- longest organ (up to 20 feet) - nearly all food digested here- carbohydrates, proteins, nucleic acids, fats -when duodenum is full no more chyme enters -3-6 hour journey How the Small intestine works PERISTALSIS- wave- like contractions PERISTALSIS- wave- like contractions SEGMENTATION- single segments alternately contract and relax - food will go back and forth in both directions- helps to mix the food with as many enzymes as possible SEGMENTATION- single segments alternately contract and relax - food will go back and forth in both directions- helps to mix the food with as many enzymes as possible 3 structures that increase area in small intestine (pg 440) 1.Circular Folds- (PLICAE CIRCULARES) deep folds 2.Villi- long simple columnar cells that look like fingerlike projections 3.Microvilli- hairlike projections from each villi The Small Intestine 3 SUBDIVISION OF THE SMALL INTESTINE 1. DUODENUM- first 10 inches- (where ducts from accessory organs are connected) 2. JEJUNUM- middle 8 feet 3. ILEUM-last 12 feet of the sm. intestine ILEOCECAL VALVE- leads to the large intestine Parts PANCREATIC DUCTS- from the pancreas COMMON HEPATIC (BILE) DUCT- from the liver and gall bladder HEPATOPANCREATIC DUCT- where pancreatic duct and common bile duct connect before entering duodenum LARGE INTESTINE- -larger in diameter than small intestine -only 5 feet in length - Absorbs as much remaining water as possible ACTIVITIES OF LARGE INTESTINE hour journey large movements a day typically after a meal -No digestive enzymes but does have resident bacteria that dissolve remaining nutrients, produce gas and makes vitamin K an some B vitamins SUBDIVISIONS 1.CECUM- 1st part located below ileocecal valve. (sac-like) 2. APPENDIX- fingerlike projection hanging from the cecum- unknown function 3. COLON- majority divided into 4 sections 4. RECTUM- vertical pouch located against the sacrum-generally empty- 5.ANAL CANAL- opens to the exterior via the anus. SUBDIVISIONS OF THE COLON 1. ASCENDING COLON- 2.TRANSVERSE COLON- 3.DESCENDING COLON- 4.SIGMOID COLON- last upward curve toward the rectum. ACTIVITIES OF DIGESTION FECES- which contains undigested food, (cellulose or fiber), mucus and millions of bacteria and enough water for a smooth passage through the rectum When feces enter the rectum causes the DEFECATION REFLEX- sigmoid colon and rectum contract and involuntary anal sphincters relax putting pressure on voluntary anal sphincters. ACCESSORY ORGANS SALIVARY GLANDS- (3) produce salivary amylase Parotid Gland- duct to upper cheeks near 2 nd molar- located in back of soft palate Sublingual Gland- duct to floor of mouth- located in front of lower jaw Submandibular Gland- duct to sides of lingual frenulum- located in back of lower jaw ACCESSORY ORGANS TEETH- used in MASTICATION (chewing) INCISORS- front 4- sharp for cutting CANINES- fanglike 2- used for tearing BICUSPIDS (PREMOLARS)-4 MOLARS-6 used for grinding ACCESSORY ORGANS TEETH- two sets DECIDUOUS- 20- should have a full set by age 2 PERMANENT-32- begin appearing between age 6 and 12 the last set of molars WISDOM TEETH emerge between ages 17 and 25 Parts of the tooth CROWN- above the gumline (gingiva) NECK- at the gumline ROOT- below the gumline ENAMEL-outer white covering- hardest substance in the body- mostly calcium salts DENTIN- bone like second layer forms majority of tooth PULP- contains blood vessels and NERVE ENDINGS CEMENTUM-covering of the root attaches to periodontal membrane PERIODONTAL MEMBRANE- ligament the holds teeth in place PARTS OF A TOOTH ACCESSORY ORGANS PANCREAS- soft pinkish gland- extends from spleen to duodenum of sm. intestine Creates 1. PANCREATIC JUICES- for digestion 2. INSULIN- hormone that decreases blood sugar levels 3. GLUCAGON- hormone that increases blood sugar levels Hypoglycemic- low levels of glucose Hypoglycemic- low levels of glucose Hyperglycemic- high levels of glucose Activities in small intestine The presence of chyme in small intestine activates the release of digestive juices PANCREATIC JUICE 1. PANCREATIC AMYLASE- DIGESTS CARBS 2. TRYPSIN, CHYMOTRYPSIN- DIGESTS PROTEIN 3. LIPASES- DIGESTS LIPIDS (FATS) 4. NUCLEASES- DIGESTS NUCLEIC ACIDS 5. BICARBONATE- NEUTRALIZES STOMACH ACID The Liver LIVER AND GALL BLADDER LIVER- largest gland in the body - contains four lobes - most of it is located on the right side but it also overlies and covers most of the stomach - held to diaphragm by the FALCIFORM LIGAMENT GALL BLADDER- small thin-walled sac that hides underneath liver- stores excess bile-until activated by duodenum hormone CHOLECYSTOKININ- Activities of small intestine BILE- yellow-green solution made by the Liver and stored in the Gall Bladder- contains no enzymes but helps break large fat globules into smaller fat molecules (EMULSIFICATION) ACCESSORY ORGANS ROLE OF THE LIVER IN METABOLISM 1.Digestion (minor role) produces BILE when activated by hormone- SECRETIN 2.Detoxifies drugs and alcohol 3.Breakdowns hormones and red blood cells 4.Produces cholesterol, blood clotting proteins, albumin 5.Maintains blood glucose levels - stores excess glucose as GLYCOGEN NUTRITION AND METABOLISM NUTRIENT- substance in food that is used by the body to promote normal growth or maintenance NUTRIENT- substance in food that is used by the body to promote normal growth or maintenance 6 CATEGORIES 1CARBOHYDRATES- starches and sugars derived from plants 2.LIPIDS-saturated fats- animalsunsaturated fats- plants 3.PROTEINS- complete proteins from eggs, milk, and meat Incomplete proteins- from legumes, nuts, cereals (1-3 are used for energy and are considered major nutrients) 4VITAMINS- most vitamins act as a coenzyme to breakdown 5MINERALS- have various roles (see Appendix C in the book) (4-5 are needed in minute amounts) 6WATER- NUTRITION AND METABOLISM METABOLISM- all the chemical reactions necessary to maintain life CATABOLISM- the breaking down of molecules (energy is released) ANABOLISM- the building up of molecules (energy is needed) ATP- the molecular source of all energy CELLULAR RESPIRATION 1 glucose molecule glycolysis Krebs cycle electron transport chain 38 ATP Carbohydrate metabolism USAGES----Is the preferred fuel to produce cellular energy. USAGES----Is the preferred fuel to produce cellular energy. GLUCOSE- (blood sugar) is used to make ATP in most cells of the body 4 kcal / gram GLUCOSE- (blood sugar) is used to make ATP in most cells of the body 4 kcal / gram Typical blood sugar 100 mg glucose / 100 ml of blood) Typical blood sugar 100 mg glucose / 100 ml of blood) FAT METABOLISM USAGES- energy storage, myelin sheath, and cushioning of organs USAGES- energy storage, myelin sheath, and cushioning of organs LIVER- controls fat metabolism LIVER- controls fat metabolism Fats are used as the reserve energy source. When glucose is absent in the cell then fat can be broken down into ATP. Fats are used as the reserve energy source. When glucose is absent in the cell then fat can be broken down into ATP. 1Gram of fat yields twice as much energy as 1 gram of carbs. 9 kcal /gram 1Gram of fat yields twice as much energy as 1 gram of carbs. 9 kcal /gram PROTEIN METABOLISM USAGESmake cell parts, enzymes, muscle fibers USAGESmake cell parts, enzymes, muscle fibers Broken down into 20 essential amino acids. Of the twenty 8 amino acids cannot be made by the body. (has to come from diet) Broken down into 20 essential amino acids. Of the twenty 8 amino acids cannot be made by the body. (has to come from diet) Can be an energy source when carbohydrates and fats are not available. 4 kcal / gram Can be an energy source when carbohydrates and fats are not available. 4 kcal / gram ENERGY BALANCE IN THE BODY IDEALLY Energy input = total energy output (heat + work+energy storage) BASAL METABOLIC RATE- amount of heat produced by the body per unit of time under basal conditions (AT REST) about Cal -production by the thyroid gland is probably most important factor TOTAL METABOLIC RATE- total amount of kilocalories the body must consume to fuel all activities Skeletal muscle activity can increase BMR by 15 or 20 times and keep these levels elevated for several hours. Factors influencing BMR 1. SURFACE AREA- 2. THYROXINE PRODUCTION- (hormone produced by thyroid gland) 3. AGE 4. STRONG EMOTIONS or INFECTIONS 5. GENDER CHOLESTEROL METABOLISM LOW-DENSITY LIPOPROTEINS (LDL)- bad transports cholesterol to the body cells for usage HIGH-DENSITY LIPOPROTEINS (HDL)- good transports cholesterol from the body cells to be eliminated (Need both types of cholesterol but in the proper ratio) (Need both types of cholesterol but in the proper ratio) BODY TEMPERATURE REGULATION- controlled by hypothalamus of the brain degrees Fahrenheit can be considered normal degrees is the considered world wide average body temperature HEAT PROMOTING MECHANISMS 1. VASOCONSTRICTION of blood vessels 2. SHIVERING- increases skeletal muscle activity -Frostbite and hypothermia can result WEIGHT MANAGEMENT TOTAL KCAL CONSUMED = TMR (then body fat remains the same) TOTAL KCAL CONSUMED = TMR (then body fat remains the same) TOTAL KCAL CONSUMED > TMR (then energy is stored as fat) TOTAL KCAL CONSUMED > TMR (then energy is stored as fat) TOTAL KCAL CONSUMED < TMR ( then fat is broken down for energy use) TOTAL KCAL CONSUMED < TMR ( then fat is broken down for energy use) HEAT LOSS MECHANISMS 1. EVAPORATION OF PERSPIRATION 2. EXPANSION OF BLOOD VESSELS- skin becomes flush and radiates out heat Heat exhaustion and heat stroke can result (FEVER- is caused by white blood cells releasing pyrogens which act on the hypothalamus to increase the body temperature. RESETS the core body temperature to a higher temperature- Vasoconstriction and shivering occurs to raise body temp. to help fight of infections.)