Presentation on theme: "The Digestive System. The Digestive System: Function Preparation of food for absorption and use by the millions of body cells Alimentary canal - tube."— Presentation transcript:
The Digestive System
The Digestive System: Function Preparation of food for absorption and use by the millions of body cells Alimentary canal - tube through your body that performs the above function.
The Mouth Structure Lips: outer boundary Cheeks: mucous membrane lateral boundary Hard/soft palate - uvula extends from Tongue
Places food during chewing Papillae contain taste buds Multiple blood vessels under tongue = high absorption of soluble drugs into circulation –Ex. Nitroglycerin pills for heart attack, –Vitamins
Salivary Glands Parotid = largest –Located in front of and below ear –Produces watery substance with enzymes Submandibular –Located below mandibular angle –Produces enzymes and mucus Sublingual = smallest –Under floor of mouth –Produces mucous type of saliva
Salivary Glands: Function Begins the break down of food through hydrolysis. Carbohydrate digestion begins in the mouth with aid of saliva.
Teeth Crown - exposed covered with enamel Neck - surrounded by gums (gingiva) Root - fits into socket
Teeth Coverings Enamel - Hardest substance in body Dentin - tissues, nerves, blood vessels Cementum - covers dentin
Dentition Permanent Teeth –Adult teeth –Secondary teeth 32 Total 3 rd set of molars come in after age 17 (wisdom teeth)
Other Organ Components Pharynx –Receives bolus (rounded mass of food) –Carries bolus to esophagus Esophagus –Collapsible tube that enters the stomach –Posterior to trachea and heart –Protected by a thick layer of mucus
Esophagus Continued Food (Bolus) moves through the esophagus and the rest of the alimentary canal by peristalsis - involuntary muscle contractions.
Stomach Located below diaphragm and liver Enlarges after meals then collapses Size of large sausage
Stomach Divisions Fundus - large portion at end of esophagus Body - central portion Pylorus - lower portion near small intestine
Sphincter Muscles Guard openings to stomach –Cardiac - esophagus to stomach –Pyloric - lower portion of stomach to small intestine. Pylorospasm - muscle will not relax to allow passage of bolus = vomiting
Stomach Function Food storage Secretion of gastric juices Churning of food and breakdown into chyme - liquid food. Absorption = water, alcohol, and drugs Glands of stomach –Gastric - secret gastric juice –Mucus - contains enzymes and hydrochloric acid.
Small Intestines 20 feet long Divisions –Duodenum = uppermost area, attaches to stomach. –Jejunum = middle area –Ileum = end portion, leads to large intestine. All set in place by mesentery (membrane)
Small Intestines Continued This is where most digestion occurs. Absorption of digestive products. Inside surface of small intestines covered with tiny projections called villi. –1mm projections –Increase surface area by 160x
Large Intestines 5-6 feet long Divisions –Ascending colon - right side of abdomen –Transverse colon - horizontally across abdomen and under liver –Descending colon - left side of abdomen –Rectum - last 7-8 inches –Anus - contains many arteries and veins Hemorrhoids - enlargement of veins in anal canal.
Large Intestines Continued Water/electrolyte absorption Forms/stores feces
Large Intestines Continued Appendix –Located just behind cecum –No functional importance in digestion. –Appendicitis = inflammation of the appendix
Accessory Organs Liver structure –Largest gland in body –Under diaphragm –Able to regenerate Liver function –Detoxifies many substances –Makes and secretes bile –Metabolizes proteins, fats, and carbs
Accessory Organs Gall bladder –Stores bile, increases its concentration Bile breaks down fat. –During digestion, empties bile into small intestines