Digestive System Structures 2.07 AKA: Alimentary Canal Digestive Tract Gastrointestinal Tract Upper GI Lower GI Approximately 30’ in length from mouth to anus 2.07 Remember the structures of the digestive system

Functions of the Digestive System Physical breakdown of food. Chemical digestion of food into the end products of fat, carbohydrates, and protein. Absorb nutrients into blood capillaries of the small intestines. Eliminate waste products of digestion.

Definitions Digestion- the process of changing complex solid foods into simpler soluble forms which can be absorbed by body cells Enzymes- chemical substances that promote chemical reactions in living things

Digestion Terminology Bolus: soft, pliable ball created from chewing and addition of saliva- slides down esophagus. Peristalsis: wavelike motions, moves food along esophagus, stomach and intestines.

Definitions Feces: undigested semi-solid consisting of bacteria, waste products, mucous and Cellulose Defecation: large intestine fills, defecation reflex triggered- colon and rectal muscles contract while internal sphincter relaxes external anal sphincter under conscious control

Digestive System Structures Primary structures Mouth Esophagus Stomach Small intestines Large intestines Accessory structures Tongue Teeth Salivary glands Pancreas Liver Gall bladder 2.07 Remember the structures of the digestive system

In the mouth… Saliva softens food to make it easier to swallow Ptyalin in saliva converts starches into simple sugar Under nervous control- just thinking of food can cause your mouth to water.

Structure of Organs of Digestion Mouth Food enters digestive system through mouth (buccal cavity) covered with mucous membrane Roof of mouth is HARD PALATE (bone) and soft palate UVULA- flap that hangs off soft palate-prevents food from going up the nose when you swallow.

2.07 Remember the structures of the Buccal cavity Tongue Teeth Salivary Glands Palate Uvula 2.07 Remember the structures of the digestive system

Tongue Attached to floor of mouth Helps in chewing and swallowing Made of skeletal muscle attached to four bones Papillae (taste buds) on the surface

2.07 Remember the structures of the Tongue Taste buds on the surface Sweet Sour Bitter Salty 2.07 Remember the structures of the digestive system

Salivary Glands Three pairs of glands Parotid gland Submandibular gland Sublingual gland PAROTID – largest salivary glands, become inflamed during mumps Secrete saliva

Teeth Gingiva – gums, support and protect teeth Mastication – chewing, teeth helps in mechanical digestion Deciduous teeth- baby teeth (#20) Adult mouth has 32 teeth (Permanent). Did you know??? Canine teeth are also known as cuspids and eye teeth.

2.07 Remember the structures of the Palate Hard Soft Uvula Flap of skin hanging in the back of the throat 2.07 Remember the structures of the digestive system

2.07 Remember the structures of the Pharynx (throat) Nasopharynx Oropharynx Hypopharynx 2.07 Remember the structures of the digestive system

Esophagus Muscular tube 10” long Connects pharynx and stomach Esophageal wall layers Mucosa Submucosa Muscular External serous

In the Stomach… Gastric (digestive) juices are released Stomach walls churn and mix (This mixture is chyme) Small amount of chyme enters duodenum at a time controlled by pyloric sphincter Takes 2-4 hours for stomach to empty. When will Meagan’s stomach be empty if she last ate at 9a.m.?

Stomach Upper left quadrant of the of the abdominal cavity Fundus Body Pylorus Stomach has muscular coat that allows it to contract (peristalsis) and push food into the small intestine

2.07 Remember the structures of the Stomach CARDIAC SPHINCTER-circular layer of muscle, controls passage of food into stomach PYLORIC SPHINCTER- valve, regulates the entrance of food into duodenum RUGAE- mucous coat lining of stomach in folds when the stomach is empty 2.07 Remember the structures of the digestive system

Small Intestines Where digestion is completed and absorption occurs Addition of enzymes from the pancreas and bile from liver/gallbladder

Small Intestines DUODENUM- first segment, curves around pancreas, 12” long JEJUNUM- Second segment , 8 ft. long ILEUM- Third segment, 10-12 ft long ABSORPTION- in small intestine, digested food passes into bloodstream and on to body cells, indigestible passes on to large intestine

2.07 Remember the structures of the Acessory organs Pancreas Secretes digestive enzymes Located behind stomach Liver Next slide Gall Bladder Stores and concentrates bile until needed by body 2.07 Remember the structures of the digestive system

Liver Largest organ in the body Located below the diaphragm, upper right quadrant Manufactures bile Connected to gallbladder and small intestine by ducts Functions: produce and store glucose in the form of GYCOGEN- Detoxify alcohol, drugs and other harmful substances Manufacture blood proteins Prepare urea from the breakdown of amino acids Store Vitamins A, D, and B complex

Gallbladder Small green muscular sac secretes bile located inferior surface of the liver Stores and concentrates bile until needed by body. When fatty foods digested, bile released by gallbladder.

In the Large intestine… Regulation of H2O balance by absorbing large quantities back into bloodstream absorbs Vitamin B complex and K Bacterial action on digested food-decomposed products excreted through colon-bacteria form moderate amounts of B complex and Vitamin K Gas formation 1-3 pints/day, pass it through the rectum (flatulence) 14 times a day, bacteria produce gas

Large Intestine Chyme - semi-liquid food Approx 2” in diameter 5’ Long AKA: colon Cecum-lower right portion of large intestine Appendix: blind sac attached to the cecum, no known function, finger like projection Rectum- last portion of large intestine Anus- external opening

Sigmoid colon S shaped part of colon, which extends 7 to 8 inches as the rectum

Structures of the digestive system