DIGESTIVE SYSTEM STRUCTURE ALIMENTARY CANAL Digestive tract or

DIGESTIVE SYSTEM STRUCTURE

ALIMENTARY CANAL �Digestive tract or GI (gastrointestinal) tract � 30 ft. tube from mouth to anus �Consists of the mouth, throat, esophagus, stomach, small intestine, large intestine, and anus �See figure 18 -1 pg. 377

ACCESSORY ORGANS of DIGESTION �Tongue �Teeth �Salivary glands �Pancreas �Liver �Gall bladder

PERITONEUM �Lines abdominal cavity �Serous membrane � 2 layers: • Mesentery �Attaches to posterior wall of abdominal cavity �Small intestines are attached to this layer • Greater omentum �Anterior portion of wall �Hangs over the organs like a “protective apron” �Contains large amounts of fat

MOUTH (FIGURE 18 -2) � Called the oral or buccal cavity � Covered in ____ membrane � Roof has hard and soft palates • Hard palate: formed from maxillary and palatine bones • Soft palate: behind hard, made from a movable mucous membrane fold and separates the mouth from the nasopharnyx � Uvula • Hangs from soft palate • Cone-shaped flap of tissue • Prevents food from entering the nasal cavity when swallowing

SALIVARY GLANDS �Three pairs • Parotid, submandibular, and sublingual • Parotid – largest �Found on both sides of the face, in front and below ears �Become inflamed when an individual has mumps �See figure 18 -4

TEETH (FIGURE 18 -5 and 18 -6) �Gingiva – gums • Support and protect the teeth �Deciduous (baby teeth) – 20 • Start around 6 mons to 2 years and may last up to age 12 �Adult mouth has 32 teeth • Start about age 6 to 25 years (wisdom)

ESOPHAGUS � 10” long muscular tube �Connects pharynx and stomach �Wall of esophagus has 4 layers • Mucosa, submucosa, muscular, and external serous layer �The muscles in the upper 3 rd are voluntary and involuntary (smooth) on the lower part

STOMACH �Cardiac sphincter • Opening from esophagus �Pyloric sphincter • Regulates entrance of food into the duodenum �Rugae • Folds in the gastric mucosa �See figure 18 -8

SMALL INTESTINE �Can be up to 20’ long �Duodenum – 12” long • Curves around head of pancreas • Food comes from stomach • Gets digestive juices from pancreas and bile from liver �Jejunum – 8 ft. long �Ileum – 10 – 12 ft. long �See figure 18 -9

PANCREAS �Feather-shaped �Located behind stomach �Endocrine and exocrine gland �See figure 8 -12 pg. 388

LIVER �Largest organ in body �Located below the diaphragm, upper right quadrant �Connected to gallbladder and small intestine by ducts �Figure 8 -12

GALLBLADDER �Small, green organ �Inferior surface of liver �Figure 8 -12

LARGE INTESTINE (Figure 18 -13) � Colon � Approx 5’ long and 2” in diameter � Cecum • RLQ of abdomen • Blind pouch � Appendix • RLG below cecum • Fingerlike projection • No digestive function � Rectum • Opens to anus • 7 -8” long � Anus • Last portion of large intestine • Guarded by 2 sphincters � 1 internal, 1 external