ANPH - Digestive system

• Stratified squamous


  Lining of the GI tract
• Macromolecules (polymers)


  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Monomers


  • Sugars
  • Fatty acids
  • Amino acids
  • Nucleotides
• Most of nutrient absorption happens in the small intestine
• Large intestine: water reabsorption takes place here
• Bile


  Produced by the liver, helps break down lipids
• Liver produces bile; gallbladder stores the bile
• Walls of the GI tract


  • Mucosa - innermost layer
  • Submucosa - contains numerous glands, blood vessels, and parasympathetic nerves
  • Muscularis - a thick layer of muscle tissue
  • Serosa - outermost layer
• The structure of layers varies in different regions throughout the length of the GI tract
• Mouth


  • Lips - covered externally by skin and internally by mucous membrane, the junction between the skin and mucous membrane is highly sensitive
  • Cheeks - lateral boundaries of the oral cavity, continuous with the lips and lined by mucous membrane, formed in large part by the buccinator muscle covered by adipose tissue, contains mucus-secreting glands
  • Hard palate - consists of portions of 4 bones; 2 maxillae and 2 palatines
  • Soft palate - forms the partition (separation) between the mouth and nasopharynx and is made of muscle arranged in an arch, suspended from the midpoint of the posterior border of the arch is the uvula
  • Tongue - solid mass of skeletal muscle covered by a mucous membrane, extremely maneuverable, has 3 parts; root, body, tip, papillae located on the dorsal (top) and lateral surfaces, lingual frenulum anchors the tongue to the floor of the mouth, intrinsic muscles important for speech and mastication, extrinsic muscles important for deglutition (swallowing) and speech
  • Salivary glands
• Pyloric valve


  One of the attachment stops for the duodenum
• Pepsin activation


  Hydrochloric acid activates pepsinogen to be pepsin
• Hydrochloric acid does not digest anything
• Amylase


  Breaks down complex carbohydrates
• Trypsin and chymotrypsin


  Work in alkaline environments
• Where amylase is found


  • Pancreas
  • Saliva
• Trypsin is not lipolytic, it is proteolytic
• Lipases


  Family of enzymes that break down fats
• Cholecystokinin is not an enzyme, it is a hormone produced in the small intestine
• Cholecystokinin


  Inhibits gastric secretions, provokes peristalsis of GI tract, triggers gallbladder and pancreas to contract
• GIP (gastric inhibitory peptide)


  Tells the stomach to stop
• Ghrelin


  Gastric hormone that produces the need to eat
• Hormones that increase movement and secretions in the stomach


  • Secretin
  • Gastrin
• Peristalsis combines with segmentation
• The gallbladder does not synthesize bile
• Fat falling into the duodenum stimulates the production of GIP
• The fecal bolus runs in the external environment
• The fecal bolus is external because the lumen is external
• Teniae coli


  Longitudinal muscle bands along the colon
• The sigmoid colon is retroperitoneal
• The spleen is intraperitoneal
• The gallbladder is intraperitoneal
• The pancreas is retroperitoneal
• The kidneys are retroperitoneal
• Haustra


  Protrusions around the surface of the colon
• Levator ani


  Muscle important for the coordination of defecation
• Lacteals do not exist in the colon
• Lacteals are found in the small intestine
• The veins of the villi go to the hepatic portal system
• Hemorrhoidal plexus


  Circulatory plexus by the anus