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49 Cards in this Set
- Front
- Back
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Digestive Tract Includes
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oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus
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What is Mastication
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Teeth break down food
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How is food propelled through the digestive tract
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Swallowing, Peristaltic contractions, Mass movements
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Four layers of the digestive tract
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-Mucosa
-Submucosa -Muscularis -Serosa (Adventitia) |
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3 layers of Mucosa
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-mucus epithelium (stratified squamous)
-lamina propria (loose CT) -muscularis mucosae (smooth muscle) |
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Where and what are the submucosal plexus, and the myenteric plexus
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- in the submucosa, and muscularis respectively
-nerve plexus -Make up the enteric nervous system |
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What are mesenteries and what do they do
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-Double layer of serous membrane, with a thin layer of loose CT
-hold organs in the abdominal cavity in place -provide a route for vessels and nerves |
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What is the Retroparitoneal?
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-Lie against the abdominal wall, no mesenteries
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What are the three main salivary glands
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-Parotid: serous, either side of cheeks
-Submandibular: serous and mucous, under tongue -Sublingual: mucous, multiple ducts along side of tongue |
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What's the difference between serous and mucous
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Serous= digestive enzyme, salivary amylase
Mucous= lubricates food |
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What is the pyloric sphincter?
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-Thick ring of smooth muscle, leads to duodenum, controls what empties out of the stomach
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What are rugae
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-Submucosa and mucosa of the stomach, large folds that stretch and smooth as the stomach volume increases
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What does the spaces in the epithelium of the stomach allow for?
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-Gastric pits, which are openings for gastric glands
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Name the four gastric glands
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-Parietal cells: HCl and intrinsic factor
-Mucous neck cells: produce mucous -Chief cells: produce pepsinogen -Endocrine cells: regulatory hormones such as gastrin and histamine |
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What does gastrin and histamine do?
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Stimulates HCl from parietal cells
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What does HCl do?
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-kills bacteria
-inactivates salivary amylase, which halts carb digestion -converts pepsinogen to pepsin |
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What does pepsin do?
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Breaks down and denatures proteins
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What does intrinsic factor do?
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It's a glycoprotein which makes b12 more easily reabsorbed in the ileum. b12 is essential for DNA synthesis
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Describe the process of HCl production by the parietal glands
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1)C02 diffuses into the cell
2)C02+H20=H2C03->HC03-, and H+ : with the help of CA 3)Antiporter exchanges HCO3- for Cl- 4)H+ actively transported by the proton pump. Exchanges H+ for K+ into the gastric duct 5)Cl- diffuse across the parietal cell, balances positively charged H+ |
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Name the three stages of digestion
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1)Cephalic
2)Gastric 3)Intestinal Phase |
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Explain the cephalic phase
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-taste, smell, or thought of food stimulate medulla oblongata, Vagus nerves carry parasympathetic action potentials to stomach. ENS stimulated- promotes parietal, chief cells, and and gastrin/histamine secretion
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Explain the gastric phase
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-distention of stomach/presence of proteins stimulates a parasympathetic reflex where mechanoreceptors carry action potentials to medulla oblongata via vagus nerves. Medulla oblongata increases action potentials in the vagus nerves, that stimulates parietal, chief cells, and gastrin/histamine. Local reflexes also stimulate secretions.
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Explain the intestinal phase
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-Acidic chyme in the duodenum inhibits gastrin secretions: chemoreceptors in the duodenum are stimulated by H+, action potentials are carried to the medulla oblongata via the vagus nerve and inhibit parasympathetic action potentials
-Local reflexes also inhibit gastric secretion -Secretin, and cholecytoskinin decrease gastric secretions |
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Where does the common bile duct, and pancreatic duct enter?
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The Duodenum
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What comes after the duodenum?
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Jejunum and Ileum which are intraperitoneal. Ileum joins larger intestine at the ileocecal junction
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What does each villi contain?
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A capillary bed and lacteal (lymph)
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What are intestinal glands?
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Pits between the villa, contain alkaline secreting cells which neutralize acidic chyme
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How does the Liver receive and return blood from the circulatory system?
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Hepatic Artery, and Hepatic Portal Vein
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What drains bile out of the liver? What drains bile out of the gall bladder?
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- 2 hepatic ducts
- Cystic duct |
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What does the hepatic ducts, and cystic duct form?
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Common bile duct, that joins with the pancreatic duct at the hepatopancreatic ampulla
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What do each of the six hexagon shaped lobules within the liver have?
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-Portal Triad: includes hepatic portal vien, hepatic artery, hepatic duct
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What is in the center of each lobule?
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Central Vein
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Where does the blood from the hepatic portal vein go?
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Toward the center of each lobule, into the central vien, which then forms into hepatic veins, then into the inferior vena cava
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What are the hepatic cords that radiate from the central vein composed of?
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Hepatocytes: functional cells of the liver
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What are hepatic sinusoids?
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Spaces between the hepatic cords for blood channels
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Does bile flow away from the center of the lobule, or towards?
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Away, via the bile canaliculi and onto the hepatic duct, then onto the common bile duct
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Name the functions of the liver
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- Bile production: bile helps neutralize, bile salts emulsify fats, absorption and secretion of cholesterol
-Storage: stores glycogen, as well as lipids, vitamins and minerals -Nutrient Interconversion: can convert nutrients if needed -Detoxification: detoxifies chemicals and drugs -Phagocytosis: recycles worn out RBC's and WBC's -Synthesis: can produce blood proteins |
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What are gall stones?
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crystallized bile salts, cholesterol aids in the formation
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How are fats broken down?
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Lipase which is mainly secreted by the pancreas
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What are the primary products of lipase digestion?
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Free fatty acids and monoglycerides
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When is the lipid digestion officially complete?
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After bile salts have mixed with the lipid droplets in the small intestine
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Explain the process in which bile salts aids in lipid transport
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1) Bile salts surround fatty acids and monoglycerides
2) Fatty acids and monoglycerides transport across the epithelial cell by diffusion 3)SER converts fatty acids and monoglycerides into Triglycerides, proteins coat this and convert it into Chylomicrons 4) Chylomicrons move via exocytosis into the lacteal->thoracic duct-> interjugular vein |
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Name secretions from the Pancreas
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-Protein Digestion: Trypsin, chymotrypsin, carboxypeptidase (all released in inactive forms [ogen])
-Starch Breakdown: Amylase -Fat Breakdown: Lipase -Neutralization of acidic chyme: HC03- |
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Explain control of secretion of Pancreatic juices
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- Vagus nerve stimulates the pancreas to release digestive enzymes
- Secretin from duodenum stimulates pancreas to secrete watery HC03- substance - CCK from duodenum stimulates pancreas to release all the other digestive enzymes |
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Is the large intestine retroperitoneal?
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No, it's attached by mesentery
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Some bacteria synthesis vitamins _ and _ which are ____
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-B and K
-Reabsorbed |
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Large intestine can break down some ___ that can usually not be broken down
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Carbs (cellulose -> glucose)
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What do bacterial actions produce in the large intestine?
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-Gas (Flatus)
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What is a hemorrhoid?
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-Rectal veins that supply the anal canal which become inflamed or enlarged
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