Lecture 16 - Epithelial Tissue IV - Digestive System

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  • Created by: yasminw24
  • Created on: 07-01-18 15:14
What are the functions of the digestive system?
Ingestion, Digestion, Propulsion, Absorption, Compaction, Absorb Water, Consolidate indigestible residue, defecation
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What parts of the digestive system are part of the gastro intestinal tract?
Mouth, pharynx, oesophagus, small intestine, large intestine and anus
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What parts of the digestive system are part of the accessory digestive organs?
Teeth, tongue, salivary glans, gallbladder, liver and pancreas
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What is the alimentary canal?
The whole passage along which food passes through the body from mouth to anus during digestion. Measures 9m
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What are the layers that are common to all parts of the digestive system?
From inside out: lumen>mucosa: strat squam epi > lamina propria > muscularis mucoae > Submucosa: Oesophageal gland > Musculris externa: inner circular layer, outer longitudinal layer > serosa
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Describe the digestive process?
Upper GI tract digestion begins: Ingestion > taking food in > Mechnical digestion - form bolour, salivary amylase break down polysaccharides> Deglutition - good bolus formed by tongue pushes into laryngopharynx travels down oesophagus by peristalsis
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What is peristalsis?
Primary means of propulsion. Alternating waves of muscles contract in: esophogus, stomach, small intestine, large intestine - moves food distally in GI tract and very poweful
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What is segmentation?
Additional means of propulsion. Non-adjacent muslce contraction in small and large intestine. Food mixing with digestive juices. Absorption increased as different parts of food mass repeatedly passed over intestinal wall
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How are stomach and intestines held in place?
Mesentery - fold of peritoneum (serous membrane fomring abdominal cavity) attaches stomach, small intestine, pancreas, spleen and others to posterior wall of abdomen
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What is the parietal peritoneum?
Portion that lines abdominal and pelvic cavities. These cavities are known as perioneal cavity
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What is the visceral peritoneum?
Covers external surface of most abdominal organs, inclyding intestinal tracct
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What are the characteristics of the stomach?
At distal end of esophagus. Three muscle layers, site of inital chemical breakdown of proteins. HCl produced by parietal cells in gastric glands of mid-region. Intrinisc factor secreted by cells. Chief cells produce pepsingoen and lipases.
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What is intrinsic factor?
Substance secreted by the stomach which enables body to absorb vitamin B12. It is a glycoprotein
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What type of tissue lines the stomach?
Simple columnar epithelium
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What is the small intestine?
Convoluted tube from pyloric sphincter to ileocecal valve. Major digestive organ - chemical breakdown and nutrient absorption occurs. Receives chime from stomach, has duodenum, jejunum, ileum. SI secretes 1-2L of isotonic intestinal juice per day Act
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What happens in the Duodenum?
Receives chime, mix bile from gallbaldder and digestive juices from pancras
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What happens in the jejunum?
More vascular than ileum. Nutrients present in food absorbed here
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What happens at the ileum?
Function mainly absorb vitamin B12, bile sats and whatever products not absorbed. Wall made up of fold each with many villi on surface
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What are the characteristics of the gall bladder?
Stores and concentrates bile, not immediatley needed. Contracts under cholecystokinin influenced from small intestine and then delivered here
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What is bile?
A surfactant that helps with fat absorption by breaking it down in intestines. Combination of fluids, fat and cholestrol
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What are the characteristics of liver?
Largest gland, 4 lobes (right,left,caudate,quadrate), porta hepatits vessels enter and leave from, hepatic artery provides oxygenated blood, heaptic portal vein brings digestion products from intestne, liver cells HEPATOCYTES produce bile, store gluc
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Characteristics of large intestine?
Frames small intestine on 3 sides, extends ileocaecal valve to anus. composed of caecum, appendux, colon, rectu, canal. Most simple coumbar epitheium = secretion absorption. Anal canal stratified squamous epitheliu resists abrasion
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Card 2

Front

What parts of the digestive system are part of the gastro intestinal tract?

Back

Mouth, pharynx, oesophagus, small intestine, large intestine and anus

Card 3

Front

What parts of the digestive system are part of the accessory digestive organs?

Back

Preview of the front of card 3

Card 4

Front

What is the alimentary canal?

Back

Preview of the front of card 4

Card 5

Front

What are the layers that are common to all parts of the digestive system?

Back

Preview of the front of card 5
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