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34 Cards in this Set
- Front
- Back
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Ingestion
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Putting food in your mouth
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Mastication
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Chewing
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Deglutition
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Swallowing
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Mechanical Digestion
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Physical breakdown of food
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Chemical Digestion
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Salivary amylase begins carbohydrate breakdown
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Digestion in the Stomach
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- Mixing: Smooth muscle contractions
- Secretion of acidic enzymes to make chyme |
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Digestion in the Small Intestine
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- Peristalsis: Waves of smooth muscle contraction
- Secretion of enzymes for chemical digestion - Absorption of nutrients |
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Digestion in the Large Intestine
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- Water and vitamin absorption
- Compaction of wastes |
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Egestion
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Forming feces to excrete
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Mucosa Histology
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- Stratified squamous epithelium at ends
- Simple columnar epithelium in stomach and intestines - Lamina propria: Underlying connective tissue - Muscularis mucosae: Smooth muscle layer |
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Submuscosa Histology
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- Connective tissue
- Capillaries - Lymphatic vessels - Submucosal plexus (sensory neurons, sympathetic, parasympathetic, enteric) |
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Muscularis Externa Histology
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- Smooth muscle layers
- Circular and longitudinal layers - Oblique layer in stomach - Myenteric plexus (sympathetic, parasympathetic, enteric) |
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Serosal Adventitia Histology
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- Simple squamous serous membrane (visceral peritoneum)
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Local Regulation of Digestion
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- Short reflexes: Sensory receptors (stretch, pH and stimulate enteric neurons to begin muscle contractions)
- Sensory receptors can also stimulate secretion by glands |
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Nervous Control of Digestion
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- Sympathetic: Inhibits digestion
- Parasympathetic: Stimulates digestion |
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Endocrine Control of Digestion
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- Enterocrinins: Hormones produced in duodenum
- Salivary amylase: Carbohydrate breakdown - Gastric and pyloric glands in stomach |
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Gastric Glands
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- Parietal cells: Intrinsic factor (which allows absorption of vitamin B12 and HCl, which acidifies chyme)
- Chief cells: Produce pepsinogen, which is converted by acid into pepsin (denatures proteins) |
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Pyloric Glands
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- G cells: Gastrin (stimulates gastric glands)
- D cells: Somatostatin (inhibits gastrin) |
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Cephalic Phase (of Stomach Activity)
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- Salivation
- Mixing - Secretion from gastric glands |
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Gastric Phase (of Stomach Activity)
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- Food arrives in stomach
- Mixing - Lots of secretion from gastric glands - Lasts for about 3 hours |
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Intestinal Phase of Stomach Activity
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- Enterocrinins inhibit gastric secretions
- Sympathetic inhibition of stomach (Alcohol is absorbed through stomach) |
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Small Intestine
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- Duodenum
* Plicae: Circular folds * Villi: Extensions to increase surface area (absorption of nutrients) * Microvilli: Brush border, brush border enzymes (carbohydrate breakdown) * Bile from the liver buffers chyme, brings pH back to neutral * Pancreatic juice: Digestive enzymes |
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Enteroendocrine Cells
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- S cells
- K cells - Brunner's glands - I cells |
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S cells
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- In crypts of hieberkuhn.
- Secretin: Stimulates bile release and insulin production (stores glucose) |
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K cells
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- Gastric inhibitory polypeptide
- Inhibits gastrin - Stimulates insulin |
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Brunner's Glands
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- Uragastrone: Inhibits gastric glands
- Mucus |
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I cells
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- Cholecystokinin (CCK): Stimulates pancreatic acini to make pancreatic juice
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Absorptive cells
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Absorb nutrients
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Paneth's cells
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Immunity
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Goblet cells
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Mucus
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Cell types
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1) Enteroendocrine cells
2) Absorptive cells 3) Paneth's cells 4) Goblet cells |
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Jejunum
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Second section of small intestine (lots of absorptive cells)
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Illeum
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Third section of small intestine
- Plicae smooth out, decrease absorption - Peyer's patches: Clusters of Paneth's cells |
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Pancreas
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- Secretions from acini enter duodenum
- Pancreatic juice is stimulated by CCK * Proteases: Break down proteins - chymotrypsin, trypsin, elastase * Amylase: Breaks down carbohydrates * Lipases: Breaks down lipids |
