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18 Cards in this Set
- Front
- Back
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why do we eat?
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- to acquire energy, carbon, and essential nutrients
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essential nutrients
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- amino acids
- fatty acids - vitamins: ORGANIC molecules with various functions, required in small amounts, coenzymes - minerals: INORGANIC molecules with various functions, required in small amounts, some are enzyme cofactors. |
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dietary deficiencies
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- undernourishment: not getting enough chemical energy (calories). causes entropy
- malnourishment: long term absence of an essential nutrient |
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four stages of food processing
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- ingestion
- digestion - absorption - elimination |
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ingestion: four feeding mechanism
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- suspension feeding: filter feeders, what is in environment
- substrate feeding: ingest material as if moves through substrate. earthworms. - fluid feeding: mosquitoes - bulk feeder: humans |
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digestion
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- intracellular: digestion inside the cells. NOT humans.
- extracellular: food is broken down outside cell, nutrients are absorbed. alimentary canals - gastrovascular cavity is both |
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alimentary canals
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- complete digestive tracts have specialized functions
- increased efficiency - sequential food processing with help from accessory glands. - food moves with help from peristalsis and sphincters |
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oral cavity in digestion
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- mechanical digestion
- saliva contains mucin (lubricates food), and salivary amylase enzyme that breaks down starch |
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stomach
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- breakdown of proteins begins
- main function: storage - folds to allow for expansion, pits contain gastric glands. |
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gastric glands
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- produce gastric juice that break down proteins
- HCl - dissolves extracellular matrix. - pepsin - breaks down proteins |
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how is the stomach protected
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- juices secreted in inactive forms.
- mucus cells |
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parietal cells
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- secrete H+ and Cl- to make HCl acid
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chief cells
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- secretes pepsinogen (inactive form of pepsin)
- becomes pepsin with mixed with HCl. |
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acid chyme
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- acid chyme leaves stomach and goes to the small intestine
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small intestine
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- three regions: duodenum (neutralizes acids, majority of digestion), jejunum, illeum (both absorb food and water)
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role of pancreas in digestion
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- secretes bicarbonate (neutralizes acids) and digestive enzymes (amylases, proteases, nucleases, lipases)
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role of liver/gall bladder in digestion
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- produces bile salts which help emulsify fats
- gall bladder stores bile salts. |
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large intestine
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- cecum: "blind pouch". appendix
- colon: finish water removal. important in conservation of water. - rectum: storage site for feces |
