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43 Cards in this Set
- Front
- Back
Function of the Digestive System
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Physically and Chemically breakdown of food; Absorb nutrients and eliminate waste
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Evolution of Digestive System
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Intracellular-> Gastrovascular Cavity-> Complete Digestive System
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Intracellular (Porifera)
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Collar Cells-> Endocytosis of food in vacuole
Food vacuole and Lysosome (Digestive Enzymes) Digestion of food-> Exocytosis of waste |
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Gastrovascular Cavity (Cnidaria, Platyhelminthes)
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Have One opening; Food into Gastrovascular Cavity-> Digestive enzymes secreted
Digestion of food-> absorb nutrients Waste out |
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Complete Digestive System (Nematoda, Annelida, Molluska, Arthropoda, Echinodermata, Chordata)
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Has two openings: mouth and anus
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Ruminant (cows, goats, sheep, camel)
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Rumen (cows store 150 L) stomach full of microorganisms; they are key for digestion; to break down cellulose into glucose
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Cellulose
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polysaccharide present in the cell walls of plants
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Birds
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Do not have teeth; need a crop and a gizzard
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Crop
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stores food and moistens it
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Gizzard
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has sand and rocks to physically breakdown food
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Length of Intestine
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Herbivore- long
Carnivore- short the harder the material is to breakdown the longer the intestinal tract |
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Pathway of Human Digestive System
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Oral Cavity-> Pharynx-> Esophagus-> Stomach-> Small Intestine-> Large Intestine
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Teeth
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responsible for the physical breakdown of food
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Saliva
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Lubricates food; The enzyme Amylase takes starch which is a polysaccharide and makes it into a disaccharide
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Pharynx
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Muscular cavity (throat)
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Esophagus
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Muscular long tube that leads to the stomach; Peristalsis helps move the food along with rhythmic waves of muscle contraction
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Epiglottis
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prevents food from going to the larynx
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Stomach
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lots of muscle layers, a muscular compartment with folds (2-4 liters of expansion)
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Lower Esophageal Sphincter
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prevents materials from going up the esophagus
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Pyloric Sphincter
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controls movement of chyme into the small intestine
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3 Functions of the Stomach
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Physical Breakdown, Chemical Breakdown, Storage of Food
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Stomach- Physical Breakdown
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growling stomach means stomach is churning the food
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Stomach- Chemical Breakdown
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Gastrin, Helicobacter pylori, Pepsinogen, Protease
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Gastrin
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A hormone that generates HCl in order to decrease the pH (pH1)
Cells in the stomach produce mucus for protection Body replaces the lining of the stomach every 3 days |
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Helicobacter pylori
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A bacteria that causes ulcers which breakdown and eat away at the stomach wall
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Pepsinogen
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breaks down into Pepsin (low pH); takes proteins and breaks them into peptides
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Protease
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breaks down proteins; waits until reaches middle where the pH is low, this way it won't breakdown the muscle of the stomach
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Chyme
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storage of food; every 20 seconds 1 teaspoon of food is released into the small intestine
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Small Intestine
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Dvodenum, Jejunum, Ileum
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Chemical Breakdown of Small Intestine- 1
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Liver produces Bile
Gallbladder stores Bile Bile Salts emulsify fats (lipids, triglycerides) Occurs in the Small Intestine |
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Chemical Breakdown of the Small Intestine- 2
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Pancreas secretes pancreatic juice into the small intestine (1 Liter per day) sodium bicarbonate, pancreatic amylase, proteases, lipases
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Sodium Bicarbonate
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helps neutralize chyme to increase pH (basic)
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Pancreatic Amylase
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breaks down the polysaccharide starch into disaccharides
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Proteases
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breakdown proteins into peptides
ex: tripsin, chymotripsin |
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Lipases
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breakdown lipids (triglycerides)
Triglycerides- glycerol and 3 fatty acids |
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Chemical Breakdown of the Small Intestine- 3
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Small Intestine will secrete enzyme that aid in digestion
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Emzymes secreted by the Small intestine
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Peptidases, Nucleases, Disacc-> Monosacc
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Peptidades
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Peptides-> Single Amino Acids
Left- Aminopeptides Right- Carboxypeptides |
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Nucleases
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Nucleic Acids(DNA or RNA)-> Nucleotides
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Small Intestine- Absorption of Nutrients
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10ft by 1 inch; 600x more surface area from folds
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Peristalsis and Segmentation
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Rhythmic muscle contraction and sloshes food back and forth to absorb as much food as possible
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Large Intestine
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Colon and Rectum; 5ft by 3in; has LOTS of bacteria; absorb water; fiber important for diet
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Bacteria in the Large Intestine produce
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Vitamin B12, K, Riboflavin, Thiamin
1/3 of dry weight of poooop |