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53 Cards in this Set
- Front
- Back
Feeding
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selection, acquisistion, and ingestion of food
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Ingestion
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process of taking food into the digestive cavity
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Digestion
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process of breaking down food.
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Peristalsis
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waves of muscular contraction that push the food in one direction
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Incisors
Canines Molars |
biting
tearing crushing & grinding |
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Salivary amylase
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chemical digestion of starch into sugar.
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Bolus
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lump of food traveling through esophagus
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pharynx & esophagus
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bolus travels through the pharynx and into the esophagus. Epiglottis closes the opening to the airway.
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sphincter
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ring of muscle that is the entrance to the stomach
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Stomach lining
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lined with epithelium that secretes mucus.
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Parietal cells
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in gastric glands in the stomach. These cells secrete hydrochloric acid.
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Chief cells
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in gastric glands secrete pepsinogen
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Pepsinogen
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when it comes into contact with acidic gastric juice in the stomach it is converted to pepsin
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Pepsin
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main digestive enzyme. It hydrolyzes proteins...converting them to short polypeptides.
it works best at pH 2. |
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Gastric juice
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in the stomach consists of the combination HCl and pepsin/pepsinogen
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chyme
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partially digested food from the stomach
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Digestion in the stomach
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-Proteins are enzymatically converted to polypeptides.
-breakdown of starch stops as salivary amylase is inactivated by the acidic pH of the stomach |
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stomach ---> small intestine
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-peristaltic waves release chyme in spurts out of the stomach and into the small intestine. through the pylorus
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Pyloric sphincter
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the stomach exit and small intestine opening
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small intestine
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Digestion is completed here. Nutrients are absorbed thru its walls.
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3 regions of the small intestine
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duodenum
jejunum ileum |
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Duodenum
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-most chemical digestion takes place here.
-Bile and enzymes are released here to act on the chyme -the epithelial cells in its lining produces enzymes catalyzes the final major nutrients |
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Intestinal villi
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-lining of small intestine has millions of these
-increase the surface area of the small intestine for digestion and absorption of nutrients. -Further there are microvilli making the intestinal surface more expanded |
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LIVER
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-secretes bile
-helps maintain homeostasis by removing or adding nutrients to the blood. -stores iron and vitamins -detoxifies alcohol and other drugs and poisons |
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Bile
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-important in the mechanical digestion of fats
-consists of water, bile salts, bile pigments, and cholesterol. -emulsifies fats. -does not enzymatically digest food |
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Liver and maintaining homeostasis
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-Converts excess glucose to glycogen and stores it.
-converts excess amino acids to fatty acids and urea. |
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Emulsification
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bile breaks down large fat globules into smaller fat droplets that can be more easily attacked by lipases.
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Lipases
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fat-digesting enzymes
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Gall bladder
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stores and concentrates bile. It releases bile into the duodenum as needed.
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Pancreas
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-secretes both digestive enzymes & hormones that help regulate the level of glucose in the blood.
-enzymes: trypsin & chymotrypsin |
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Trypsin & chymotrypsin
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digest polypeptides to dipeptides
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Pancreatic lipase
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degrades fats
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Pancreatic amylase
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breaks down almost all types of carbohydrates except cellulose...to disaccharides
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RNAase & DNAase
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In pancreas.
Split nucleic acids to free nucleotides |
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bicarbonate
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-pancreas secretes it into the duodenum.
-raises the pH of the chyme to 8. |
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Carbohydrate digestion
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Mouth & Small intestine
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Carb digestion in the mouth
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Salivary glands
Salivary amylase Breaks down polysaccharides into maltose and smaller polysaccharides |
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Carb digestion in the small intestine
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-Pancreatic amylase breaks down undigested polysaccharides into maltose + disaccharides
-In the lining of the duodenum (maltase, sucrase, lactase) help hydrolyze maltose, sucrose and lactose to their monosaccharides. |
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Protein digestion
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stomach & small intestine
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Protein digestion in the stomach
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Gastric glands
Pepsin help break down proteins into short polypeptides |
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Protein digestion in the small intestine
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-In the pancreas trypsin & chymotrypsin help hyrdolyze polypeptides into shorter peptides and dipeptides.
-In the lining of the duodenum peptidases and dipeptidases break small polypeptides and peptides into amino acids |
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Lipid digestion
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in Small intestine
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Lipid digestion in the small intestine
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-In the liver, bile salts break down globs of fats into emulsified fat droplets
-In the pancreas, pancreatic lipase breaks down emulsified fat droplets into fatty acids + glycerol |
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Nerves & hormones regulating digestion
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-salivary gland secretion is controlled by the nervous system
-secretion of digestive juices is regulated by both nerves & hormones -sensing food causes the brain to send neural signals to the gastric glands to secrete HCl and pepsin. -when food enters the stomach the medulla sends messages to endocrine cells in the stomach wall that secrete the hormone gastrin. This stimulates the stomach to release gastric juices. |
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Jejunum & ileum
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part of small intestine. The absorbtion of food monomers occurs at the intestinal villi.
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nutrients & blood
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A nutrient molecule has to pass thru an epithelial lining of the intestine.
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Liver and circulation
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-Amino acids and glucose are transported directly to the liver by the hepatic portal vein.
-Certain toxic substances are released into the liver |
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Products of lipid digestion
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-Free fatty acids & monoglycerides enter an epithelial cell and they are reassembled in2 triglycerides in the smooth ER.
-The triglycerides with cholesterol & phospholipids are packaged in2 chlyomicrons. -The chlyomicrons enter the blood |
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chylomicrons
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-triglycerides + cholesterol + phospholipids
-protein-covered fat droplets |
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Cecum
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blind pouch connecting the small intestine to the big one. The appendix projects from the end of it.
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Colon
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cecum to the rectum
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Large intestine
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cecum. ascending colon. transvese colon. descending colon. sigmoid colon. rectum. anus.
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Fiber
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is a type of cellulose that stimulates peristalsis.
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