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106 Cards in this Set
- Front
- Back
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What does the digestive system consist of?
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-Mouth and Tongue
-Salivary Glands -Pharynx -Esophagus -Stomach -Small Intestine -Large Intestine -Liver -Pancreas |
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What are the functions of the digestive system?
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-Ingestion
-Mechanical digestion -Chemical digestion -Secretion -Absorption -Excretion |
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Serosa
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Outer tough connective tissue membrane for PROTECTION
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Muscularis Externa
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LONGITUDENAL and CIRCULAR muscle layers for CONTRACTION
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Submucosa
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Loose connective tissue, blood vessels and GLANDS for SECRETION
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Mucosa
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Made up of three layers:
(1)Muscularis Mucos (Very thin) (2)Lamina Propria (Conn Tiss) (3)Epithelium Lining (Lines inside of GI tract facing the lumen) *Function for digestion and absorption of nutrients |
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"Little Brain"
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GI Tract (Functions independently)
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Sensory Neurons
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Monitor GI tension, chemicals and hormone levels in the blood
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Interneuronal Circuits
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OUTPUT controls GI muscles motility, blood flow and secretions
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Myenteric Plexus
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-Linear chains of neurons located between longitudinal and circular muscle layers
-Controls GI muscle tone, contractions intensity, frequency and velocity |
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Submucosal Plexus
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-Non-linear neurons scattered in the submucosa
-Control intestinal secretions and absorption |
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Parasympathetic NS
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Activates ENS
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Sympathetic NS
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Inhibits ENS
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Digestive Enzymes
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Protein catalysts that speed up the digestion chemical reactions at body temperature
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When are digestive enzymes NOT altered?
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During the reaction
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What are digestive enzymes sensitive to?
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Changes in temperature and pH
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Hydrolytic Enzymes (Digestive Enzymes)
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Use water to split food molecules
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Mastication
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Break and lubricate food for easy swallowing plus increasing the surface area
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Parotid Glands
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-Inferior to the zygomatic arch
-Serous Secretion and amylase |
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Sublingual Glands
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-On the floor of the mouth
-Mucous secretion (mucins) ONLY |
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Submandibular Glands
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-On inner surface of mandible
-Serous, mucous, amylase |
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(step 1)What pushes bolus of food from what cavity into where?
*Swallowing* |
Tongue; Oral; Oropharynx
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(step 2)What closes the nasopharynx and what closes the glottis?
*Swallowing* |
Soft Palate; Epiglottis
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(step 3)Which sphincter opens during the Esophageal phase?
(step 3)What propels bolus down esophagus toward stomach? *Swallowing* |
Upper Esophageal; Peristalsis
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(step 4)Which sphincter opens that allows bolus to enter the stomach?
*Swallowing* |
Cardiac (Lower Esophageal)
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Storage (STOMACH FUNCTIONS)
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Holding of food during feeding
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Mechanical Digestion (STOMACH FUNCTIONS)
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Grinding waves make liquid chyme and push it into the small intestine
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Chemical Digestion (STOMACH FUNCTIONS)
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Pepsin begins proteins digestion
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Absorption (STOMACH FUNCTIONS)
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Limited to water, alcohol and drugs
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Mucous Neck Cells (GASTRIC GLANDS)
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Secrete protective mucous (mucins)
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Parietal Cells (GASTRIC GLANDS)
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Secrete hydrocholoric acid and intrinsic factor
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Chief Cells (GASTRIC GLANDS)
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Secrete pepsinogen and gastric lipase
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G Cells (GASTRIC GLANDS)
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Secrete the hormone gastrin which stimulates gastric secretions
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Pepsinogen is converted to active enzyme pepsin in the stomach lumen by what?
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Hydrochloric Acid (HCL)
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Pepsin digests proteins to smaller what?
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Polypeptides
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Gastric lipase starts what?
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Lipids Digestion
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Which layers does the small intestine include?
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Serosa, muscularis externa, submucosa and mucosa
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How many villi does mucosa contain?
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4 to 5 million
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What is villus convered with?
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Columnar Epithelium and goblet cells
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What is the function of the blood capillaries inside the villus?
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Nutrients absorption
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What is the function of the lymphatic capillary (lacteal) inside villus?
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Lipid digestion products absorption
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Mechanical Digestion (SMALL INTESTINE)
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-Peristalsis propels chyme along intestine
-Segmentation move chyme back and forth to mix it thoroughly |
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Chemical Digestion (SMALL INTESTINE)
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-Enzymes from pancreas and small intestine complete digestion of protein, starch, disaccharide sugars and fat
-Gallbladder empties bile into small intestine to aid in fat digestion |
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Absorption (SMALL INTESTINE)
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of most substances
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The pancreas extends from what to what?
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Duodenum to Spleen
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What are the parts to the pancreas?
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-Head
-Body -Tail |
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Most cells in the pancreas are what?
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Exocrine producing digestive enzymes
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The endocrine cells in the pancreatic islets produces what?
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Hormones
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Acinar Cells
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Exocrine cells that secrete digestive enzymes into ducts
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Duct Cells
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Secrete a BICARBONATE solution to BUFFER the acidic chyme from stomach and raise its pH from 2-3 to 7-8
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Proteins (DIGESTION)
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-By PROTEOLYTIC enzymes
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The four enzymes that are secreted for proteins digestion are secreted as what?
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Inactive Proenzymes
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Where are proenzymes sequentially activated to form active enzymes?
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Duodenum
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What do the active enzymes (proteins digestion) digest?
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Proteins & Polypeptides to:
-Tripeptides -Dipeptides -Single Amino Acids |
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Starch (Digestion)
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-Remaining starch is digested in the intestine by pancreatic amylase enzyme to disaccharides
-Digestion is the same as in the mouth |
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Fats (Digestion)
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-Triglycerides digested in the small intestine by pancreatic lipase enzyme
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What does the digestion of each triglyceride yield (fat digestion)?
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A monoglyceride molecule and two fatty acid molecules
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Bile from the gallbladder is required so that what can take place?
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Pancreatic lipase can digest fats more efficiently
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Bile flows from the gallbladder down the bile duct into where to do what?
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Duodenum; To mix w/and emulsify the fats
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Emulsification
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Breaking fats drops into very small droplets for efficient enzyme action
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What does bile aid in?
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Absorption of digested fats
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What is bile a medium for?
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Bilirubin and cholesterol excretion by the liver
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What do the lobes of the liver contain?
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Microscopic liver lobules
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What do the lobes of the liver consist of?
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Rows of liver hepatocytes and rich blood supply
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What supplies blood at the six corners of each liver lobule?
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Branches of the hepatic artery and portal vein
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Blood flows toward the center of each lobule through what?
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Liver Capillaries (sinusoids)
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Rows of liver cells surround what?
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Capillaries
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Blood flows from capillaries into what in the center of the lobule?
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Central Vein
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Liver Macrophages
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KUPFFER cells in the capillaries phagocytes microorganisms
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What does the liver synthesize?
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Bile
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Bile flows from liver through what into where?
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Hepatic Duct; Gallbladder
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What does the gallbladder stores and concentrates?
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Biles
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What do the common hepatic duct and cystic duct from gallbladder unite to form?
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The Common Bile Duct
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What does the common bile duct unite with?
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Pancreatic Duct
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Bile and pancreatic juices enter what?
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Duodenum
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What are the functions of the liver?
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-Carbohydrate, lipid and amino acid metabolism
-Storage of glycogen, vitamins and iron -Removal of hormones and antibodies -Removal of waste products -Detoxification of drugs and toxins -Phagocytosis by Kupffer cells -Bile synthesis and secretion -Plasma protein synthesis |
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What are digestion by intestinal enzymes referred as?
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Brush-Border Enzymes
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Where are the brush-border enzymes located?
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Microvillus of intestinal cells
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Peptidase (DIGESTION BY INTESTINAL ENZYMES)
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Digest small peptides into single amino acids
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Intestinal Lipase (DIGESTION BY INTESTINAL ENZYMES)
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Digest fats into glycerol and free fatty acids
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Disaccharides (DIGESTION BY INTESTINAL ENZYMES)
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Digest disaccharides to individual monosaccharides
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Absorption (SMALL INTESTINE)
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The transfer of substances into absorptive cells then into the blood or lymph
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What do villi and microvilli of absorptive cells provide?
(SMALL INTESTINE) |
A very large surface area for absorption
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What type of substances are absorbed in the small intestine?
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-Most digested foods
-Water -Electrolytes -Vitamins |
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In Blood
(SMALL INTESTINE) |
-Monosaccharides
-Amino Acids -Electrolytes -Short Chain Fatty Acids -Water -Water-soluble vitamins |
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In Lacteal
(SMALL INTESTINE) |
-Fats
-Fat-soluble vitamins in chylomicrons |
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What layers make up the large intestine?
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-Serosa
-Muscularis Externa -Submucosa -Mucosa |
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What does the submucosa in the large intestine contain and what does it secrete?
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Deep Crypts w/intestinal glands and secretes LOTS OF MUCUS
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Mucosa in the large intestine DOESN'T contain what?
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Villi
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Mucosa in the large intestine is covered by what?
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Simple Columnar Epithelium
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Digestion of undigested food by?
(FUNCTIONS OF THE LARGE INTESTINE) |
Bacteria
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Formation of vitamin B & K by?
(FUNCTIONS OF THE LARGE INTESTINE) |
Bacteria
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Absorption of?
(FUNCTIONS OF THE LARGE INTESTINE) |
-Water
-Electrolytes -Vitamins -Bile Salts |
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Feces formation by?
(FUNCTIONS OF THE LARGE INTESTINE) |
Bacterial Action
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Propelling feces by?
(FUNCTIONS OF THE LARGE INTESTINE) |
Mass Movement Contractions
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When is the desire for defecation initiated?
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When mass movement contractions in the colon push feces into the rectum
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What do tonic contractions of the internal and external anal sphincters prevent?
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Actual defecation EXCEPT IN BABIES
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What is the internal anal sphincter made of?
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Smooth Muscle
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What relaxes the internal anal sphincter?
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Parasympathetic PELVIC NERVE stimulation
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What constricts the internal anal sphincter?
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Sympathetic HYPOGASTRIC NERVE stimulation
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What is the external anal sphincter made of?
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Skeletal Muscle
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The external anal sphincter is innervated by?
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PUDENDAL NERVE
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What type of conscious control is the external anal sphincter under?
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Voluntary
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Intrinsic Reflex
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-A myenteric plexus reflex initiated by distension of rectum w/fecal matter
-Trigger PERISTALSIS in colon and rectum plus relaxation of the interal anal sphincter -Too weak to cause defecation |
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Parasympathetic Reflex
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-Rectum distension transmit signals to sacral segments of spinal cord via pelvic nerve
-Intensify peristalsis and the relaxation of interal anal sphincter |
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Conscious Control
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-Relaxation of the external anal sphincter
-Contraction of abdominal muscles -Emptying of the descending colon and rectum |
