Term
| digestive tract is made up of: |
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Definition
| oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine |
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Term
| Functions of the digestive system: |
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Definition
1.Ingestion-when materials enter the oral cavity
2. Mechanical processing-tearing and mashing by the teeth, mixing and churning by the stomach and intestines
3. Digestion- the chemical breakdown of food into small organic fragments suitable for absorption by the digestive epithelium.
4. Secretion-the release of water, acids, buffers, and salts
5. Absorption-the movement of organic molecules, electrolytes, vitamins, and water across the digestive epithelium and into the interstitial fluid of the digestive tract.
6. Excretion-the removal of wastes from the body. |
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Term
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Definition
| lined by a serous membrane, the visceral peritoneum, and the parietal peritoneum |
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Definition
Double sheets of peritoneal membrane
-stabilize the position of the attached organs
-prevent the intestines from becoming entangled during digestive movements or sudden changes in body position |
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Definition
| stabilizes the position of the stomach and provides an access route for blood vessels and other structures entering or leaving the liver |
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Definition
| an enormous pouch that extends inferiorly between the body wall and the anterior surface of the small intestine |
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Term
| 4 layers of the digestive tract |
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Definition
1. the mucosa
2. the submucosa
3. the muscularis externa
4, the serosa |
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Term
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Definition
the inner lining of the digestive tract
consists of an epithelium and a lamina propria of areolar tisue |
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Definition
| A layer of areolar tissue that also contains blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, and scattered lymphatic tissue. |
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Definition
2 layers of smooth muscle cells
inner layer is the circular muscle
outer layer is the longitudinal layer |
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Definition
| A layer of dense irregular connective tissue that binds the mucosa to the muscularis externa |
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Definition
| smooth muscle cells dominate |
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Term
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Definition
| A serous membrane which covers the muscularis externa along most portions of the digestive tract inside the peritoneal cavity. |
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Definition
| Waves of muscular contractions that propel a bolus along the length of the digestive tract. |
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Term
| Functions of the lining of the digestive tract |
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Definition
Safeguards surrounding tissues against 1.the corrosive effects of digestive acids and enzymes
2. mechanical stresses, such as abrasian
3. bacteria |
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Term
| Visceral peritoneum (serosa): |
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Definition
| covers organs within peritoneal cavity |
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Term
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Definition
| lines inner surfaces of body wall |
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Term
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Definition
| Helps stabilize position of liver |
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Term
| Adipose tissue in greater omentum: |
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Definition
Conforms to shapes of surrounding organs
Pads and protects surfaces of abdomen
Provides insulation to reduce heat loss
Stores lipid energy reserves |
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Term
| Submucosal Plexus (plexus of Meissner) |
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Definition
Innervates the mucosa and submucosa
Contains: sensory neurons, parasympathetic ganglionic neurons, sympathetic postganglionic fibers |
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Term
| Serosa- visceral peritoneum: |
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Definition
serous membrane covering muscularis externa
Except in oral cavity, pharynx, esophagus, and rectum: where adventitia, a dense sheath of collagen fibers, firmly attaches the digestive tract to adjacent structures |
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Term
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Definition
cycles of contraction churn and fragment the bolus & mix contents with intestinal secretions
Does not push materials in any one direction |
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Term
| Functions of the oral cavity |
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Definition
1.Sensory analysis of material before swallowing
2.Mechanical processing through actions of teeth, tongue, and palatal surfaces
3.Lubrication-Mixing with mucus and salivary gland secretions
4.Limited digestion of carbohydrates and lipids |
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Term
| The oral cavity is lined with: |
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Definition
| Stratified squamous epithelium |
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Term
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Definition
1. Mechanical processing by compression, abrasion, and distortion
2. Manipulation to assist in chewing and to prepare food for swallowing
3. Sensory analysis by touch, temperature, and taste receptors
4. Secretion of mucins and the enzyme lingual lipase |
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Term
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Definition
| an enzyme that starts to digest lipids immediately in the mouth |
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Term
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Definition
| Produces a serous secretion, the enzyme salivary amylase, which breaks down starches (complex carbohydrates). |
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Term
| Sublingual salivary glands |
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Definition
| Produce a mucous secretion that acts as a buffer and lubricant |
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Term
| Submandibular salivary glands |
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Definition
| Secrete a mixture of buffers, glycoproteins called mucins, and salivary amylase |
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Term
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Definition
1. lubricate the mouth
2. moistening and lubricating food in the mouth
3. dissolving chemicals that can stimulate the taste buds and provide sensory information about the food |
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Term
| pharyngeal constrictor muscles |
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Definition
| Push the bolus toward and into the esophagus |
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Term
| Palatopharyngeus and stylopharyngeus muscles |
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Definition
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Term
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Definition
| Elevate the soft palate and adjacent portions of the pharyngeal wall |
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Definition
| A hollow muscular tube that conveys solid food and liquids to the stomach. |
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Term
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Definition
1. The buccal phase
2. The pharyngeal phase
3. The esophageal phase
4. The bolus enters stomach |
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Term
| 4 functions of the stomach |
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Definition
1. storage of ingested food
2. mechanical breakdown of ingested food
3. disruption in chemical bonds in food through the action of acid and enzymes
4. production of intrinsic factor |
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Term
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Definition
| A glycoprotein needed for the absorption of B12 in the small intestine |
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Term
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Definition
smallest part of the stomach
Abundant mucous glands, secretions coat connection with esophagus, protect from stomach acid |
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Term
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Definition
shallow depressions that open onto the gastric surface
Mucous cells at the base or neck of each gastric pit, actively divide, replacing superficial cells |
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Term
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Definition
prominent folds in the stomach mucosa
allow the gastric lumen to expand |
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Term
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Definition
Produce a mucous secretion
enteroendocrine cells produce gastrin |
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Term
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Definition
| Secrete intrinsic factor & hydrochloric acid (H++ Cl-) |
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Term
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Definition
| Secrete pepsinogen (inactive proenzyme) |
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Term
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Definition
*Ghrelin- rises before meal, signals hunger, falls signal fullness
Obestatin- decreases appetite
Leptin- induces satiety |
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Term
| Regulation of Gastric Activity |
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Definition
Production of acid and enzymes by the gastric mucosa can be
Controlled by the CNS
Regulated by short reflexes of ENS
Regulated by hormones of digestive tract |
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Term
| Cephalic phase of gastric activity |
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Definition
Gastric secretions begin- smell, taste, think of food
Prepares stomach to receive food
Parasympathetic stimulation of mucus, chief, parietal cells
Emotional states can inhibit or exaggerate this phase
Lose hunger- upset, stressed
Secrete gastric juices angry, stressed- ulcer |
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Term
| Gastric phase of gastric activity |
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Definition
Food arrives in stomach
Presence of protein stimulate mixing, secretion of gastrin, pH drops
Lasts 3-4 hrs |
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Term
| Intestinal phase of gastric activity |
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Definition
chyme arrives in small intestine
Controls rate of gastric emptying to ensure digestion & absorption coordinated
Lasts hrs |
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Term
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Definition
Distention of duodenum by chyme stimulates stretch receptor triggers the enterogastric reflex.
Temporarily inhibits gastrin production & stimulation- preventing further discharge of chyme- gives duodenum time to secrete mucus & neutralize acid, protects lining.
Lipids & carbs stimulate CCK, GIP- allowing time for fats to be absorbed.
pH drop below 4.5 stimulates the secretion of secretin |
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Term
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Definition
| the first segment of the small intestine, a mixing bowl |
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Term
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Definition
fingerlike projections in the mucosa of the small intestine
-brush border |
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Term
| circular folds (plicae circulares) |
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Definition
| permanent features in the intestinal lining |
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Term
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Definition
| a lymphatic capillary that transports materials that cannot enter blood capillaries, for example, chylomicrons |
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Definition
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Term
| Functions of the duodenum |
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Definition
To receive chyme from stomach
To neutralize acids before they can damage the absorptive surfaces of the small intestine
Duodenal glands- submucosal glands- produce lots of mucus when chyme arrives |
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Term
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Definition
| lymphoid nodules protect from large intestine’s bacteria |
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Term
| Intestinal glands - Crypts of Lieberkühn |
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Definition
Openings from intestinal glands to intestinal lumen at bases of villi
Stem cells reproducing at base of glands
Entrances for brush border enzymes
Enteropeptidase- enzyme activates trypsinogen |
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Term
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Definition
Head- broad, in loop of duodenum
Body – slender, extends toward spleen
Tail- short and rounded |
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Term
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Definition
primarily an exocrine organ
-produces digestive enzymes and buffers |
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Term
| Pancreatic duct (duct of Wirsung) |
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Definition
| Delivers digestive enzymes and buffers to the duodenum |
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Term
| The endocrine cells of the pancreatic islets secrete: |
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Definition
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Term
| The exocrine cells secrete: |
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Definition
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Term
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Definition
Acinar cells and epithelial cells of duct system secrete pancreatic juice into small intestine
Pancreatic juice- alkaline mixture of digestive enzymes, water, ions |
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Term
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Definition
1000 mL (1 qt) pancreatic juice per day
Controlled by hormones from duodenum
Secretin triggers pancreatic secretion (bicarbonate, phosphate buffers elevate pH of chyme)
CCK- stimulates production of pancreatic enzymes
Contain pancreatic enzymes |
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Term
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Definition
Pancreatic alpha-amylase- carbohydrase- enzymes that breaks down starches, similar to salivary amylase
Pancreatic lipase- breaks down complex lipids
Releases products (e.g., fatty acids) that are easily absorbed
Nucleases- break down nucleic acids
Proteolytic enzymes- break certain proteins apart, include
Proteases break large protein complexes
Peptidases break small peptides into amino acids |
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Term
| Proenzymes secreted by pancreas are |
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Definition
Trypsinogen
Chymotrypsinogen
Procarboxypeptidase
Proelastase |
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Term
Once inside the duodenum, enteropeptidase located in brush border triggers conversion of trypsinogen to trypsin
Trypsin produces: |
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Definition
Chymotrypsin
Carboxypeptidase
Elastase |
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Term
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Definition
| the 2nd section of the small intestine, the bulk of chemical digestion and nutrient absorption occurs here |
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Term
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Definition
| last portion of the small intestine, ends at the ileocecal valve |
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Term
| intestinal juice functions |
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Definition
-moistens chyme
-helps buffer acids
-keeps both digestive enzymes and the products of digestion in solution |
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Term
| intestinal glands (crypts of Lieberkuhn) |
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Definition
| Glandular pockets that extend deep into the underlying lamina propria |
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Term
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Definition
| -help protect the duodenal epithelium -increase their secretions in response to: local reflexes release of enterocrinin by the enteroendocrine cells of the duodenum parasympathetic stimulation through the vagus nerves |
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Term
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Definition
| stimulates motility and secretion along the entire small intestine |
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Term
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Definition
| Triggers the opening of the ileocecal valve |
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Term
| Pancreatic duct (duct of Wirsung) |
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Definition
| delivers secretions to the duodenum |
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Term
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Definition
-Pancreatic alpha-amylase: breaks down certain starches (similar to salivary amylase)
-Pancreatic lipase: breaks down certain compound lipids
-nucleases: break down RNA or DNA
-Proteolytic enzymes: break apart certain proteins. |
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Term
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Definition
Stimulates the production and secretion of pancreatic enzymes.
Also stimulation by the vagus nerve increases secretion of pancreatic enzymes. |
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Term
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Definition
| Triggers the pancreatic secretion of a watery buffer solution with a pH of 7.5-8.8. |
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Definition
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Definition
| marks the division between the left and right lobes of the liver |
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Definition
| marks the path of the fetal umbilical vein |
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Term
| Each portal area contains: |
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Definition
-a branch of the hepatic portal vein
-a branch of the hepatic artery proper
-a small branch of the bile duct |
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Term
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Definition
1. Metabolic regulation
2. Hematological regulation
3. Bile production |
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Term
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Definition
| Stores and concentrates bile |
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Term
| 3 parts of the large intestine |
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Definition
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