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80 Cards in this Set

  • Front
  • Back
Tracheoesophageal fistula:
-congenital
-both trachea and esophagus have common origin
-2 types;
1. esophogeal atresia (esoph closed off)
2. fistula connecting with both tubes open
What is the most frequent cause of intestinal obstruction in newborns?
duodenal atresia
Omphalocele:
-herniation of visceral at base of umbilical cord
Anal agenesis:
-imperforate anus
-anus was not fully developed at birth
-corrected with surgery
3 functions of saliva:
-secreted by salivary glands
1. moisten for swallowing
2. allow for tasting
3. contains salivary amylase
salivary glands consist of 4 glands:
1. parotid glands
2. submaxillary glands
3. sublingual glands
4. buccal glands
salivary amylase:
-initiate the digestion of dietary starches
-converts polysaccharides to dextrin and maltose
List the parts of the gastrointestines:
1. oral cavity
2. pharynx
3. esophagus
4. stomach
5. small intestine
6. larger intestine
Pharynx:
-soft palate that moves upward with swallowing
-epiglottis closes
-muscles propel food
Esophagus:
(food has the right of way)
-mucus facilitates food passage
-strong peristalic action
-lower esophagus sphincter
Lower esophagus sphincter:
-prevents regurgiation
-physiological circular fibers
-not a true sphincter
Parts of the stomach:
1. cardia (opening of esoph to stomach)
2. fundus (left of cardia orifice)
3. body (central)
4. antrum (btn body and pylorus)
pylorus:
-orifice encircled by a ringlike muscle that opens into the small intestine
Stomach glands:
1. chief
2. parietal
3. mucous
4. gastrin
chief glands:
-stomach glands that secretes pepsinogen which converts to pepsin when exposed to low pH of the gastric juices
parietal glands:
-stomach glands secrete HCL and gastric intrinsic factor (necessary for the absorption of B12)
mucous glands:
-stomach glands that secrete mucous that are resistant to the highly acidic secretions
gastrin glands:
-secreted at antrum of stomach and duodenum
-hormone secreted by glands in the mucous membrane of the stomach
-stimulates the production of gastric acid
Small intestine:
-digestive and absorptive functions occur (most H2O is absorbed here)
-contain villi for surface area
-secretes digestive juices and receives secretions from the liver and pancreas
-fast cell turnover
Brunner's glands:
-mucus producing glands
-located at duodenum
-secrete large amounts of alkaline mucus protecting duodenum from acid content in the chyme and digestive enzymes
-influenced by ANS
ileocecal valve:
-valve prevents backflow of feces from the cecum into the small intestine
4 Parts of the large intestine:
1. cecum
2. colon (ascending, transverse, descending, sigmoid)
3. rectum
4. anal canal
Function of large intestine:
-no villi
-absorbs water and electrolytes (although most water is absorbed from the small intestine)
5 Layers of intestinal wall:
1. mucosa (muscularis mucosa)
2. submucosa
3. circular muscle
4. longitudinal muscle
5. serosa
What 2 layers of the intestinal wall consist of smooth muscle?
circular and longitudinal muscle
What areas of the intestinal wall consist of skeletal muscle?
mouth to proximal esophagus and anus
Describe the electrical activity of the GI smooth muscle:
-almost constantly present
-graded degree of intensity
2 types of muscle contractions in the intestinal walls:
1. tonic contractions
2. rhythmic contractions
tonic contractions:
-det amount of pressure in segment of bowel
-det amount of resistance in sphincters
rhythmic contractions:
-responsible for mixing and propulsion of contents
-degree varies
intramural neurons:
-contained within the wall of the gastrointestinal tract
-consist of 2 networks, myenteric and submucosal plexuses
Auerbach's plexus:
=myenteric plexus
-located btn muscle layers
-control GI movements
Meissner's plexus:
=submucosal plexus
-control secretions
-sensory functions such as stretch impulses
afferent nerve fibers:
-transmit information about GI tract
-respond to irritation, distention, presence of chemical substances
-may be exitatory or inibitory response
Gastrin:
-food entering stomach
-INCREASES;
1. gastric motility
2. constriction of LES (prevents reflux)
3. production of gastric glands
Cholecystokinin:
-from duodenal mucosa
-response to fatty substances
-increases contractility of gallbladder
Secretin:
-secreted in duodenum
-stimulated by entry of acidic juice from liver or pancreas
-neutralizes
Gastric inhibitory peptide:
-from upper intestinal mucosa
-responds to fat and some CHO
-decreases emptying stomach when there is an oversupply of nutrient substances
2 types of intestinal movement:
1. Peristalsis
2. mixing movements
peristalsis:
=propulsive
-stimulus is distention of intestinal walls
-circular constriction squeezes materials in front forward movement
chewing:
-mixes with saliva (bolus)
-action of teeth to change food to it's simplest, basic form
3 stages of swallowing:
1. oral stage
2. pharyngeal stage
3. esophageal stage
Oral stage:
-first stage of swallowing
-contraction of pharyngeal muscles with inhibition of respiration
-tongue action involved
Pharyngeal stage:
-second stage of swallowing
-involves epiglottis and vocal cords
Esophageal stage:
-3rd stage in swallowing
-consists of (upper) skeletal and (lower) smooth muscle
-peristalic wave occurs
-lower esophageal sphincter relaxes allowing bolus to enter stomach
What cranial nerve is a stimulus for the mouth?
Nerve V
What cranial nerve is the swallowing center?
Nerve IX (medulla)
What cranial nerve stimulates oral and pharyngeals?
Nerve X (vagus)
4 Motor functions of the stomach:
1. gastric filling and storage
2. emptying
3. regulation of gastric emptying
4. vomiting
What pressure changes take place with emptying of the stomach?
antral pressure exceeds duodenal pressure
2 main functions of gastrin:
1. enhances peristalsis
2. relaxes pylorus
chyme:
-highly acidic
-impedes gastric emptying
vomiting:
-sensory nerve endings in the pharynx, viscera and labyrinth
-process: vomiting center in medulla-glottis closes-trachea-LES relaxed-abd muscles contract-stomach empties
2 functions of gastroenteric reflux:
1. increases gastric motility
2. increases activity in the small intestine
What is the main stimulus of the small intestine?
stretch receptors
What would cause a peristalic rush?
intense irritation of the mucosa
How is motility of the small intesting controlled?
-thru the vagus nerve
-thru distention +/or irritation
-paralytic ileus (no peristalsis)
cholecystokinin:
-located in duodenum and jejunum
-stimulated by amino acids
-slows gastric emptying
ileocecal sphincter:
-normally closed
-interior of cecum and lower end of ascending colon
-regulates the flow of chyme into the bowels
-distention of cecum prevents reflux
2 functions of the large intestine:
1. absorption of water and electrolytes
2. storage of fecal mass
Colonic movements of the large intestine:
-inactive most of the time
-presence in proximal colon, haustral churning, contents to mucosa
-500cc of chyme enters each day (400cc is absorbed)
secretin:
-located in duodenum
-stimulated by acid pH or chyme entering duodenum
-decreases motility
colonic movements:
-inactive most of the time
-presence in proximal colon, haustral churning, contents to mucosa
-500cc chyme enters each day
(400cc)
defecation:
-distention of rectum
-from ileum to distal colon (18 hours)
-voluntary and involuntary
gastric inhibitory peptide:
-released from the intestinal mucosa in response to increased conc of glucose and fats
-inhibits gastric acid secretion, gastric motility and gastric emptying
Histamine:
-powerful stimulant to parietal cells
-released from antigen-antibody reaction
-H2 antagonists to reduce acid
digestion of lipids:
-mostly triglycerides but also phospholipids, cholesterol, vit A,D,E,K
-occurs in small intestine (emulsified by bile)
pancreatic lipase:
breaks down fatty acids and glycerol
cholesterol:
-esterase in pancreatic juice breaks down cholesterol and fatty acids to be absorbed
Name 2 polysaccharides:
maltose and dextrin
pancreatic amylase:
-produces maltase, sucrase and lactase
cellulose:
-not digested
-fiber
-gives proper bulk to the stool
How much glucose is produced by carbohydrate digestion?
80%
digestion of proteins:
-begins in stomach by pepsin secreted by chief cells
pepsin:
-secreted by chief cells in response to acid pH
-convert from pepsinogen
-inactivated when it enters the intestine by the alkaline pH
pancreatic enzymes:
-breaks down protein
-they are trypsin, chmotrypsin, carboxypeptidase, elastase
distal ileum:
-absorbs Vit B12 and bile salts
-contains bacteria and desquamated epith cells
-digestive secretions
-contain residues of food (cellulose)
carbohydrates:
-absorbed as monosaccharides
-polysacch and disacch are not absorbed due to high molecular weight
lipids:
-dissolved by bile salts for absorption (emulsification)
-absence of bile causes a reduction of fat absorption
-fat soluble vitamins are absorbed with fat
-monoglycerides are reduced to fatty acids and glycerol by lipase
-triglycerids + cholesterol + phospholipids --> chylomicrons --> into lacteals
maturation:
-initally gastric motility is not well coordinated so digestion of solid foods is inadequate
-at 12 weeks, peristalsis is good but slow so adequate absorption is needed