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23 Cards in this Set

  • Front
  • Back
Describe the structure of the GI wall
smooth muscle layers
Mucosa- epithelium, lamina propria, muscularis mucosa,
submucosal plexus- sensory motor
Circular- narrows the lumen
Myenteric Plexus- motor neurons
Longitudinal- shorten the tube
tight junctions
Describe the pathway of fats from lumen of small intestine to the lymphatic system
Fat droplet is emulsified by bile salts, pancreatic lipase and colipase.
Transported in micelles and released for diffusion across intestinal epithelial cell.
FA and monoglycerides are synthesized into triglycerides in the SER.
Triglycerides aren transported in chylomicrons.
Chylomicrons transport fat soluble nutrient and empty it into the lacteal of the lymph system.
What are the fat soluble vitamins?
A, D, E, AND K
How are water soluble vitamins absorbed?

What about Vitamin B12
by diffusion or mediated transport

Vit B12 binds IF secreted by oxyntic (parietal) cells of stomach
Vit B12 deficiency causes
pernicious anemia.. due to decrease in erythrocye formation
due to decrease IF from parietal cells
due to damage to lower part of ileum where absorption occurs
Gastrin Profile
site of production
inhibited by
synthesized by G cells in the antrum of stomach
stimulated by aa, peptides IN STOMACH and ACh
inhibited by acid in stomach, SS
Action: stimulates acid secretion from parietal cells, increase stomach motility and has trophic effects on digestive organs
Gastrin: responds to breakdown products of protein in stomach
CCK profile
site of production
inhibited by
made by small intestine
stimulated by aa, FA in SM. INTESTINE
Inhibits acid secretion and motility
Potentiate secretin's release of bicarb from pancreas and liver
relaxes sphincter of oddi
site of production
inhibited by
Secretin made by SMALL INTESTINE
Stimulated by acid in small intestine
Inhibits acid secretion and motility
stimulates bicarb secrtion
works with CCK
site of production
inhibited by
Responds to glucose and fat in SM. Intes.
Stimulates insulin secretion from pancreas
Cephalic phase
sight, smell, taste, chewing, emotions to CNS to vagus to GI nerves plexus
Gastric Phase
stretch, acidity, aa, peptides to CNS to parasympathetic causes release to ACh to cause G cells to secrete Gastrin to cause parietal cells to secrete HCl and IF.
Intestinal Phase
stretch, acid, osmolarity and digestive products
GI hormones Secretin > inhibits acid secretion by parietal cells
GIP which stimulates insulin secretion
Steps to swallowing
1) Tongue pushes food bolus to the back of the pharynx
2) Soft palate is elevated to prevent food from entering the nasal passages
3) Epiglottis covers the glottis to prevent food or liquid from entering the trachea and UES relaxes
4)Food descends into esophagus
Gastric Cell Types and Their Secretions
Parietal cells
Chief Cells
G cells
Mucus cells
Parietal cells in body of stomach secrete HCL and IF in response to Gastrin, Histamine adn ACh from vagus

Chief Cells in the body of stomach secrete PEPSINOGEN in response to Vagal stimulation (ACh)

G Cells in the antrum of the stomach secrete Gastrin and are stimulated by vagus via GRP, inhibited by SS and acid

Mucous Cells in the antrum stimulate the mucus and pepsinogen because of stimulated by vagus nerve
describe the response of the GI system to increase acid from STOMACH
think Feedback Mechanism
Incr acid from stomach
> increase SECRETIN secretion from Small Intestine into the plasma
>>incr. bicarbonate secretion from the pancreas
>>> incr. flow of bicarbonate into small intestine
>>>> incr. neutralization of intestinal acid in the small intestine
describe the response of the GI system to increase intestinal fatty acids and amino acids
think Feedback Mechanism
incr. intestinal fatty acids and amino acids
> increase CCK secretion by small intestine into the plasma
>> increase enzyme secretion from pancreas (trypsin, chymotrypsin, elastase, carboxypeptidase, pancreatic lipase)
>>> increase flow of enzymes into small intestine
>>>> increase digestion of fats and protein in the small intestine
If the salivary glands were unable to secrete amylase, what effect would this have on starch digestion?
Not significantly affected because pancreatic amylase would digest starch that reaches the small intestines
Whole milk or a fatty snack consumed before ingestion of Alcohol decreases the rate of intoxication. By what mechanism may fat be acting to produce this effect?
the fat decreases gastric emptying and alcohol is mostly absorbed in the small intestines which causes alcohol to take less time to get to the small intestine where alcohol is rapidly absorbed
A patient brought to a hospital after a period of prolonged vomiting has an elevated heart rate, decreased blood pressure and below normal blood K and below normal acidity. Explain these symptoms in terms of conseq. of excessive vomiting
Vomiting causes loss of H from stomach.
Acid from stomach secretions normally stimulates the pancreas to secrete bicarbonate into the small intestines. Results in an arterial blood that is alkaline because no H is secreted to neutralize the bicarb
Can fat be digested and absorbed in the absence of bile salts?
Yes but only a small amount. Without adequate bile salts and phospolipids to emulsify fats only fats at the surface of the large droplet is available for digestion by lipase. The undigested fats are passed into the large intestine where bacteria there produce compounds that increase colonic motility and promote the secretion of fluid into the lumen of the large intestine > steatorrhea
How might damage to the lower portion of the spinal cord affect defecation?
Damage to the lower portion of the spinal cord produces a loss of voluntary control over defecation due to disruption of the somatic nerves to the skeletal muscle of the external anal sphincter.
Damage to the somatic nerbes leaves the external sphincter in a continuously relaxed state. Under these conditions, defecation occurs whenever the rectum becomes distended and the defecation reflex is initiated.
One of th older but no longer used procedures in the treatment of ulcers is abdominal vagotomy. By what mechanism might this procedure help ulcers to heal and decrease the incidence of new ulcers.
Impulses in the parasympathetic nerve directly stimulates acid secretion by the parietal cells
causes release of gastrin which increases acid secretion.
Vibrio Cholerae causes diarrhea
by stimulating Cl- secretion
Cholera toxin catalyzes ADP ribosylation of the alpha s subunitys of the Gs protein coupled to adenylyl cyclase permanently activating it. Intracellular cAMP increases as a result. Cl- channels in the luminal membrane open and Cl- leaves and so does Na and water.