Intro to Gastro Flashcards
What are the 2 general categories of the GI system?
hollow & solid organs
What are the hollow organs of the GI system?
mouth esophagus stomach SI LI w/ rectum anus
What are the solid organs of the GI system?
salivary glands
liver
pancreas
gallbladder
What are the 5 tastes of the tongue?
sweet sour salty bitter umami (savory)
What amino acid does umami respond to?
glutamate
What makes up saliva? How much is produced each day?
1.5 L produced each day salivary amylase salivary lipase mucus (to lubricate the food) lysozyme to kill the bacteria
What is another name for salivary amylase?
ptyalin
Swallowing has 2 phases. What are they? What controls each phase?
oropharyngeal phase: voluntary control
esophageal phase: autonomic control
How long is the esophagus tube?
8-12 inches
What 2 general things happen in the esophagus?
peristalsis: primary (initial response to food), secondary, & tertiary (makes sure that things are going in the right direction)
muscle contraction
What ends the esophagus? …something that contributes to heartburn…
the lower esophageal sphincter
thought that this is what prevents heartburn when it is tightly contracted…
muscles & flesh surrounding the LES also help prevent heartburn…why obesity is associated with heartburn
What controls entry & exit to the stomach?
lower esophageal sphincter (entry to the stomach) pyloric sphincter (exit to the stomach)
How much can the stomach hold?
4 cups or a treinta size Starbucks drink
What substances are secreted in the stomach?
HCl enzymes (protease, lipase) mucus gastrin intrinsic factor (vitamin B12)
What are 2 weird functions of the stomach?
assists in calcium absorption
makes dietary minerals soluble for absorption
What are the 3 phases of gastric acid secretion?
Cephalic Phase
Gastric Phase
Intestinal Phase
What happens in the cephalic phase of gastric acid secretion?
Pepsin & HCl secreted by the sense of food…
What happens in the gastric phase of gastric acid secretion?
Nutrients such as AA stimulate the G cells in the stomach to produce gastrin.
Distension of the stomach also stimulates the G cells in the stomach to produce gastrin.
The release of gastrin stimulates the parietal cells to secrete HCl.
This acid slows bacterial growth which prevents enteric infections & Small intestinal Bacterial Overgrowth
What is the approximate pH of the stomach?
1-4
What are 3 things that can cause an increased risk for small intestine bacterial overgrowth?
achlorhydria
gastrectomy
Gi disease
What are the 3 main cells that are found in the stomach?
G cells secrete Gastrin
Chief cells secrete pepsinogen & gastric lipase
Parietal cells secrete acid
Where is chyme formed?
in the stomach
Are a lot of nutrients absorbed in the stomach?
NO
What protects the stomach from the digestive process?
the mucosa
What are 2 things that increase the transit time thru the stomach?
solid meal
higher fat content
How long does it take a liquid meal to exit?
1-2 hours
How long does it take a solid meal to exit?
2-3 hours
What happens in the intestinal phase of gastric acid secretion?
Chyme causes the duodenum to release CCK & Secretin.
These stimulate the pancreas & gallbladder to release bile, bicarb, enzymes
Where does most digestion & absorption happen? How long is this portion of the GI tract?
SI
5-7 meters
What are the 3 parts of the SI & how long are each of them?
duodenum (.5 meters)
jejunum (2-3 meters)
ileum (3-4 meters)
When stuff is absorbed by the SI walls…where does it go?
If water soluble–>blood
If fat soluble–>lymph
How long is the LI? What is absent here? What happens here?
3-4 feet
villi & enzymes are absent
not much digestion
absorption of water, minerals, vitamins happens here…
bacteria break down fiber & produce Vitamin K here
feces are prepared
What is the gastrocolic reflex? What does the patient feel? What disease may this explain? What mediates this reflex?
increase in the motility of the colon in response to a stretch in the stomach
patient feels the urge to defecate after a meal
could explain irritable bowel syndrome
Mediators: Serotonin, Neurotensin, CCK, gastrin
Where is stool stored for elimination?
the rectum
What are the 4 basic mechanisms for nutrient absorption?
passive, active, megacytosis, pinocytosis
What is one thing that can be absorbed by the gastric epithelium?
ALCOHOL
