GI exam #1 Flashcards
(175 cards)
Purpose of the GI tract
to supply nutrients for use at the cellular level
- meet nutritional needs
- and eliminate waste
Process of the GI tract
1) ingestion
2) digestion
3) absorption
4) elimination
Ingestion
taking in food
-intake, chewing anddeglutition
digestion
molecules for absorption (into chyme)
absorption
transfer from GI tract to circulation
elimination
excretion of waste products of digestion
Components of GI tract
mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus,
Accessory organs to GI tract
teeth, tongue, salivary glands, liver, gallbladder, pancreas
Mucosa
innermost layer of GI tract
- -Protects, secretes, absorbs
- —lumen/ small intestines: form folds “villi” and increase absortive capacity (surface area)
Submucosa
contains blood and lymph vessles
—transports nutrients
(connective tissue)
Muscularis (muscular) layer
Smooth muscle fibers arranged in circular and longitudinal groups.
—-motility
Serosa (serous) layer
outer covering
—protection
Peritoneum
lines walls of entire abdominal cavity. Forms the peritoneal cavity
Two folds of peritoneum
Mesentary and Omentum
Mesentary
blood and lymph
Omentum
fat covering for protection
Blood supply of GI tract
aorta–>celiac artery–> superior and inferior mesenteric arteries
–superior and inferior mesenteric arteries supply small and large intestine
—venous blood draiing GI tract empties into portal vein - carries nutrient rich blood to liver
(25-30% total caridac output is going directly to GI tract. increases after eating. more blood to transport nutrients)
Mucous
- from mouth to anus.
- protects and lubricates (only secretion in esophagus)
Digestive secretions
- enzymes, hormones, digestive juices, bile, pancreatic juices
- produced throughout GI w/ very specific functions
Peristalsis
wavelike movements
-stimulus is expansion of lumen of tract by food
Gastrocolic and duodenocolic reflex
leads to urge to poop after eating
particularly strong in the morning
Bacteria
normal component of GI tract. Essential for function. Major component of colon
-aids digestion (proteins) 10% of stool
Sympathetic
inhibits or decreases digestive actions. “slows down” S-S
Pararsympathetic impules
-increase GI activities “picks up”
P-P