Lect 1: GI overview Flashcards
what is found at the bottom opening of the stomach?
pyloric sphincter
Absorptive cells line the upper part of the villi and contain _________ which are necessary for the final digestion of proteins and carbohydrates, forming products that can be absorbed.
brush border enzymes
what is the product of the stomach called?
chyme
where is the common bile duct located?
the beginning of the duodenum
the majority of the contents of the chyme are absorbed by ____
mid jejunum
the small intenstine can histologically be distinguished from the large intestine and colon by:
the villus lining
the one-cell thick lining of the small intestines:
enterocytes
what are the two nerve plexuses that line the gi tract? what do they do?
myenteric (movement-mostly local), submucosal (secretion)
where is the submucosal plexus?
between the circular muscle and the submucosa
where is the myenteric plexus?
between the longitudinal and circular muscle
skeletal muscle in the GI tract is found at:
the mouth, upper esophagus and external anal sphincter
the internal area of a villus cells is known as a ____
crypt of Lieberkuhn
what is the first pass effect?
absorbed nutrients go into the portal veins which go directly through the liver.
most fats go into the ____, are dumped into the ____ and go through the _____ back to the ____
lymphatics, large vessels of the thoracic cavity, systemic circulation, liver to be processed
what are the functions of the GI tract?
DEEPMASS digestion, endocrine, elimination, protection, motility, absorption, secretion, storage
fluid intake is about ____
2 Liters/day
saliva secretion is about ____
1.5 liters/day
gastric secretions are about _____
2 liters/day
bile secretion is about ___
.5 liters/day
pancreatic juices secretion is about _____
1.5 liters/day
intestinal buffers and secretions are about ____
1.5 liters/day
on any given day, there are about ____ liters of fluid trunning through your tract
9-10
the movement of fluids and gases in and out of the intestines can be heard as sounds called ____
borborygmi
the small intestine absorbs about ______ of fluid a day
8.5 liters
the colon absorbs about ____ of fluid a day
400 mL
we excrete about ____ of water a day
100 mL
parasympathetics in the GI tract are mainly from the ____
vagal to transverse colon, then pelvic nerves to anus
sympathetics to the GI tract are from the:
post-ganglionic adrenergic fibers from celiac, superior and inferior mesenteric and hypogastric plexes
cells that line the Crypts of Lieberkuhn include..
- Goblet cells - secrete thick mucus
- Stem cells
- Endocrine cells - produce and secrete hormones into the blood, including gastrin, secretin, cholecystokinin, gastric inhibitory peptide (aka glucose insulinotropic peptide) and motilin.
The enteric nerves are crucial to the efficient actions of the GI tract from ____ through the______.
esophagus to colon
Blood flow to the intestines increases for _____ after eating, to facilitate absorption.
3-6 hours
epithelial secretions serve to _____
lubricate, protect and digest material
Liver functions:
- Secretion of bile (lipid digestion)
- storage of nutrients
- production of cellular fuels
- plasma proteins, clotting factors
- detoxification
- phagocytosis
Pancreas secreates:
- buffers and digestive enzymes – by exocrine cells
- hormones – by endocrine cells to regulate digestion
Gallbladder functions:
Storage and concentration of bile
Large intestine functions
- Dehydration and compaction of indigestible materials for elimination
- resorption of water and electrolytes
- host defense
Small intestine functions:
- Enzymatic digestion
- absorption of water, organic substrates, vitamins, and ions
- host defense
Stomach functions:
- Chemical breakdown of food by acid and enzymes
- mechanical breakdown via muscular contractions
Salivary gland function:
Secretion of lubricating fluid containing enzymes that initiate digestion
Enteric nervous system (ENS), acts locally with input from ____ and _____
autonomics and local receptors
T/F: Central nervous system (CNS) does not take part in regulation of GIT
False - helps with anticipatory sensory responses and reflexes
Lumenal receptors, including chemo-, mechano- and osmoreceptors respond to ____ and signal to ______.
- acidity and chemical composition of the chyme, its osmolarity, and stretch, respectively. \
- These receptors signal the ENS and endocrine cells.
T/F: Hormones in GIT affect other organs only in an endocrine fashion.
False - Hormones in the GI tract act in endocrine and paracrine manners to affect other parts of the GI tract and related organs.
