Lower GI Tract Flashcards
The stomach and intestine have a complex network of neurons called?
The Enteric nervous system
what is particular about the digestive neural circuits that have to do with the CNS?
there is no CNS involvement- no interneurons
What are the three major stages of gastric function?
cephalic, gastric, intestinal
Explain the three phages of gastric function?
Cephalic- smell, sight, thought of food- causes secretion of gastric juices in prep for arrival of food
Gastric- entry of food in stomach- even more gastric secretions and muscle contractions
Intestinal phase- sphincter allows small amounts of chyme to enter stomach
Mechanoreceptors (afferent neurons of a reflex) are embedded in the muscular walls of the stomach. As food enters the stomach, the mechanoreceptors will ___________ the rate of action potentials to efferent neurons (hint – think of baroreceptors!).
increase
Result of increased action potentials of mechanoreceptors causes the release of even more gastric secretions initiated in the cephalic stage AND muscle contractions. This is an example of what type of feedback?
Positive
Where do absorbed nutrients go?
absorbed by villi
enter bloodstream at capillary, collected in vein
goes to liver via hepatic portal system
liver helps remove and metabolize nutrients
Blood in the hepatic portal vein is nutrient _____ and oxygen _____?
rich; poor
Hepatic triads are made up of what?
arterioles: O2 rich blood supply to liver
bile ducts: collect bile
Hepatic venues: O2 poor, nutrient rich from GI
Liver cells form _____ surrounded by ______ ______.
Lobules
hepatic triads
What is the purpose of the central vein in Liver Lobules?
carries deoxygenated blood out of liver lobule
What is the exocrine and endocrine function in the pancreas?
exocrine function- pancreatic enzymes (Acinar cells)
Endocrine function- hormones (Langerhands)
What is the roll of Langerhans cells?
synthesize insulin or glucagon INTO capillaries
What is the role of insulin and glucagon?
Insulin: responds to high blood glucose - gets liver to store glucose
Glucagon: responds to low blood glucose- gets liver to release glucose
Type 1 and Type 2 Diabetes
Type 1: total lack of insulin production
Type 2: insulin resistance
A person has an auto-immune disease where their immune cells produce antibodies that match their own Islet cells. This results in which type of diabetes?
Type 1
One result of diabetes is an increase of glucose in the initial filtrate of the nephron. Subsequently, the PCT is unable to reabsorb all the glucose. This causes a(n) ________ in filtrate osmolarity.
increase
If filtrate osmolarity increases, how does this affect water reabsorption (think of osmosis in the nephron loop)?
increase urination
the large intestine functions reabsorption of water and salts resulting in _____.
feces
What are the four regions of the large intestine?
ascending, transverse, descending, sigmoid
Longitudinal muscular is modified to form ____ ____ that result in pocked called _______.
tenia coli
haustrum
Cholera bacteria produce a toxin that causes uncontrollable movement of ions into the lumen of the large intestine. What would be the result of this?
diarrhea
the microorganisms in our gut are called the ___ ________.
gut microbiome
the anal canal is controlled by what two sphincters?
internal- involuntary
external- voluntary
mucosa layer in the rectum is stratified and produces extra _____ during deification.
mucus
