UNIT 6b Flashcards
STUDY
GI function regulation has what reflexes?
- long (integrated in brain)
- short (integrated in gut) –> called gut bain sometimes
long reflexes characteristics
- sensory info from GI
- feedforward reflexes: sight, smell, thought of food, emotion can cause us to stimulate our GI tract
- efferent always autonomic: increase parasympathetic (excitatory) and decrease sympathetic (inhibitory)
- dont need to have anything in GI tract
goal: increase secretion increase motility
small reflexes characteristics
- integrated within gut
- enteric nervous system (gut brain)
- submucosal plexus receive signals from lumen, regulate secretion
- motility regulated by neurons in myenteric plexus
- have to have something in your GI tract
parallels between enteric system and CNS
ENTERIC SYSTEM:
- has intrinsic neurons
- release neurotransmitters and neuromodulators
- integrating centre
- has glial support cells
- BBB similarity called a difussion barrier but acts exactly same as BBB (blood brain barrier)
GUT PEPTIDES ARE MAJOR ________ PLAYERS
REGULATOR PLAYERS
GUT PEPTIDES ARE PRODUCED BY?
cells within the lamina propria
travel of peptides
can travel paracrine or endocrine (blood)
effects of gut peptides:
- effects motility (altered peristalsis, gastric emptying)
- effects endocrine & exocrine secretion
- some peptides act on brain
can gut peptides also be called hormones?
yes, they travel endocrine via the blood
GUT peptide endocrine pancreas goals
increase inulin
decrease glucagon
GUT peptide endocrine brain goals
hunger
satiety
the Duodenum is the beginning of what?
small intestine
how did the pancreas know there was an increase in stomach acid as it hits duodenum based on pavlov?
pancreas secretion was thought to be controlled by vagus nerve, he says that this was ALL NEURAL
how did the pancreas know there was an increase in stomach acid as it hits duodenum based on Bayliss and starling?
- dissected the nerves
- put acid in duodenum
- pancreas secreted bicarb still
so it NOT neural
hypothesis: blood born signal
what are the gut hormones
- Gastrin family
- Secretin family
- Motilin
swallowing reflex
- tongue pushes food (bolus) against soft plate and back of mouth triggering swallow reflex
- breathing inhibited as bolus passes
- food moves downward into esophagus and propelled by peristaltic waves
swallowing reflex is integrated in medulla, cranial nerves mediate reflex
regulation of cephalic stage
- brain perceives food, smell, visually etc
- coordinated in medulla
- travels in vagus nerve
- gets to taregt cells
- secretion and motility
regulation gastric phases
- food reaches stomach
2 stretching detects peptides and amino acids need digesting
3 digestion occurs
are local and occur in the stomach
- short reflexes
what are the three functions of the stomach and describe them?
- storage:
- receives food and relaxes w/out storage problem can arise (gastric dumping syndrome) - digestion:
- most important, break down molecules into chyme, secretion of enzymes, acid and hormones. - protection:
- protects itself from acid and antimicrobial acid
IMPORTANT SLIDE SECRETORY CELLS OF GASTRIC MUCOSA
IMPORTANT SLIDE SECRETORY CELLS OF GASTRIC MUCOSA
Parietal cells make?
H+
chief cells make? w/ H+ present
pepsin
what are the two major products of the gastric mucosa?
-> H+
-> pepsin
_______ is a key regulator in being part of cranking up the parietal cells to create H+
gastrin
Intestinal phase jobs:
- regulate itself by being ready to do its jobs (secretion)
- regulates stomach
- looks ahead to get downstream products of digestion for whole body level
small intestine feedbacks to stomach true of false?
true
small intestine has feedforward system true or false?
true
what are the roles of GIP? acts on _______ breakdown
carb breakdown
1. insulin secretion
2. negative feedback to stomach to stop acid secretion and gastric motility
fats + proteins need what for creating pancreatic enzyme secretion
CCK
acid in small in needs what for bicarb secretion and why is this important
- secretin is needed
- important because it neutralizes the pH which is important for the rest of digestion and absorption
GLP is also involved in insulin secretion yes or no
yes
small intestine has a lot of feedback to _________
stomach
CCK also causes contraction in gall bladder to release bile into the intestine true or false
true
preventing auto or self digestion: WHAT DOES PANCREAS DO?
ZYMOGENS (IN ACTIVE ENZYMES) ARE ACTIVATED TO PROTECT PANCREAS BY ACTIVATING TRYPSINOGEN TO TRYPSIN WHICH ACTIVATES ENZYMES
pancreatic enzymes are triggered by?
- CCK
- NEURAL
LUMPS ON LARGE INTESTINE ARE CALLED WHAT
HAUSTRA
surface facing lumen is _____ (large intestine)
smooth
how many sphincter of large intestines
- internal and external
role of large intestine
- remove water
-formation of feces
-motility
segmental contractions also means
swishing back and forth
mass movements occurs ______/ times a day
3-4 times a day
two types of diarrhea
- osmotic
- secretory
what is diarrhea
imbalance between absorption and secretion
______ diarrhea
- undigested lactose, sorbitol, or olestra
osmotic diarrhea
______ diarrhea
- bacterial toxins increase Cl- secretion
- can cause death
- serious
- ex: cholera
- can lead to sever dehydration
- metabolic acidosis (losing BICARB)
- too much secretion ( from CFTR)
secretory
what diarrhea can be purposely mimicked?
osmotic diarrhea have osmotic laxatives
cholera toxin targets what channel and is it regulated
- CFTR
- yes regulated
cholera
1. contaminated in _______ (developed countries)
2. contaminated in _______ (developing countries)
- food
- water
who is more at risk for cholera?
- people w/ reduced gastric acidity
- young children
- immune suppressed individuals
need to ingest a lot of bacteria for cholera why?aprox how much
- needs to survive stomach acid
- aprox: 100 million bacteria
cholera toxin interferes with?
ability of G alpha subunit to nip off phosphate (GTP) to GDP and shut off cholera stays in GTP meaning that subunits are separated and activated . will keep chloride channel when it should not be.
CFTR channel is the mutated channel in
cystic fibrosis
cystic fibrosis vs cholera
cystic fibrosis: under secretion of CL-
cholera: over secretion of CL-
cystic fibrosis is common fatal recessive single-gene disorder of ___________
europeans descendants