Lecture 3 Flashcards
LEFT SIDE of the picture
LEFT SIDE
esophagus
stomach
gallbladder
ileocecal valve
RIGHT SIDE of the picture
upper or lower esophageal sphincters
pylorus
sphincter of Oddi
Pancreas
Colon
Small Intestine
Internal and external anal sphincters
The stomach is divided into what four pieces?
cardia
Fundus
Corpus (Body)
Antrum
what do sphincters do?
control food movement
what sphincters in the stomach?
lower esophageal sphincter
pyloric sphincter
what is the lower esophageal sphincter responsible for
ensures that the meal does not reflux into the esophagus under normal conditions
what does the pyloric sphincter responsible for
controls emptying
Read right to left in a circle
- lower esophageal sphincter
- cardia
- fundus and body
- greater curvature
- antrum
- pylorus
- lesser curvature
- secretion resovoir
- Mixing and grinding
distal end of esophagus to proximal half of duodenum and liver
foregut
distal half of duodenum to splenic flexure and pancreas
midgit
extends from the splenic flexure to the rectum
hindgut
what are the foregut, midgut, and hindgut supplied by?
celiac trunk
abdominal aorta
inferior mesenteric artery
foregut structures
distal end of esophagus
stomach
proximal duodenum
pancreas
gallbladder
liver
what is the gut’s role in nutritional support
provides the body with water, electrolytes, vitamins, nutrients
guts role in self defense
immune defenses (more lymphocytes than in bloodstream)
high tolerance of dietary antigens
knows to keep benefits of common bacteria
primary function of gut
absorption
gut invloved in secretion by
salivary glands, stomach, liver, gallbladder, pancreas
digestion
turns food into things we can use with the help of enzymes
movement in the gut happens through?
peristalsis
the bodys master control unit
central nervous system
bodys link to the outside world
peripheral NS
what part of peripheral NS help with fight or flight?
the autonomic NS
- sympathetic NS
- parasympathetic NS
connections for Parasympathetic Nervous systems come from?
cranial nerve 10
sympathetic NS signals that cut of digestion come from ?
MANY DIFFERENT PLACES very reduntant
the brain gut axis includes
CNS
Autonomic NS
Enteric NS
enteric NS has sensors, however they are not too helpful bc ____?
the arent specfic
systems in intrinsic control
enteric nervous system
- myenteric (muscle) and submucosal plexuses
extrinsic control includes what systems
parasympathetic and sympathetic
what can override the normal control of GUT function
sympathetic NS
effects of the sympathetic nervous system
slows motility
inhibits secretion
what is the enteric/instrinsic nervous system
“little brain” autonomous in function and located in the wall of the gut
- plexuses (neurotransmitters)
red =
blue=
arterial (O2)
venus (no O2)
what are the layers of the plexuses?
- Myenteric - increase motility
- Ach, serotonin, NO, substance P
- Submucosal - increase absorption
- VIP, enkephalins, substance P
*these layers have different neurotransmitters
where do short reflexes occur?
within the intestinal wall itself
where do long reflex pathways occur?
from GI tract
to prevertebral sympathetic ganglia
spinal cord
brainstem
and back
control of gut reflexes
secretions
peristalsis
mixing
inhibitory features of gut reflexes include
sympathetic stimulation
gastric emptying is inhibited by duodenal distension or intense pain
stimulatory features of the gut reflexes
parasympathetic stimulation
increased secretions
increasing volume of gastric contents
what reflex allows the ileocecal valve to relax in response to gastric distention and allow the ileum ti empty any remaining contents into the colon to prepare for an incoming meal
gastro-ileal
what reflex recognizes the absorptive capacity of the proximal small intestine has been extended and stomach delays release of contents
ileal brake
what reflex occurs when there is over distension of one segment that results in relaxation of smooth muscle in the rest of the intenstine
intestinal-intestinal relex
what reflex signals from the colon and small bowel inhibiting stomach motility and secretion of gastric acid
entero-gastric
what reflex involves distention and filling of the colon which inhibits emptying of ileal contents
colono-ileal
what reflex is initiated by gastric distension and produces a generalized increase in colonic motility with mass movement clearing the colon
gastro-colic
sphincters or valves are functional segments of gut made of _______ muscle, regulate movement in response to a meal, and are under involuntary control by the _______ nervous system
smooth
enteric nervous system
inhibitory mediators specific to GUT motility
vasoactive intestinal polypeptide (VIP)
nitric oxide
stimulating mediators specific to GUT motility
motilin
serotonin
what is the result of VIP?
inhibitory action
- promotes relaxation of the gastrointestinal smooth muscle
what is the result of nitric oxide?
inhibitory action
- relaxation
- promotes an ileus with excessive concentrations
result of motilin
stimulating action
- stimulates gastrointestinal motility
- “migrating motor complex”
what result does serotonin have on gut motility?
stimulating action
- activates intrinsic and extrinsic afferent neurons to initiate peristaltic and secretory reflexes
integration of peristalsis and sphincter relaxation is brought about by the combined activity of the _____ and _______.
vagus nerve
enteric nervous system
gut distention occurs from what movement
propulsion or peristalsis
peristaltic and constrictive movements are called ______. and these happen every _____.
mixing (segmentation)
5 to 30 seconds
slow waves are paced by ______.
intersitial cells of Cajal
interstitial cells of cajal are specialized cells found throughout the _________, that are essential for ________.
GI tract
gut motility “pacemaker cells”
set basal rhythm
phases of waves in GI tract motility or MMC (Migrating motor complex)
phase one (no contractions) - 80 min
phase two (irregular contractions) - 6 min
phase three (regular contractions) - 3 min
what does spikes in motility patterns mean?
triggered by distensions, medications or disease states (laxatives or inflammations)
associated with rising in the morning, eating, prior and with defecation
Migrating motor complex (MMC)
occurs during unfed or fasted state.
“housekeeping function” - sweeps any undigested material along the length of the entire GI tract
enzymes are released more at what part of the system.
beginning in esrly GI tract
three main gut hormones
gastrin, CCK, secretin
gastrin is produced in the _______, stimulized by _________, and stimulates _____ in stomach and _____ in intestine
gastric antrum
Amino acids in stomach
aced secretion and growth
stimulates small intestinal growth, and intestional motility
cholecystokinin (CCK) and secretin produced in the _______, and effects the stomach hhow?
small intestine
inhibits acid secretion
the bacterial flora of a given subject is essentially equivalent to a ________
fingerprint
where do the numbeers of bacteria and anaerobes start to rise
beginning in the distal small intestine (end)
saliva contains antimicrobial peptides known as ______ and ______ that control microbiota
defensins and lysozymes
stomach contains _______ that limits the colony counts and controls microbiota
gastric acid
small intestine has ______ and ______ that control microbiota
motility (peristalsis)
mucosal secretion of fluid and IgA secretion
Microbiota in the COLON
the colon permits large numbers of bacteria
ileocecal valve keeps organisms in the large intestine
what allows the system to aborb what it needs to
arterial supply
what allows the system to aborb what it needs to absorb
hi
stages of food ingestion
oral stage
pharangyl stage
esophageal phase
what does the oral stage of eating invlove
lubrication
chewing
reducing microbes
deglutition (swallowing) - bolus goes from oral cavity to stomach, while protecting the airway and preventing air into the stomach
what happens in the pharangeal stage of eating?
gag reflex to food bolus, allows selective passage
initiates tracheal closure, esophageal opening, and passage of food bolus to the upper esophagus
what happens in the esophageal stage of eating?
under normal circumstances, food remains in esophagus for only a few seconds.
relaxation of lower esophageal sphincter permits entry of the food bolus into the stomach
What does saliva do?
digests enzymes and begins breakdown of saltines
neutralizes acid from the esophagus
reduces bacterial counts (removed iron so they cant grow)
protects enamel
how to look at and track food nolus thru esophagus
barium swallow
what prevents food from going into the trachea
epiglottis
primary peristalsis originate in the ______.
secondary peristalsis originate in the ________.
phahrynx
esophagus
how much can a stomach hold and what does it do
1.5 L
breaks down food mechanically
_____ empty from stomach faster than ______.
_______ empty faster in a meal
liquids
solid meals
starch carbs
average emptying time from ingestion?
average emptying from stomach
24 hrs
4 hours
what is receptive relaxation important for and what causes it?
essential for stomach to store (reservoir)
acetylcholine relaxes the gastric smooth muscle layers which drops gastric pressure
insires pressure in stomach does not increase until food is gone
gastric emptying is delayed until the _________ is able to process its contents
duodenum
what stimulates secretin release
acids
what reduces gastric motility and increases pyloric sphincter tone
secretin
what stimulates release of scholecystokinin (CCK), gastric inhibitory peptide (GIP), vasoactive intestinal polypeptide (VIP), ad petide YY ?
proteins
what roles do gastric secretions have?
Gastric acid (pH of 2.0)
- dissolves food
- necessary for iron and B12 absorption
- activates pepsinogen
- stimulates secretin
gastric glands made of different cell types that open into _______ allow gastric secretion to occur
gastric pits
