GI phys overview Flashcards
(131 cards)
1
Q
define Bolus
A
rounded mass of food ready to swallow
2
Q
define Borborygmi-
A
abdominal rumbling sounds.
3
Q
define Chyme
A
semifluid mass of partly digested food passed from the stomach to the duodenum
4
Q
Define Diverticulum
A
outpouching of GI wall
5
Q
define Eructation
A
belching
6
Q
Define Peristalses
A
propulsion of food through the esophagus and intestines
7
Q
Define Postprandial
A
after feeding
8
Q
Define Sitophobia
A
fear of eating
9
Q
DEfine Steatorrhea-
A
fatty stools
10
Q
small intestine prefix
A
ileo
11
Q
large intestine prefix
A
colo
12
Q
rectum prefix
A
proct
13
Q
Upper GI structures
A
Oral Cavity, Pharynx, Esophagus, Stomach, Small intestine
14
Q
Lower GI structures
A
large intestine
15
Q
what are the parts of the small intestine
A
duodenum,jejunum, ileum
16
Q
what are the parts of the large intestine
A
cecum,colon,rectum,anus
17
Q
What are the accessory organs of GI tract?
A
Salivary glands (parotid, submandibular, sublingual)
Exocrine Pancreas
Liver- Hepatic system
Gallbladder- Biliary system
18
Q
What spincters are voluntary control?
A
external anal and upper esphageal
19
Q
pylorus sphincter connects what?
A
stomach to the small intestine
20
Q
what does the sphincter of oddi connect?
A
the galbladder to the small intestine
21
Q
what does the small intestine have to increase surface area?
A
villus and crypts
22
Q
what does the colon have to increase surface area?
A
just crypts
23
Q
what are special about the GI epithelial cells?
A
constant renewal, stem cells at the base of the crypts divide, differentiate and migrate to the tips of the villi
24
Q
Why is it important that GI epithelial cells renew every 3-6 days?
A
Prevent the accumulation of mutations due to toxin exposure
25
What are the 4 major GI wall types?
Mucosa, submucosa, muscularis externa, serosa
26
What does the muscularis externa contain in its layer
circular muscle (mechanical digestion), myenteric nerve plexus, longitudinal muscle for propulsion
27
what is a diverticulum?
single pouch protruding from alimentary tract. Usually false not true. inflammation due to lack of fiber, can progress to diverticulitis
28
What are some characteristics of mucus? Secreted by?
viscous, hydroscopic gel, goblet cells
29
How are mucin monomers combined into plexes?
by disulfide links,
| 2 layers in the stomach and colon, 1 layer in small intestine
30
What protects the protein core of the mucus?
- Glycosylation protects the protein core from proteases (pepsin) in the stomach
31
What are enterocytes coated with
transmembrane mucins
32
what are the 4 basic processes faciliation caloric uptake?
Digestion, Absorption – excess capacity (95% of diet lipids)
| Secretion, Motility – under neural and hormonal control
33
What does the teeth do for digestion?
mastication
34
What does the salvia do?
lubricates and breaks down, with chewing creates the bolus
35
What does the stomach do for digestion?
movements and pepsin digests food into chyme
36
what does the duodenum do for digestion?
brush border enzymes from pancrease and bile salts from liver
37
Where are amino acids, monosaccharides, and
| lipids absorbed
small intestine-duodenum and jejunum
38
where are cobalamine (B12) and bile salts/acids absorbed?
small intestine-ileum
39
What absorbs water and electrolytes
small and large intestines
40
What does absorption depend on?
Splanchnic Circulation, 1-5 litersAt depending on vasomotor tone
41
At rest, how much CO goes to the gut?
21%
42
what is the blood flow from the intestine?
portal vein to the liver allowing for detoxification.
43
Where does the liver get its blood from?
1/4 blood from hepatic artery, 3/4 blood form portal vein
44
by how much can flow increase during increased gut activity?
4-5 Liters
45
What happens to blood flow to the GI tract during exercise and emergencies
massive vasoconstriction shunts blood away from the gut.
46
what does the enterohepatic circulation do
Recycling of bile salts/acids from the ileum, can alter drugs (what body goes to Rx), some metals get secreted into feces
47
What are the metabolic vasodilatiors that increase blood flow?
CO2, H+, K+, adenosine, etc
48
Chylomicrons are too large to pass through the capillary cells, so what happens to them?
they get absorbed through lacteals which empty into blood stream via thoracic duct
49
what is mesenteric ischemia due to?
occlusive mechanisms like thombi, or
non-occlusive mechanisms including prolonged reflex vasoconstriction (due to hypovolemia, heart failure) or abnormal levels of circulating vasoconstrictors (e.g, epinephrine, angiotensin II)
50
what are the effects of mesenteric ischemia?
Postprandial Pain, Sitophobia (fear of eating)
Necrosis of the tips of the villi
Loss of barrier function of the wall of the gut and uptake of vasodilator toxins (endotoxin) from the gut resulting in Septic Shock
51
The fluid environment of the GI tract is supplied by what
organs that drain into the GI tract and GI epiethlial
52
What does the fluid in the GI tract contain
ions, digestive enzymes, mucins, and bile
53
Where are majority of the fluids reabsorbed
reabsorbed in the small intestine with nutrients
54
What regulares secretion of the GI system?
Parasympathetic, hormonal, and enteric nerves
55
What is transmural water movement driven by?
osmotic gradients
56
How does water move across the epithelium?
through the cells (transcellular route) perhaps with the help of specific water channels (aquaporins) and between cells (paracellular route) according to osmotic gradients driven by active electrolyte transport.
57
What is conductivity defined by in regards to the epithelia
leakiness, depends on the variable presence of absense of tight junction
58
What coupled activity mediates fluid uptake?
electroneutral NACL absoprotion with NA/H exhanged on the apical side, CL/HCO3- exchange in apical membrane
59
what is secretory diarrhea
infection-increases CL secretion drwaring water into lumen
60
what is osmotic diarrhea
small bowel overgrowth leads to production of organic acids suffiencet enough to pull water from blood stream via osmosis
61
What does fluid flux depend on?
surface area available for ion transport and residence time in the lumen
62
What is the action of some antidiarrheal in regards to fluid flux
slows transit to increase fluid absorption
63
What controls the length of time food takes for digestion and absoprotion?
motility
64
Time spent in the Esophagus
10 seconds
65
time spent in the stomach
4-5 hours
66
time spent in the SI
2.5-3 hours
67
time spent in the LI
30-40 hours
68
total time it takes food to digest?
36-48 hiours
69
What is most of the GI tract made up of?
SMOOTH MUSCLE
70
What are the exceptions to most of the GI tract being made of muscle
striated muscle in upper third of esophagus, pharynx, external anal sphincter
71
GI smooth muscle contractile characteristics- describe the rhythmic
Rhythmic “phasic” (seconds) contractions and long “tonic” contractions (minutes to hours)
72
How is basal tone maintained in regards to Gi smooth muscle?
bassal resting tone is maintained w/o elevation in intraceullar CA2+ and without energy expenditure. (sphincters)
73
What can GI smooth muscle do in response to stretching?
DEPOLARIZE! leading to contraction
74
Proximal pressure on a sphincter causes the sphincter to do what?
relax
75
distal pressure a sphincter causes the sphincter to do what?
contract
76
The slow waves electrical activity is initiated by
interstitial cells of Cajal are phasic and propagated over a few centimeters
77
What are the slow waves due to?
increase in calcium followed by repolarization by K+ channels
78
What can change in the slow waves-amplitude or frequency?
AMPLITUDE! by signals releasing calcium from internal stores or opening Ca++ channels on plasma membrane
79
Parasympathetics release of AcH binds to what receptor? and causes what?
Myscarinic-increase of CA into cell, phophorylation of myosin and increase ATP actvity by increase myosin/actin binding. this leads to contraction
80
What do peristaltic contractions do to the bolus of food?
propel intestinal contents forward, longitindal
81
wha do Segmenting contractions do to the bolus of food?
contractions of circular muscles in small and
| large intestine that locally mix contents (churning), nonpropulsive
82
What controls the migrating motor complex?
motiln
83
what is the migrating motor complex?
relaxation of sphincters and contractions in stomach and small intestine occurring during fasting
84
what is also know as the mini brain?
the enteric nervous system,can operate independently of CNS! but control of secretion and motility may be less than optimal.
85
Where are the submucosal nerve plexus?
small and large intestine, sensory and blood flow, Meissner’s
86
Where is the myenteric nervous plexus?
between circular and longitudinal muscle layer from esophagus to internal anus
Auerbach’s
87
changes in GI tract are detected by what?
intrinsic sensory receptors including: stretch receptors, osmoreceptors, and chemoreceptors
88
Do Chemosensitive taste receptors always evoke taste?
NO! they are other places in the body besides the mouth
89
What excites the afferent sensory neurons of the enteric nervous system?
distension of the gut wall or chemical signals from the lumen of the gut transmitted to sensory neurons.-like 5HT
90
many of the sensory neurons are stimulated by serotonin (5-HT) released from what kind of cells?
mucosal enterochromaffin cells (ECL) - respond with a few action potentials followed by hyperpolarization (adaptation)
91
What transfers the info about the gut environment?
the myenteric plexus- relays signals up and down the gut
92
The enteric efferent motorneurons are found where? what kind of neuron are they?
myenteric plexus , unipolar
93
What excites the efferent motorneurons?
Fast ESPS's, respond to sustaintined trains of AP
94
What does the efferent motorneurons carry?
information to GI smooth muscle, vascular smooth muscle, GI exocrine secretory cells and GI endocrine secretory cells
95
What do the excitatory motorneurons release?
release acetylcholine, neurokinin A and substance P
96
what do the inhibitory fibers release
vasoactive intestinal peptide (VIP) and nitric oxide (NO) on smooth muscle cells.
97
Long neural reflexes involve?
CNS AND ANS
98
short neural reflexes invovle?
only nerves of the enteric plexus
99
Nutrients activate what neural reflexes?
both autonomic nervous system and enteric nervous system promoting secretion and motility.
100
Afferent information leaving GI tract is carried by ?
Extrinsic Autonomic Nervous System -para and sympathetics
101
parasympathetics relsease what in the GI tract?
AcH! AGAIN! via vagus nerve
102
parasympathetics activate what in the GI tract?
REST AND DIGEST! stimulates activity of the enteric plexuses, increases GI motility and secretory activity.
103
Sympathetics mostly relese in the GI tract
andregerics-epi,
104
Sympathetics inhibits what in the GI tract? other actions?
DECREASES ACTIVITY! inhibits activity of the enteric plexuses, decreases GI motility, contracts GI sphincters, constricts GI microvasculature
105
What does the vaso-vagal efferent response do?
coordinate excitatory and inhibitory activity within the Enteric Nervous System to mediate peristalsis
106
What does the vaso-vagal afferent go?
to autonomic centers in the medulla
107
What are the neurotransmitters of the enteric nervous system?
AcH, gastrin releasing peptide, substance P, Vasoactive intestinal peptide, NO
108
Who releases AcH? Where does it go?
primary excitatory transmitter from sensory cells and from motoneurons to muscle, epithelium, secretory cells and at interneuronal junctions. intracellular Ca++
109
Who releases Gastrin releasing peptide? function?
released from vagal nerve endings to stimulate G cell secretion of gastrin
110
When is substance P released? and usually with who?
an excitatory transmitter generally co-released with acetylcholine
111
Vasoactive Intestinal Peptide (VIP) action is?
DILATION! Promotes motility
Relaxes smooth muscle in esophagus and stomach
Stimulates fluid secretion and promotes dilation of the GI vasculature. increases cAMP
112
What kind of neurotransmitter is NO? What is it usually corealsed with?
inhibitory transmitter co-release with VIP from inhibitory motoneurons, hydrophobic- intracellular targets.
113
What are the primary Gastro-Intestinal Hormones
Gastrin, Cholecystokinin (CCK) , Secretin, Gastric Inhibitory Peptide or Glucose-Dependent Insulinotropic Peptide (GIP), and Motilin
114
Gastrin is released from what cells?
G cells in antrum of stomach (vagus_
115
what does gastrin detect?
detect amino acids leading to pepsinogen and H+ release.
116
CCK is released from what kind of cells? Due to what? Stimulates what?
- I cells in D/J detectdetect fat and amino acids, secretion of pancreatic enzymes and bile salts involved in fat uptake
117
Secretin is released from what kind of cells? Due to what? Stimulates what?
S cells primarily in D/J detect acid stimulates secretion of pancreatic juice including bicarbonate and inhibits gastric motility.
118
GIP s released from what kind of cells? Due to what? Stimulates what?
K cells in D/J detect carbohydrates and fat to inhibit gastric acid secretion and stimulate insulin release from pancreas.
119
Motilin is released from what kind of cells? Due to what? Stimulates what?
secreted by endocrine cells; released cyclically during fasting state to initiate Migrating Motor Complex
120
Histamine in the GI tract is from what kind of cells and does what?
(ECL cells) , endocrine regulartor
121
Somatostatin in the GI tract is from what kind of cells and does what?
(D cells)- paracrine regulators
122
Where are digestive enzymes store?
specialized cells and and products are packaged into zymogen granules and stored.
123
How do digestive enzymes get released
Secretion usually involves a stimulus-induced increase in either cAMP or [Ca+2]i (or both) … which then leads to zymogen granule docking and dumping.
124
T/F because of all the bacteria we have in our guy, its equivalent to being outside of our body
TRUE
125
How is gas produced?
some of it is swallowed when eating, neutralization of gastic acid by bicarbonate generates CO2 , Gas byproducts of fermentation of fiber in colon can be used by other bacteria, excreted by lungs, and evacuated
126
Borborygmi, "stomach rumble" is actually?
CREATED BY GAS IN THE BOWELS!
127
Why do people have flammable gas?
because of methenobrevibacter smithii
128
bacterial overgrowth syndrome occurs because of
delayed small intestine transit and diverticulum
129
what are side effects of bacterial overgrowth syndrome
Gas and bloating from fermentation , Compete for B12 uptake leading to anemia, Deconjugate bile acids leading to steatorrhea, Produce toxins altering epithelium
130
How do you diagnose bacterial overgrowth syndrome
Diagnose with hydrogen breath test
131
What are properties of the GI tract that limit growth of bad bugs
Saliva contains lactoferrin, lysozyme, and secretory IgA
Acidic environment in stomach
More lymphocytes in GI than the circulating immune system
Mucus- IgA, lysozyme, lactoferrin
Paneth cells secrete antimicrobial peptides
Digestive enzymes cleave bacteria
Diarrhea
Vomiting
Microflora prevent colonization of pathogenic microorganisms (probiotics and prebiotics,
