GI 3 Flashcards
(115 cards)
1
Q
what kind of neurons regulate GI function
A
ANS
Enteric nervous system
2
Q
besides neurons, what else regulates GI function
A
Paracrine mediators (local cells from diffusion) Hormones (reach gut via blood)
3
Q
what are the parasympa nuclei(and associated nerves) that supply to the Enteric nervous system
A
Vagal nucli( via Vagus Nerve) Sacral spinal cord (via pelvic nerve)
4
Q
do both the sympathetic and parasympathetic supply to the enteric nervous system
A
Yes
5
Q
what are the plexus’s assocaited with the enteric nervous system
A
Myenteric Plexus
Submucosal plexus
6
Q
what part of the GI tract does the sympathetic have direct effect on asside from affecting it via the Enteric system
A
Blood vessels
7
Q
what of the GI does the enteric system have an efect on
A
Smooth muscle
Secretory cells
Endocrine cells
Blood vessels
8
Q
what level of the wall in the GI is the submucosal nerve plexus found
A
in the submucosa
9
Q
what level of the wall in the GI is the myeneric nerve plexus found
A
Muscularis Exteerna
10
Q
what do motor neurons of the ENS do
A
Muscle contraction
Gland function
11
Q
what do Interneurons do in the ENS
A
regulate interactions between different layers of the GI tissues
12
Q
what types of neurons are in the ENS
A
Sensory neurons
13
Q
what types of receptors are found in the GI(used for reflexes
A
Mechanoreceptors
Osmoreceptors
Chemoreceptors
14
Q
what initates reflex arcs of the GI tract
A
Distension of the wall
Chyme osmolarity
Chyme acidity
Chyme concentration
15
Q
what does the long reflex of the GI involve
A
invovles the CNS (using afferent and efferent neurons from the GI walls)
- factors in sight, smell, taste
16
Q
path of the long reflex of the GI
A
- stimulus in GI acts on receptors of GI walls
- afferent neurons to CNS from vagal sensory neurons
- efferent ANS (PNS or SNS)
- act on nerve plexus
- acts on smooth muscle or gland of GI wall
17
Q
what does the the short reflex of the GI invovle
A
all that the long one does but lacks the afferent and efferent nerves from the CNS (CNS not invovled)
18
Q
what types of hormones can act on the GI
A
peptides
neurotransmitter/neuroendocrine hormones
19
Q
what are the 4 hormones that regulate digestion
A
Gastrin
Cholecystokinin (CCK)
secretin
Glucose-dependent Insulinotropic peptide
20
Q
what is the CCK feedback look
A
CCK stimulated by fatty acid
CCK stimulates enzyme production of pancrease
enzyme production reduces CCK activation
21
Q
Do hormones of GI act on only 1 type of cell
A
No, work on multiple
22
Q
what cells can CCK activate
A
stimulate Pancreas, liver, gallbladder,
inhibit stomach emptying
23
Q
do each hormone of GI act along
A
can be synergistic (one can poentiate the other)
24
Q
what are the phases of GI control
A
Cephalic Phase
Gastric Phase
Intestinal
25
what nerve fibers stimulate the Cephalic phase
Parasympa nerve fibers affecting the ENS
26
what initiates the cephalic phase
When recetpors in head are stimulated
27
what is involved in control of the gastric phase
short and long neural reflexes
| Gastrin
28
what all causes the gastric phase
Distension
Acidity
Amino acids
Peptides
29
what is involved in control of the intestinal phase of Gi control
Short and long neural reflexes
Secretin
CCK
GIP
30
what causes the Intestinal phase
Distesion
Acidity
Osmolarity
Various digestive products
31
what is the immune function of stomach
Kills many bacteria
32
what does the stomach do to food
Initiates digestion of food
33
what does the stomach deliver to the dueodenum
Chyme
34
what determines the rate that the stomach delivers chyme to the duodenum
secretion rate of bile salt, bicarb, digestion enzymes
rate of enzyme breakdown of carbs, fats, and proteins
small intestine transit
35
what are the 3 anatomic sections of the stomach
Fundus
body
Antum
36
what are the glandular regions of the stomach
Oxytic (mesial)
| Pyloric (distal)
37
what are the cells of the gastric pit
mucous neck cells
Cheif cells
Parietal cells
38
what do parietal cells produce
HCL
| Intrinsic factor
39
where is HCL produced
By parietal cells in the fundus and body (oxyntic gland area)
40
where is intrinsic factor produced
By parietal cells in the fundus and body (oxyntic gland area)
41
what do chief cells produce
Pepsinogen
42
where is pepsinogen produced
by chief cells in the body and the antrum (oxyntic and pyloric gland area)
43
where is mucous produced
in mucous neck cells throughout the stomach
44
where is bicarb produced
Epithelial cells through the stomach
45
where is gastrin produced
G cells in the NAtrum (pyloric gland area)
46
where is somatostatin producd
D cells through the stomach ath the base of gastric gland
47
where is histamine produced in the GI tract
Enterochromaffin-like cells
48
how is HCL secereted
- Cl brough in from the Capillary by being transported aginst Bicarb(makes spare H+ from carbonic anhydrase)
- Cl flows into staomach along with K
- ATP helps pump H into stomach and pump K back into the cell
49
what is invovled in regulating acid secretion
Tubulovesicular membrane
| Intracellular cancliculus
50
what is the strongest HCL stimulant
Histamine
51
what triggers histamine release
Gastrin or ACh
52
do Gastrin and Ach only act on histmaine to relaese HCL
No, can directly act on Parietal cells
53
what is the intracellular message for relase of HCL from pareital cells
Second messenger activitation
54
what is the action of Somatostatin
Inhibit HCL
55
what does Somatostatin act on to inhibit HCl secretion
G cells
| Pareital cells
56
what are the cephalic aspects that regulat HCl secreteion
Sight
Smell
taste
Also mech stimulation from chew and swallowing
57
what does the cephalic regulation of HCl seceretion active
PNS to produce Ach
58
what is the intesinal phase effect on HCl secretion
initially enhances HCl secretion by later inhibits it
59
what does the pH of chyme need to be for secretin to be produced
less than 3
60
what aspects inside the stomach decrease HCL production via CCK
High H+
amino acids
Fatty acids
- all stimulate CCK
61
what increases gastrin secretion
gastric phase distesnion, protein, peptides, amino acids
62
activity of gastrin
act on parietal cells to increase HCL secretion
63
why does HCL degrade gatric tisssue
Muscus neck cells
| Gastric epithelial cells produce Na, Cl, K , HCO3 that keeps the surface of cells at ph 7
64
how is pepsin produced
released as pepsinogen as a zymogen (proenzyme to be cleaved)
- cleaved by HCL into Pepsin
65
why doesn't pepsin degrade stomach tissue
do to mucous layer so, it is not activated till its in the Low pH zone of the stomach
66
how does gatric motility occur neuologically
does like peristallic waves with action potentials occuring once cresting AP
67
what does gastric motility/emptying factors relate with
same factors that affect HCl secretion
68
what inhibits the secretion and motility in the stomach
Secretin and CCK (enterogastrones)
69
what stimualtes the secretion of Secretin and CCK
increased acidty, fats, amino acids, hypertonicit, distenstion in the dueodenum
70
what are the exocrine products of the pancrase
```
Bircab
Digestive enzymes (lots
```
71
how does the pancreas activate inactive enzyme
1. Pancrease releases Typrinogen
2. trypsinogen converted to trypsin by membrane bound enterokinase
3. Trypsin takes inactive enzymes to active enzymes in the intestinal lumen
72
what potentiates CCK secretion
Secretin
73
how is bicarb secreted
Like HCl but in reverse
74
how is bicarbonate secretion regulated
Hormone: secretin
Feedback: acidity
75
what does the liver do for digestion
Produces bile
76
where does the liver secrete bile
Canaliculi (small ducts)
77
what do canaliculi drain into
convege and drain into larger bile ducts
78
what is found in bile
```
Bile salts (and other salts)
Lecithin
Cholesterol(related to bile salts)
Bile pigments (bilirubin) and other metabolic end products
trace metal
Bicarb
```
79
what stimulates secretion of bicarb
stimulation of epithelial cells of ducts by secretin
80
how much bile salt does the liver synth
20-60mg of bile salts
81
how much bile salt does is secreted a day
1,200-3,600 mg
82
how can more bile salts be secreted than synthesized
recycled through the enterohepatic circulation
83
increase in plasma cck lead to what
increase in bile flow into duedenum
84
when is absorption maximized
when chyme/bolus is continuously brough into contact with the intestinal tissue
- also importat to contract small intestine
85
what are the types of smooth muscle contraction
Peristalsis
| Segmentation
86
what is peristalsis
Progressive contraction of successive sections of circular smooth muscle
87
what is segmentation
Closely spaced contractions of circular muscle layer
88
what happens when segmentation is rhythmic
chyme/bolus is mixed and slowly moved downward
89
how does the food move during absorption in the small intestine
segmental contraction
90
what contractions occur after must absorption has occured
peristaltic contraction
91
what drives peristalsis
migrating myoelectric complex
92
where does the myoelectric complex that drives peristalsis begin
lower stomach
93
speed of the myoelectric complex that drives peristalsis
travels 2 feet prior to dying
94
what initiates the myoelectric complex of peristalsis
intestinal hormone motilin
95
how does the food bolus enter the large intestine
Ileocecal valve (sphincter
96
what makes up the bolus that enters the large intestin
small intestine secretion
| undiestable foods
97
what is the cause of farts
bacteria fermenting stuff in the large intestine
98
what is the primary purpose of the large intestine
tranpsort Na from lumen to blood
99
what is bicarb secretion in the large intestine coupled with
Cl ion absorption
100
what is the benifit of bacterial fermentation of food bolus
absorb nutrients from food
101
what does the large intestine do with the remaining food folus
Eliminate it from the body
102
how does motility of the large intestine control
occurs as slow segmentation contracts
103
how often do peristaltic-like contractions in the large intestine occur
3-4 times per day
104
what is the roll of the mouth in digesting
Chewing
Salivation
Amylase
Lipase
105
what is the roll of the stomach in digestion
HCl
Pepsinogen
Lipase
Gastrin
106
what is the roll of the small intestine in digestion
Hormones (secretin, Cholecystokinin)
107
what is the roll of the pancreas in digestion
proteases
Lipase
Amylase
HCO3
108
what is the roll of the liver in digestion
Bile
109
what is the roll of the small intestine in digestion
absoprtion (carbs proetin, fats, vitamines, minerals)
110
what is the roll of the large intestine in digestion
Absorption (Na, Cl, water)
111
what determines the rate at which food moves through the stomach
Pacemaker cells
| magnitude determined by excitatory stimuli
112
what kind of contractions are found in the stomach
Peristalsis from body to pyloric sphincter
113
what kind of contractions occure in the smalle intestine
Segmentation and peristaltic contraction
114
what controls peristalsis in the small intestine
Migrating myoelectric complex (initiated by motilin)
115
how does the large intestine move
Slow segmentation contractions in massive movements
