GI module 1 Flashcards
1
Q
What are the structures of the alimentary canal?
A
The alimentary canal is the GI tract:
Mouth, esophagus, stomach, SI, LI, rectum, anus
2
Q
What are the accessory organs of the digestive system?
A
Liver, gallbladder, exocrine pancreas
3
Q
name the layers of the GI tract from inner to outer
A
Mucosa
submucosa
muscularis
adventitious (serosa)
4
Q
Which layer needs to be smooth enough to be able to pass and absorb/neutralize stool?
A
mucosa layer
5
Q
What are the 3 parts of the mucosa layer of the GI tract?
A
Mucosa epithelium
lamina propria
muscularis mucosae
6
Q
Which layer of the mucosa allows local movement and has a role in IBD and or secretion/absorption dysfunction?
A
Muscularis mucosae
7
Q
What layer of the GI tract contains glands and associated ducts?
A
submucosa
8
Q
What are the sublayers of the muscular layer of the GI tract?
A
Circular
Longitudinal
9
Q
What is the adventitious (serosa) layer made up of?
A
connective tissue
10
Q
What part of the Nerovous system is the enteric system part of?
A
ANS
11
Q
What is the parasympathetic system responsible for in the GI?
A
Excitatory action
12
Q
What is the sympathetic system responsible for in the GI?
A
Inhibitory action
13
Q
What are the 3 enteric plexuses?
A
submucosal plexus (meissner) Myenteric plexus (Auerbach) Subserosal plexus
14
Q
What plexus is also known as the Meissner plexus?
A
submucosal
15
Q
what plexus is also known as the Auerbach plexus?
A
Myenteric
16
Q
Where is the submucosal plexus located and what is it responsible for?
A
Submucosa
Secretion
17
Q
Where is the myenteric plexus located and what is it responsible for?
A
Between circular and longitudinal layers of muscular
Motility
18
Q
What is the subserosal plexus responsible for in the GI tract?
A
ANS innervation of BV and CT
19
Q
What are the 3 general functional components of enteric plexuses?
A
Sensory neurons
Motor
Interneurons
20
Q
What do the sensory neurons in the enteric plexus monitor in the GI tract?
A
Chemical status
21
Q
What do the motor neurons in the enteric plexus control in the GI tract?
A
Motility (peristalsis)
Blood flow (smooth muscle of GI vasc.)
Secretions (cells of mucosa/submucosa)
22
Q
What do the the interneurons of the enteric plexus control in the GI tract?
A
Communication between sensory and motor _ mechanism for intrinsic control (short loop reflexes)
23
Q
What do the terms appetite and satiety mean?
A
appetite - Hunger
satiety - sensation of fullness
24
Q
What two centers (nuclei) control appetite and satiety?
A
Lateral center (appetite) Medial center (satiety)
25
Where are the centers for appetite and satiety located?
hypothalamus
26
What hormone is released by the stomach and sends a chemical message to the brain to stimulate appetite?
Ghrelin
27
What hormones stimulate the medial center in the brain to suppress appetite?
GI hormones (CCK, GLP-1 etc.)
Leptin
PYY
Insulin
28
Where is Leptin released from and what is significant about it?
Fat cells and chief cells
| It is the longest lasting of all the hormones that stimulate appetite
29
Where is PYY released from
the SI after a meal
30
When is Insulin released?
by pancreas after increased blood glucose after a meal
31
What hormone is effected in obesity leading to more weight gain?
"leptin resistance" leads to effectiveness of sensation of satiety to be blunted.
32
What occurs when Ghrelin levels are decreased?
decreased levels in obesity
33
Which GI hormones are considered "fast acting"
Ghrelin
PYY
Insulin
34
When do Ghrelin levels rise?
just before a meal
35
What is the pathway of nerves in the sympathetic system?
Thoracic and lumbar regions
36
What is the function of the sympathetic system on the GI tract?
inhibitory-
decreased peristalsis
inhibits blood flow to GI tract
37
What is the pathway of the parasympathetic system in the GI tract?
Vagus nerve and pelvic nerves of the sacral plexus
38
What is the primary function of the parasympathetic system in the GI tract?
Excitatory
Increase peristalsis and secretions
relax involuntary sphincters of GI tract
facilitate blood flow to GI tract.
39
Peristalsis requires ______ and ______ so the vagus nerve has a "dual" role in smooth muscle of the GI tract?
relaxation and contraction
40
Intrinsic system can feedback on itself and function autonomously. This is referred to as "____________"
brain in the gut
41
Wha is the general function of the Myenteric (auerbach's)plexus?
controls motility
42
What is the general function of the submucosal plexus (Meissner's)?
Secretion and absorption
43
What are the 7 specific functions of the enteric nervous system?
Motility
Regulation of Fluid exchange and local GI blood flow
Regulation of gastric and pancreatic sensation
Regulation of GI endocrine cells
Defense reaction
Entero-enteric reflexes
ENS and CNS interaction
44
What are the primary excitatory neurotransmitters in the intrinsic nervous system?
Ach and sub P
45
What are the primary inhibitory neurotransmitters in the intrisic nervous system?
NO and VIP
46
What is the summary job of the Extrinsic nervous system?
Directly influences the intrinsic system
| By Parasympathetic and sympathetic nervous system
47
What is the summary job of the intrinsic nervous system (enteric)?
```
Myenteric plexus (Auerbach's)-muscular layers controls motility
Submucosal (Meissner's)-located within/beneath mucosal layers so controls secretions
```
48
What are the 3 salivary glands of the mouth?
Submandibular
sublingual
Parotid
49
What controls the stimulation of salivary glands?
Both parasympathetic and sympathetic systems
| NOT hormones
50
t/f saliva is controlled by hormones?
F!! it is controlled by parasymp and sympathetic systems
51
What makes up saliva? Why?
Water-controls pH
Salivary amylase-Starch digestion
IgA-immune defense
52
What kind of muscle is the esophagus made up of?
Upper third-striated (voluntary)
Middle-mixed
Lower-smooth (involuntary)
53
Where is the UES located?
junction of lower pharynx and esophagus
| approx at level of cricoid cartilage
54
What is the normal tone of the UES?
50mmHg (can be up to 70/80 if totally constricted)
55
UES is considered a/n ___________ sphincter?
Anatomical
56
What is the function of the UES?
Prevents air from entering esophagus during ventilation
57
Location of the LES?
Narrowing of the esophagus at junction of esophagus and stomach
58
What is the normal tone of the LES?
20mmHg
59
LES is considered a/n ____________ sphincter?
Not a true anatomical sphincter
60
What is the function of the LES?
Barrier to reflux of acidic content of stomach
61
What is the only voluntary phase of swallowing?
Oropharyngeal
62
What occurs during the oropharyngeal phase?
Chen the food and push it posteriorly
63
What occurs during the pharyngeal phase?
Soft palate closes off nasopharynx
Epiglottis closes off larynx/trachea
Food is pushed into the esophagus
64
How long does it take for food to be pushed into the esophagus?
1-2 seconds
65
What are the two involuntary phases of swallowing?
Pharyngeal phase
| esophageal phase
66
What occurs during the esophageal phase?
Bolus enters esophagus and ends as the bolus enters the stomach
67
How long does the esophageal phase of swallowing take?
5-10 seconds (or more)
68
What phase does the dual innervation of the UES (relaxation followed by contraction) propagating down occur?
esophageal phase
69
Esophageal muscular pressures range from ______- _____?
35-80mmHg
70
Upper and lower esophagus tends to have a pressure ranging from ____ - _____?
60-80 mmHg
71
Mid esophagus pressures tend to be ____ - _____?
30-45 mmHg
72
Less than ______ mmHg contraction may leave food residue within the esophagus
Less than 30mmHg
73
What stimulus increases the forces of esophageal contraction?
tension (distention)
74
What nerve pathway controls peristalsis?
Parallel vagal inhibitory and excitatory pathways (Vagus nerve)
75
What are the peristaltic excitatory signalers in the vagus nerve?
Ach
76
What are the peristaltic inhibitory signalers in the vagus nerve?
NO
77
What occurs during primary peristalsis (5 step pathway)
```
Oral phase
Pharyngeal Peristalsis
UES relaxation
esophageal peristalsis
LES relaxation
```
78
What phases are involved in primary peristalsis?
```
Swallow reflex (voluntary phase)
Esophageal wave (involuntary phase)
```
79
When does secondary peristalsis occur?
When the whole food bolus does not get passed down on the first try.
80
What phase(s) are involved in the secondary peristalsis?
Esophageal peristaltic wave (DOES NOT include swallowing reflex).
81
What occurs during secondary peristalsis? (pathway 3 steps)
Bolus or food residue DISTENTION causes intrinsic feedback to:
1. Constrict esophagus above the distention
2. Relax esophagus below distention
3. Push residue/bolus along
82
How long does it take for a single swallow of food to initiate esophageal contraction?
5-10 seconds
83
Why is attempting to swallow food more frequently than 10-15 seconds difficult?
A short refractory period follows peristaltic contraction inhibiting ability to swallow a second bite of food.
84
How long does it take to swallow a liquid?
1-2 seconds
85
Why is it possible to swallow multiple sips of a drink under the normal 5-10 seconds that it would take to swallow food?
Deglutitive inhibitions prevents esophagus from ongoing contraction. This inhibitions causes the esophagus to stay relaxed to allow more liquid to descend.
86
LES tone is a net result of what 3 factors?
Myogenic tone (independent of neural input)
Excitatory vagal tone (cholinergic)
Inhibitory vagal tone (nitregeic-Nitric Oxide)
87
What are the factors the INCREASE LES pressure?
Vagus nerve influence (Ach)
Gastrin
Some meds to tx GERD
88
What are the factors that DECREASE LES pressure?
Vagus nerve influence (NO, VIP)
Hormones-Progesterone, secretin, glucagon
Common foods/substances- are suggested (fried food, tomato, citrus etc.)
89
Define the pathology of GERD
Decreased LES pressure and ineffective clearance of mechanism of secondary peristaltic waves.
90
What does chronic recurrent GERD eventually cause?
Destruction of the esophageal wall (esophagitis)
91
What medications are used to Tx. GERD?
Antacids-neutralize acid
Histamine-dec. acid secretion histamine receptors
PPI-stop acid secretion
Parasympathetic drugs-increase LES tone
92
What might cause decreased LES/risk factors for GERD?
```
Hiatal hernia
Pregnancy
Excess ETOH
tobacco
obesity
```
93
Define Achalasia
LES fails to relax-pt get's pain w/ eating and drinking
94
What is achalasia also known as?
Cardiospasm
95
What must be ruled out first clinically when DDX'ing for Achalasia?
Cardiac issue-strong mimicry.
96
What are the tx strategies for achalasia?
Pneumatic dilation
| Meds to relax LES
97
Define Esophageal Varices
Severely dilated sub-mucosal veins in the esophagus
98
What is the primary cause of esophageal varices?
Portal hypertension (common with cirrhosis)
99
What do patients with esophageal varices have a strong tendency to develop?
Bleeding-chronic long term GI bleed can progress to severe systemic consequences/
100
What MIGHT untreated GERD develop into?
Barrett's esophagus
101
What is Barrett's esophagus
a condition in which abnormal cells develop in the esophagus due to exposure to stomach acidd
102
What are the normal esophageal cells replaced with in Barrett's esophagus?
Metaplastic columnar mucosa
103
Do all patient with GERD develop BE?
NO
104
Will all patients with BE develop cancer?
NO risk is 1:300
105
T/f the amount of dysplasia in BE increases a patient's risk of cancer?
True
106
Where are polypoid mass adenocarcinomas most commonly found in the esophagus?
Lower
107
What is the most common esophageal cancer in the US?
polypoid-Adenocarcinoma
108
Where are Squamous cell carcinomas of the esophagus most commonly found?
upper esophagus
109
What is the most common for of esophageal cancer in the world?
Esophageal squamous cell carcninoma
