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Pathophys II MHM - Exam 1 > GI Module 1 > Flashcards

GI Module 1 Flashcards

1
Q

Organs of the GI (alimentary) tract

A 
Mouth
Esophagus
Stomach
SI / LI
Rectum
Anus
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2
Q

Accessory organs of digestive system

A

Liver, gallbladder, exocrine pancreas

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3
Q

Layers of GI tract from inner to outer

A
  1. Mucosa
  2. Submucosa
  3. Muscularis
  4. Adventitious (serosa)
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4
Q

What are the sub-layers of the mucosa from inner to outer?

A
  1. Mucosa epithelium
  2. Lamina propria
  3. Muscularis mucosae
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5
Q

What does the submucosa contain?

A

Glands and associated ducts

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6
Q

What are the layers of the muscularis?

A

Circular and longitudinal layers

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7
Q

What is the adventitious (serosa) composed of?

A

Connective tissue

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8
Q

Define the enteric nervous system

A
  • Considered part of ANS
  • Functions autonomously
  • Influenced extrinsically via para/sympathetic nervous systems
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9
Q

Enteric plexuses

A
  1. Meissner plexus (submucosal)
  2. Auerbach plexus (myenteric)
  3. Subserosal plexus
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10
Q

Meissner plexus

A
  • Located in submucosa

- Secretion!

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11
Q

Auerbach plexus

A
  • AKA myenteric
  • Located b/w circular and longitudinal layers of muscularis
  • Motility!
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12
Q

Subserosal plexus

A

ANS innervation of blood vessels and connective tissue

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13
Q

What are the functional components of enteric plexuses?

A
  1. Sensory neurons
  2. Motor neurons
  3. Interneurons
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14
Q

What is the function of sensory neurons in enteric plexuses?

A
  • Monitor distension and “chemical status” of tract

* Sympathetic nerves

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15
Q

What stimuli to the enteric plexuses cause GI visceral pain?

A
  1. Distension
  2. Chemical (inflamm response)
  3. Ischemia (lactate, H+, K+)
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16
Q

What is the function of motor neurons in enteric plexuses?

A
  • Motility (peristalsis)
  • Blood flow
  • Secretions
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17
Q

What is the function of interneurons in enteric plexuses?

A
  • Communication b/w sensory and motor neurons

- Mechanism for INTRINSIC control (short loop reflexes)

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18
Q

Define appetite

A

Hunger

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19
Q

Define satiety

A

Sensation of fullness/satisfied

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20
Q

How are appetite and satiety regulated?

A

2 centers (nuclei) in hypothalamus:

  • Lateral center (appetite)
  • Medial center (satiety)
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21
Q

Function of lateral center

A
  • Stimulate appetite

- Excitatory to hunger contractions in stomach

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22
Q

What is ghrelin?

A
  • Gastric hormone - “Hunger hormone”
  • Fast acting
  • Other roles: memory, sleep
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23
Q

Function of medical center

A
  • Suppress appetite
  • Inhibitory to hunger contractions in stomach
  • Stimuli = GI hormones, leptin, PYY, insulin
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24
Q

What is leptin?

A
  • Long term role in energy balance and suppressing food intake
  • Released from fat and chief cells
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25
Q

What is PYY?

A
  • Fast acting
  • Counteraction to ghrelin
  • Released after a meal by the small intestine
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26
Q

How does obesity affect hunger hormones?

A
  • Leptin is increased (“resistance”)

- Ghrelin is decreased

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27
Q

Is insulin fast or slow acting?

A

Fast

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28
Q

Function of sympathetic system to GI tract

A

Inhibitory - decreases peristalsis and secretions

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29
Q

Function of parasympathetic system to GI tract

A

Excitatory

*Vagus, pelvic nerves of sacral plexus

30
Q

What is the extrinsic regulation of the GI tract?

A

Sympathetic and parasympathetic

31
Q

What is the intrinsic regulation of the GI tract?

A

*Located within GI tract wall
Auerbach (myenteric) plexus = motility
Meissner (submucosal) plexus = secretions

32
Q

How does the intrinsic system of the GI tract function?

A

Autonomously (“brain in the gut”)

33
Q

How is salivation controlled?

A

Autonomic - both para and sympathetic STIMULATE salivary glands
*NOT by hormones at all

34
Q

What is saliva composed of?

A
  • Water w/mucus, Na, bicarb, Cl, K
  • Salivary amylase
  • IgA
35
Q

Where is digestion initiated?

A

In the mouth by salivary amylase

36
Q

What is the pH of saliva?

A

6.4 - 7.0

37
Q

What is the function of bicarbonates in saliva?

A

Maintain pH to neutralize bacteria (tooth decay)

38
Q

What is the purpose of IgA in saliva?

A

Prevents infection

why animals lick their wounds

39
Q

General functions of saliva

A
  1. Control pH
  2. Starch digestion
  3. Immune defense
40
Q

What muscle is the upper esophageal sphincter?

A

Cricopharyngeus

41
Q

Where is the UES located?

A
  • Junction of lower pharynx and esophagus

- Approx at level of cricoid cartilage

42
Q

What is the function of the UES?

A

Prevent air from entering esophagus during ventilation

43
Q

Is the UES considered a ____ (true/false) anatomical sphincter?

A

TRUE

44
Q

Location of lower esophageal sphincter

A

Just proximal to junction of esophagus and stomach

45
Q

Functions of the LES

A

Barrier to reflux from the stomach

46
Q

How is the LES maintained?

A

Increased smooth muscle tone

47
Q

What is belching a result of?

A

Air pressure in stomach exceeds LES pressure

48
Q

What is the normal “tone” of the esophagus?

A

20 mmHg

49
Q

Phases of swallowing and their lengths

A
  1. Voluntary (1-2 secs)

2. Esophageal (5+ secs) - UES contracted (closed)

50
Q

What comprises the voluntary phase of swallowing?

A
  1. Oropharyngeal phase - UES closed

2. Pharyngeal phase - UES relaxed

51
Q

What is the range of esophageal muscular pressures?

A

35 - 80 mm Hg

  • Upper and lower esophagus tend to be higher (60-80)
  • Mid esophagus tends to be lower (30-45)
52
Q

Peristaltic contractions of

A

30 mm Hg

53
Q

How is peristalsis controlled?

A

Parallel vagal inhibitory (NO) and excitatory (ACh) pathways

54
Q

What hormones excite and inhibit peristalsis?

A 
Excite = ACh
Inhibit = NO
55
Q

Define primary peristalsis

A 
"Normal" wave as bolus descends
Swallow reflex (voluntary) + esophageal wave (involuntary)
56
Q

Define secondary peristalsis

A

Food residue from ineffective primary peristalsis or a bolus that is “stuck”
*Consists of esophageal wave (involuntary) ONLY

57
Q

Difference between primary and secondary peristalsis

A
  • Primary consists of both swallowing AND esophageal phases

- Secondary is ONLY esophageal (involuntary) phase

58
Q

Process of swallowing food

A
  • Single swallow initiates esophageal peristalsis lasting 5-10 secs
  • Short refractory period inhibits more swallowing
59
Q

Process of swallowing liquids

A
  • Swallow every 1-2 seconds
  • Quick subsequent swallows creates an inhibitory reflex (deglutitive inhibition) that prevents esophagus from ongoing contraction (allows more liquid to descend)
60
Q

Deglutitive inhibition

A
  • Occurs with swallowing LIQUIDS
  • Quick subsequent swallows creates a reflex where esophagus cannot contract
  • Allows more liquid to descend
  • Last swallow will end the reflex and start full peristaltic contraction
61
Q

LES tone is a result of 3 factors:

A
  1. Myogenic tone (independent of any neural input)
  2. Excitatory vagal tone (cholinergic)
  3. Inhibitory vagal tone (nitric oxide)
62
Q

Factors that increase LES pressure:

A
  1. Vagus nerve excitatory pathway (ACh)
  2. Gastrin
  3. Meds to treat GERD
    * Increased LES pressure = closed LES
63
Q

Factors that decrease LES pressure:

A
  1. Vagus nerve inhibitory pathway (NO, VIP)
  2. Hormones (progesterone, secretin, glucagon)
  3. Foods/substances (fried food, tomatoes, citrus, tobacco, alcohol, caffeine)
64
Q

GERD

A

Decreased LES pressure and ineffective clearance mechanism of secondary peristaltic waves

65
Q

Achalasia

A
  • LES fails to relax - pain w/eating and drinking
  • “Cardiospasm”
  • Etiology is unknown but thought to be defect of intrinsic esophagus plexus
66
Q

Treatment for achalasia

A 
Pneumatic dilation (stretch LES to relax)
Meds to relax LES (Botox an option)
67
Q

Esophageal varices

A
  • Severely dilated sub-mucosal veins in esophagus
  • MC caused by portal HTN
  • Increases risk of bleeding
68
Q

Barrett’s esophagus

A
  • Normal esophageal squamous epithelium is replaced by abnormal metaplastic cells due to exposure to stomach acids
  • GERD can cause this but not always
  • Increased risk of cancer
69
Q

What is the MC esophageal cancer in the US?

A

Adenocarcinoma (polyploid mass)

70
Q

Where is adenocarcinoma of the esophagus most commonly found?

A

Lower esophagus

71
Q

What is the MC esophageal cancer in the world? What part of the esophagus is it mostly found?

A

Esophageal squamous cell carcinoma

Upper esophagus

Pathophys II MHM - Exam 1 (9 decks)

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