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Sem 4, case 1 (oesophageal cancer) > GI anatomy overview (lecture) > Flashcards

GI anatomy overview (lecture) Flashcards

1
Q

What is the mouth otherwise referred to as?

A

Oral cavity
Buccal cavity

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2
Q

What type of epithelium is the “oral mucosa”?

A

stratified squamous epithelium

(Thick and resistant to abrasion)

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3
Q

Where is the oral mucosa found?

A

Lining the oral cavity

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4
Q

What are childhood “milk” teeth called?

A

Deciduous teeth

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5
Q

What does the oral mucosa produce and secrete?

A

Defensins to inhibit bacterial growth

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6
Q

What is the role of defensins produced by the oral muscosa?

A

Inhibit bacterial growth

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7
Q

How many deciduous teeth does a child have?

A

20

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8
Q

When do deciduous teeth come in?

A

First 6-24 months of life

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9
Q

What are adult teeth called?

A

Permanent teeth

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10
Q

At what age should all deciduous teeth have been replaced, roughly?

A

Approx 12 yrs old

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11
Q

What is the bony ridge called that hold the sockets of the teeth?

A

Alveolar ridge of the maxilla (top) and mandible (bottom)

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12
Q

How many permanent teeth does an average person have?

A

32

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13
Q

How many incisors are in an adult mouth?

A

8

  • 4 top (2 each side)
  • 4 bottom (2 each side)
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14
Q

What is the action of incisors?

A

Slice and cut

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15
Q

How many canines does an adult mouth have?

A

4

  • 2 top (1 each side)
  • 2 bottom (1 each side)
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16
Q

What is the action of canines?

A

Tear and rip

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17
Q

How many premolars are in an adult mouth?

A

8

  • 4 top (2 each side)
  • 4 bottom (2 each side)
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18
Q

What is the action of premolars?

A

Grind and crush

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19
Q

How many molars does an adult mouth have?

A

12

  • 6 top (3 each side)
  • 6 bottom (3 each side)
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20
Q

What is the action of molars?

A

Grind and crush (mainly grind)

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21
Q

What are cavities?

A

Gradual demineralisation of enamel

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22
Q

What causes cavities?

A

Acid production from bacteria in plaque

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23
Q

What is the formula for types of teeth in 1 quadrant of the mouth (e.g the top left side) ?

A

2I, 1C, 2PM, 3M

2 incisors
1 canine
2 premolars
3 molars

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24
Q

Name the 4 types of teeth in an adult mouth…

A
  • incisors
  • canines
  • premolars
  • molars
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25
Q

Name the teeth in 1 quadrant of the mouth in order, front to back…

A
  • central incisor
  • lateral incisor
  • cuspid (canine)
  • first premolar (bicuspid)
  • second premolar (bicuspid)
  • first molar
  • second molar
  • third molar
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26
Q

What is another name for cavities?

A

Dental caries

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27
Q

What can missing teeth cause?

A

Excessive wear on the corresponding teeth above/below the abscess

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28
Q

What are the 3 main salivary glands?

A

Parotid
Sublingual
Submandibular

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29
Q

What % of saliva is water?

A

Approx 99%

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30
Q

Is saliva acidic, neutral or alkaline?

A

Slightly acidic (pH 6.75 - 7) to provide optimal conditions for enzyme action

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31
Q

What enzymes does saliva contain?

A
  • lipase
  • alpha-amylase
  • lysozyme
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32
Q

What does saliva contain?

A
  • water (99%)
  • lipase
  • amylase
  • lysozyme
  • mucoproteins (mucin for lubrication)
  • immunoglobulins (esp, IgA)
  • electrolytes
  • calcium and phosphate (dental repair)
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33
Q

Which immunoglobulin is most abundant in saliva?

A

IgA

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34
Q

What approximate pH is saliva at?

A

6.75 - 7

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35
Q

Which element in saliva acts to lubricate the passage of food ?

A

Mucoprotiens (mucin)

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36
Q

Where are the salvatory nuclei located?

A

Pons and medulla

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37
Q

What type of receptors in the mouth stimulate watery saliva production ?

A

Mechanoreceptors
Chemoreceptors

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38
Q

Which type of receptors trigger saliva production when non-food objects enter the mouth?

A

Mechanoreceptors

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39
Q

What is the composition like of saliva produced in reaction to:
a) non-food stimuli ?
b) food stimuli ?

A

High water content = non-food stimuli
High enzyme content = food stimuli

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40
Q

Name the 2 intrinsic nerve plexuses in control of gut function …

A

Myenteric nerve plexus
Submucosal nerve plexus

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41
Q

Are the myenteric/submucosal nerve plexuses sympathetically or parasympathetically innervated?

A

Parasympathetic innervation

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42
Q

Which cranial nerve regulates the enteric nervous system (ENS)?

A

CN X = Vagus

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43
Q

What are the 3 divisions of the autonomic nervous system ?

A

Sympathetic NS
Parasympathetic NS
Enteric NS

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44
Q

What is the Enteric Nervous System (ENS) ?

A

The nervous system exclusively influencing the GI system

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45
Q

What are the 2 principle components of the enteric nervous system ?

A
  • myenteric (Auerbach’s) plexus
  • submucosal (Meissner’s) plexus
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46
Q

What is the function of the myenteric plexus?

A

Controls digestive tract motility

Increase muscular tone/strength/velocity of muscular contractions in peristalsis

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47
Q

What is the function of the submucosal plexus?

A

Controls absorption

Controls localised secretions, local muscular action, blood flow and, therefore, absorption of nutrients

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48
Q

What are the layers of the wall of the GI tract?

A
  • lumen of GI tract
  • mucosa
  • submucosa (containers submucosal plexus)
  • muscularis externa (circular muscular layer -> myenteric plexus -> longitudinal muscular layer)
  • serosa
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49
Q

What 2 layers make up the muscularis externa in the GI tract wall?

A
  • circular muscular layer (inner)
  • longitudinal muscular layer (outer)
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50
Q

What action does contraction of the circular muscular layer have in the gut?

A

Squeezes gut contents

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51
Q

What action does contraction of the longitudinal muscular layer have in the gut?

A

Shortens that portion of the gut

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52
Q

Are the smooth muscle layers in the gut (muscularis externa) regulated or spontaneously active?

A

Smooth muscle in the gut is spontaneously active

regulated by enteric or extrinsic neurones

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53
Q

What are the pace maker cells of the gut called?

A

Interstitial cells of cajal (found in circular smooth muscle)

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54
Q

Where are the pacemaker cells (cells of cajal) found in the gut lining?

A

In the circular muscle layer of the muscularis externa

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55
Q

What can a loss of interstitial cells of cajal result in?

A

Gut motor dysfunction disorders

56
Q

How long is the average oesophagus in adults?

A

Approx. 25cm long

(Pharynx to stomach)

57
Q

What structures are contained within the submucosal layer of the GÌ tract?

A
  • blood vessels
  • lymphatics
  • nerves
  • lymphoid tissue
  • mucus glands
58
Q

Which sections of the oesophagus are voluntary/involuntary with regards to innervation of muscularis externa muscle?

A
  • first 1/3 = voluntary skeletal muscle (decide to swallow)
  • last 1/3 = involuntary smooth muscle (food pushes through involuntarily)
  • middle third = mixed
59
Q

What is adventitia?

A

The outer layer of fibrous connective tissue surrounding an organ

60
Q

What is the outer layer of the oesophagus mainly made up of?

A

Adventitia fixed to adjacent structures via connective tissue
(fibrous connective tissue)

61
Q

Which part of the oesophagus is cover with serosa (rather than adventitia?)

A

Serosa = past the diaphragm

62
Q

Is the oesophagus held open or closed during relaxation periods?

A

The oesophagus is closed until food/an object pushes through it

63
Q

What is the mucosa like within the oesophagus?

A

Highly folded (when oesophagus is closed)

64
Q

What kind of epithelium is found in the oesophagus?

A

Stratified squamous epithelium

resists abrasion

65
Q

What is the epithelium like in the GI tract after the oesophagus (at gastro-oesophageal junction) ?

A

Columnar epithelium (glandular)

66
Q

What is a condition called that is seen in some patients prior to developing oesophageal cancer?

A

Barrett’s oesophagus

67
Q

What is Barrett’s Oesophagus?

A

Unusual change of the epithelium within the oesophagus (from normal stratified to the columnar epithelium seen in gastric tract) due to to repeated damage from gastric reflux

68
Q

What can cause Barrett’s Oesophagus ?

A

Acid/gastric reflux

69
Q

Which general part of the stomach undergoes peristalsis?

A

Lower part of stomach

70
Q

Which valve in the stomach acts in response to peristalsis?

A

Pyloric valve

71
Q

What features of the stomach cause vigorous churning and slow gastric emptying of the stomach?

A
  • peristalsis
  • pyloric valve
72
Q

What are the longitudinal mucosal folds called in the stomach ?

A

Rugae

73
Q

Are the stomach’s mucosal and submucosal layers thin or thick?

A

Thick

74
Q

What is one factor that controls the rate of gastric emptying of the stomach?

A

The caloric value of the contents in the duodenum

(duodenum = the next part of GI tract connected to stomach)

75
Q

Which valve separates the stomach and the duodenum?

A

Pyloric valve / pylorus

76
Q

What is the period/state between meals called?

A

Interdigestive state

77
Q

When does the migrating motor complex (MMC) occur?

A

Between meals, in the interdigestive state

78
Q

How long can it take for the migrating motor complex (MMC) to pass along the small intestine?

A

Up to 2 hours

79
Q

What is the role of the migrating motor complex (MMC) ?

A

“House keeping” role = sweeps undigested material through the gut after eating

80
Q

What is the migrating motor complex (MMC)?

A

Small irregular contractions of the small intestine during a period of ‘fasting’

81
Q

What acts as a signal to stop the migrating motor complex (MMC)?

A

Release of gastrin and cholecystokinin in response to eating

eating triggers peristalsis which is better suited to nutrient absorption

82
Q

Where is gastrin released from ?

A

The stomach

83
Q

What is gastrin?

A

Peptide hormone that aids in gastric motility

84
Q

Where is cholecystokinin (CCK) released from ?

A

The small intestine

85
Q

What is cholecystokinin (CCK)?

A

A peptide hormone that stimulates fat and protein digestion

86
Q

Which peptide hormone is a potent inhibitor of gastric emptying? What is it responding to?

A

Cholecystokinin (CCK)
Stops gastric emptying in response to high caloric value in the duodenum

87
Q

What are the 3 parts of the small intestine in order?

A
  • duodenum (closest to stomach)
  • jejunum
  • ileum
88
Q

What are the parts of the large intestine, in order ?

A
  • cecum
  • ascending colon
  • transverse colon
  • descending colon
  • rectum
  • anus
89
Q

What is another term for the large intestine?

A

The colon

90
Q

Which part of the colon has the longest transit time?

A

The transverse colon

91
Q

What is the average transit time in the colon?

A

2-3 days !

92
Q

Is the colon active:
a) constantly ?
b) spontaneously ?
c) during eating ?
d) during fasting ?

A

The colon is active constantly

93
Q

Haustral contractions Vs peristalsis in the colon?

A

Haustral contractions
= circular muscle contractions every 20/25 mins
= move food along the colon, from one haustra (pocket/bulge) to the next
= slow and continuous

Peristalsis
= circular + longitudinal muscle contractions 1/2 times a day
= shifts formed faecal matter from colon to rectum/anus
= relatively fast/forceful and infrequent

94
Q

What does contraction of circular muscles in the colon cause?

A

Haustra = the rippled-looking bulges/pockets of the gut that are full of food

95
Q

What is a haustrum?

A

A pocket in the colon formed by circular muscle contraction on either side of food

gives the colon it’s rippled/bulging appearance

96
Q

What is the gastrocolic reflex ?

A

Powerful propulsive contractions are initiated in the colon when food enters the stomach

= dispels waste products to allow space for the new food entering

97
Q

Where is gastrin produced/secreted?

A

Pyloric antrum (just before the valve)

98
Q

Which cells produce gastrin in the stomach?

A

G cells

99
Q

What are the functions of the stomach ?

A
  • mix food
  • act as a reservoir
  • synthesise intrinsic factor
  • start digestion (activates enzymes)
  • destroy some bacteria/pathogens
  • absorb some water, alcohol and B12
100
Q

What is the only essential function of the stomach ?

A

Synthesis of intrinsic factor

(Intrinsic factor allows B12 absorption)

101
Q

What does intrinsic factor do?

A

Allows for B12 absorption in the intestines

102
Q

What is the rough pH of the stomach?

A

pH 1 - 2
(very acidic)

103
Q

Which acid is found in the stomach?

A

Hydrochloric acid

104
Q

Where is the majority of alcohol absorbed in the GI tract?

A

Duodenum and jejunum
(Small intestine)

105
Q

Name the exocrine and endocrine gastric (stomach) secretions …

A

EXOcrine secretions:
- hydrochloride acid
- mucus
- Pepsinogen
- intrinsic factor

ENDOcrine secretions:
- gastrin
- somatostatin

106
Q

What do goblet cells secrete in the stomach?

A

Alkaline mucus
(to protect the epithelium from acidic conditions within stomach)

107
Q

What do mucous cells secrete in the stomach?

A
  • Mucus
  • Pepsinogens
108
Q

What do parietal cells secrete in the stomach?

A
  • gastric acid
  • intrinsic factor
109
Q

What do chief cells secrete in the stomach?

A
  • pepsin
  • gastric lipase
110
Q

What do G cells secrete in the stomach?

A

Gastrin

111
Q

What do D cells secrete in the stomach? Where are they found?

A

Secrete: somatostatin
Found: in antrum (close to pyloric valve)

112
Q

What is the function of hydrochloric acid in the stomach?

A
  • kills pathogens/bacteria
  • initiates digestion
  • produces pepsin from pepsinogen precursor
113
Q

What is the function of mucus in the stomach?

A

Protects mucosal surface from damage caused by HCl

114
Q

What is the function of pepsinogen in the stomach?

A

Precursor of the endopeptidase pepsin

115
Q

What is the function of intrinsic factor in the stomach?

A
  • Important in the absorption of B12 (in the gut)
  • important in erythropoeisis
116
Q

What is the function of gastrin in the stomach?

A

Stimulates gastric acid production for digestion

117
Q

What is the function of somatostatin in the stomach?

A

Inhibits release of gastrin

118
Q

What is an endopeptidase? Function?

A

An enzyme that hydrolyses the inner bonds between amino acids (rather than the terminal/end bonds) = shortens amino acid chains

119
Q

Stimulation of which nerve increases pepsinogen secretion in the stomach?

A

Vagus nerve
(CN X)

120
Q

Which neurotransmitter acts to increase pepsinogen secretion via CN X ?

A

Acetylcholine

121
Q

Which chemicals act as stimulants for the secretion of hydrochloric acid (HCl) in the stomach?

A
  • acetylcholine (via vagal input)
  • gastrin (from G cells)
  • histamine (from enterochromaffin cells)
  • other hormones
122
Q

Stimulation of which nerve can increase secretion of HCl in the stomach?

A

Vagus nerve
(CN X)

123
Q

What are the factors/chemicals that inhibit gastric acid secretion?

A
  • somatostatin
  • secretin
  • gastric inhibitory peptide (acts on parietal cells)
124
Q

What are the 3 phases of gastric acid secretion called?

A
  1. Cephalic phase (40%)
  2. Gastric phase (50%)
  3. Intestinal phase (10%)
125
Q

Roughly what % of gastric acid secretion occurs in the cephalic phase?

A

40%

126
Q

Roughly what % of gastric acid secretion occurs in the gastric phase?

A

50%

127
Q

Roughly what % of gastric acid secretion occurs in the intestinal phase?

A

10%

128
Q

Which phase(s) of gastric acid secretion is/are vagally (CN X) mediated ?

A

Cephalic phase
Gastric phase

129
Q

What factors trigger the Cephalic phase of gastric acid secretion?

A

Thought, smell, sight and taste of food

130
Q

How does the Cephalic phase result in gastric acid secretion?

A
  • Thought/sight/taste/smell of food releases Acetylcholine (via vagus nerve)
  • ACh stimulates parental cells and G cells to release gastrin
131
Q

How does the gastric phase result in gastric acid secretion?

A
  • Distension, reflex activation of enteric neurones and vagal outflow stimulates parietal cells and G cells to secrete gastrin + gastric acid
    - digested proteins in stomach stimulate G cells too
132
Q

How does the intestinal phase result in gastric acid secretion?

A

Amino acids in the blood (from protein digestion) directly stimulate parietal cells to produce gastric acid

133
Q

What are the 2 mechanisms that inhibit gastric acid secretion ?

A
  1. Gastric mechanism
  2. Duodenal mechanism
134
Q

How does the gastric mechanism of inhibiting gastric acid secretion work?

A
  • if proteins are in the stomach they create a buffer to keep lumen pH > 3 (normal)
  • as stomach empties, lumen pH falls below pH 3
  • stimulates D cells to release somatostatin to inhibit gastrin release
135
Q

How does the duodenal mechanism of inhibiting gastric acid secretion work?

A

as stomach empties into duodenum lumen pH falls

  1. acidification of duodenal lumen stimulates secretin release (inhibits gastrin secretion)
  2. acidification of duodenal lumen + presence of fatty acids and salt release gastric inhibitory peptide which acts on parietal cells to inhibit HCL secretion
136
Q

List the 6 major GI hormones and where they’re produced…

A
  1. Gastrin // G cells in antrum of stomach
  2. Motilin // duodenum
  3. Gastric inhibitory peptide (GIP) // small intestine
  4. Cholecystokinin (CCK) // small intestine
  5. Secretin // small intestine
  6. Vasoactive intestinal peptide (VIP) // glands and nerves

Sem 4, case 1 (oesophageal cancer) (6 decks)

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