GI histology Flashcards

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1
Q

what organs are found within alimentary canal?

A

esophagus, stomach, large and small intestine

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2
Q

types of muscle of alimentary canal

A
  • esophagus = only one with striated muscle

- rest of organs = smooth muscle

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3
Q

types of tissue in alimentary canal

A
  • oral cavity and esophagus = non-keratinized stratified squamous epith.
  • rest of organs = simple columnar
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4
Q

what is found within the submucosa?

A

Meissner’s plexus (nerves and ganglion)

-also blood vessels

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5
Q

what is found within the muscularis externa?

A

Auerbach’s (myenteric) plexus (nerves and ganglion)

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6
Q

serosa vs adventitia

A
  • serosa = mesothelium + connective tissue - found in distal portion of esophagus
  • adventitia = only connective tissue - found w/I most of esophagus
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7
Q

what does the muscularis mucosae layer in esophagus contain?

A

longitudinally oriented bundles

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8
Q

types of glands in esophagus

A
  1. mucosal glands (esophageal cardiac glands)
    - only in terminal esophagus
  2. submucosal glands (esophageal glands proper)
    - entire esophagus
    - tubuloalveolar glands
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9
Q

what types of muscle are in muscularis externa of esophagus?

A
  • upper portion = skeletal muscle
  • middle 1/3 portion = skeletal and smooth muscle
  • lower portion = smooth muscle
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10
Q

Barrett’s esophagus

A

metaplasia of esophageal epith.

  • transition from non-keratinized Strat. squamous epith. to simple columnar epith.
  • caused by gastroesophageal reflux
  • precursor for adenocarcinoma
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11
Q

stomach functions

A
  1. store food = chyme formation, expandable, rugae
  2. food digestion = secrete HCl, pepsin, lipase
  3. regulate GI through gherlin and gastric secretions
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12
Q

pepsin

A

breakdown proteins

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13
Q

lipase

A

breakdown TAGs

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14
Q

HCl

A
  • destroy bacteria
  • breakdown protein
  • convert pepsinogen to pepsin
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15
Q

endocrine cells role in GI regulation

A

secrete gherlin and gastrin to increase gastric acid secretions

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16
Q

where are the glands of the stomach located?

A

mucosa layer

-cardiac, fundic, and pyloric glands

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17
Q

3 layers of muscularis externa of stomach?

A
  • inner oblique
  • middle circular
  • outer longitudinal
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18
Q

what cells are found in the gastric mucosa?

A

surface mucous cell - secretes insoluble mucous –> forms the lining of the stomach protecting cells from HCl (contact can lead to gastric ulcers)

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19
Q

where are the gastric glands located?

A

lamina propria

  • cardiac, fundic, pyloric glands
  • also contain lymphoid tissue and have leukocytes to prevent infection if infiltration occurs
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20
Q

fundic glands

A

parts: isthmus (apical), neck (principle piece), and base (next to muscularis mucosa)
- parietal, gastric chief, mucous neck, progenitor, and enteroendocrine cells

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21
Q

parietal cell

A
  • secrete HCl and intrinsic factor for vit. B12 absorption
  • largest & contain a lot of mitochondria (eosin - red color)
  • active cell = intracellular canicullu w/ microvilli for HCl and intrinsic factor production
  • resting cell = tubulovesicular system for storage
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22
Q

deficiency of parietal cells (ex. chronic gastritis)

A

no intrinsic factor –> no absorption of vit. B12 –> no Hb synthesis –> pernicious anemia

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23
Q

gastric ulcers

A
  • destroy epithelial barrier by HCl release

- if untreated, can penetrate deeper into stomach causing peritonitis

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24
Q

gastric chief cells

A
  • secrete pepsinogen (convert pepsinogen to pepsin)
  • secrete gastric lipase (breakdown TAGs)
  • pepsin = breakdown protein
  • many RER for protein synthesis (hematoxylin-blue color)
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25
Q

mucous neck cell

A
  • secrete soluble mucous
  • heterochromatic nucleus with “frothy” cytoplasm
  • no staining of eosin or hematoxylin
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26
Q

enteroendocrine cell aka G cell

A
  • secrete gastrin = increase gastric acid
  • secrete gherlin = increase appetite/hunger
  • both released into lamina propria to enter bloodstream
  • contain microvilli and secretory granules
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27
Q

progenitor cell

A

stem cells

  • become surface mucous cells or other gland cells
  • shorter life span for surface mucous cells –> exposed to acid and chyme and need to regenerated more
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28
Q

cardiac gland

A
  • around esophageal orifice
  • secrete mucous for gastric reflux protection
  • shorter gastric pit
  • no parietal/chief cells
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29
Q

pyloric gland

A
  • pyloric antrum
  • secrete mucous for gastric reflux protection
  • longer gastric pits
  • darker than cardiac
  • no parietal/chief cells
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30
Q

carcinoma of stomach

A

surface epithelial cells

-intestinal metaplasia - contain many goblet cells

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31
Q

adenocarcinoma of stomach

A

glandular epithelium

-ring shaped cells

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32
Q

stages of stomach cancers

A
  1. early
    - penetrate submucosa and good prognosis
  2. late
    - penetrate to muscularis externa and bad prognosis
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33
Q

functions of the small intestine

A
  1. digestion (main)
  2. absorption
  3. synthesis and secretion (digestive enzymes)
  4. antimicrobial
  5. regulate GI function (enteroendocrine cells)
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34
Q

layers of the small intestine

A
  • mucosa
  • submucosa
  • muscularis externa
  • serosa/adventitia
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35
Q

what makes up the plicae circularis?

A

mucosa and submucosa

  • found in the distal duodenum and proximal jejunum
  • permanent fold
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36
Q

what makes up the villi?

A

mucosa only

  • evaginations of mucosa containing surface epith.
  • lamina propria is the core
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37
Q

microvilli

A

the cells on the villi

-very small and look like brush border

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38
Q

role of plicae circularis, villi, and microvilli?

A

increase surface area for better absorption

  • lacteals absorb lipids packages in chylomicrons
  • vascular loops absorb carbs and AAs
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39
Q

crypt of lieberkuhn

A

invaginations of epithelium that forms a gland

-contain paneth and progenitor cells

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40
Q

celiac disease

A

gluten enteropathy

  • hypersensitivity to gluten
  • atrophy of villi (complete or incomplete loss)
  • steatorrhea (fatty feces) –> no villi or lacteals to absorb lipids
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41
Q

what type of epithelium is the alimentary canal?

A

simple columnar epith. containing microvilli

-except esophagus

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42
Q

enterocyte functions (most prominent)

A
  • microvilli to increase surface area for absorption
  • tight junctions for barrier against bacteria and immune cells
  • digestion of carbs/proteins by vascular loops in lamina propria (enzymes in glycocalyx)
  • digestion of lipids
  • transcytosis of IgA
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43
Q

how are lipids digested by enterocytes?

A

lipid breakdown in lumen –> resynthesis of triglycerides in SER –> form protein coat (chylomicrons) –> transport via lacteals to lymphatic vessels

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44
Q

how is IgA transcytosed in enterocytes?

A

plasma cells make IgA –> bind to receptors on enterocytes and endocytosed –> released into lumen for bacterial and mucosal protection

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45
Q

Goblet Cell

A

unicellular mucous glands

  • mainly in large/small intestine
  • do not stain with H&E –> frothy, white areas
  • heterochromatic (nonactive) nucleus
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46
Q

M cell

A

antigen presenting cells

-microfolds capture antigen and transport it from lumen to lymphoid follicle for antibodies to made against it

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47
Q

what is a lymphoid follicle?

A

area of clusters of immune cells

-contain lymphocytes, neutrophils, or macrophages

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48
Q

enteroendocrine cells

A

GI function regulation

  • produce hormones gastrin and gherlin
  • aka APUD cells
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49
Q

intraepithelial lymphocytes

A

mucosal immunity

  • bone marrow derived
  • T lymphocytes
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50
Q

paneth cells

A

eosinophilic granules contain antibacterial enzymes to protect the crypt from bacterial growth

  • base of the crypt
  • bright red staining cytoplasm
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51
Q

progenitor cells

A

stem cells of epith. and gland (crypt)

  • found in crypt
  • mitotic cells
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52
Q

lamina propria of small intestine

A

connective tissue that contains leukocytes - GALT

  • diffuse = lymphocytes and Macs
  • scattered = duodenum and jejunum
  • peyer’s patch = aggregated lymphoid follicles in ileum
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53
Q

lymphoma (maltoma)

A

thickening of lamina propria due to infiltration of lymphocytes

  • from MALT
  • cancer of small intestine
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54
Q

blood supply in small intestine

A

vascular plexus in submucosa extends as vascular loops into villi
-collect nutrients

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55
Q

lymphatics of small intestine

A

fats packaged as chylomicrons transported by lacteals to enter lymphatics in submucosa

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56
Q

Brunner’s glands

A

mucous glands - produce alkaline fluid to neutralize gastric acid

  • found within submucosa
  • only in duodenum
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57
Q

what is found in submucosa of small intestine?

A
  • messiener plexus
  • brunner’s glands
  • vascular plexus
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58
Q

what is found in the muscularis externa layer of small intestine?

A
  • inner circular layer
  • outer longitudinal layer
  • Auerbach’s plexus
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59
Q

what contains mostly adventitia?

A

duodenum

-distal duodenum, ileum, and jejunum contains serosa (mesothelium + connective tissue)

60
Q

where are submucosal (Brunner’s) glands located?

A

duodenum

61
Q

where are Peter’s patches and most goblet cells found?

A

ileum

62
Q

regions of large intestine

A
  • cecum
  • colon
  • rectum
  • anus
63
Q

function of large intestine

A
  • reabsorption - electrolytes and water

- eliminate waste

64
Q

mucosa of large intestine

A
  • no paneth cells in crypts of lieberkuhn - only progenitor
  • no villi
  • many goblet cells
65
Q

muscularis externa of large intestine

A
  • inner circular layer

- outer longitudinal layer - forms thick bands of tiniae coli

66
Q

serosa of large intestine

A

contain omental appendices - fat projections

67
Q

adenocarcinoma

A

most common large intestine cancer

  • arise in patients with adenomatous polyps or ulcerative colitis
  • treat with total resection
68
Q

regional differences in large intestine

A
  • colon - largest, contains tiniae coli
  • vermiform appendix - aggregated lymphoid nodules
  • rectum - transverse rectal folds
69
Q

what are the 4 layers of the GI tract?

A
  1. mucosa (epith., lamina prop., muscularis mucosa)
  2. submucosa (blood & lymph vessels, meissner plexus)
  3. muscularis (aka muscularis externa) - Auerbach nerve plexus b/w inner circular & outer longitudinal muscle
  4. serosa (mesothelium + connective tissue)
70
Q

what 2 nerve plexuses comprise the enteric nervous system?

A
  • Meissner plexus (in submucosa)

- Auerbach plexus (in muscularis externa)

71
Q

Auerbach’s plexus

A

b/w the smooth muscle layers of muscularis externa

-controls peristalsis

72
Q

Hirschsprung disease (congenital aganglionic megacolon)

A

dilation and hypertrophy of the colon due to reduced or loss of ganglion in myenteric plexus of gut and rectum
-loss of peristalsis contractions (gut motility)

73
Q

oral cavity wall structure

A
  1. mucosa (epithelium contains keratinized & non-keratinized epith., lamina propria, no muscularis mucosa)
  2. submucosa (salivary glands, Meissner plexus)
  3. muscularis externa (skeletal muscle, Auerbach’s plexus
  4. no serosa or adventitia
74
Q

function of Meissner (submucosa) plexus

A
  • motility of the mucosa and submucosa

- secretory activity

75
Q

lips

A
  • vermilion zone - red/pinkish color from dermal papillae containing capillaries
  • contains minor salivary glands
76
Q

cold sores

A

contagious blisters on outside of mouth

-caused by HSV type 1 (reside in trigeminal ganglion in dormant state)

77
Q

canker sores (aphthous ulcers)

A

sores inside the mouth

-may be due to virus, autoimmune, or allergic rxn

78
Q

tongue

A
  • intrinsic muscle - alter shape
  • extrinsic muscles - move tongue
  • terminal groove (sulcus) divides tongue into lingual tonsil (post.) & mucosal projections (ant.)
  • foramen cecum - thyroid origin
79
Q

leukoplakia

A

cancer of oral region

-white patch or plague

80
Q

where does the majority of cancers of oral cavity arise from?

A

stratified squamous epith. –> squamous cell carcinoma

-ulcers, malignant keratinocytes

81
Q

purpose of lingual papillae

A

gustation via taste buds

  • taste buds scattered everyone (not constricted to papillae)
  • taste buds contain supportive cells & basal (stem) cells
  • salty, sour, bitter, sweet, savory
82
Q

filiform papillae

A
  • most numerous
  • entire surface of tongue
  • scrape food off surface (sand paper)
  • NO taste buds
83
Q

Fungiform papillae

A
  • “mushroom”
  • most numerous at apex and sids
  • has taste buds
84
Q

foliate papillae

A
  • posterolateral folds

- has taste buds

85
Q

circumvallate (vallate) papillae

A
  • anterior to terminal groove
  • taste buds down sides
  • surrounded by moat like trenches where serous salivary (von Ebner) glands drain into
86
Q

function of von Ebner glands

A
  • flush food particles away from vallate papillae

- contain lipase to prevent formation of film that would hinder gustation

87
Q

4 types of teeth

A
  1. incisors - cutting, one root
  2. canines - grasping and tearing, one root
  3. premolars - crushing, two roots
  4. molars - crushing, 3 roots
88
Q

3 calcified mineral substances of tooth

A
  1. dentin - bulk of tooth
  2. enamel - covers crown
  3. cementum - covers root
89
Q

enamel

A

overlies dentin of crown

  • hardest substance in body (Ca2++ hydroxyappetite)
  • studied by decalcification & ground sections
  • ameloblasts make enamel
  • cannot repair enamel
  • acidic pH –> dental carries
90
Q

dentin

A

bulk of tooth

  • 2nd hardest substance in body (Ca2++ hydroxyappetite)
  • odontoblasts make dentin
  • viable for life
  • can be repaired
91
Q

cementum

A

outer layer of root of tooth (over dentin)

  • anchors periodontal lig. to roots of tooth
  • made by cementoblasts
  • viable for life
92
Q

pulp of tooth

A

consists of blood vessels, nerves, fibroblasts
-center of tooth
4 regions
1. odontoblastic layer - overlies pulp layer & under dentin layer
2. cell free zone
3. cell rich zone
4. core

93
Q

periodontal ligament

A

attaches to cementum and alveolar bone

  • holds tooth in place
  • shock absorber
  • sharpes fibers (type 1 collagen fibers)
94
Q

gingiva

A

bound to periosteum of jaw bone

  • junctional epith. - attaches gingiva to enamel
  • gingival sulcus - site for periodontal disease
95
Q

how can food lodged in teeth cause damage?

A

bacterial flora secrete organic acids to dissolve food –> can dissolve Ca2++ hydroxyappetite causing tooth decay
-fluoride makes enamel more resistant to bacteria by decreasing the acids (Fluoroapatite crystals instead of hydroxyapatite crystals)

96
Q

what happens if you don’t brush or floss teeth?

A
  • biofilm known as plaque
  • plaque can calcify forming calculus - covering for bacteria to grow causing gingivitis
  • progressive gingivitis –> attack periodontal lig. –> periodontitis
97
Q

what are the 2 components of salivary glands?

A
  1. ducts - deliver saliva to oral cavity
  2. secretory cells - tell you whether acinus contains serous, mucous, or both

roles - moisten mucous membrane and food, digestion, germicidal protection

lobes –> lobules

98
Q

what are found w/I the lobules of salivary glands?

A

adenomeres - secretory units of glands that contain acini cells (serous or mucous)
-both types of acini dump into intercalated ducts

99
Q

how do you identify serous acini?

A
  • round nuclei
  • stain dark
  • protein secreting, accumulation of RER and ribosomes
100
Q

how do you identify mucous acini?

A
  • flattened nuclei
  • stain light
  • GAG secretion
101
Q

2 types of intralobular ducts

A
  1. intercalated ducts - continuous w/ acini, simple squamous

2. intralobular - striated, infoldings that allow products to enter, cuboidal

102
Q

interlobular (excretory) ducts

A

excretory ducts that enter oral cavity

  • larger than intralobular ducts
  • columnar to strat. columnar
103
Q

parotid gland

A
  • largest salivary
  • SEROUS acini - stain dark, round nucleus
  • opens into vestibule of oral cavity
104
Q

submandibular gland

A
  • make up most of saliva
  • both serous and mucous acini (mostly serous)
  • dark and light stains
  • opens into lingual frenulum
  • some mucous acini surrounded by cap cells (serous demilune) that secrete serous fluid
105
Q

sublingual gland

A
  • smallest salivary gland

- mainly MUCOUS acini - light stain, flat nuclei

106
Q

xerostomia

A

dry mouth
-caused by decreased production of saliva
causes
-medications, cancer therapy (radiation), Sjogren’s, nerve damage
effects
-cracks in tongue, breakdown teeth, oral infections, gingivitis

107
Q

hepatocytes

A

major cell of liver - endocrine and exocrine functions

  • bile production (digest fat)
  • hormone & protein synthesis (high RER & Golgi)
  • metabolic functions
  • detoxification via SER
108
Q

lobules of the liver

A
  • contain capillaries called sinusoids
  • hexagon shape
  • portal triad and lymph vessels on outside
  • central vein in center
109
Q

what is found w/I the portal triad?

A
  • hepatic portal vein
  • hepatic artery
  • bile duct
110
Q

where does the blood supply travel in liver lobule?

A

from periphery to the central vein

-dual blood supply by portal triad

111
Q

where does lymph and bile travel in liver lobule?

A

from center to periphery

112
Q

function of RER in hepatocytes

A

protein synthesis

-basophilic staining

113
Q

function of SER in hepatocytes

A
  • enzymes for detoxification and for conjugating bilirubin to glucuronate
  • formation of bile
  • put bile components into bile canaliculi to enter bile ducts in periphery
114
Q

metabolic functions of hepatocytes

A

storage of glucose, fat, and iron

115
Q

function of peroxisomes of hepatocytes

A

oxidation of fats and breakdown of hydrogen peroxide

116
Q

the celiac trunk

A

supplies the foregut

-gives rise to common hepatic, left & right gastric, and splenic artery

117
Q

what are the 2 sources of blood supply to the liver?

A
  • hepatic artery proper (supplies the O2)
  • hepatic portal vein (supplies the nutrients)
  • found in portal spaces
  • branches –> hepatic arteriole & hepatic portal venule
118
Q

blood drainage of the liver

A

central vein –> 3 hepatic veins (right, middle, and left) –> IVC –> right atrium

119
Q

portal spaces

A

periphery of the lobules

  • contain portal triad
    1. hepatic arteriole (lot of smooth muscle, round)
    2. portal venule ( large, irregular lumen)
    3. bile ductule (simple cuboidal epith.)
120
Q

what are sinusoids?

A

special capillaries b/w the plates of hepatocytes

  • where portal venule and hepatic arteriole drain
  • converge at central vein
  • fenestrated endothelium - take up nutrients, O2, release hormones
121
Q

zones of the hepatic lobule

A

zone 1 - least affected by ischemia (closer to blood supply); oxidative processes, most susceptible to blood borne pathogens
zone 2 - intermediate
zone 3 - most affected by ischemia

122
Q

space of disse (perisinusoidal space)

A

b/w the sinusoids and the hepatocytes

-contains lymphatic capillaries that flow towards lymph vessels in portal spaces

123
Q

bile canaliculi

A

anastomoses of bile channels –> form bile canals of Hering –> dump into bile ductules in portal space –> right and left hepatic ducts to leave liver
-canal of Hering composed of cholangiocytes (cuboidal)

124
Q

Kupffer cells

A

liver macrophages

  • found in lumen of sinusoids
  • phagocytose foreign matter and breakdown RBCs
125
Q

Ito (fat storing or hepatic stellate cells)

A

fibroblasts in space of disse

  • lipid droplets that store vit. A and fat
  • produce extracellular matrix components
  • divide forming myofibroblasts - pathogenesis of fibrosis and portal HTN (no exchange of nutrients due to connective tissue)
126
Q

classic liver lobule

A
  • hexagon
  • ENDOCRINE function (make proteins & hormones)
  • portal spaces on edge of lobule
  • blood flows to central vein to go to rest of body
127
Q

portal lobule

A
  • triangle formed by 3 central veins on corners
  • EXOCRINE function (make bile)
  • portal triad (bile ductule) at the center
  • flow of bile from bile canaliculi to bile ductules
128
Q

hepatic acinus (acinus of Rappaport)

A
  • blood supply carrying nutrients and O2 (which varies) from periphery to central vein
  • diamond (2 portal triads & 2 central veins)
  • 3 zones
129
Q

periportal hepatocytes of acinus

A

zone 1

  • nearest portal triad
  • get most O2, hormones, and nutrients
  • more oxidative metabolism (glycogen & protein synthesis)
130
Q

zone 3 hepatocytes

A
  • near the central vein
  • least amount of O2 and nutrients
  • 1st to show ischemic necrosis and fat accumulation
  • lipolysis, glycolysis, drug/ETOH detox
131
Q

cirrhosis

A

advanced stage of liver disease associated w/ fibrosis

  • connective tissue fills perisinusoidal space interfering w/ metabolic exchange w/ sinusoids (no detox or hormone release)
  • fibrosis from Ito cells
  • scar tissue from trying to heal itself
  • caused by alcohol or hepatitis
  • fibrosis destroys portal tract to central vein
132
Q

fatty liver disease

A

steatosis - accumulation of fat in lipid droplets

  • associated with alcoholism or obesity
  • may produce non-infectious hepatitis –> steatohepatitis
133
Q

nonalcoholic fatty liver disease

A

too much storage of fat (not caused by alcohol)

  • obesity or insulin resistance
  • can lead to non-alcoholic steatohepatitis (NASH) –> fat accumulation, inflammation (WBCs), and scarring –> can progress to cirrhosis and liver failure
134
Q

gallbladder

A

stores, concentrates, and released bile

-bile enters duodenum when there is dietary fat

135
Q

function of enteroendocrine cells of small intestine

A

release CCK –> contraction of gallbladder and secretion of pancreatic juice

136
Q

gallbladder histology

A
  1. mucosa - columnar epith., lamina propria, no muscularis mucosa
    - branched mucosal folds (appear glandular) –> Rokitansky-Aschoff crypts/sinuses
  2. no submucosa
  3. muscularis externa (contract & empty GB)
  4. adventitia and serosa
137
Q

what is cholelithiasis?

A

formation of gallstones

  • formed by reabsorption of water from bile or from gallbladder not emptying correctly
  • excess cholesterol from liver –> cholesterol stones
  • excess bilirubin from SER –> pigment stones (black) which cause inflammation
138
Q

what can gallstones lead to?

A

biliary obstruction –> lead to chronic cholecystitis

  • block flow in cystic duct
  • can be acute or chronic cholecystitis
139
Q

acute cholecystitis

A
  • suddenly; sever pain in abdomen
  • obstruction of neck or cystic duct
  • most common reason for emergency cholecystectomy
140
Q

chronic cholecystitis

A

inflammation that lasts a long time

  • gallstones can pass
  • periodic attacks when gallstones cause blockage
  • damage caused by the repeat attacks causing inflammation –> scarring, wall thickening, parcelain GB)
141
Q

pancreas

A
  1. exocrine functions - make digestive enzymes and bicarb rich buffering fluid by acinar cells
  2. endocrine functions - make hormones by islets of langerhans
142
Q

pancreatic acinar cells function

A

produce digestive enzymes that breakdown nutrients when entering duodenum

  • round nuclei and zymogen granules (house proenzymes)
  • enzyme release by CCK (main) and ACh
143
Q

centroacinar cells

A

secrete a watery, bicarb rich fluid to alkalinize the hydrolytic enzymes of acinar cells
-bicarb secreted when secretin signals (from enteroendocrine cells); also from ACh

144
Q

pancreatic cancer

A

usually carcinoma of the duct cells in the head region

  • high mortality (asymptomatic until metastasis)
  • poorly defined acinar cells and a lot of fibrosis on histo
145
Q

pancreatitis

A

inflammation of pancreas - destroy pancreatic acinar cells

  • acute - activate proenzymes and digest tissue
  • chronic - fibrosis and loss of pancreas function

causes - duct obstruction, acinar cell injury, defective intracellular transport
effects - inflammation, edema, breakdown proteins, fat necrosis, hemorrhage