GI histology Flashcards
1
Q
what organs are found within alimentary canal?
A
esophagus, stomach, large and small intestine
2
Q
types of muscle of alimentary canal
A
- esophagus = only one with striated muscle
- rest of organs = smooth muscle
3
Q
types of tissue in alimentary canal
A
- oral cavity and esophagus = non-keratinized stratified squamous epith.
- rest of organs = simple columnar
4
Q
what is found within the submucosa?
A
Meissner’s plexus (nerves and ganglion)
-also blood vessels
5
Q
what is found within the muscularis externa?
A
Auerbach’s (myenteric) plexus (nerves and ganglion)
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
7
Q
what does the muscularis mucosae layer in esophagus contain?
A
longitudinally oriented bundles
8
Q
types of glands in esophagus
A
- mucosal glands (esophageal cardiac glands)
- only in terminal esophagus - submucosal glands (esophageal glands proper)
- entire esophagus
- tubuloalveolar glands
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
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
11
Q
stomach functions
A
- store food = chyme formation, expandable, rugae
- food digestion = secrete HCl, pepsin, lipase
- regulate GI through gherlin and gastric secretions
12
Q
pepsin
A
breakdown proteins
13
Q
lipase
A
breakdown TAGs
14
Q
HCl
A
- destroy bacteria
- breakdown protein
- convert pepsinogen to pepsin
15
Q
endocrine cells role in GI regulation
A
secrete gherlin and gastrin to increase gastric acid secretions
16
Q
where are the glands of the stomach located?
A
mucosa layer
-cardiac, fundic, and pyloric glands
17
Q
3 layers of muscularis externa of stomach?
A
- inner oblique
- middle circular
- outer longitudinal
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)
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
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
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
22
Q
deficiency of parietal cells (ex. chronic gastritis)
A
no intrinsic factor –> no absorption of vit. B12 –> no Hb synthesis –> pernicious anemia
23
Q
gastric ulcers
A
- destroy epithelial barrier by HCl release
- if untreated, can penetrate deeper into stomach causing peritonitis
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)
25
mucous neck cell
- secrete soluble mucous
- heterochromatic nucleus with "frothy" cytoplasm
- no staining of eosin or hematoxylin
26
enteroendocrine cell aka G cell
- secrete gastrin = increase gastric acid
- secrete gherlin = increase appetite/hunger
- both released into lamina propria to enter bloodstream
- contain microvilli and secretory granules
27
progenitor cell
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
28
cardiac gland
- around esophageal orifice
- secrete mucous for gastric reflux protection
- shorter gastric pit
- no parietal/chief cells
29
pyloric gland
- pyloric antrum
- secrete mucous for gastric reflux protection
- longer gastric pits
- darker than cardiac
- no parietal/chief cells
30
carcinoma of stomach
surface epithelial cells
| -intestinal metaplasia - contain many goblet cells
31
adenocarcinoma of stomach
glandular epithelium
| -ring shaped cells
32
stages of stomach cancers
1. early
- penetrate submucosa and good prognosis
2. late
- penetrate to muscularis externa and bad prognosis
33
functions of the small intestine
1. digestion (main)
2. absorption
3. synthesis and secretion (digestive enzymes)
4. antimicrobial
5. regulate GI function (enteroendocrine cells)
34
layers of the small intestine
- mucosa
- submucosa
- muscularis externa
- serosa/adventitia
35
what makes up the plicae circularis?
mucosa and submucosa
- found in the distal duodenum and proximal jejunum
- permanent fold
36
what makes up the villi?
mucosa only
- evaginations of mucosa containing surface epith.
- lamina propria is the core
37
microvilli
the cells on the villi
| -very small and look like brush border
38
role of plicae circularis, villi, and microvilli?
increase surface area for better absorption
- lacteals absorb lipids packages in chylomicrons
- vascular loops absorb carbs and AAs
39
crypt of lieberkuhn
invaginations of epithelium that forms a gland
| -contain paneth and progenitor cells
40
celiac disease
gluten enteropathy
- hypersensitivity to gluten
- atrophy of villi (complete or incomplete loss)
- steatorrhea (fatty feces) --> no villi or lacteals to absorb lipids
41
what type of epithelium is the alimentary canal?
simple columnar epith. containing microvilli
| -except esophagus
42
enterocyte functions (most prominent)
- 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
43
how are lipids digested by enterocytes?
lipid breakdown in lumen --> resynthesis of triglycerides in SER --> form protein coat (chylomicrons) --> transport via lacteals to lymphatic vessels
44
how is IgA transcytosed in enterocytes?
plasma cells make IgA --> bind to receptors on enterocytes and endocytosed --> released into lumen for bacterial and mucosal protection
45
Goblet Cell
unicellular mucous glands
- mainly in large/small intestine
- do not stain with H&E --> frothy, white areas
- heterochromatic (nonactive) nucleus
46
M cell
antigen presenting cells
| -microfolds capture antigen and transport it from lumen to lymphoid follicle for antibodies to made against it
47
what is a lymphoid follicle?
area of clusters of immune cells
| -contain lymphocytes, neutrophils, or macrophages
48
enteroendocrine cells
GI function regulation
- produce hormones gastrin and gherlin
- aka APUD cells
49
intraepithelial lymphocytes
mucosal immunity
- bone marrow derived
- T lymphocytes
50
paneth cells
eosinophilic granules contain antibacterial enzymes to protect the crypt from bacterial growth
- base of the crypt
- bright red staining cytoplasm
51
progenitor cells
stem cells of epith. and gland (crypt)
- found in crypt
- mitotic cells
52
lamina propria of small intestine
connective tissue that contains leukocytes - GALT
- diffuse = lymphocytes and Macs
- scattered = duodenum and jejunum
- peyer's patch = aggregated lymphoid follicles in ileum
53
lymphoma (maltoma)
thickening of lamina propria due to infiltration of lymphocytes
- from MALT
- cancer of small intestine
54
blood supply in small intestine
vascular plexus in submucosa extends as vascular loops into villi
-collect nutrients
55
lymphatics of small intestine
fats packaged as chylomicrons transported by lacteals to enter lymphatics in submucosa
56
Brunner's glands
mucous glands - produce alkaline fluid to neutralize gastric acid
- found within submucosa
- only in duodenum
57
what is found in submucosa of small intestine?
- messiener plexus
- brunner's glands
- vascular plexus
58
what is found in the muscularis externa layer of small intestine?
- inner circular layer
- outer longitudinal layer
- Auerbach's plexus
59
what contains mostly adventitia?
duodenum
| -distal duodenum, ileum, and jejunum contains serosa (mesothelium + connective tissue)
60
where are submucosal (Brunner's) glands located?
duodenum
61
where are Peter's patches and most goblet cells found?
ileum
62
regions of large intestine
- cecum
- colon
- rectum
- anus
63
function of large intestine
- reabsorption - electrolytes and water
| - eliminate waste
64
mucosa of large intestine
- no paneth cells in crypts of lieberkuhn - only progenitor
- no villi
- many goblet cells
65
muscularis externa of large intestine
- inner circular layer
| - outer longitudinal layer - forms thick bands of tiniae coli
66
serosa of large intestine
contain omental appendices - fat projections
67
adenocarcinoma
most common large intestine cancer
- arise in patients with adenomatous polyps or ulcerative colitis
- treat with total resection
68
regional differences in large intestine
- colon - largest, contains tiniae coli
- vermiform appendix - aggregated lymphoid nodules
- rectum - transverse rectal folds
69
what are the 4 layers of the GI tract?
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
what 2 nerve plexuses comprise the enteric nervous system?
- Meissner plexus (in submucosa)
| - Auerbach plexus (in muscularis externa)
71
Auerbach's plexus
b/w the smooth muscle layers of muscularis externa
| -controls peristalsis
72
Hirschsprung disease (congenital aganglionic megacolon)
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
oral cavity wall structure
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
function of Meissner (submucosa) plexus
- motility of the mucosa and submucosa
| - secretory activity
75
lips
- vermilion zone - red/pinkish color from dermal papillae containing capillaries
- contains minor salivary glands
76
cold sores
contagious blisters on outside of mouth
| -caused by HSV type 1 (reside in trigeminal ganglion in dormant state)
77
canker sores (aphthous ulcers)
sores inside the mouth
| -may be due to virus, autoimmune, or allergic rxn
78
tongue
- 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
leukoplakia
cancer of oral region
| -white patch or plague
80
where does the majority of cancers of oral cavity arise from?
stratified squamous epith. --> squamous cell carcinoma
| -ulcers, malignant keratinocytes
81
purpose of lingual papillae
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
filiform papillae
- most numerous
- entire surface of tongue
- scrape food off surface (sand paper)
- NO taste buds
83
Fungiform papillae
- "mushroom"
- most numerous at apex and sids
- has taste buds
84
foliate papillae
- posterolateral folds
| - has taste buds
85
circumvallate (vallate) papillae
- anterior to terminal groove
- taste buds down sides
- surrounded by moat like trenches where serous salivary (von Ebner) glands drain into
86
function of von Ebner glands
- flush food particles away from vallate papillae
| - contain lipase to prevent formation of film that would hinder gustation
87
4 types of teeth
1. incisors - cutting, one root
2. canines - grasping and tearing, one root
3. premolars - crushing, two roots
4. molars - crushing, 3 roots
88
3 calcified mineral substances of tooth
1. dentin - bulk of tooth
2. enamel - covers crown
3. cementum - covers root
89
enamel
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
dentin
bulk of tooth
- 2nd hardest substance in body (Ca2++ hydroxyappetite)
- odontoblasts make dentin
- viable for life
- can be repaired
91
cementum
outer layer of root of tooth (over dentin)
- anchors periodontal lig. to roots of tooth
- made by cementoblasts
- viable for life
92
pulp of tooth
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
periodontal ligament
attaches to cementum and alveolar bone
- holds tooth in place
- shock absorber
- sharpes fibers (type 1 collagen fibers)
94
gingiva
bound to periosteum of jaw bone
- junctional epith. - attaches gingiva to enamel
- gingival sulcus - site for periodontal disease
95
how can food lodged in teeth cause damage?
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
what happens if you don't brush or floss teeth?
- biofilm known as plaque
- plaque can calcify forming calculus - covering for bacteria to grow causing gingivitis
- progressive gingivitis --> attack periodontal lig. --> periodontitis
97
what are the 2 components of salivary glands?
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
what are found w/I the lobules of salivary glands?
adenomeres - secretory units of glands that contain acini cells (serous or mucous)
-both types of acini dump into intercalated ducts
99
how do you identify serous acini?
- round nuclei
- stain dark
- protein secreting, accumulation of RER and ribosomes
100
how do you identify mucous acini?
- flattened nuclei
- stain light
- GAG secretion
101
2 types of intralobular ducts
1. intercalated ducts - continuous w/ acini, simple squamous
| 2. intralobular - striated, infoldings that allow products to enter, cuboidal
102
interlobular (excretory) ducts
excretory ducts that enter oral cavity
- larger than intralobular ducts
- columnar to strat. columnar
103
parotid gland
- largest salivary
- SEROUS acini - stain dark, round nucleus
- opens into vestibule of oral cavity
104
submandibular gland
- 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
sublingual gland
- smallest salivary gland
| - mainly MUCOUS acini - light stain, flat nuclei
106
xerostomia
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
hepatocytes
major cell of liver - endocrine and exocrine functions
- bile production (digest fat)
- hormone & protein synthesis (high RER & Golgi)
- metabolic functions
- detoxification via SER
108
lobules of the liver
- contain capillaries called sinusoids
- hexagon shape
- portal triad and lymph vessels on outside
- central vein in center
109
what is found w/I the portal triad?
- hepatic portal vein
- hepatic artery
- bile duct
110
where does the blood supply travel in liver lobule?
from periphery to the central vein
| -dual blood supply by portal triad
111
where does lymph and bile travel in liver lobule?
from center to periphery
112
function of RER in hepatocytes
protein synthesis
| -basophilic staining
113
function of SER in hepatocytes
- 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
metabolic functions of hepatocytes
storage of glucose, fat, and iron
115
function of peroxisomes of hepatocytes
oxidation of fats and breakdown of hydrogen peroxide
116
the celiac trunk
supplies the foregut
| -gives rise to common hepatic, left & right gastric, and splenic artery
117
what are the 2 sources of blood supply to the liver?
- hepatic artery proper (supplies the O2)
- hepatic portal vein (supplies the nutrients)
- found in portal spaces
- branches --> hepatic arteriole & hepatic portal venule
118
blood drainage of the liver
central vein --> 3 hepatic veins (right, middle, and left) --> IVC --> right atrium
119
portal spaces
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
what are sinusoids?
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
zones of the hepatic lobule
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
space of disse (perisinusoidal space)
b/w the sinusoids and the hepatocytes
| -contains lymphatic capillaries that flow towards lymph vessels in portal spaces
123
bile canaliculi
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
Kupffer cells
liver macrophages
- found in lumen of sinusoids
- phagocytose foreign matter and breakdown RBCs
125
Ito (fat storing or hepatic stellate cells)
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
classic liver lobule
- hexagon
- ENDOCRINE function (make proteins & hormones)
- portal spaces on edge of lobule
- blood flows to central vein to go to rest of body
127
portal lobule
- 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
hepatic acinus (acinus of Rappaport)
- blood supply carrying nutrients and O2 (which varies) from periphery to central vein
- diamond (2 portal triads & 2 central veins)
- 3 zones
129
periportal hepatocytes of acinus
zone 1
- nearest portal triad
- get most O2, hormones, and nutrients
- more oxidative metabolism (glycogen & protein synthesis)
130
zone 3 hepatocytes
- near the central vein
- least amount of O2 and nutrients
- 1st to show ischemic necrosis and fat accumulation
- lipolysis, glycolysis, drug/ETOH detox
131
cirrhosis
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
fatty liver disease
steatosis - accumulation of fat in lipid droplets
- associated with alcoholism or obesity
- may produce non-infectious hepatitis --> steatohepatitis
133
nonalcoholic fatty liver disease
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
gallbladder
stores, concentrates, and released bile
| -bile enters duodenum when there is dietary fat
135
function of enteroendocrine cells of small intestine
release CCK --> contraction of gallbladder and secretion of pancreatic juice
136
gallbladder histology
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
what is cholelithiasis?
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
what can gallstones lead to?
biliary obstruction --> lead to chronic cholecystitis
- block flow in cystic duct
- can be acute or chronic cholecystitis
139
acute cholecystitis
- suddenly; sever pain in abdomen
- obstruction of neck or cystic duct
- most common reason for emergency cholecystectomy
140
chronic cholecystitis
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
pancreas
1. exocrine functions - make digestive enzymes and bicarb rich buffering fluid by acinar cells
2. endocrine functions - make hormones by islets of langerhans
142
pancreatic acinar cells function
produce digestive enzymes that breakdown nutrients when entering duodenum
- round nuclei and zymogen granules (house proenzymes)
- enzyme release by CCK (main) and ACh
143
centroacinar cells
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
pancreatic cancer
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
pancreatitis
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
