Histology 17 HY Flashcards
1
Q
3 layers of the mucosa
A
epithelium, lamina propria(CT) and muscularic mucosae(SM)
2
Q
consists of dense irregular connective tissue
A
submucosa
3
Q
consists in most parts of alimentary tract as 2 layers of smooth mm
A
muscularis externa
4
Q
beneath the layer of muscularis externa costists of simple squamous epithelium called the mesothelium, and a little CT
A
serosa
5
Q
Parts of the digestive tract don’t contain serosa such as thoracic pt of esophagus, duodenum, ascending/descending colon, rectum, and anal canal. they instead are attached to the abdominal/pelvic wall by CT called?
A
adventitia
6
Q
3 functions of the mucosa
A
protections, absorption secretion
7
Q
the epithelium of the mucosa: one function is a barrier of protection from outside pathogens. in the esophagus what is the epithelium made out of? in the rest of the GI tract
A
non keratinized stratified squamous; simple columnar cells
8
Q
has an absorptive function is a circumferentially oriented submucosal fold along most of the SI
A
plicae circulares
9
Q
principal site of absorption for digestion products are mucosal projections that cover the entire surface of the SI
A
villi
10
Q
tightly packed microscopic projections of the apical surface of intestinal absorptive cells help to further inc the surface available for absorption
A
microvilli
11
Q
projections from apical plasma membrane epithelial absorptive cells providing more surface for adsorption and has enzymes essential in the final steps of protein and sugar digestion
A
glycocalyx
12
Q
Secretion by glands is important for lubrication, buffering, as wella s secreting enzymes HCl hormones, water, and antibodies. there are mucosal, submucosal glands as well as ____ glands that lie outside of the digestive tract and deliver their secretions via ducts into the duodenum. Name the 2
A
extramural digestive glands-liver and gall bladder!
13
Q
where do the mucosal glands extend into? this region also contains blood vessels that transport absorbed substances and lymphatic tissues to protect against pathogens
A
lamina propria
14
Q
in the ileum extensive aggregates of lymphoid nodules occupy mysh of the lamina propria and subucosa. what are these called
A
peyers patches
15
Q
this divides the mucosa and submucosa and when it contracts it forms ridges in the mucosa to facilitate absorption and secretion
A
muscularis mucosae
16
Q
the submucosa contains blood and lymphatics also, as well as parasympathetic and sympathetic nerves. the nerves of the parasympathetic ganglion represent the ___ nervous system-responsible for innervating SM in alimentary canal and can function independently of the CNS. name of plexus in the submucosa?
A
enteric nervous systems-Meissners plaxus
17
Q
2 locations where the submucosa gontains glands-helps to ID certain regions of the GI
A
esophagus and initial portion of duodenum
18
Q
Muscularis externa: Inner mm layer is oriented how? outer mm layer oriented how? the 2 layers are divided by connective tissue which contains what(3)
A
circularly; longitudinally; myenteric(auerbachs plexus), blood and lymph vessels
19
Q
Contraction of the muscularis externa produces peristalsis- contraction of the inner layers causes what? while contraction of the outer layer causes what
A
inner layer-mixes food; outerlayer-propels contents forward
20
Q
longitudinal SMm layer of muscularis externa thickens in the large intestine to 3 distinct bands called
A
teniae coli
21
Q
Pharyndoesophageal sphincter(superior), inferior lower esophageal sphincter, pyloric sphincter(controls release of chyme), ileocecal valve, and internal anal sphincter are all made of thickened parts of what muscularis externa layer to create sphincters or valves
A
circular mm layer(inner layer)
22
Q
GERD is characterized by inflammation of the esophageal mucosa, strictures, difficulty swallowing, and chest pain. what is ti dt
A
abnormal relaxation of inferior esophageal sphincter-allows acid to reflux from stomach into esophagus
23
Q
in the esophagus the muscularis externa differs than that found in the rest of the digestive tract in that the upper third is componsed of what type of mm? as you move down this type of mm becomes intermixed with SM until in the distal 1/3 of the tract it is all sm
A
striated mm
24
Q
the thoracic outermost part of the esophagus is covered by? while the abdominal pt of the esophagus is covered by
A
adventitia; serosa
25
Glands are present in the esophagus wall, both secrete mucus but there are 2 types
1.)___ lie in submucosa are scattered throughout but more concentrated in upper half.
2.)____ found in lamina propria of mucosa-resent in terminal part of esophagus and sometimes at the beginning of the esophagus
esophageal glands proper; esophageal cardiac glands
26
ESOPHAGEAL GLANDS PROPER SECRETE MUCUS FOR LUBRICATION AND TRANSIENT__ CAN OCCUR IN THEM BECAUSE OF THE VISCOUS NATURE OF THE FLUID. ESOPHAGEAL CARDIC GLANDS SECRETE NEUTRAL MUCUS AND IF NOT FULLY EFFECTIVE and excessive reflux results in ____ aka heart burn-->can progress to GERD
cysts; pyrosis
27
____mm is innervated by somatic motor neurons of the vagus nerve in the esophagus
___mm is inverated by visceral motor neurons of the vagus
striated; smooth
28
4 regions of the stomach
cardia, fundus, body, and pylorus
29
3 histologic regions of the stomach
1.)____ near esophageal orifice contains cardiac glands
2.)___ near proximal pyloric sphincter contains pyloric glands
3.)___ largest part of stomach between cardia and pylorus contains gastric glands
cardiac region; pyloric region, fundic region
30
longitudinal folds in the body of the stomach they do not alter surface area but serve to accomodate EXPANSION and filling of stomach
rugae
31
shallow trenches in the stomach that divide the stomach surface into ___ areas. These grooved areas increase surface area for secretion
mamillated areas
32
numerous openings in the stomach mucosal surfaces are called? gastric glands open into the bottom of these
gastric pits-aka foveolae
33
simple columnar cells line the gastric pits and are caled surface mucous cells. each of these possessa cup of _____ that stain PAS blue reflecting the presence of mucin, lots of bicarb and K helping to protect it from the acidic environment. ___ stimulates the secretion of bicarb and inc the thickness of the mucus coat to help supply nutrients to damaged stomach mucosa
mucinogen granules; prostaglandins
34
the lining of the stomach isn't absorptive but can absorb some water salts and lipid soluble drugs. 2 drugs that enter the lamina propria by damaging the gastric epithelium to cause problems and also can interfere with the hydrophobic properties of the gastric mucosa
alcohol NSAIDs/aspirin
35
the fundic or gastric glands produce gastric acid and empty into the gastric pits. each gland has a neck and fundic segment. between the gastric pit and the gastric gland is the __ which is where stem cells are located
isthmus
36
In addition to water/electrolytes the gastric gland(beneath the isthmus!) has many different cell types:
1.) ___ cells produce hydrochloric acid aids in protein digestion. HCL also helps to activate pepsinogen
2.) ___ cells produce pepsinogen which gets activated to pepsin by HCL to splite peptides
3.) ____ cells in the gland secrete mucus to contribute to the physiologic gastric mucosa barrier.(secretion is stimulated by vagus)
4.) ___ cells also secrete intrinsic factor that binds B12 and is essential for its absorption in the ileum
5.) ___ cells in the gland secrete gastrin and other hormones that genter circulation or act locally on gastric epithelial cells
parietal cells; chief cells;musucus neck cells; parietal; enteroendocrine cells
37
HCl is bacteriostatic and so most bacteria entering the stomach get destroyed! what bacteria has urease which converts urea to ammonia forming a protective ammonia cloud contributing to its survival in the stomach? lack of intrinsic factor from parietal cells causes what
H pylori; pernicious anemia and B12 def
38
parietal cells are also called what name
oxyntic
39
most abundant cell types in the neck segment of the fundic/gastric glands
parietal and mucous neck cells
40
most abundant cell types located in the fundic segment of the fundic/gastric glands
enteroendocrine cells and chief cells
41
things that can cause pernicious anemia
achlorhydria-destroys gastric mucosa-no intrinsic factor; peptic ulcer disease-->ulcers can produce IF; H2 antagonists prevent IF and and acid secretion
42
H pylori contains LPS antigen that mimics those expressed on gastric epithelial cells what does this cause
antibodies develop that bind H pylori and gastric mucosa to cause damage
43
chief cell stains ___ dt the large amt of rER contained in it. the parietal stains with ___ dt extensive amt of membrane made up of intracellular canaliculus, tubulovesicular system, mitochondria
basophilic; eosin
44
system in parietal cells serving as a reservoir of plasma membran containing active proton pumps? gets inserted into plasma membrane on intracellular canilicular system to inc surgace area and proton pump number available
tubulovesicular membrane system
45
parietal cells have 3 different membrane receptors for substances that activate HCl secretion what are the receptors
gastrin receptor(gastrin activation of this receptor is major path for parietal cell stimulation), Histamine H2 receptor, acetylcholine M3 receptor
46
After parietal cell stimulation
1.) production of __ in parietal cell cytoplasm by carbonic anhydrase rxn
2.) transport of ___ from cytoplasm to lumen of canaliculus by the H/K ATPase pump(K goes into cytoplasm)
3.) Transport of __ and __ from cytoplasm into canliculus through channels.
4.) Formation of ___ from ions that were transported into the lumen of the canliculus
H+ ions; H+ ions; K and CL; HCL
47
parietal cells secrete intrinsic factor--> what can cause malabsorption of B12 and pernicious anemia
autoantibodies to intrinsic factor or parietal cells!
48
syndrome characterized by excessive secretion of Hcl by continuously stimulated parietal cells-->can't adequately get neutralized causing gastric/duodenal ulcers. pts get abdominal pain, diarrhea, and steatorrhea.
Zollinger Ellison syndrome aka gastrin producing tumor!
49
2 types of enteroendocrine cells-closed(don't reach lumen) and open(exposed to lumen)-which serve as the primary chemorecetpros sampling the gland lumen and releasing hormones based on info obtained? which secrete in response to neural and paracrine mechanisms
open; closed
50
endocrine cells are distributed throughout the gastrointestinal epithelium and are described as a diffuse neuroendocrine system. an exception to this is in the pancreas where they formed accumulations called
endocrine islets of langerhans
51
diffuse neuroendocrine systems includes neurons and endocrine that their secretions is regulated by what type of receptors
g protein receptors and tyrosine kinase activity
52
neoplastic transformation of the diffuse neuroendocrine system can occur resulting in gastroenteropancreatic neuroendocrine tumors-these most commonly occur where? cause __ syndrome characterized by diarrhea, episodic flushing, bronchoconstriction, and right sided cardiac valve disease
appendix; carcinoid syndrome
53
some enteroendocrine cells can be classified as amine precursor uptake and decarboxylation cells(APUD)- there are also APUD cells that are derived from neural crest cells but these ones in the digestive tract are derived from what
stem cells that make all the other epithelial cells of the digestive tract
54
enteroendocrine cells produce not only endocrine hormones like gastrin ghrelin that diffuse into the blood but also secrete paracrine hormones-example of paracrine hormone it secretes that inhibits other endocrine cells
somatostatin
55
agent released from nerve endings and can also be secrteed by enteroendocrine cells to activte afferent neurons to send signals to CNS and enteric nervous system
neurotransmitters
56
gastrointestinal peptides haven't been classified as hormones and they are designated as what type of hormones?examples include pancreatic polypeptide, peptide YY and glucagon like peptide 1
candidate hormones
57
cardiac glands of the stomach are composed of what cell type?they are tubular tortous glands and what tey secrete reaches the lumen of the gastric pit va a short duct lined by columnar cells
mucus secreting cells
58
pyloric glands are tubular, wide, secretory cells , emptying into the gastric pits, have enteroendocrine cells disperse in them and secret what
mucus
59
surface mucus cells of the stomach are renewed how frequently? is dt mitotic activity of isthmus stem cells
every3-5 days
60
parietal cells have a long life span (150-200d), chief/enteroendocrine cells life span 60-90d, and mucuous neck cells life span is 6 days.
parietal cells may have originated from a bacterium called neurospora crass why is this a thought
the H/K ATPase they possess are very similar to the on ein the bacterium
61
thing sm cells from the inner layer of the muscularis mucosae of the stomach extend into the lamina propria and are thought to help the outflow of what
gastric gland secretions
62
the gastric submucosa is of course dense connective tissue containing the messiners plexus this inncervates __ of the submucosa and ___ of the muscularis mucosae
vessels; sm
63
the gastric muscularis externa has 3 layers oriented from out to in->longitudinal, circular, and obliquely- these mm are innverated by what plexus? while when actually looking at the stomach this orientation isn't perfect the basic function of the differently oriented mm is what?
myenteric(auerbachs plexus); mix chyme!
64
gastric serosa is continuous with the parietal peritoneum of the abdominal cavity via the __ omentum; and the visceral peritoneum of the liver at the __ omentum
greater; lesser
65
enzymes, esp disaccharidases and dipeptidases are located in the microvilli of what cell in the SI
enterocytes
66
permanent transverse folds contianing a core of submucosa-most numerous in duodenum and dec number in ileum is an absorptive surface
plicae circulares
67
2 other structures that inc the absorptive area in teh SI
villi and microvilli
68
villi of the SI are projections of the ___. The have a core of loose CT covered by ____ epithelium. The core of the villus is an extension of the lamina propia and contains many different cells type and also contains a blind ending lymphatic capillary called the _____
mucosa; simple columnar; lacteal
69
_____ are glands composed of simple columnar epithelium that continuous with the epithelium of the villi
crypts of lieberkuhn
70
lamina propria of SI contain numerous nodules of lymphatic tissue. they are large and most numerous in the ileum and are called
peyers patches
71
in the plasma membrane of the microvilli located especially in the durodenum is the enzyme ___ which converts trypsinogen to trypsin(peptide digestion)
enteropeptidase(enterokinase)
72
Carbohydrates are also broken down by enzymes in the enterocytes. In pts with a deficiency in the disaccharidase___ they are unable to tolerate milk and suffer from diarrhea
lactase
73
3 final products of carbohydrate digestion that get broken down by enzymes in the enterocytes, absorbed into venous capillaries and transported to the liver via the portal system
galactose, fructose-->glucose
74
triglycerides are broken down into glycerol and fatty acids. they then get converted to chylomicrons and are taken away from the intestine via? they then are disassembled and used throughout the body
lymphatic vessels(lacteals)
75
proteins get digested into amino acids and dipeptides-are dipeptides of certain aa absorbed via a different pathway than that of free amino acids? disease assoc
no; hartnups-pts fed dipeptides->free aa seen in blood but when fed free aa not seen in blood
76
Enterocytes are columnar cells have microvilli on their apical surface which forms a ___ border. in the microvilli they contain actin filaments which insert into the _____ ___ which contracts allowing microvilli to spread apart allowing for a more absorptive area
striated border; terminal web
77
_____ establish a barrier between the intestinal lumen and the epithelial intercellular compartment
tight junctions
78
enterocytes are also secretory cells they not only secrete H20 and electrolytes to balance the intestinal fluid but also synthesize and secrete _____ ___ that get inserted into the plasma membrane
glycoprotein enzymes
79
goblet cells secrete mucus increase in number from duodenum to ileum. the cell rests on the basal lamina. the basal portion of the goblet cell contains the nucleus rER and mitochondria. apical to the nucleus are many _____ that get filled with large mucinogen granules
golgi apparatus
80
cell type in SI maintaining mucosal innate immunte by secreting antimicrobial sustances helping to regulate the normal bacterial flora of the SI
paneth
81
Paneth cells secrete ___ which digests the cell wall of certain bacteria and ___ which function as mediators of CD8
lysozyme; alpha defensins
82
enteroendocrine cells in the SI like the stomach have open and closed cells: activation of taste receptors on the open cells activates ____ cascade that regulate GI functions by acting on the brain-gut-adipose axis
g protein signaling cascade
83
2 hormones released by enteroendocrine cells fo the SI that inc pancreatic and gallbladder activity and inhibit stomach secretory function and motility
CCK and secretin
84
hormone secreted by enteroendocrine cells that stimulates insulin release
GIP(gastric inhibitory peptide)
85
hormone secreted by enteroendocrine cells that initiate gastric and intestinal motility
motilin
86
epithelial cell overlying peyers pathches have microfolds(not villi) their function is to get antigens from gut lumen and transport them into the vicinity of CD4 cells on the basolateral surface
M cells
87
gastric associated lymphatic tissue is prominent in the _____ of the digestive tract and works with M cells and epithelial cells to sample antigens in the space
lamina propria
88
the mucosal surface of SI is constantly challenged by microorganisms. plasma cells in the lamina propria secrete ___ antibodies which bind polymeric immunoglobulin receptor on the basal membrane of epithelial cells. the complex then gets transported to the apical surface where it is released into the gut lumen. The complex is cleaved by the secretory component extracellularly and is now known as secretory IgA
IgA
89
Secretory IgA is reall important in preventing attachment and invasion of pathogens. ex. it binds a glycoprotein on the viral envelope of __ virus preventing its attachment, internalization and replication
HIV
90
The duodenums submucosa has __ glands which secretes highly alkaline stuff to neutralize the chyme delivered to duodenum
brunners glands!
91
In the SI:Contraction of the muscularis externa produces segmentation and peristalsis contractions- contraction of the inner layers causes what? while contraction of the outer layer causes what
inner layer(circular mm)-mixes food; outerlayer(longitudinal)-propels contents forward
92
Intestinal stem cells are located in the base of the intestinal gland-what transcription factor determines the fate of differentiating cells in the intestinal stem cell niche? expression causes goblet enteroendocrine and paneth cell formation; inhibitiion creates enterocytes
Math1
93
sacculations between teniae coli on external surface of cecum and colon
haustra coli
94
small fatty projections of the serosa on the outersurface of the colon
omental appendices
95
major cell difference type in colon vs SI
colon contains crypts of lieberkuhn but NO villi!
96
primary function of the columnar absorptive cells in the colon
rebsorption of water and electrolytes-have tight junctions!
97
Numerous goblet cells are contained in the colon that secrete a lot of mucus what does this allow
facilitate elimination of solid waste
98
Columnar absorptive cells predominate over goblet cells but the ratio decreases where in the large intestine? LI also has most of the same cells as the SI except what cell type
rectum; paneth cells
99
intestinal cells in the LI just like in the SI arise from a single stem cell population: for both parts of the intestine cell turnover rates are the same: for absorptive and goblet cells how long do they last? what about enteroendocrine cells
6 days; 4 weeks
100
Lamina propria of LI is similar to the rest of the digestive tract but a few features are different:
1.) ______ lies between epithelium and venous capillaries is very thick. participates in regulation of water and electrolyte transport into the vascular compartment
2.)______fibroblast population that regularly replicate adjacent to stemcells; migrate with epithelial cells but their fate is unknwon
3.)______ is continuous with the ileum but is more extensively developed and large lymphatic nodules distort the regular spacing of intestinal glands and extend into the submucosa
4.) _____ is generally absent some does drain within the muscularis mucosae
1. collagen table 2. pericryptal fibroblast sheat 3. GALT 4. Lymphatic vessels
101
Muscularis externa of the LI: in cecum and colon the outer layer in part is condensed into large bands called ____ . between these bands the regular longitudinal layer forms a thin sheet. in the rectum, anal canal, and appendix the longitudinal sm that is seen also in the SI is uniformly thick
teniae coli
102
muscularis externa: teniae coli penetrate the inner circular mm layer at irregular intervals. this leads to discontinuous contraction and the formation of ____
(note also that the LI muscularis externa still does segmentation adn peristaltic contractions)
haustra coli
103
cecum forms a blind pouch creating the appendix-what is the difference though between the muscularis externa of the appendix v the cecum
muscularis externa of the cecum has tenaie coli while appendix has uniform longitudinal sm layer
104
in many adults normal structure of the appendix is lost and blockage either by fibrous tisse, thick mucus or stool entering the appendix from the cecum can cause
appendicitis
105
common tumor of enteroendocrine cells found in the appendix
carcinoid
106
The really neat thing that occurs in the Large intestine when a patient has Ulcerative colitis assoc with LI lymph tissue? this allows you to monitor active inflammation occurring in UC and the progress of treatment
in pts with UC the normal absent lymphatic tissue in the LI actually proliferates so if lymphatic vessels inc in UC it signals active inflammation but if they dec it means that the pt is responding to treatment
107
what is so cool about the large intestine and the presence of adenomas in it dt the lymphatic distribution in the LI
adenomas that develop have slow rate of metastasis dt absence of lymphatic channels and so if it is confined to the mucosa you can snip it off and thats adequate treatment
108
upper part of rectum is distinguised from the rest of the large intestine dt the presence of
transverse rectal folds
109
Anal canal has longitudinal folds called anal columns. between these columns are anal sinuses. the anal canal can be divided into 3 zones based on epithelial lining:
1.)____ zone: found in upper 1/3 of anal canal contains simple columnar epithelium
2.)____ zone in middle 1/3 of canal has stratified suamous columnar epithelium between simple columnar epithelium and stratified squamous epithelium
3.) ___ zone found in lower 1/3 of canal lined by stratified squamous epithelium and continuous with perineal skin
colorectal zone, anal transtional zone, squamous zone
110
Anal glands extened into submucosa and muscularis externa. sometimes they get surrounded by diffuse lymphatic tissue which can lead to the formation of
pathologic fistulas(between anal canal and perianal skin)
111
apocrine glands found in the skin surrounding the anal orifice
circumanal glands
112
submucosa of the anal columns contain superior rectal actery and rectal venous plexus enlargement of these is called what
internal hemorrhoids
113
what forms the internal anal sphincter
circular layer of muscularis externa
114
what forms the external anal sphincter
striated mm of the pelvic floor
