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Histo Exam 3 > Digestive System (Lower GI) > Flashcards

Digestive System (Lower GI) Flashcards

(107 cards)

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1
Q

so approximately how long is the small intestine?

A

> 6 meters long

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2
Q

what are the regions of the small bowel?

A

duodenum, jejunum, and ileum

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3
Q

what are the main general functions of small intestine?

A

hormone secretion, digestion, nutrient absorption

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4
Q

key features of duodenum, jejunum, and ileum?

A

duodenum: brunner’s gland’s in submucosa, broad/short villi, incomplete serosa - mostly adventitia
jejunum: long finger-like villi, well developed lacteals, numerous Paneth cells in crypts
ileum: short, finger-like villi, Peyer’s patches, Paneth cells

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5
Q

what tissue modifications increase surface area in the small intestine?

A

plicae circulares, villi, and microvilli - increase luminal surface area > 400-600x

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6
Q

what the heck are the valves of Kerckring?

A

another name for plicae circulares, permanent spiral folds of mucosa/submucosa

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7
Q

where would someone find valves of Kerckring?

A

found in duodenum distal half, jejunum, & proximal half of ileum

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8
Q

if you saw finger/leaf-like projections in the mucosa of the small intestine, what would you call it?

A

intestinal vili

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9
Q

the villus core of intestinal villi consists of what?

A

lamina propria with plasma cells, lymphocytes, fibroblasts, mast cells, smooth muscle cells, capillaries & a single lacteal

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10
Q

what are lacteals?

A

blind-end lymphatic channel - absorbs fat as chylomicrons

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11
Q

what are the capillary plexi that drain the intestinal villi

A

villus capillary plexus and pericryptal capillary plexus

these drain into submucosal venules

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12
Q

what are the crypts of lieberkuhn

A

simple tubular glands that extend from the middle of the villus to base of epithelium near muscularis mucosae

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13
Q

the crypts are composed of what types of cells?

A

goblet cells, columnar cells, enteroendocrine cells, regenerative cells, & Paneth cells

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14
Q

what would you find on the apical surface of enterocytes

A

microvilli

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15
Q

what do microvilli core contain?

A

actin filaments linked with fimbrin and villin

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16
Q

how is actin in the microvillus core anchored?

A

anchored to plasma membrane by myosin I & calmodulin

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17
Q

what is the role of actin “rootlets”

A

they are at the base of actin bundles and are cross-linked by intestinal forms of spectrin to adjacent rootlets.

ends of these rootlets attach to cytokeratin-containing intermediate filaments

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18
Q

what are terminal webs composed of

A

cytokeratin-containing intermediate filaments (attached to rootlets) and spectrin

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19
Q

what is the small intestine’s motility controlled by?

A

autonomic nervous system

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20
Q

where would you find Meissner’s plexus & Auerbach’s myenteric plexus?

A

Meissner’s plexus - submucosa

Auerbach’s myenteric plexus - between inner & outer smooth muscle layers of muscularis externa

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21
Q

what is the cell type for intestinal epithelium?

and what types of cells comprise this layer? (5 types)

A

intestinal epithelium are all Simple Columnar Epithelium:

goblet cells
absorptive cells (enterocytes)
paneth cells
antigen processing cells (M cells & dendritic cells)
enteroendocrine cells
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22
Q

Goblet cells are _______ (unicellular/multicellular) glands producing mucinogen which (is/is not) identical to that in the stomach

A

Goblet cells are unicellular glands producing mucinogen which is not identical to stomach mucous secretions

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23
Q

mucinogen in goblet cells accumulates in membrane-bound granules in the (apical/basal) region

A

apical region

think about where they will be expected to release these-into the lumen of the intestine

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24
Q

after mucinogen is released, it is converted to _______

A

mucous

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25
"if you were a little person" traveling down the small intestine from duodenum to ileum, you would expect to see (more/fewer) goblet cells
more - goblet cells increase in number from the duodenum to ileum
26
enterocytes are another name for
surface absorptive cells
27
surface absorptive cells are (short/tall) (columnar/cuboidal) cells
surface absorptive cells are tall columnar cels
28
what structural characteristic about enterocytes is probably most important to their funtion
apical surface possesses microvilli covered by glycocalyx | remember microvilli increase surface area for absorption
29
per Dr. Turek, what binds really well to the glycocalyx and could contribute to the pathology in Gluten enteropathy?
plant lectin (e.g. wheat & rye)
30
back to enterocytes, what type of intercellular connections do they have?
well-developed zonulae occludens (tight junctions) zonulae adherens lateral plications
31
how often are enterocytes renewed? and where do these cells tend to be in the intestine?
renewed every 5-6 days cells divide down in crypt and migrate up villus - slough@ villus tip
32
where and with what do enterocytes digest carbohydrates?
in the brush border of the cell membrane, enterocytes have lactase, maltase, and sucrase to digest carbs
33
if an enterocyte was to have a deficiency in lactase, what would be expected to happen?
deficiency in lactase = lactose intolerance = diarrhea
34
so proteins are initially digested where and with what?
they are initially digested by pepsin, trypsin, chymotrypsin, etc. in the lumen of the stomach
35
by the time they get to the small bowel, what are first enzymes to digest these partially digested proteins?
by the time they get to the intestines, enterokinase & aminopeptidase in microvilli degrade oligopeptides into di/tripeptides
36
what digests these di/tripeptides in enterocytes?
cytoplasmic peptidases degrade di/tripeptides to amino acids
37
what happens to fully digested proteins (amino acids) after they've been broken down by enterocytes?
amino acids diffuse or are transported across the basal plasma membrane into blood
38
where is lipid broken down in enterocytes and what is it broken down into?
lipids are broken down in the lumen of intestines to fatty acids and monoglycerides by pancreatic lipase & bile salts
39
what happens to the broken down lipids in the lumen? how do they get into the intestine?
FAs & monoglycerides form into micelles and diffuse across the microvilli
40
the micelles get linked to what proteins in microvilli?
they get linked to fatty acid binding protein (FABP) ^makes sense, right?
41
so this complex of micelle + FABP go where to form what
transported, esterified in smooth ER to form triglycerides
42
where do triglycerides go after formation to form apolipoprotein complexes (e.g. chylomicrons)?
they go to the Golgi
43
where do chylomicrons go after being formed?
they fuse with baso-lateral plasma membrane & move into intercellular space & then lacteals
44
what are DNES and APUD cells again?
they are enteroendocrine cells (also found in stomach, half-moon shape) secrete gastrin, cholecystokinin, gastric inhibitory peptide and other hormones
45
What does the M in M cell stand for? | where are they found
M cells = microfold cells (cell surface has microfolds rather than microvilli) they are found on epithelium over lymphoid nodules in ileum
46
function of M cells
function in antigen uptake, processing, and transport to lymphocytes & macrophages in lamina propria
47
what can the basolateral portion of M cells form? what could someone find in these formations?
basolateral portion may form an intraepithelial pocket - B cell located in these pockets
48
what are the antigens in M cells processed by?
antigens are processed in protease (cathepsin E) and are transcytosed to B cells
49
what are dendritic cells closely associated with?
closely associated with lymphoid follicular epithelium in Peyer's patches
50
what can dendritic cells do to expose itself with the intestinal lumen?
may extend cell processes across basal lamina & between enterocyte tight junctions so that a small portion is exposed to the intestinal lumen
51
how would you identify a Paneth cell?
large eosinophilic apical secretory granules | occur @ bottom of crypts of Lieberkuhn
52
what do Paneth cells produce?
produce lysozyme continuously secrete defensins produce tumor necrosis factor alpha
53
what do lysozymes do?
cleaves peptidoglycan in bacteria cell walls
54
what's another name for secretins
cryptidins
55
what are secretins secreted in response to?
in response to bacteria, bacterial antigens, food-related stimulation by acetylcholine
56
what is the functional role of defensis
protecting regernative cells in crypt
57
what is tumor necrosis factor alpha
proinflammatory cytokin
58
where do you find regenerative cells
found in lower half of crypt
59
what do regenerative cells regenerate into?
may differenitate into absorptive or goblet cell
60
where would you find lamina propria in intestinal villi
occupies villi core & interstices between the cryptes of Lieberkuhnk
61
where would you find lacteals?
lamina propria
62
where would you find Brunner's glands?
submucosa in duodenum
63
brunner's glands branch into what?
tubuloalveolar glands
64
what kind of secretion do Brunner's glands have? why?
alkaline secretion of neutral and alkaline glycoproteins & bicarb ions & gastric inhibitory proteins protects intestine from acidic chyme (receiving contents from stomach)
65
what does gastric inhibitory peptide do?
polypeptide hormone that enhances epithelial cell division and inhibits gastric HCl production
66
characteristic features of ileum
Peyers patches! contains aggregate lymphoid nodules (part of gut-associated lymphoid tissue (GALT))
67
primary function of cecum & colon?
absorption of water & electrolytes
68
do the cecum and colon have villi?
of course not, that's a small intestine thing
69
what types of cell epithelium would expect with what types of cells involved?
simple columnar epithelium - goblet, absorptive (enterocyte?), & some enteroendocrine cells
70
how would you describe the lamina propria of large intestine?
its really similar to the lamina propria of small intestine lymphoid nodules and closely packed crypts
71
does the large intestine have Paneth cells?
of course not, that's an ileum/jejunum thing
72
what type of submucosal contents would you find in the cecum/colon?
fibroelastic connective tissue Meissner's plexus NO glands
73
what're the characteristics of large bowel's muscularis externa?
inner circular layer of smooth muscle | modified outer longitudinal layer of smooth m. (gathered in 3 longitudinal smooth muscle bands that form teniae coli)
74
what are the sacculations that teniae coli can form are called
haustra
75
what would you find between the smooth muscle layers of the large intestine?
Auerbach's (myenteric) plexus between muscle layers
76
the appendix is a short ______ arising from the ______
diverticulum, cecum
77
does the appendix have a lumen? and how would you describe it?
yes - narrow, irregularly shaped lumen often containing debris
78
walls of appendix have lots of?
lots of lymphoid nodules in mucosa & submucosa in middle-aged individuals
79
proposed purpose of appendix in young people? what about in general?
immune system function higher risk for intestinal carcinomas later in life if removed early, reservoir of bacteria to repopulate gut after diarrheal disease
80
appendix mucosa has what type of epithelium cells
simple columnar epithelium wiht goblet cells
81
lamina propria of appendix mucosa has what type of lymph tissue and is capped by what?
lymphoid nodules capped by M cells
82
does the appendix have villi?
nope
83
what types of cells does the appendix have in its shallow crypts? (5)
``` goblet surface columnar regenerative some Paneth cells many enteroendocrine cells deep in crypts ```
84
what is the rectum most similar to? how is it different
it's most similar to the colon fewer & deeper crypts of Lieberkuhn
85
the anal mucosa has longitudinal folds called ___ ______ | and the regions between these are called _____ _______
longitudinal folds called anal columns regions between these adjacent columns are called anal sinuses
86
how does anal epithelium change? rectum to anal canal distal to anal valves and at the anus
starts as simple columnar changes to simple/stratified cuboidal/columnar ditsal to anal valves: occasionally stratified squamous nonkeratinized @ anus: stratified squamous keratinized
87
gastritis is a gastric mucosal inflammation that is common in what age group of people?
middle-aged and older individuals
88
gastritis is caused by?
unknown etiology - we don't know
89
does gastritis affect the superficial layer of mucosa or the entire thickness?
it can be either superficial or affect the entire thickness causing mucosal atrophy
90
do you want to see flashcards on gastric/peptic ulcers?
if yes, go over the upper GI segment; Turek just copies and pastes stuff
91
what can malabsorption disorders cause? | don't overthink it
can lead to malnutrition, result in wasting disease
92
what the heck is gluten enteropathy - nontropical sprue
rye & wheat glutens bind to intestinal villi reducing the surface area available for absorption
93
how do you treat gluten enteropathy?
treat by eliminating wheat and rye products
94
idiopathic steatorrhea is what?
when you have stools with high fat content | due to malabsorption of digested fats
95
what is idiopathic steatorrhea caused by
unknown etiology
96
malabsorption of what vitamin could lad to clotting insufficiency?
vitamin K
97
malabsorption of what vitamin could lead to pernicious anemia?
B12
98
what allows for the absorption of vitamin B12?
parietal cells release gastric intrinsic actor which allow for absorption of vitamin B12
99
what is the 2nd highest cause of cancer death in the US
colorectal carcinoma
100
what is colorectal carcinoma usually arising from?
adenomatous polyps - can be asymptomatic for years
101
what age are people more likely to get colorectal carcinoma?
> 50 yrs, highest incidence in 60-70 y/o group
102
how do you treat colorectal carcinoma?
colon resection - highest survival rates found in patients whose tumors do not extend beyond muscularis mucosae
103
appendicitis is associated with what symptoms?
pain in RLQ of abdomen, fever, nausea, vomiting and high white blood count (high wbc)
104
how do people die from appendicitis?
appendix ruptures > peritonitis/endotoxic shock > death
105
rectal bleeding during defectation is caused by?
hemorrhoids -breakage of dilated thin-walled vessels of venous plexuses above or below anorectal line
106
hirschsprung's disease is also called?
megacolon
107
what happens in hirschsprung's disease?
mutation of endothelin B receptor/ligand, endothelin 3 and rearranged during transfection (?) main point: prevents migration and differentiation of neural crest cells into neurons of enteric nervous system

Histo Exam 3 (6 decks)

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