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PATHOLOGYY2S2 > small intestine > Flashcards

small intestine Flashcards

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1
Q

what is the basic anatomy of small intestine ?

A

duodenum

jejunum

Ileum

6 meters

large intestine is 1.5 meters

mucosa

submucosa

muscularis

serosa/adventitia

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2
Q

what is the main function of small intestine ?

A

absorption

we have villi to increase the surface area to absorb

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3
Q

what is the basic histology of small intestine ?

A

Absorptive

mucus

paneth ( secrete antimicrobial peptides and proteins )

goblet cells

enterocytes

enteroendocrine cells

Villi

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4
Q

describe the basic histology of Large intestine ?

A

Mucus

absorptive

enteroendocrine

Crypts like stomach

no villi

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5
Q

what are the 2 major pathologies of small intestine ?

A

Malabsorption

intestinal obstruction happen in small intestine more than large intestine because its narrower lumen

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6
Q

what are some intestinal pathology ?

A

Congenital

Enterocolitis

Malabsorption

Malabsorption

IBD ( inflammatory bowel disease )

Vascular

Diverticular

Obstruction

tumors

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7
Q

what are congenital disorders of intestine ?

A

Duplication

Malrotation

Gastroschisis

Omphalocele ( trisomy )

Atresia/ stenosis spectrum –> in any part of GIT

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8
Q

what is omphalocele ?

A

Cele = sac

intestine, liver, other organs

are outside the abdomen inside a SAC

the sac is made by peritoneum , amnion

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9
Q

what is gastroschisis ?

A

Intestines are outside of the abdomen through a hole in the abdomen

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10
Q

what is atresia ?

A

Congenital condition where a body passage or opening is absent or closed

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11
Q

what is stenosis ?

A

narrowing of a body passage or blood vessels , which can be congenital or acquired

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12
Q

which part of the pregnancy is more sensitive ?

A

First trimester ( first 3 months )

very sensitive because it is when the babys organ brain, heart start forming

any harm from infection, drug, alcohol, poor nutrition can cause birth defect or miscarriage

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13
Q

describe duodenal atresia ?

A

failure of small bowel to canalize

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14
Q

what is duodenal atresia associated with?

A

Down syndrome

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15
Q

what are the clinical presentation of duodenal atresia?

A

Polyhydramnios - not being to swallow amniotic fluid = leads to increased amniotic fluid

Stomach distension + distended blind loop of duodenum = DOUBLE BOUBLE SIGN ( cuz stuff cant pass )

Bilious ( greenish ) vomiting - Backs up and includes bile as atresia after proximal duodenum

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16
Q

what is MECKEL diverticulum ?

A

terminal ileum , vitelline duct

outpouching or bulge in the lower part of small intestines ( ileum )

Most prevalent congenital abnormality of GIT in 2% of normal population

it is a true diverticulum ( contain all layers of intestinal wall )

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17
Q

describe the meckel diverticulum disease?

A

normally the vitelline duct ( yolk sac to the midgut )

it will atrophy and become fibrous cord connecting umbilicus and bowel

in the disease the proximal vitelline duct will be persistent leading to the bulging of terminal ileum

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18
Q

what are the rule of two in meckel diverticulum

A

2 inches

2:1 male to female

2 ft away from ileocecal junction

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19
Q

what is the clinical presentation of meckel diverticulum ?

A

Bleeding

Heterotopic gastric mucosa - acid producing

Volvulus

Intussusception

obstruction

usually first 2 years of life

feel feces behind umbilicus on palpitation

most are asymptomatic

ASSOCIATED WITH OTHER CONGENITAL ANOMALIES

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20
Q

what are the complications of meckel diverticulum ?

A

perforation

entero umbilical fistula

ulceration

Hemorrhage

Intussusception

obstructions

carcinoids and other tumors

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21
Q

what causes intestinal obstruction?

A

More common in small intestines because narrow lumen

Scarring

adhesions –> MOST IMPORTANT

neoplasm

volvulus

intussusceptions

Inflammation

Stones

Strictures

Atresias

Hernias

Fecal impaction

ITS A SURGICAL EMERGENCIES

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22
Q

what is abdominal hernia?

A

Weakness or defect peritoneal cavity wall

protrusions or serosa lined pouch of peritoneum —> hernia sac

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23
Q

what are the common abdominal hernias ?

A

inguinal

femoral canals

umbilicus

surgical scars

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24
Q

describe the external herniation in inguinal hernia?

A

inguinal hernias ( narrow orifices )

small intestine may be entrapped and impair venous drainage leading to STASIS AND EDEMA

leading to permanent entrapment or incarceration ending with arterial and venous compromise or strangulation can result infarction

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25
what is volvulus ?
twisting of bowel along mesentery complete twisting of a loop bowel about its mesenteric base of attachment produces intestinal obstruction and infarction
26
what is intussusception ?
Telescoping of proximal segment of bowel into the distal segment one segment of the intestine , constricted by a wave of peristalsis suddenly becomes TELESCOPED into immediately distal segment of bowel Once trapped the invaginated segment is propelled by peristalsis farther into distal segments pulling its mesentery along behind it
27
what causes intussusception ?
In kids : lymphoid hyperplasia , especially terminal ileum cuz of peyers patches dragged into cecum Adults : Tumors
28
what happens due to intussusception ?
Infarction due to blood vessels being squashed as sucked into distal bowl current jelly stools colicky pain palpable mass
29
what is the treatment of intussusceptions ?
Enema Surgery
30
what is hirschsprung disease ?
congenital aganglionic megacolon Congenital defect in colonic innervation disruption of migration of neural crest cells from the cecum to the rectum Resulting in distal intestinal segment lacking both meissners submucosal plexus and auerbach myenteric plexus ( aganglinosis ) absence of coordinated peristaltic contractions resulting in functional obstruction results dilation proximal to affected segment ( DILATION ) --> the thing wont be able to contract and secrete stool resulting in dilation and obstruciton 1 of 5000 live births , more common in males but more severe in females
31
what is the clinical presentation of hirschsprung disease?
failure to pass meconium ( first stool pass by newborn ) obstructive constipation
32
what is the blood supply of Bowel?
Celiac ( foregut ) Superior mesenteric ( Midgut ) Inferior mesenteric ( hindgut ) as they approach the intestinal wall the superior and inferior mesenteric arteries fan out to form mesenteric arcades
33
what is the point of these mesenteric arcades / connections ?
the interconnections between arcades and collateral supplies and make it possible for Small intestines and colon To tolerate slowly progressive loss of blood supply from one artery BUT acute compromise of any major vessels can lead to infarction of several meters of intestine
34
what are the types of ischemic bowel disease ?
mucosal infarction mural infarction transmural infarction
35
what is mucosal infarction ?
infarction no deeper than muscularis mucosa it is in the mucosa only
36
what is mural infarction ?
mucosa and submucosa
37
what are the causes of mucosal and mural infarction ?
hypoperfusion ---> cardiac failure, shock , dehydration
38
what is transmural infarction ?
all 3 layers are affected
39
what are the causes of transmural infarction ?
acute vascular obstruction like severe atherosclerosis aortic aneurysm oral contraceptive embolization aortic atheromas
40
which parts of intestinal segments are susceptible to ischemia?
the intestinal segments at the end of their respective arterial supplies its called the watershed zone they have less blood flow and relay smaller blood vessels for nutrients these areas are more susceptible for ischemia example splenic flexure
41
why are small bowel infarction very susceptible ?
Cuz high ATP requirement
42
what are arterial infarct causes ?
Emboli thrombi Dissection
43
what are venous infarct causes ?
strangulation volvulus adhesion stasis thrombus
44
what causes transmural infarction ?
Embolism/thrombosis of SUPERIOR MESENTERIC ARTERY due to atrial fibrosis vasculitis ( polyarteritis nodosa- abdo pain , melena ) Thrombosis of mesenteric veins : Polycythemia vera Lupus anticoagulant - increases inappropriate thrombosis
45
describe mucosal infarction ?
marked by hypotension lumenal worst as furthest from supply Present : abdominal pain bloody diarrhea Decreased bowel sounds
46
what is angiodysplasia ?
Malformed submucosal and mucosal blood vessels ( twisted , dilated ) pathogenesis is unknown
47
what is the most common location of angiodysplasia ?
Cecum or right colon occur in elderly , less than 1% in adult population 20% of major episodes of lower intestinal bleeding may be chronic and intermittent or acute massive
48
what is hemorrhoids ?
dilated anal and perianal collateral vessels that connect the portal and caval venous system Relieve elevated venous pressure within the hemorrhoid plexus 5% of the general population
49
what are the causes of hemorrhoids ?
increased abdominal pressure pregnancy chronic constipation
50
what are malabsorption syndromes?
defective absorption of fats, fat and water soluble vitamins , proteins , carbohydrates, electrolytes, minerals and water could involve any of the 4 phases of nutrients absorption
51
what are the 4 phases of malabsorption syndromes?
Intraluminal digestion Terminal digestion Transepithelial transport Lymphatic transport
52
what is intraluminal digestion ?
proteins , carbohydrates and fats are broken down into : absorbable forms by pancreatic enzymes , bacteria , st acids
53
what is terminal digestion ?
hydrolysis of carbonhydrates and peptides by disaccharidass and peptidase respectively in the brush border of Small intestine mucosa
54
what is transepithelial transport ?
nutrients fluids and electrolytes are transported across and processed within the small intestinal epithelium
55
what is lymphatic transport?
of absorbed lipids
56
what are the sign and symptoms of malabsorption ?
diarrhea ( nutrients malabsorption and excessive intestinal secretion , flatus abdominal pain ) Weight loss inadequate absorption of vitamins and minerals leading to : anemia mucositis due to pyridoxine , folate , vitamin b12 deficiency bleeding due to vitamin K deficiency osteopenia due to calcium or vitamin D deficiency Neuropathy due to vitamin A or B12 deficiency
57
what are the other names of celiac disease ?
Celiac sprue gluten sensitive enteropathy white people , european ( 0.5 -1%)
58
what is celiac disease ?
immune mediated enteropathy triggered by ingestion of gluten containing cereals : wheat , rye , barely in genetically predisposed persons
59
what happens in celiac disease ?
Immobilization of T cells Progressive mucosal atrophy --> villous flattening Relieved by gluten withdrawal
60
describe the pathogenesis of celiac disease ?
Gluten is digested by luminal and brush border enzymes into amino acids and peptides One of the peptides is gliadin ( resistant to degradation proteases ) Gliadin is deamidated by tissue TRANSGLUTAMINASES (tTS) and the modified gliadin interacts with HLA- DQ2 or HLA-DQ8 on antigen presenting cells and be presented to CD4 + T cells T cells produce cytokines that are likely to contribute to the tissue damage and characteristics mucosal histopathology in addition to characteristics B cells having HLA-DQ2 and HLA-DQ8 genetics markers increase the risk of developing celiac disease
61
what is the clinical presentation of celiac disease ?
Kids : Abdominal distention Diarrhea Failure to thrive Adults : Chronic diarrhea Bloating
62
what is celiac disease associated with ?
Dermatitis herpetiformis
63
what is dermatitis herpetiformis ?
Skin condition linked to celiac disease itchy , blistering rashes appear on elbows, knees , buttocks occur because the immune system to gluten , similar to how it affects intestines in celiac disease
64
what are serology tests done in celiac disease ?
Anti gliadian anti transglutamase
65
how is diagnosis done ?
Biopsy from second portion of the duodenum or proximal jejunum ( exposed to the highest concentration of dietary gluten )
66
compare normal intestine to celiac disease intestine ?
Mucosa of celiac disease has : blunting and flattening of villi dense plasma cells infiltrating the lamina propria Chronic infiltration
67
what is tropical sprue ?
chronic diarrheal disease from possibly infections origin involves small intestines and it is characterized by malabsorption of nutrients
68
what is the difference between celiac disease and tropical sprue?
Occurs in tropical places Arises after infectious diarrhea Responds to antibiotics Damage more to jejunum and ileum ( DUODENUM IS LESS INVOLVED ) Jejunum absorbs folic acid so this may be deficient Ileum absorbs vitamin B12
69
describe lactase ( disaccharidase ) deficiency ?
Lactase deficiency gives raise to osmotic diarrhea so cant break down lactose , disaccharide osmotically active lactose remains in the lumen osmotically active so draw in water causes watery diarrhea Present when persons drink milk : abdominal distension Diarrhea
70
what are the 2 types of lactase deficiency ?
Congenital lactase deficiency : rare , autosomal recessive disorder caused by mutation in gene encoding lactase Acquired lactase deficiency : downregulation of lactase gene expression Common among native americans and african americans , chinese
71
what are viral infections causing enterocolitis ?
Rotavirus ( 69% ) Calciviruses Norwalk like Sapporo likes enteric adenovirsuses Astroviruses
72
what are the bacterial infections causing enterocolitis ?
E. coli salmonella Shigella Campylobacter Yersinia Vibrio Clostridium difficile Clostridium perfringens TB bacterial overgrowth
73
what are the parasitics causes of enterocolitis ?
Ascaris Strongyloides Necator Enterobius Trichuris Diphyllobothrium Tenia , hymenolepsis Amebiasis Giardia
74
what causes pseudomembranous colitis ?
Antibiotic therapy that disrupts normal microbiota allow C. difficile to grow these organism release toxins that disrupt epithelial function
75
what are the grossly features pseudomembranous colitis ?
Hyperemic mucosal surface covered by yellow green exudate
76
what are the microscopic features of pseudomembranous colitis ?
Inflammatory response Volcano like eruption of neutrophils Mucopurulent Pseudomembranous
77
Describe S.I tumors ?
Rare 3-6^ of GIT neoplasm Benign : Adenomas : Single or multiple , most often in duodenum and ileum , they increase the risk of malignancy Malignant : Carcinoids Adenocarcinomas

PATHOLOGYY2S2 (12 decks)

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