Small Bowel

Embryology

100

Persistence of this leads to a Meckel's diverticulum

Vitelline duct

200

The small bowel is derived from the midgut aside from this structure, which is derived from the foregut

Duodenum

300

Midgut herniation persists until week ___ of fetal gestation

10

400

Crypt formation begins in the ___ to ___ weeks of gestation

10th, 12th

(Crypt layer is site of continual cell renewal and proliferation)

500

The proximal jejunum completes a ___ degree rotation before re-entering the abdomen

270

Anatomy

100

Small bowel wall consists of these four layers

Serosa, muscularis propria, submucosa, mucosa

200

How long is the entirety of the small intestine?

270-290 cm 

300

What is the blood supply of the small bowel? (aside from proximal duodenum)

Superior mesenteric artery

400

Microvilli increase absorptive capacity by ___-fold

30

500

These are the main cell type in the mucosa 

Absorptive enterocytes

Physiology

100

Trypsinogen becomes activated by this enzyme

Enterokinase

200

80-90% of protein digestion occurs here

Jejunum

300

These are small, spherical globules composed of bile salts that are highly fat soluble and help accelerate fat digestion

Micelles

400

Pacesetter potentials are thought to originate in this portion of the small intestine

Duodenum

500

80-90% of all fat is absorbed and transported to the blood through lymph in this form

Chylomicrons

Endocrine + Immune Function

100

Synthesis and secretion of this immunoglobulin is one of the major protective mechanisms for the intestinal tract

IgA

200

Fuel source for colonic cells

Butyrate

300

These cells, contained within follicle-associated epithelium, recognize antigens 

M (microfold) cells

400

Gut-associated lymphoid tissue is localized in these four areas

Peyer patches, lamina propria lymphoid cells, Paneth cells, intraepithelial lymphocytes

500

The duodenum and jejunum produce this hormone, which initiates the migrating motor complex

Motilin

Obstruction

100

Most common cause

Adhesions

200

True or false: there is substantial evidence supporting the use of prophylactic antibiotics in non-toxic appearing patients with small bowel obstruction

FALSE

300

CT findings concerning for ischemia (6)

Bowel wall thickening (>3mm), mesenteric edema, fluid trapped between loops, decreased bowel wall enhancement, pneumatosis intestinalis, mesenteric or portovenous gas

400

A dilated loop of bowel measuring greater than this is considered concerning for high grade small bowel obstruction

2.5 cm

500

Incidence of strangulation and other complications increases after this time period

12 to 24 hours