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Flashcards in GI Deck (139):
1

Foregut

Pharynx to duodenum

2

Midgut

duodenum to transverse colon

3

Hindgut

Distal transverse colon to rectum

4

Failure of rostral fold closure

Sternal defects

5

Failure of lateral fold closure

Omphalocele, Gastroschisis

6

Gastroschisis

Extrusion of abdominal contents through abdominal folds; NOT covered by peritoneum

7

Omphalocele

Persistence of herniation of abdominal contents into umbilical cord, COVERED BY PERITONEUM

8

Failure of caudal fold closure

Bladder extrosphy

9

Penile abnormality associted with bladder extrosphy

Epispadas

10

Duodenal atresia

failure to recanalize
* seen in trisomy 21

11

Jejunal, ileal, colonic atresia

due to vascular accident (apple peel atresia)

12

Midgut development

6th week - midgut herniates through umbilical ring
10th week - returns to abdominal cavity + rotates around SMA

13

Pathology of GI development

Malrotation of midgut, omphalocele, intestinal atresia or stenosis, volvulus

14

Most common tracheoesophageal anomaly

Esophageal atresia with distal tracheoesophageal fistula (TEF)

15

Sx of esophageal atresia w/ TEF

Newborn baby with drooling, choking, vomiting on first feeding. TEF allows air to ender stomach (visible on CXR). Cyanosis is secondary to laryngospasm (to avoid reflux-related aspiration)

16

Clinical test of esophageal atresia w/ TEF

Failure to pass NG tube into stomach

17

CXR of gasless abdomen

Pure atresia (isolated) esophageal atresia

18

Congenital pyloric stenosis

hypertrophy of pylorus causes obstruction. Palpable "olive" mass in epigastric region and nonbilious projectile vomiting at 2 weeks of age. Treatment is myoectomy. Usually in first born males.

19

Embryo origin of pancreas

derived from foregut.

20

Ventral pancreatic buds contribute what?

Pancreatic head and main pancreatic duct. Uncitate project

21

Dorsal pancreatic buds form what?

Pancreatic body, tail, isthmus, and accessory pancreatic duct

22

Annular pancreas

ventral pancreatic bud abnormally encircles 2nd part of duodenum; forms a ring of pancreatic tissue that causes duodenal narrowing

23

Pancreas divisim

ventral and dorsal root fail to fuse at 8 weeks

24

Embryo origin of spleen

Arises from mesentery of stomach (hence is mesodermal) but is supplied by foregut (celiac artery)

25

Retroperitoneal structures

Include GI structures that lack a mesentary and non-GI structures

26

Result of injury to retroperitoneal structures

Cause blood or gas accumulation in retroperitoneal space

27

Name retroperioneal structures

"SAD PUCKER"
S-uprarenal (adrenal) gland
A-orta and IVC
D-uodenum (2nd and 3rd parts)
P-ancreas (EXCEPT TAIL)
U-reters
C-olon (decending and ascending)
K-idneys
E-sophageus (lower 2/3)
R-ectum (lower 2/3)

28

Falciform ligaments

connects liver to anterior abdominal wall
contains ligamentum teres hepatis (derivative of fetal umbilical vein)
- derivative of ventral mesentary

29

Hepatoduodenal ligament

connects liver to duodenum
contains: Portal triad (hepatic artery, portal vein, common bile duct)
- can do Pringle maneuver
- connects greater and lesser sacs

30

Pringle maneuver

Hepatoduodenal ligament may be compressed between thumb and index finger placed in omental foramen to control bleeding.

31

Gastrohepatic ligament

connects liver to lesser curvature of stomach
- contains gastric arteries
- separates greater and lesser sacs on RIGHT
- may be cut during surgery to access lesser sac

32

Gastrocolic

connects greater curvature to transverse colon
- structures contain gastroepiploic artery
- part of greater omentum

33

Gastrosplenic

connects greature curvature and spleen
- contains short gastrics, LEFT gastroepiploic vessels
- seperate greater and lesser sacs on LEFT

34

Splenorenal

connect spleen to posterior abdominal wall
- contains splenic artery and vein, tail of pancreas

35

Layers of gut wall (inside to outside)

"MSMS" - inside to outside
M-ucosa
S-ubmucosa
M-uscularis externa
S-erosa

36

Musosa of gut

-epithelium (absorption)
-lamina propria (support)
-muscularis mucosa (motility)

37

Submucosa of gut

- submucosal nerve plexus (Meissner's) - controls secretory activity

38

Muscularis externa of gut

include Myenteric nerve plexus (Auerbach's)

39

Serosa of gut

- serosa when intraperitoneal
- adventitia when retroperitoneal

40

Ulcers of gut are found in which gut layers?

Can extend into submucosa, inner or out muscular layer

41

Erosions are found in which gut layers

Only in mucosa

42

Frequencies of basal electric rhythm

Stomach - 3 waves/min
Duodenum - 12 waves/min
Ileum - 8-9 waves/min

43

Esophagus: Histology

Nonkeratinized stratified squamous epithelium

44

Stomach: Histology

Gastric glands

45

Duodenum: Histology

Villi and microvilli for increased absorptive surface
Brunner's glands (submucosa) and crypts of Lieberkuhn

46

Jejunum: Histology

Plicae circulares and crypts of Liberkuhn

47

Ileum: Histology

Peyer's patches (lamina propria, submucosa), plicae circularis (proximal ilum) and crypts of Liberkuhm

48

Colon: Histology

has crypts but no villi, numerous goblet cells

49

Four sites of portosystemic anastomoses

1. Esophagus
2. Umbilicus
3. Rectum
4. TIPS (artificial transjugular intrahepatic portosystemic shunt - used for tx of portal hypertension)

50

Esophagus anastomosis

Clinical sign: esophageal varices
Connects left gastric to esophageal

51

Umbilical anastomosis

Clinical sign: caput medusae
Below umbilicus: connects paraumbilical to superficial and inferior epigatric
Above umbilicus: connects paraumbilic to superior epigastric and lateral thoracic

52

Rectum

Clinical sign: internal hemorrhoids
Connects superior rectal to middle and inferior rectal

53

Common sx of portal hypertension

Varices of gut, butt, and caput (medusae)

54

Tx of portal hypertension

TIPS - transjugular intrahepatic porosystemic shunt between portal vein and hepatic vein percutaneously relieves portal hypertension by shunting blood to systemic circulation

55

Pectinate (dentate) line

where endoderm (hindgut) meets ectoderm

56

Pathology ABOVE pectinate line

Internal hemorrhoids, Adenocarcinoma
Receives arterial supply from superior rectal artery (branch of IMA)
Venous drainage is superior to rectal vein --> inferior mesenteric vein --> portal vein

57

Pathology BELOW pectinate line

External hemorrhoids, squamous cell carcinoma
Arterial supply: Inferior rectal artery (branch of internal pudendal artery)
Venous drainage to inferior rectal vein --> internal illiac ven --> IVC

58

Internal hemorrhoids (painful or not painful?

NOT PAINFUL, because receives visceral innervation. Lymphatic drainage to deep nodes

59

External hemorrhoids

PAINFUL. Receive somatic innervation (inferior rectal branch of pudendal nerve)
Lymphatic drainage to superficial inguinal nodes

60

Apical surface of hepatocytes

face bile canaliculi

61

Basolateral surface of hepatocytes

face sinusoids

62

Zone I of liver

Periportal zone - affected first by viral hepatitis. Areas in which branch of portal vein/ hepatic artery are located)

63

Zone II of liver

Intermediate zone

64

Zone III - Pericentral vein (Centrilobular zone)

affected 1st by ischemia - farthest away from hepatic artery
- contains P-450 system
- most sensitive to toxic injury
- site of alcoholic hepatitis

65

Result of gallstone blocking ampulla of Vater

blocks bile and pancreatic ducts

66

Result of tumor arising in head of pancreas (near duodenum)

Can cause obstruction of common bile duct

67

Femoral region organization

Lateral to medial: "NAVEL"
N-erve
A-rtery
V-ein
E-mpty pace
L-ymphatics

68

Femoral triangle

contains femoral vein, artery, nerve

69

Femoral sheath

Fascial tube 3-4 cm BELOW inguinal ligamen. Contains femoral vein, artery, and canal (deep inguinal lymph nodes) BUT NOT FEMORAL NERVE

70

Hernia

protrusion of peritoneum through an opening- usually a site of weakness

71

Diaphragmatic hernia

abdominal structures enter thorax
- may occur infants due to defective pleuroperitoneal membrane

72

Hiatal hernia

common hernia in which stomach herniates upward through esophageal hiatus of diaphragm

73

Sliding hiatal hernia

most common. GE junction displaced upwards. "Hourglas stomach"

74

Paraesophageal hernia

GE juction is normal. FUNDUS protrudes into thorax

75

Indirect hernia

goes through INTERNAL inguinal ring, external inguinal ring, and INTO scrotum.
- Enters internal inguinal ring LATERAL to inferior epigastric artery

76

Cause of indirect inguinal hernia in infants

Due to failure of processus vaginalis to close (can form hydrocele). Much more common in males

77

Direct inguinal hernia

protrudes through inguinal (Hasselbach's triangle. Bulges directly rhough abdominal wall MEDIAL to inferior epigastric artery. Goes through ONLY the external (superficial) inguinal canal.
- Covered by external spermatic fascia. Usually in oldern man

78

Mneumonic for Indirect/Direct Inguinal Hernias

MDs don't LIe

-Medial to inferior epigatric - Direct
-Lateral to inferior epigastric -Indirect

79

Femoral hernia

protrudes BELOW inguinal ligament through femoral canal and lateral to pubic tubercle. More common in women.

80

Most common cause of bowel incarceration

Femoral hernia

81

Hasselbach's Triangle

Inguinal Triangle
- Inferior epigatric vessels
- Lateral border of rectus abdominus
- Inguinal ligament

82

Gastrin

- found in G cells (antrum of stomach)
- increases gastric H+ secretion
- increases growth of gastric mucosa
- increases gastric motility

83

Gastrin regulation

- INCREASED by stomach distention/alkanization, amino acids, peptides, vagal stimulation
- DECREASED by stomach pH < 1.5

84

Associations w/ gastrin

HIGHLY elevated in Zollinger-Ellision syndrome
-Increased by chronic PPI use
- Phenylalanine and tryptophan are potent stimulators

85

Cholecystokinin

-made by I cells (duodenum, jejunum)
- increase pancreatic secretion
- increase gall bladder contraction
- DECREASES gastric emptying
- DECREASE sphincter of Oddi relaxation

86

Cholecystokinin regulation

- increased by fatty acids, amino acids

87

Cholecystokinin Notes

Cholecystokinin acts on neuronal muscarininc pathways to cause pancreatic secretions

88

Secretin

S cells (duodenum)
- increase pancreatic HCO3 secretion
- decrease gastric acid secretion
- increases bile secretion

89

Secretin regulation

Increased by fatty acids in lumen of duodenum

- Increased HCO3 neutralizes gastric acid in duodenum allowing pancreatic enzymes to function

90

Somatosatin

secreted by D cells (pancreatic islets, GI mucosa)
- decreases gastric acid and pepsinogen secretion
- decreases pancreatic and small intestine fluid secretion
- decreases gallbladder contraction
- decreases insulin and glucagon release

91

Somatostatin regulaton

- increased by acid
- decreased by vagal stimulation
- inhibitory hormone.
- Antigrowth hromone effects (inhibits digestion and absorption of substances needed for growth)

92

Glucose-dependent insulinotropic peptide

K cells (duodenum, jejunum)
Exocrine: decreases gastric H secretion
Endocrine: increases insulin release

93

Glucose-dependent insulinotropic peptide: regulation

increased by fatty acids, amino acids, oral glucose
- Also known as GIP
- An oral glucose load is used more rapidly than IV due to GIP

94

Vasoactive intestinal polypeptide (VIP)

Parasympathetic ganglia in sphincters, gallbladder, small intestine
- Increases water and electrolyte secretion
- Increases relaxation of intestinal smooth muscle and sphincters

95

VIP Regulation

- Increased y distention of vagal stimulation
- Decreased by adrenergic input

96

VIPoma

- non alpha, non-B islet pancreatic tumor that secretes VIP.
Associated with WHDA syndrome -
Watery Diarrhea, Hypokalemia, and Achlorydia

97

Nitric Oxide

Increases smooth muscle relaxation, including lower esophageal sphincter

98

NO and its implication in achalasia

Loss of NO secretion is implicated in lower esophageal tone in achalasia

99

Motilin

- found in small intestine
- produce migrating motor complexes

100

Motilin regulation

- increased in fasting state
- motilin receptor agonists (such as erythromycin) are used to stimulate intestinal peristalsis

101

Intrinsic factor

- found in parietal cells (stomach)
- Vitamin B12 - binding porein (required for B12 uptake to terminal ileum)

102

Autoimmune destruction of parietal cells

Chronic gastritis and pernicious anemia

103

Gastric acid

- secreted by parietal cells (stomach)
- decrease stomach pH

104

Gastric acid regulation

- Increased by histamine, ACh, gastrin
- Decreased by somatostatin, GIP, prostaglandin, secretin

105

Gastrinoma

gastrin-secreting tumor that causes continuous high levels of acid secretion

106

Pepsin

- found in chief cells (stomach)
- protein degestin

107

Pepsin regulation

increased by vagal stimulation, local acid
Inactive pepsinogen --> pepsin by H+

108

HCO3

- made by mucosal cells (stomach, duodenum, salivary glands, pancreas) and Brunner's glands (duodenum)
- neutralizes aics

109

HCO3 regulation

Increased by pancreatic and biliary secretion with secretiin
- HCO3 is trapped in mucus that covers the gatric epithelium

110

Saliva

secretion from parotid, submandibular, and sublingual glands is stimulated by SYMPATHETIC and PARASYMPATHETIC acitivity.
Amylase digests starch, Bicarb neutralizes bacterial acids, Mucins lubricate food
Normally hypotonic because of absorption but more isotonic with higher flow rates

111

Discuss atropine and parietal cells

Atropine blocks vagal stimulation of parietal cells. Vagal stimulation of G cells (secretes gastrin) is unaffected because uses GRP as neurotransmitter not ACh

112

Gastrin increases acid secretion through its effect on which cells

ECL cells (which lead to histamine release) rather than through direct effect on parietal cells

113

Brunner's glands

located in duodenal submucosa. Secretes alkaline mucus. Hypetrophy seen in peptic ulcer disease

114

Nature of pancreatic secretions

Isotonic fluid
low flow --> high Cl-
High flow --> High Bicarb

115

Alpha-amylase

Pancreatic secretion. Digests starch.
*Secreted in active form

116

Lipase, Phospholipase A, colipase

Pancreatic secretions. Aids in fat digestion.

117

Pancreatic proteases

- Digests proteins
- Includes trypsin, chemotrypsin, elastase, carboxypeptidases

118

Trypsinogen

Converted to active enzyme trypsin --> activation of other pro-enzymes and creation of more trypsinogen (positive feedback loop)

119

Enterokinase/ Enteropeptidase

converts trypsinogen to trypsin
- secreted from duodenal mucosa

120

Salivary amylase

Starts carbohydrate digestion. Hydolyzes alpha 1,4 linkages to yield disaccarides (maltose and alpha limit dextrins)

121

Pancreatic amylase

Highest concentration in duodenal lumen, hydrolyzes starch to oligosaccharides and disaccharides

122

Oligosaccharide hydrolases

At intestinal brush border.
RATE LIMITING STEP in carbohydrate digesti, produce monosaccharide from oligo-disaccharides

123

Monosaccharide absorption

- Only monosaccharides (glucose, galactose, fructorse) are absorbed by enterocytes. All are transported to blood by GLUT-4

124

Glucose and galactose absorption

Taken by SGLT1 (Na+ dependent)

125

Fructose absorption

Facilitated diffusion by GLUT-5.

126

D-xylose absorption test

Distinguishes GI mucosal damage from other causes of malasborption

127

Fe absoprtion

absorbed as Fe2+ in DUODENUM

128

Folate absorption

Absorped in jejunum

129

B12 absorption

absorbed in terminal ileum, along with bile acids, requires intrinsic factor

130

Peyer's patches

unencapsulated lymphoid tissue found in lamina proproa and submucosa of ileum. Contains specialized M cells that take up antigen

131

Discuss B cells and Peyer's Patches

B cells stimulated by germinal centers of Peyer's patches differentiate in to Ig-A secreting plasma cells, which ultimately reside in lamina propria.
IgA receives protective secretory component and is then transported across epithelium to deal with intraluminal antigen

132

Bile Composition

composed of bile salts (bile acids conjugated to glycine/taurine, making them water soluble), phospholipids, cholesterol, bilirubin, water, and ions.

133

Bile Function

Digestion and absorption of lipids and fat soluble vitamins.
Cholesterol excretion (body's only means of eliminating cholesterol)
Antimicrobial activity (via membrane disruption)

134

Enzyme that catalyze bile formation

Cholesterol 7-alpha hydroxylase catalyzes rate limiting step.

135

Bilirubin

product of heme metabolism. Bilirubin is removed from by liver, conjugated wth glucuronate, and excreted in bile

136

Direct bilrubin

Made in liver
- conjugated in glucuronic acid; water soluble

137

Indirect bilirubin

Unconjugated - water insoluble
- made from breakdown of heme

138

Trace Heme break down

1. RBCs lyse
2. Heme breaks down to form unconjugated bilirubin (water insoluble)
3. Albumin- complexes w/ unconjugated bilirubin for transport to liver
4. UDP-glucoronsyl transferase in liver conjugates bilirubin to make direct bilirubin
5. Direct bilirubin is secreted into gut and broken down by gut bacteria to become urobillinogen

139

Discuss pathway of urobillinogen

Product of gut bacteria breakdown of direct billirubin.
2. 80% of urobillinogen is excreted into feces
3. 20% of urobillinogen is absorted into gut - small fraction is excreted in kidney as urobilin (gives pee its color)
- majority of absorbed urobillinogen is recirculated in the enterohepatic circulation