Fa: Gastrointestinal - Anatomy - 2A

Front 1

What structure is formed where the endoderm (hindgut) meets the ectoderm?

Back 1

Pectinate (Dentate) Line

Front 2

What is the location of the Pectinate line?

Back 2

Formed between where endoderm (hindgut) ends and ectoderm begins

Front 3

What pathology occurs above the pectinate line?

Back 3

- Internal hemorrhoids
- Adenocarcinoma

Front 4

What is the arterial and venous supply to the area above the pectinate line?

Back 4

- Arterial supply: superior rectal artery (branch of IMA)
- Venous drainage: superior rectal vein → inferior mesenteric vein → portal system

Front 5

What pathology occurs below the pectinate line?

Back 5

- External hemorrhoids
- Anal fissures
- Squamous cell carcinoma

Front 6

What is the arterial and venous supply to the area below the pectinate line?

Back 6

- Arterial supply: inferior rectal artery (branch of internal pudendal artery)
- Venous drainage: inferior rectal vein → internal pudendal vein → internal iliac vein → IVC

Front 7

How does the area above and below the pectinate line compare in terms of the pathology that occurs there?

Back 7

Above pectinate line:
- Internal hemorrhoids
- Adenocarcinoma

Below pectinate line:
- External hemorrhoids
- Anal fissures
- Squamous cell carcinoma

Front 8

How does the area above and below the pectinate line compare in terms of the arterial supply?

Back 8

Above pectinate line:
- Superior rectal artery (branch of IMA)

Below pectinate line:
- Inferior rectal artery (branch of internal pudendal artery)

Front 9

How does the area above and below the pectinate line compare in terms of the venous drainage?

Back 9

Above pectinate line:
- Superior rectal vein → inferior mesenteric vein → portal system

Below pectinate line:
- Inferior rectal vein → internal pudendal vein → internal iliac vein → IVC

Front 10

How do internal and external hemorrhoids compare?

Back 10

Internal hemorrhoids:
- Above pectinate line
- Visceral innervation → not painful

External hemorrhoids:
- Below pectinate line
- Somatic innervation (inferior rectal branch of pudendal nerve) → painful

Front 11

What causes an anal fissure? Symptoms?

Back 11

- Tear in the anal mucosa below the pectinate line
- Pain while Pooping: blood on "toilet" paper
- Located Posteriorly since this area is Poorly Perfused

Front 12

What surface of the hepatocytes faces the bile canaliculi?

Back 12

Apical surface of hepatocytes

Front 13

What surface of the hepatocyte faces the sinusoids?

Back 13

Basolateral surface of hepatocytes

Front 14

What are the zones of the liver?

Back 14

- Zone I: periportal zone
- Zone II: intermediate zone
- Zone III: pericentral vein (centrilobular) zone

Front 15

What is the name of Zone I? Characteristics?

Back 15

Periportal Zone:
- Affected first by viral hepatitis
- Ingested toxins (eg, cocaine)

Front 16

What is the name of Zone II?

Back 16

Intermediate Zone

Front 17

What is the name of Zone III? Characteristics?

Back 17

Pericentral Vein (Centrilobular) Zone
- Affected first by ischemia
- Contains cytochrome P-450 system
- Most sensitive to metabolic toxins
- Site of alcoholic hepatitis

Front 18

Which type of hepatitis affects the different zones of the liver?

Back 18

- Viral: zone I
- Alcoholic: zone III

Front 19

Which type of toxins affects the different zones of the liver?

Back 19

- Ingested toxins (eg, cocaine): zone I
- Metabolic toxins: zone III

Front 20

Where are the cytochrome P-450 enzymes located in the liver?

Back 20

Zone III (pericentral vein zone)

Front 21

Which part of the liver is affected first by ischemia?

Back 21

Zone III

Front 22

What is the branching pattern of the biliary structures?

Back 22

- L & R Hepatic Ducts drain bile from liver into Common Hepatic Duct
- Common Hepatic Duct takes bile to be stored in gallbladder via Cystic Duct or to drain into Duodenum via Common Bile Duct

Front 23

Which duct drains the gallbladder?

Back 23

Cystic duct → Common Bile duct → Sphincter of Oddi / Ampulla of Vater → Duodenum

Front 24

What happens if a gallstone reaches the common channel at the Ampulla of Vater?

Back 24

Can block both the bile and the pancreatic ducts

Front 25

What are the potential implications of tumors that arise in the head of the pancreas?

Back 25

Can cause obstruction of the common bile duct (preventing bile from entering the duodenum)