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GERR Micro-anatomy > Microanatomy of GI Glands > Flashcards

Microanatomy of GI Glands Flashcards

1
Q

What are the 4 accessory organs of the GIT

A

1- Liver
2- Pancreas
3- Gallbladder
4- Salivary glands

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2
Q

List lobes of liver

A
  • largest gland in body
  • 4 lobes : right , left, quadrate, caudate
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3
Q

Describe the micro anatomy of the liver ( epithelium , blood supply )

A
  • mainly epithelial tissue , little CT
  • 2 major blood vessels : hepatic artery and hepatic portal vein
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4
Q

Key features of hepatic artery

A
  • supplies 30% of blood passing through liver
  • Rich in oxygen ,
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5
Q

Key features of Hepatic portal vein

A
  • supplies 70% of blood passing through liver
  • take what’s absorbed by GIT and takes to liver for processing
    low in oxygen
  • high in nutrients
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6
Q

What is the Portal Hepatis

A

the hilum of the liver where the vessels enter and divide into branches
- includes : nerves, hepatic vein , common hepatic duct , lymphatic vessels, hepatic artery and hepatic portal vein

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7
Q

How is the liver drained and what type of blood is leaving

A
  • by the hepatic vein that empties into IVC
  • highly nutrient blood
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8
Q

What is the common hepatic duct

A

takes bile produced in liver to gallbladder

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9
Q

What are the functions of the liver ( 5)

A

1- exocrine gland function - bile synthesis
2- endocrine gland function - plasma protein synthesis
3- process nutrients absorbed in GIT and store till needed
4- degrades toxins
5- destroys won-out RBC, pathogens

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10
Q

What are the two ways to describe liver morphology

A

1- Classic Lobule ( 3 lobes )
2- Liver Acinus

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11
Q

What is the Classic Lobule model based on

A

histology of liver

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12
Q

Main Features of Classic Lobule Model

A
  • Polygonal lobes
  • irregular rows of hepatocytes ( liver cells)
  • hepatocytes arranged around central vein , radiating outward
  • Peripheral portal areas ( in corner )
  • Vascular sinusoids
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13
Q

What is in portal areas

A

Hepatic portal vein
Bile duct
Lymphatic vessels

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14
Q

What are vascular sinusoids and function

A
  • where blood will drain
  • nutrients and toxins in blood will pass through sinusoids into hepatocytes for processing
  • will drain blood into central vein of lobule which drains into hepatic vein
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15
Q

Label Lobule

A
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16
Q

Label

A
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17
Q

Label Portal Area

A
18
Q

What is the Liver Acinus Model based on

A

based on liver function

19
Q

Main features of Liver Acinus Model

A
  • Spread over 2 lobules inbetween central veins of lobes
  • Hepatocytes and sinusoids within them
  • peripheral Portal areas in classic lobule
  • central vein in middle in classic lobule
  • Acinus is seperated in zones , hepatocytes in each zone have different metabolic activity depending on distance from portal area
20
Q

What does the Liver Acinus Model help explain

A
  • oxygen gradient : hepatocytes farer from blood supply will be supplied with blood with lover o2 levels
  • distribution of drug metabolism enzymes : hepatocytes farthest from portal area have most enzymes
  • zones of histological damage due to ischaemia or toxicicity
21
Q

Describe Zone 1

A
  • closest to blood suply
  • farthest from terminal hepatic venule ( central vein in classic module )
  • recieve oxygen and nutrient rich blood
  • actively synthesis glycogen and plasma proteins
22
Q

Describe Zone 2

A
  • intermediate hepatocytes
  • recieve second class blood
23
Q

Describe Zone 3

A
  • furthest from portal area
  • recieve blood lowest in oxygen and nutrients
  • Closest to terminal hepatic venule
  • site of alcohol and drug detoxification
  • most susceptible to hypoxia and toxic damage since they get the least oxygen and nutrients and the most toxins
24
Q

What can cause damage to zone 3

A

if there is low perfusion cells could die

25
Q

How thick are rows of hepatocytes and why

A

one cell thick so they can easily exchange with blood suplly flowing through sinusoids

26
Q

What is the role of the central vein

A

taakes deoxygentaed blood from sinusoids and drains into IVC

27
Q

How is bile produced and travels

A
  • Bile is produces by hepatocytes
  • travels through small intercellular channels called bile canaliculi
  • drain into bile duct at portal area
  • Bile and blood DO NOT MIX
28
Q

Describe Bile Canalculi position and formation

A
  • intercellular channels sealed by tight junstions and formed by hepatocytes plasma membrane
29
Q

Describe Sinusoid microanatomy

A
  • lined with fenestrated epithelium for exchange
30
Q

Describe Hepatocyte Sinusoid boundry

A

Space of disse: where plasma filters to make contact with microvili of hepatocyte

  • in between microvilli and sinusoid epithelium
31
Q

What are Kupffer cells

A
  • macrophages that break old RBC
  • located on inner walls of sinusoids
  • derived from circulating monocytes
  • phacoytose any foreign matter
32
Q

Where are Bile canalculi located

A

inbetween/ in hepatocytes

33
Q

Is the pancreas divided

A
  • divided into lobules by CT septa
  • has portions that are both endocrine and exocrine
34
Q

Explain the exocrine portion of the pancreas

A
  • composed of serous acini ( secretory unit ) and branching duct system
  • produce enzymes for food digestion
  • produce in inactive form to avoid self-digestion and transported to duodenum
35
Q

Explain the endocrine portion of pancreas

A
  • composed of islets of langerhand ( specialized epithelial cells ) and blood capillaries within them
  • produce hormones : insulin , glucagopn, somatostatin , pancreatic polypeptide
36
Q

What are serous acini

A
  • secretory units that produce digestive enzymes which are secreted into small ducts that drain into main duct that goes to duodenum
37
Q

How do islets of langerhans present in micrograph

A
  • pale staining cells
38
Q

Describe microanatomy of islet

A
  • compact mass of epithelial cells
  • 4 cell types : alpha cells ( glucagon ) beta cells ( insulin ) delta cells (somatostatin) f-cells ( pancreatic polypeptide )
  • 4 cells can’t be visualized with normal staining
39
Q

Role of salivary glands

A

produce secretions from mostly acinar type units

40
Q

Label part of pancreas

A
41
Q

Label

A

GERR Micro-anatomy (5 decks)

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