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ANAT 261 > Liver & Pancreas > Flashcards

Liver & Pancreas Flashcards

1
Q

What are different functions of the liver?

A
  1. Endocrine Secretion → Somatomedin (promoted by GH to allow growth of epiphyseal plate), Albumin, fibrinogen, prothrombinm, transferring, VLDL, etc. (not typical hormonal organ)
  2. Exocrine Secretion → Bile acids, bilirubin (also secretes phospholipids and cholesterol)
  3. Inactivation/Elimination of substances
  4. Conversion of substances: T4 (Thyroxine, Thyroid hormone) → T3 (mor potent)
  5. Hemopoiesis → During fetal development (1st organ to produce RBCs, taken over by bonne marrow)
  6. Storage of substances → Glycogen, lipids
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2
Q

How is the liver important for inactivation/elimination of substances?

A

Glucuronyl transferase conjugates glucuronic acid to bilirubin but also to barbiturates, antihistaminics, anticonvulsants, insecticides and other drugs
Endocytosis of hormones and cholesterol (LDL particles)
- Drugs we don’t want in our body are conjugated with glucoronic acid and eliminated from our body
- Liver absorbs substances (receptor for every hormone) by endocytosis → fuse with lysosomal compartment → hormones/drugs are digested

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3
Q

What are the different blood vessels of the Liver?

A

Into Liver → Outside Liver
Portal vein + Hepatic artery → … → Hepatic vein

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4
Q

What is the Porta Hepatis in the liver?

A

*Also called Hilum / not the same as the portal space which is in each lobule
It is the structure by which the capsule of CT penetrates inside the liver to give rise to lobes → lobules

Has 3 structures:
1. Hepatic Artery
2. Portal Vein
3. Bile duct

It is a transverse fissure located in the inferior surface, where the major vessels and ducts enter or leave the organ.

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5
Q

What blood can be found in the sinusoids of the liver?
What is the function of this circulation unit?

A

The branches of the hepatic artery deliver arterial blood into the sinusoid. The branches of the hepatic portal vein send venous blood rich in nutrients from the intestine into the same sinusoids
- Both mix in the sinusoids

As the blood flows toward the central vein it gives up oxygen and nutrients to the liver cells and picks up metabolized and synthesized products made by liver cells (endocrine function)

Blood empties into central vein of the lobule → veins → out through porta hepatic → vena cava

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6
Q

What is the portal space?

A

*3-7 portal spaces/lobule
It is where the interlobular CT of the liver enlarges
Find 3 structure:
- Bile duct →
- Portal Venule (branched from hepatic vein)
- Hepatic Arteriole (branched from hepatic artery)
*Venule and arteriole later join to form sinusoids and dump their contents into the central vein of the lobule

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7
Q

What are kupffer cells?

A

**They are a type of Macrophages cells (eat the bad stuff)
Bulky cells which have processes that go to opposit sides/different regions of the sinusoids
- Endocytotic action
Found in the endothelial layer of the sinusoids

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8
Q

How is the Bile duct epithelium classified?

A

Simple cuboidal epithelium

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9
Q

What are important organelles found in hepatocytes?
What structures line both sides of hepatocytes?

A

Organelles:
- Lots of endocytic and exocytic vesicles
- Smooth and rough ER
- Peroxisome

Outside → more out:
- Microvilli on both sides (plasma membrane of hepatocytes)
- Space of Disse
- Reticular fibers
- Endothelial cells
- Sinusoid

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10
Q

What junctions hold neighbouring hepatocytes together?

A

On both side of bile canaliculi → tight junctions do not let bile leak (bile emulsifies lipids so dangerous for the membrane)
*Can cause jaunidice or hepatitis
*Bile is also toxic for CT where accumulates and in the brain
Closer to microvilli → desmosomes to provide structure

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11
Q

How does Receptor-Mediated Endocytosis occur in hepatocytes?

A

Hepatocytes have a receptor for every molecules that can’t stay in circulation forever → Hormones, LDL, HDL, Chylomicrons, etc.
The molecules binds to its receptor → Endocytic vesicle → Internalized and becomes an Endosome → Fuses with acidic endosomes (pH 5.5) → dissociation of the ligand with its receptor, receptor is recycled to the surface and ligands mature to multivesicular body which allows digestion/degradation of ligands → Lysosome

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12
Q

What is the process of secretion of VLDL in hepatocytes?

A

VLDL = Apoliprotein + lipids
RER → synthesizes apolipoproteins
SER → Store long-chain fatty acids, triacylglycerols, phospholipids and cholesterol
They are both brought to the Golgi → they bud off and become exocytic vesicles → exocytosed

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13
Q

What is Peroxisme?

A

It is a hepatocyte organelle that has catalase which catalyses 2x H2O2 → 2x H2O + O2

H2O2 is a toxic byproduct of:
- b-oxidation of FA
- Catabolism of EtOH
- Break down of purines (AMP/GMP) to uric acid
- Cholesterol synthesis

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14
Q

What is the composition of the bile? Where is it synthesized?

A

Synthesized in the Smooth ER
- Cholesterol + Taurine = Taurocholic acid
- Cholesterol + Glycine = Glycocholic acid
- Bilirubin conjugated to glucuronic acid

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15
Q

What is the portal lobule vs the classic lobule?

A

Portal lobule = exocrine secretory unit → 3 central veins surrounding central 1 portal space
Classic lobule = Multiple portal space surrounding a central vein → lined by interlobular CT

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16
Q

What is a Hepatic acinus?

A

Parallelogram/ovoid structure formed by 2x CV and 2x PS
In the middle, there is interlobular CT with sinusoid branch points

17
Q

What is the turnover rate of Hepatocytes?

A

150 days → low and expanding epithelium (compared to skin which turns over every 25 days)
After surgical excision, cells divide actively until the organ reaches its normal size
But repeated damage to the hepatocytes results in the proliferation of CT → a condition known as cirrhosis

18
Q

What is the mitotic index of hepatocytes?

A

1 cell/20,000

19
Q

What are the 2 main glandular functions of the pancreas?

A

Pancreas = mixed exocrine and endocrine gland

Endocrine portion → islet of Langerhans
Exocrine protion → compound acinar gland similar in structure to parotid gland
- Produces slightly alkaline fluid and proteins (>15 enzymes and pro-enzymes/zymogens) → secreted in small intestine for digestion

20
Q

What is the structure of the pancreas?

A

Head → accomodated in the C shape of duodenum
Body
Tail → where most carcinomas occur

In the middle runs the main pancreatic duct → Interlobar duct → Interlobular duct → Intralobular duct → Intercalated duct
*Exocrine pancreas (divided in lobes and lobule by CT) → compound acini
*Duct system is connected to embryonic intestine

21
Q

Where does the pancreas and salivary

A

Both pancrease and salivary glands are derived from evaginations of the endodermal lining of the embryonic (primitive) intestine

22
Q

Where do the islets of Langerhans originate/differentiate from?

A

*Endorcine pancreas

Some cell from the acini further differentiate and detach from the acini to become islets of Langerhans

23
Q

What are cells like in the serous acini?

A

PANCREAS
Acinar cells:
- Pyramidal cells
- No myoepithelial cells (as in parotid glands)
- Basophilic near the base (RER, nucleus, mitochondrias)
- Acitophilic near the lumen (zymogenic granules)

*Centro Acinar cells lining the lumen

24
Q

What are the differences bewteen parotid glands and the pancreas serous glands?

A

SEE

25
Q

What are the cells lining the intercalated ducts like?

A

*1st duct after the acini (pancreas)
Short cuboidal cells (sometimes almost squamous)

26
Q

What organelles are found in the serous acinar cells of the pancreas?

A

From base to apex:
- RER for protein synthesis + Mitochondria
- Nucleus
Golgi → packs enzymes/pro-enzymes into condesing granules → become zymogen granules as they migrate and mature → exocytosed
- Microvilli by which cells are exocytosed
- TJ between acinar cells to prevent leakage of digestion enzymes
- Desmosomes for structure

27
Q

Which enzymes allow regulation of exocrine secretions in the pancreas?

A

Secretin → stimulates secretion of H2O and bicarbonate (pH buffer)

Cholecystokinin (CCK) → produced by enteroendocrine cells of the duodenum and promote exocytosis of zymogen granules for digestion

28
Q

What are 4 proenzymes found in zymogenic granules ?
Which enzyme is responsible for making their active form?

A
  1. Trypsinogen → Trypsin
  2. Pro-Carboxypeptidase → Carboxypeptidase
  3. Pro-Elastase → Elastase
  4. Pro-Phospholipase-A → Phospholipase-A

*Enterokinase in the microvilli of the enterocytes of the duodenum converts them to their active form

29
Q

What are 4 enzymes found in zymogenic granules ?

A
  1. Lipase (importance of TJ, role in pancreatitis) → if leaks, it destroyes membranes and organelle’s membranes
  2. Amylase
  3. RNAse
  4. DNAse

*Trypsin inhibitor secreted by centracinar cells

30
Q

What are the different cells of the islet of Langerhans (Endocrine pancreas)?

A

Alpha-cells → more acidophilic stain (acidophilic granules), secrete glucagon

Beta-cells → most abundant, paler staining, secrete insulin

D-cells → secrete somatostatin (can see with H&E stain)

Also have few capillaries

31
Q

What is the role of glucagon?

A

Role in maintaining normal concentrations of glucose in the blood (opposit effect of insulin)

Synthesized as proglucagon → processed to glucagon within a-cells
Final product = 29 AA linear peptide, very conserved

Progulcagon is also …

32
Q

What is the liver surrounded with?

A

Covered by a dense CT capsule → Glisson’s capsule
lined by a peritoneum

33
Q

What is the pathway of bile through the liver?

A
  1. Secreted by Golgi in hepatocytes
  2. Into Bile canaliculi
    Follows direction towards the portal space (opposit to blood flow in sinusoids)
  3. Drained into cholangioles/canal of Hering
  4. Emptied into bile duct in portal space

ANAT 261 (21 decks)

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