Liver Flashcards Preview

ESA 1 - Body Logistics > Liver > Flashcards

Flashcards in Liver Deck (23)
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1
Q

Which cells constitute the liver and what is special about these?

A
  • 80% composed of hepatocytes

- Have high regeneration potential - useful for liver transplant.

2
Q

What are the 5 functions of the liver?

A
  1. Metabolism (anabolism & catabolism)
  2. Storage
  3. Immunity
  4. Exocrine function - bile production
  5. Endocrine function
3
Q

The liver is involved in the anabolism (synthesis) of which molecules?

A
  1. Plasma proteins (e.g. Albumin, coagulation factors, Fe and Cu transport proteins)
  2. Complement components
  3. Glycogen
  4. Haematopoiesis in foetus
4
Q

The liver is involved in the catabolism (breakdown/toxin degradation) of which molecules?

A
  1. Drugs and poisons (via cytochrome P450)
  2. Hormones
  3. Haemoglobin
  4. Can take over removal of aged RBCs after splenectomy
5
Q

What is the role of the liver in storage?

A
  • Storage of carbohydrates and fats as:
    1) glycogen
    2) lipoproteins
    3) triglycerides
  • Storage of iron and vitamins A, B12, D and K (liver is very nutritious organ)
6
Q

Describe the role of the liver in immunity. Why is it an effective immune organ?

A
  • Filtering function: Kupffer cells (type of fixed macrophage) line the sinusoids and play important role in capturing/digesting pathogens and cellular debris.
  • Large volume of blood passing through hepatic portal system and liver allows Kupffer cells to clean large volumes of blood very quickly.
7
Q

What is the exocrine function of the liver?

A
  • Hepatocytes produce bile (1 litre/day) - active role in digestion.
  • Bile passes through bile ducts and is stored in the gall bladder. Presence of fat-containing food stimulates duodenum cells to release cholecystokinin - bile secreted to duodenum and emulsifies fat.
8
Q

How is haem excreted from the body?

A
  1. Kupffer cells destroy old RBCs, but haem cannot be recycled.
  2. Hepatocytes convert haem to bilirubin pigment.
  3. Bilirubin added to bile to be excreted from the body.
9
Q

How does the liver act as an endocrine gland?

A

Produces:

  1. Angiotensinogen (hormone causing vasoconstriction)
  2. Thrombopoietin (hormone regulating production of platelets)
  3. Insulin-like growth factor 1 (IGF-1) (hormone important in growth and anabolism)

In connection with endocrine function:

  1. Modifies vitamin D and thyroxin to active forms
  2. Breaks down insulin, glucagon, oestrogen and progesterone
10
Q

Describe the gross anatomy of the liver.

A

Consists of 4 distinct lobes:

  1. Left
  2. Right
  3. Caudate (posterior side of right lobe, wraps around vena cava)
  4. Quadrate (inferior to caudate lobe, wraps around gall bladder)
11
Q

Where does the peritoneum connect with the liver?

A
  1. Coronary ligament
  2. Left triangular ligament
  3. Right triangular ligament
  4. Falciform ligament
12
Q

Why is the blood supply to the liver unique?

A

Has 2 separate blood supplies:

  1. Proper hepatic artery supplies O2-rich blood from aorta - 25%.
  2. Hepatic portal vein supplies nutrient-rich blood (collects in vein after passing through capillaries of the spleen, stomach, pancreas, gall bladder and intestines) - 75%.
13
Q

How does blood leave the liver?

A

Hepatic vein carries nutrient- and O2- poor blood away from the liver to the inferior vena cava and heart.

14
Q

Which vessel enables bile to leave the liver?

A

Common hepatic duct.

15
Q

What is a sinusoid?

A

Irregular tubular space for passage of blood, taking the place of capillaries and venules in the liver, spleen and bone marrow.
Endothelial cells have large gaps.

16
Q

What are portal triads?

A

Hepatic portal vein + proper hepatic artery + common bile duct

17
Q

Describe a hepatic lobule.

A
  • Hexagonal (or irregular polygonal) arrangement of hepatocytes.
  • Surrounded by portal triads, off which branch hepatic sinusoids - allow hepatocytes to extract nutrients for the metabolism or storage of macromolecules and to access oxygen.
  • Proper hepatic arterioles and hepatic portal venules drain into a central vein (terminal hepatic venule) when then coalesces into a hepatic vein.
18
Q

What surrounds portal triads and what arises from this?

A
  • Periportal space of Mall

- Lymphatics arise from this and drain to the liver hilum and then onto the hepatic duct

19
Q

What is a more pathologically significant structure of hepatocytes units than the liver lobule?

A
  • Liver acinus (between 2 central veins) as it is the cells nearer this acinus that get damaged by toxins.
20
Q

What structure transports bile into bile ducts?

A

Bile canaliculi

21
Q

What is the space of Disse?

A
  • Gap between sinusoids lumen and hepatocytes.
  • Allows passage of blood, enabling cells to take up products using large microvilli surface area.
  • Contains stellate (Ito) cells.
22
Q

What are stellate cells?

A
  • Cells full of cytoplasmic vacuoles containing vitamin A.
23
Q

What happens to hepatic stellate cells in liver cirrhosis?

A
  • Cells lose their vitamin A storage capability and differentiate into myofibroblasts that synthesise and deposit collagen within the perisinusoidal space - liver fibrosis.
  • Collagen surrounds the central vein, constricting it and leading to portal hypertension.
  • Leads to many pathologies, e.g. Oesophageal varices.