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DIG > L05 - Liver > Flashcards

L05 - Liver Flashcards

1
Q

What is the main digestive function of the liver?

A
  • Prod of bile
  • Carb and fat metabolism
  • Storage of vit and minerals
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2
Q

Where is bile stored?

A

Gallbladder (approx 100ml)

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3
Q

What is the function of bile?

A

A complex substance req for the emulsification, hydrolysis, and uptake of fats in the duodenum
Fats –> fatty acids
- Excretion of some substances which can’t be cleared by kidneys (cholesterol, bilirubin)

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4
Q

What are hepatic lobules?

A
  • Smallest functional units of the liver

- Liver parenchyma organised as thousands of small hepatic lobules

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5
Q

Describe the structure of the liver (microscopic)

A
  • Hepatocytes form irreg plates arranged radially around a small central vein
  • Peripherally, each lobule has 3-6 portal areas with more fibrous CT, each of which contains 3 interlobular structures that comprise the portal triad
  • Each anatomical lobule is hexagonal shaped and drained by a central vein
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6
Q

What are the three interlobular stuctures that comprise the portal triad?

A
  • Venule branch of portal vein (blood rich in nutrients but low in O2)
  • Arteriole branch of hepatic artery (supplies O2)
  • One or two small bile ducts of cuboidal epithelium, branches of bile conducting system
    (- Also contains lymphatic vessels and vagus nerve (parasympa) fibres)
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7
Q

Describe the structure of the liver (macroscopic)

A
  • 2 lobes separated by the falciform ligament

- Covered by a fibrous layer known as Glisson’s capsule

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8
Q

What is the quadrate lobe of the liver?

A
  • Functionally related to the left lobe of the liver
    Bounded by:
    Left - Fissure for the ligamentum teres (round ligament)
    Right - Fossa for the gallbladder
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9
Q

What is the caudate lobe of the liver?

A
  • Functionally it is separate from the right and left lobes of the liver
    Bounded by:
    Left - Fissure for the ligamentum venosum
    Right - Groove for the inferior vena cava
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10
Q

What is the arterial supply to the liver?

A
  1. Right hepatic artery from the hepatic artery proper (branch of common hepatic artery from coeliac trunk)
  2. Left hepatic artery (same as right)
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11
Q

What is the bare area of the liver?

A

The nonperitoneal layer

  • A large triangular area on the diaphragmatic surface of the liver (it has no peritoneal covering)
  • Attached directly to the diaphragm by loose CT (in direct contact with the diaphragm)
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12
Q

What is the falciform ligament?

A
  • Attaches the anterior surface of the liver to the anterior abdominal wall and forms a natural anatomical division between the left and right lobes of the liver
  • The free edge of this ligament contains the ligamentum teres, a remnant of the umbilical vein
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13
Q

What is the coronary ligament (anterior and posterior folds)

A
  • Attaches the superior surface of the liver to the inferior surface of the diaphragm and forms the boundaries of the bare area of the live
  • Anterior and posterior folds unite to form the triangular ligaments on the right and left lobes of the liver
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14
Q

What is the triangular ligaments (right and left)?

A

Left - formed by union of ant and post coronary ligament at apex of liver and attaches the left lobe to the diaphragm
Right - formed similar to left, adjacent to the bare area and attaches the right lobe of the liver to the diaphragm

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15
Q

What is the lesser omentum and which ligaments does it consist of?

A
  • Attaches the liver to the lesser curvature of the stomach and first part of the duodenum
  • Hepatoduodenal ligament; surrounds the portal triad
  • Hepatogastric ligament (stomach to liver)
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16
Q

What are hepatic recesses?

A

Anatomical spaces between the liver and surrounding structures

  • Of clinical importance as infection may collect in these areas, forming an abscess (collection of pus caused by bact infection)
    1. Subphrenic spaces
    2. Subhepatic space
    3. Morison’s pouch
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17
Q

What is the subphrenic space?

A
  • Located between the diaphragm and anterior and superior aspects of the liver
  • Divided into a right and left by the falciform ligament
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18
Q

What is the subhepatic space?

A
  • A subdivision of the supracolic compartment (above the transverse mesocolon)
  • Peritoneal space located between the inferior surface of the liver and the transverse colon
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19
Q

What is the morisons’s pouch? *hepatorenal

A
  • A potential space between the visceral surface of the liver and right kidney
  • Deepest part of the peritoneal cavity when supine (lying flat), therefore pathological abdominal fluid such as blood or ascites (abnormal build up of fluid in the abdomen) is most likely to collect in this region in a bedridden patient
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20
Q

Why is blood supply to the liver unique?

A

It has a dual blood supply:

  1. Hepatic artery (proper) (25%)
  2. Hepatic portal vein (75%) - from gut
    - Approx 25% of CO enters liver
    - Blood content up to 30% of liver weight and up to 15% of total blood content
    - Blood enters, mixes in the sinusoids and drains via hepatic veins into the IVC near right atrium
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21
Q

What does the hepatic artery proper supply?

A
  • Supplies the non-parenchymal structures of the liver with arterial blood
  • Derived from the coeliac trunk
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22
Q

What does the hepatic portal vein supply?

A
  • Supplies the liver with partially deoxy blood, carrying nutrients abs from SI
  • Dominant blood supply to the liver parenchyma
  • Allows the liver to perform its gut-related functions, such as detoxification
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23
Q

What is the venous drainage of the liver?

A
  • Central veins of the hepatic lobules form collecting veins which then combine to form multiple hepatic veins
  • These hepatic veins then open into the inferior vena cava
24
Q

What is the parenchyma of the liver innervated by? (hepatocytes?)

A
  • Hepatic plexus
  • Contains sympa (coeliac plexus) and parasympa (vagus nerve) nerve fibres
  • Enter the liver at the porta hepatis and follow the course of branches of the hepatic artery and portal vein
25
Q

What is the Glisson’s capsule innervated by?

A

The fibrous covering of the liver (Glisson’s capsule) is innervated by branches of the lower intercostal nerve

26
Q

What will the pain from distension of the Glisson’s capsule feel like?

A

Distension of the capsule results in a sharp, well-localised pain

27
Q

Where do lymphatics in the anterior aspect of the liver drain into?

A

Hepatic lymph nodes
- These lie along the hepatic vessels and ducts in the lesser omentum, and empty in the colic lymph nodes which in turn drain into the cisterna chyli

28
Q

Where do lymphatics in the posterior aspect of the liver drain into?

A

Phrenic and posterior mediastinal nodes

- Joins the right lymphatic and thoracic ducts

29
Q

Why might variations in the gross liver anatomy occur?

A
  1. Genetic variations
    - Hereditary anatomical displacement
    - Accessory lobes
  2. Internal factors
    - Portal (vein) thrombosis (blockage or narrowing of the portal vein by a blood clot)
    - Cardiac cirrhosis
    - Fibrosis and atrophy
  3. External factors
    - Impression effects
  4. Lobular atrophy
30
Q

The division of segments in the liver are based upon what factors?

A
  1. Blood supply
  2. Bile drainage
    - Each segment has an independent system important for
    - Within each segment, the tissues can be divided into lobule/ acinus - the funcitonal units of the liver
31
Q

What does each lobule/ acinus of the liver segments consist of?

A
  1. Plates of hepatocytes
  2. Sinusoidal channels
  3. Inlet and exit BV
  4. Bile canaliculi
32
Q

What are sinusoidal channels?

A
  • Low press vascular channels that receive blood from terminal branches of the hepatic artery and portal vein at the periphery of lobules and deliver it into central veins
  • Lined with endothelial cells and flanked by plates of hepatocytes
33
Q

What are bile canaliculi?

A
  • Thin tube that collects bile secreted by hepatocytes

- Empty into a series of progressively larger bile ductules and ducts which eventually become common hepatic duct

34
Q

What are the 8 different segments of the liver?

A 
1. 
2.
3.
4.
5.
6.
7.
8.
35
Q

What is the biliary epithelium in the liver?

A
  • Interconnecting ducts that transport bile out of the liver to the duodenum
  • Forms collecting vessels of inc size to collect canalicular bile
  • Polarised cuboidal or columnar epithelial cells
  • Dense BM
36
Q

Describe the endothelium in the liver

A
  • Squamous epithelial cells
  • Line the hepatic vasculature
  • Protect the parenchyma from blood cells, bacteria and viruses
  • Filters fluids
  • Selective uptake of solutes and particles
  • Scavenging of waste products
37
Q

What are some of the normal endothelial functions?

A
  1. Anti-thrombogenic surface
  2. Regulation of coagulation
  3. Regulation of leukocyte traffic
38
Q

What are Kupffer cells?

A

Hepatic macrophages located within the sinusoids

- 80% of all macrophages in the body

39
Q

What are the function of Kupffer cells?

A
  • Phagocytosis
  • Reg of microcirc
  • Removal of endotoxin
  • V active receptor-medaited endocytosis
  • Can prod cytokines, present antigen and stimulate IR
40
Q

What are stellate cells?

A

Any neuron in the CNS that have a star-like shape formed by dendritic processes radiating from the cell body

  • Ito cells or lipocytes
  • 15% of non-hepatocyte cells in liver (nonparenchymal)
  • (- Can transform to a more fibroblast-like morphology in disease)
41
Q

What are the function of stellate cells?

A

Nonparenchymal, quiescent cells whose main function is to store vitamin A and maintain the normal BM type matrix
- Perisinusoidal fat/ retinoid storing cells

42
Q

How many times is bile recycle per day and why?

A

6-8 times

- To recycle bile salts

43
Q

Approx how many L of bile is prod?

A

Approx 0.5L of bile prod by hepatocytes

44
Q

What are some of the immune functions of the liver?

A
  1. Protection against pathogen arriving in blood
  2. Phagocytosis of old or dying cells
  3. Innate immune functions
  4. Induction of tolerance
45
Q

What are the detoxification/ elimination functions of the liver?

A
  1. Urinary excretion (solubilisation of compounds)
  2. Biliary excretion (lipophilic compounds)
  3. Biotransformation of drugs
    Phase 1 = Ox or red to make soluble (P450)
    Phase 2 = Conjugation to make water soluble
  4. Elimination of ammonia by product of protein metabolism
46
Q

What are the stages of liver damage/ failure?

A
  1. Inflammation (fatty liver)
    - Liver is enlarged or inflamed
  2. Fibrosis
    - Scar tissue formation to replace healthy tissue in the inflamed liver
  3. Cirrhosis
    - Severe scarring built up –> difficult for liver to function
  4. End stage liver disease
  5. Liver cancer?
47
Q

What are some complications of cirrhosis?

A
  1. Ascites (swelling of abdomen)
  2. Varices in oesophagus (enlarged veins)
    - Bleeding from varices
  3. Renal failure
  4. Liver cancer
48
Q

What are the main causes of cirrhosis in the EU?

A
  1. Viral infection
  2. Alcohol and metabolic syndrome
  • PREVENTABLE!!!
49
Q

What is viral hepatitis?

A

Viruses selectively infect hepatocytes (A-E)

  • The v strong IR causes severe hepatitis
  • IS then kills the infected hepatocytes
  • Some viruses cleared whilst some cause chronic ongoing infection and IR which drives the dev of fibrosis and end stage liver failure
  • 5 different types
50
Q

How is hepatitis A transmitted?

A

Faecal-oral route

- When uninfected person ingests food or water that has been contaminated with the faeces of an infected person

51
Q

How is hepatitis B transmitted?

A 
Horizontal transmission;
- Blood 
- Semen 
- Bodily fluids infected with hep B virus enters uninfected person body
Vertical transmission:
- Mother to baby 
- Placenta, breast milk or direct contact during or after birth  
- Vaccine available
  • 10% dev chronic hep B
  • Most ppl can fight off infection
  • Infected as child more likely to clear it
  • Responsible for 30% cirrhosis cases and 15% primary liver cancer
52
Q

How is hepatitis C transmitted?

A
  • Direct inoculation of blood
  • Needle use
  • No vaccine
  • Treatable - 12 wks antiviral treatment
  • 90% of those infected probs don’t know chief
53
Q

How is hepatitis D transmitted?

A

Percutaneous (via skin) or mucosal contact with infectious blood
- Coinfection with HBV or as superinfection in people with HBV infection

54
Q

How is hepatitis E transmitted?

A

Faecal-oral route

- Faecal-contaminated drinking water

55
Q

Where is hepatitis B most common?

A
  • Sub-Saharan Africa
  • Asia
  • Amazon region of S. America
  • Bit in Eastern Europe
56
Q

What is non-alcoholic fatty liver disease?

A
  • Presence of fatty accumulation in greater than 5% of hepatocytes
  • Ranges from just f at to hepatitis and fibrosis
  • Inc risk of dev HCC (hepatocellular carcinoma)

DIG (31 decks)

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