Lecture 6 - Liver and Bile Flashcards
How much cardiac output does the liver receive
25%
The liver is multipurpose, a few of its functions…
- Exocrine organ (bile acid secretion)
- Storage organ (glycogen, iron)
- Endocrine organ
- Metabolism/detoxification
Where do absorbed nutrients go before delivery to peripheral tissues
Liver
What nutrients does the liver process
- Carbohydrates (glycogenesis/gluconeogenesis/glycogenolysis)
- AA -> functional proteins/pre-hormones
- Store vitamins
- Triglyceride handling
Uses of glucose in the liver of non-ruminants
Glycogen synthesis, f.a. synthesis
New glucose (gluconeogenesis) is formed from
Propionate, lactate, aa
Difference between amylose and amylopectin
Amylopectin is branched, easier to get glucose from it
Both starch
What does the liver synthesize triglycerides from
Fatty acids that were synthesized in the liver (non-ruminants)
F.a. mobilized from adipose tissue
What fats does the liver synthesize
Triglycerides
Lipoproteins (VLDL)
Ketones
Function of lipoproteins
Transport TG around body
What does the liver synthesize with regards to proteins
Non-essential amino acids
Which aa can the liver synthesize
Tyrosine from phenylalanine
Cysteine from methionine
Glutamate from glutamine
What is phenylketonuria
Lack of enzyme that converts phenylalanine to tyrosine = phe accumulates (toxic to brain) = brain damage
How does the liver detoxify ammonia
Urea production
Glutamine production
Things the liver is responsible for synthesizing
- Albumin
- Coagulation factors
- Transport proteins
- Immunologic proteins (e.g. complement)
- Bile salts
What is albumin? Responsible for…
Protein that transports non-esterified f.a. and drugs
Responsible for colloid osmotic pressures of plasma (keeps water in blood)
What happens when albumin is deficient
Colloid osmotic pressure fails = edema (swelling)
Proteins the liver makes responsible for blood clotting…
Fibrinogen, prothrombin
Protein made by liver that does iron transport
Transferrin
How does the liver function in protection?
- Prevents bacteremia (bacteria that get across gut barrier)
- Breakdown toxins and hormones
What kinds of toxins does the liver metabolize
Drugs and xenobiotics
How does the liver clear drugs etc from the body
Makes them hydrophilic (converts non-ionic to anions)
This facilitates excretion by the kidney (cannot cross membranes) and prevents reabsorption
If given meds, what must you do in terms of the liver to prevent excretion
Inhibit the liver enzyme responsible
Are substances bound to proteins cleared by the kidneys?
No, the liver
What happens when the liver is damaged
Stellate cells produce fibrous scar tissue to wall off damage
A lot of fibrous scarring = sclerosis or cirrhosis
What endogenous and exogenous compounds does the liver excrete
Endo = bilirubin
Exo = antibiotics
What is not excreted by the liver when someone has jaundice
Bilirubin
Where is bilirubin found in someone with jaundice
Red blood cells
Extracted by hepatocytes
Three causes of jaundice
Haemolytic: too much bilirubin in blood
Hepatic: liver is damaged, hepatocytes not functioning
Post-hepatic: after the liver
GIT is drained into the liver by..
Hepatic portal vein
Slide 16***
Splanchnic circulation
The portal triad contains…
- Hepatic artery
- Hepatic portal vein
- Bile duct
Histology of the liver contains
Central vein, portal triad, kuppfer cells, sinusoids, space of disse
What are canaliculi
Canals join to bile ductules
What are sinusoids
Spaces btw hepatic cords, venous capillary in the liver
Characteristics of hepatocytes
Heterogeneous (cell population w diff roles)
Periportal or perivenous
What is the space of disse
Peri-sinusoidal space
What are kuppfer cells
Line the hepatic sinusoids
Remove bacteria, immune complexes, and damaged erythrocytes by endocytosis
What are hepatocytes
Major cells in the liver
Slide 30**
makes no sense
How would the liver lower cholesterol levels
Excrete more bile acids
Where are bile acids stored/concentrated
Gall bladder
