Liver Physiology Flashcards
Metabolic functions of Liver
- Storage site for Vitamins esp VitA, Vit B12, D (prevents deficiency for 3-4 months)
- Stores iron as ferritin until needed -blood- iron buffer )(apoferritin)
- Form coagulation fx
- removes/ excretes drugs
- Immunoglobulin function- Kuppfer cells- act as sive for Bacteria & antigens.
Buffer for carbs
Provision of ketones when starvation
Emergency glucose generation
Liver: free fatty acids –> beta oxidation-> ketones–> acetates.
What coagulation Fx does the liver make?
Fibrinogen Prothrombin Accelerator globulin Factor VII Vit K
What factors is ViT K needed for?
1972
2,7,9,10.
What drugs does the liver excrete?/ hormones
Excretes/ detoxifies into bile many drugs
Sulfunimides, penicillin, ampicillin, erythromycin.
Endocrine Hormones/ chemically altered or excreted esp thyroxine.
Steroid hormones: oestrogen, aldosterone, cortisol.
Liver failure–> Xs hormones in body fluids, so over activity of liver to compensate.m
Biritubin in bile:
Used as a diagnostic tool for haemolytic diseases + some liver diseases.
How many days do RBCs survive?
120days
What happens to fragile RBCs Hb?
Fragil membranous rupture–> released HB is phagocytosed by teticuloendothelial cells
What does Hb separate into?
Globin & Heme
What happens to heme?
- Free iron- transported to blood by transferrin
2. 4 purrole nuclei (bilirubin substrate)
What happens to the biribun substrate?
Becomes biliverdin by Heme oxygenase then unconjuvated bilirubin which is released by macrophages into plasma
Goes to Liver
Then it combines w/ albumin and they are transported to blood together.
Is glycogen stored in acute liver failure?
Cannot be stored in liver.
Remember, there is no glucgenolysis from muscles to blood glucose.
Alcohol + atherosclerosis reversible.
Alcohol = not atherosclerosis.
What happens in atherosclerosis in alcoholics?
NOT normal circulating glucose
1. Hypoglycaemic mostly.
Shaking hands,
What happens when the liver stops working?
- No ketones.. Given.
2. No cholesterol : synthesis: 80-90% in Liver
Lack of atherosclerosis in alcoholics
FFA–> atherosclerosis
Long hypoglycaemic periods, FFAs low in circulation, relseased from adipocytes.
No ketone production, no cholesterol synthesis, FFAs are used as the only energy source.
Tissues normally prefer ketones + glucose
Might even absorb cholesterol from palques.
Amino acid metabolism
AAs– body bot very economical
Cant reuse AA that u absorb from food
Split them into N and carbon backbones
Then re-synthesise them by adding the N tomthe carbon backbone
Synthetic avtivity of hepatocytes
Plasma proteins- everything except immunoglobulins.
Clotting factors
Acute phase protein - immunological protein production
⭐️ more susceptible to infxs
⭐️⭐️⭐️ albumin: protein of world.
LPS (lipopolysaccharide)
Bacterial lipopolysacharides, the outermost layer of gram _ve bacteria
It binds to pattern recognition receptors in APCs (macrophage + dendritic cells) and causes activation (massive amounts of cytokines -enough to kill u)
Gut full of gram -ve Bacteria. Some die. When dead they release LPS…
⭐️ crucial function of bile salts is to neutralise LPS.
+ not absob ot.
So… U r more susceptible to immunological diseases.
Detoxifying/ excretory role
Kideny–> gets rid of wate soluble toxins/ pharma cpds.
Liver: turns lipid soluble molecules to water soluble (microsomal oxidation, conjugation to suphate)
–> makes them excretable and somts biologically inactive.
Som the excreted into bile.
Some drugs tho rely on liver for chemical modification.
Acute liver disease
ALF rare
Commonest -70-80% drug related
Commonest- paracetamol overdosing
20-30% remaining:
Fulminant viral hepatitis
Poisoning( mushrooms, recreational drugs, pesticides)
Liver blood flow prbs- shock, sepsis, Budd-Chiary = hepatic vein thrombosis (compensated)
Blood cannot leave liver, adipocytes hypoxia.
ALF⬆️⬆️ unconjugated bilirubin.
Idiopac
What are stellate cells in the liver?
Perisinusoidal cells in the space of Disse, involved in liver fibrosis, producing scar tissue, involved in liver damage.
