Toxicology Flashcards
What is toxicology?
Toxicology is the study of adverse effects of chemical, physical or biological agents on people, animals and the environment.
What is NOAEL and LOAEL?
NOAEL - no observed adverse effects level - lowest level where adverse side effects aren’t seen.
LOAEL - lowest observed adverse effects level - lowest level at which adverse effects are seen.
The liver has two blood supplies. Describe these.
Hepatic portal artery - carries oxygen rich blood from the aorta
Hepatic portal vein - carries nutrient rich blood from the GIT
What are the main functions of the liver?
Metabolism Secretion of Bile Plasma protein synthesis Detoxification Vitamin D activation Phagocytosis Vitamin and mineral store
The liver produces and secretes 250-1500 ml of bile per day. What does bile contain?
What is the function of bile?
Contains bilirubin, bile acids and salts, phospholipids, cholesterol, inorganic ions.
Function: bile is involved in the emulsification and reabsorption of dietary lipids and fat soluble vitamins (Vit A, B, E, K).
Why is the liver a target for toxic compounds?
Because a large volume of blood passes through it which leads to increased levels of exposure.
Liver necrosis is a type of liver toxicity. How does it happen?
Necrosis occurs when hepatocytes are injured.
Liver necrosis is a type of liver toxicity. How does it happen?
Necrosis occurs when hepatocytes are injured causing the infiltration of lymphocytes. Can cause irreversible damage resulting in death of patient.
Indicators of necrosis is increased aspartate and alanine aminotransferases (AST and ALT).
Liver necrosis is a type of liver toxicity. How does it happen?
Necrosis occurs when hepatocytes are injured causing the infiltration of lymphocytes. May cause irreversible damage resulting in death of patient.
Indicators of necrosis is increased aspartate and alanine aminotransferases (AST and ALT) - these leak from dying cells.
Necrosis can also occur when compounds bind to components of liver cells such as mitochondria resulting in damage, so ATP depletion, failure of ATP proton pumps, cellular homeostasis fails, hepatocytes swell and leak.
Dying cells activate lymphocytes - inflammatory response starts.
How does liver cirrhosis occur?
Cirrhosis occurs due to continued cellular toxicity through chronic alcohol consumption or hepatitis.
Happens when there is an accumulation of extensive amount of collagen fibres in response to injury or inflammation. In these cases, hepatocytes may not be regenerated but at replaced by collagen fibres.
