Alcohol Flashcards
What liver problems can alcohol cause?
Fatty liver disease leading to alcoholic hepatitis, fibrosis and cirrhosis. It also exacerbates the decreased oxygen supply to the centrilobular hepatocytes.
What biochemical markers suggest alcohol damage to the liver?
Raised GGT with normal ALP.
How is alcohol metabolised?
Ethanol is converted in peroxisomes to acetaldehyde by alcohol dehydrogenase. Acetaldehyde is very hepatotoxic and causes symptoms like nausea and vasodilation (causing flushing).
Acetaldehyde is converted to acetic acid by acetaldehyde dehydrogenase, and that can then be excreted.
Why is hypoglycaemia a side effect of alcohol abuse?
The conversion of ethanol to acetaldehyde also converts NAD to NADH. The accumulation of NADH causes the conversion of pyruvate to lactic acid so pyruvate is not available for gluconeogenesis leading to hypoglycaemia (but lactate can be converted to glycogen via the Corri cycle).
Also the hepatocytes are forced to take up more oxygen to accept the electrons which can lead to hypoxia that can lead to cell death especially in the perivenous hepatocytes.
Why does alcoholism result in a fatty liver?
The accumulation of NADH due to acetaldehyde production leads to an accumulation of hydrogen which decreases oxidation of fatty acids in mitochondria, so there is increased lipogenesis in the hepatocytes.
What is 1 unit of alcohol?
8g of absolute alcohol.
Half a pint of beer (300ml).
One small glass of wine (100ml).
A shot of spirits (25ml).
What are the recommended alcohol limits for women?
2-3 units a day, with 1-2 alcohol free days a week, not exceeding 14 units per week.
What are the recommended alcohol limits for men?
3-4 units a day, with 1-2 alcohol free days a week, not exceeding 21 units per week.
What is the first stage of vomiting called?
Antiperistalsis
What are the two inputs to the chemoreceptors trigger zone (CTZ)?
Vagal afferent a triggered by 5-HT release from enterochromaffin cells in the gut.
Input from the vestibular apparatus triggered by acetylcholine, histamine, dopamine.
What is the function of the vomiting/emetic centre?
To coordinate the physical act of vomiting
What are the three inputs to the vomiting/emetic centre?
Vagal afferent said triggered by 5-HT release from enterochromaffin cells in the gut.
Signals from the chemoreceptors trigger zone (CTZ).
Signals from higher cortical centres (due to pain, repulsive sights and smells, emotional factors).
Which intracellular signalling mechanism do histamine, acetylcholine, gastrin activate in the parietal cells?
Histamine activates H2 receptors, which raise the intracellular cAMP level.
Acetylcholine activates muscarinic receptors which increase intracellular Ca2+.
Gastrin activates CCK2 receptors which increase intracellular Ca2+.
