Unit 8 Week 2: Chlamydia and risky behaviour Flashcards
physiological functions of the liver
bile production
carbohydrate metabolism
lipid metabolism
protein and ammonia metabolism
storage functions
bile production liver
hepatocytes
into the bile canaliculi to smaller ducts then large ducts then eventually to the duodenum or gall bladder
following the secretion of bile into the duodenum undergoes enterohepatic circulation
bile components arent excreted are recylced by conversion into bile acids by gut bacteria for reuse by absorption in ileum
components of carbohydrate metabolism
glycogenolysis
gluconeogenesis
glycolysis
glycogenesis
glycogenolysis
liver can break down glycogen, stored form of glucose, into glucose-6-phosphate. This process is stimulated by the hormone glucagon
gluconeogenesis
liver can synthesis new glucose molecules from non carb resources such as amino acids, lactate, glycerol. This is stimulated by the hormones glucagon and cortisol
glycolysis
liver can also use glucose for energy, glucose is converted into pyruvate, enters citric acid cycle to generate ATP
glycogenesis
can store excess glucose as glycogen. Stimulated by the hormone insulin
componetns of lipid metabolism
lipogenesis
lipolysis
beta oxidation
lipoprotein metabolism
lipogenesis
process of synthesising new fatty acids from glucose, amino acids and other precursors. Synthesises and releases triglycerides, stored in adipose tissue as a long term energy source
lipolysis
breaking down and storing fat into fatty acids. Stimulated by hormones such as glucagon and adrenaline
beta oxidation
beta oxidation of fatty acids into acetyl-CoA, which then enters the citric acid to generate ATP
lipoprotein metabolism
involved in the synthesis and metabolism of lipoproteins which are responsible for transporting lipids through the body, low and high density lipoproteins
components of protein and ammonia metabolism
protein synthesis
amino acid catabolism urea cycle
protein synthesis
synthesis many plasma proteins, including albumin, fibrinogen and globulins, these proteins are responsible for maintaining osmotic pressure and transporting molecules
amino acid catabolism
breaks down amino acids, used for energy or synthesis or other molecules, converted to pyruvate, acetyl CoA or other intermediates that then enter the citric acid
urea cycle
converting toxic ammonia into urea, involves a series of enzymatic reactions that occur in the liver, resulting urea is excreted in the urine
storage functions of the liver
glycogen
vitamins
minerals
drug and toxin
glycogen storage
liver stores glycogen, broken down into glucose when the body needs energy
vitamin storage
storage of several vitamins, including vitamins A, D and b12, released into blood stream when needed
mineral storage
stores minerals such as Iron and copper, these are used for a variety of functions such as oxygen transport and enzyme function
drug and toxin storage
can store certain drugs and toxins, can accumulate in the liver overtime, can lead to liver damage or dysfunctions if it reaches toxic levels
pathophysiology of alcohol related liver disease
alcohol readily absorbed from stomach
mostly absorbed from the small intestine
cant be sotred
mainly catabolised in he liver by alcohol dehydrogenase, ADH and microsomal enzyme oxidation system, MEOS
alcohol metabolism via ADH pathways
ADH, a cytoplasmic enzyme, oxidizes alcohol into acetaldehyde.
Acetaldehyde dehydrogenase (ALDH), a mitochondrial enzyme, then oxidizes acetaldehyde into acetate.
Chronic alcohol consumption enhances acetate formation.
These oxidative reactions generate hydrogen, which converts nicotinamide-adenine dinucleotide (NAD) to its reduced form (NADH), increasing the redox potential (NADH/NAD) in the liver.
The increased redox potential inhibits fatty acid oxidation and gluconeogenesis, promoting fat accumulation in the liver.
alcohol metaoblism via MEOS pathway
Chronic excessive alcohol consumption induces the MEOS (mainly in endoplasmic reticulum), increasing its activity.
The main enzyme involved is CYP2E1.
When induced, the MEOS pathway can account for 20% of alcohol metabolism.
This pathway generates harmful reactive oxygen species, increasing oxidative stress and formation of oxygen-free radicals.
hepatic fat accumulation
Fat (triglycerides) accumulates throughout the hepatocytes for the following reasons:
Export of fat from the liver is decreased because hepatic fatty acid oxidation and lipoprotein production decrease.
Input of fat is increased because the decrease in hepatic fat export increases peripheral lipolysis and triglyceride synthesis, resulting in hyperlipidemia
Hepatic fat accumulation may predispose to subsequent oxidative damage.
endotoxins in the gut due to alcohol
alcohol changes gut permeability
increases absorption of endotoxins released by bacteria in the gut
in response to the endotoxins which the impaired liver can no longer detoxify Kupffer cells release free radicals and increase oxidative damage
oxidative stress increases
Liver hypermetabolism, caused by alcohol consumption
Free radical–induced lipid peroxidative damage
Reduction in protective antioxidants (eg, glutathione, vitamins A and E), caused by- alcohol-related undernutrition
Binding of alcohol oxidation products, such as acetaldehyde, to liver cell proteins, forming neoantigens and resulting in inflammation
Accumulation of neutrophils and other white blood cells (WBCs), which are attracted by lipid peroxidative damage and neoantigens
Inflammatory cytokines secreted by WBCs
Accumulation of hepatic iron, if present, aggravates oxidative damage. Iron can accumulate in alcohol-related liver disease through ingestion of iron-containing fortified wines
resultant inflammation cell death and fibrosis as result of alcohol
A vicious circle of worsening inflammation occurs:
Cell necrosis and apoptosis result in hepatocyte loss, and subsequent attempts at regeneration result in fibrosis
Stellate (Ito) cells, which line blood channels (sinusoids) in the liver, proliferate and transform into myofibroblasts, producing an excess of type I collagen and extracellular matrix.
As a result, the sinusoids narrow, limiting blood flow.
Fibrosis narrows the terminal hepatic venules, compromising hepatic perfusion and thus contributing to portal hypertension
Extensive fibrosis is associated with an attempt at regeneration, resulting in liver nodules. This process culminates in cirrhosis
cause of alcoholic fatty liver, steatosis
lipid accumulation:
FA uptake increases
lipogenesis increases
beta oxidation decreases
VLDL release decreases
cause of alcohol steatoheptatitis
inflammation:
kupffer cell activation
TLR4/NFKb pathway
cytokine/ ROS increases
cause of alcohol fibrosis/ cirrhosis
fibrosis:
protein adduct
PKC and TGF beta pathway
profibrotic effect of ROS
cause of heptatocellular carcinoma
carginogenesis:
DNA/protein adduct
dna integrity decreases
dna repair decreases
3 stages of alcohol related liver disease
alcoholic fatty liver disease
alcoholic heptatitis
cirrhosis
alcoholic fatty liver disease
Drinking a large amount of alcohol, even for just a few days, can lead to a build-up of fats in the liver. This is called alcoholic fatty liver disease, and is the first stage of ARLD.
Fatty liver disease rarely causes any symptoms, but it’s an important warning sign that you’re drinking at a harmful level.
Fatty liver disease is reversible. If you stop drinking alcohol for 2 weeks, your liver should return to normal.
alcoholic hepatitis
Alcoholic hepatitis – which is unrelated to infectious hepatitis – is a potentially serious condition that can be caused by alcohol misuse over a longer period. When this develops, it may be the first time a person is aware they’re damaging their liver through alcohol.
Less commonly, alcoholic hepatitis can occur if you drink a large amount of alcohol in a short period of time (binge drinking).
The liver damage associated with mild alcoholic hepatitis is usually reversible if you stop drinking permanently.
liver cirrhosis
Cirrhosis is a stage of ARLD where the liver has become significantly scarred. Even at this stage, there may not be any obvious symptoms.
It’s generally not reversible, but stopping drinking alcohol immediately can prevent further damage and significantly increase your life expectancy.
A person who has alcohol-related cirrhosis and doesn’t stop drinking has a less than 50% chance of living for at least 5 more years.
treatment for alcohol related liver disease
no specific medical treatment
stop drinking
liver transplant may be required
effects of alcohol on gall bladder
Small amounts = reduce risk of gallstones and gallbladder pain
Heavy drinking = lead to gallbladder problems and pain
effects of alcohol on the brain physically
Difficulty walking
Blurred vision
Slurred speech
Slowed reaction times
Impaired memory
Alcohol-related brain damage (ARBD), e.g Wernicke–Korsakoff syndrome
effect of alcohol on the brain psycholocially
depressant
affects inihibtion
depression
slows cognitive functioning
how cna dependency develop
long temr alcohol uses and reduces number of neurotransmitters in our brains
need some to ward off anxiety and depression so drink to relieve
alcohol damage to nerve cells
toxic
can cause brain cells to die
brain tissue shrink
damage to blood vessle alcohol
can lead to high blood pressure
alcohol and mental health
depression
anxiety
psychosis
suicide and self harm
chlamydia as a pathogen
Chlamydiae are gram-negative, obligate intracellular pathogens (require a eukaryotic host to replicate and for ATP).
Chlamydia trachomatis and Chlamydia pneumoniae, the major species that infect humans.