D3 - Functions of the liver
Functions
Blood flow
Jaundice
High Density Lipoprotein (HDLs)
See D1: deficiencies/excess/imbalances --> cholesterol
Into the liver
Hepatic artery
Oxygenated blood from the heart to supply liver cells
Hepatic portal vein
Leading out of the liver
Deoxygenated blood from the capillaries of the small intestine (oxygen was consumed there), going through the liver to reach the heart
Hepatic vein
Deoxygenated blood going towards the heart
Oxygenated blood originally from the hepatic artery have been consumed by liver cells
Low pressure
Can have a lot/little nutrient depending of digestion and absorption
High pressure
Low nutrient content
Low pressure
Blood has stabilised nutrient level after being regulated by liver
High nutrient (originally) - excessive stored in the liver
Low nutrient - liver releases nutrient that has been stored previously
Nutrient storage and regulation
Remove or add substance to blood to maintain homeostatic level
Venules and arterioles go to sinusoids, come in contact with hepatocytes regulate nutrients
Breakdown of erythrocytes
Kupffer cells engulf (phagocytosis) and break down haemoglobin from old RBCs
Detoxification
Remove toxins that are consumed - alcohol, pesticides, preservatives
Kupffer cells engulf toxin through phagocytosis
Kupffer cells contain a lot of lysosome with enzymes to digest waste materials
Hepatocytes change the chemical structure of toxin to make it water-soluble --> can be excreted through urine
Consequences of alcoholism
Inflammation - swollen liver tissues
Fat accumulation --> some sinusoids die --> replaced with fat --> liver becomes not functional, cannot process nutrients
Cirrhosis - sinusoids replaced with scar tissue --> not functional
Stores glycogen, iron, vitamin A and D
High blood glucose - insulin stimulates hepatocytes to absorb glucose and convert to glycogen for storage
Low blood glucose - glucagon stimulates liver to break down glycogen and supply glucose to bloodstream
Erythrocytes (red blood cells) only live for 120 days --> membrane ruptures and releases haemoglobin molecules
Haemoglobin is made up of 4 polypeptides, each made up of a heme group with an iron atom
The heme group is turned into bilirubin (along with bile salt) --> bile in the liver
Iron is sent to bone marrow to make new RBCs
Conversion of cholesterol to bile salt
Hepatocytes produce bile salt from excessive cholesterol
Bilirubin + bile salt --> bile
Bile - emulsifies/breaks down fat --> increase surface area for enzymes to digest them
Production of plasma proteins
Fibrinogen - found in blood plasma, helps blood clotting
Albumin - regulate osmotic pressure on cells and blood vessel walls
Produced by hepatocytes
Having too much bilirubin in the blood stream
Bilirubin - yellowish pigment
Infant jaundice
Skin and eye turn yellow
Premature new borns
Liver is not developed enough to turn bilirubin into bile
Treatment - exposure of blue light --> molecular change in bilirubin --> breakdown --> eliminated through urine and feces
If untreated, baby can lead to brain damage --> deafness, cerebral palsy (affect muscle movement, motor skills)
Adult jaundice
Caused by malfunctioning liver, gall bladder or bile duct
Same symptoms and consequences (plus itchiness) as infant jaundice
Cholesterol has a bad reputation for causing coronary heart disease and other health issues
This is not often the case, depends on whether cholesterol is being carried to/from body tissues
LDL - carry cholesterol in liver --> body tissue
HDL - carry cholesterol, body tissue --> liver for removal of cholesterol from blood