Option D.3 Function of the Liver Flashcards
Give an example of how the liver regulates nutrients in blood
- liver maintains correct amount of glucose
when glucose level is high, liver releases insulin;
to stimulate hepatocytes to take up glucose;
to convert to glycogen;
when glucose level low, hepatocytes are stimulated;
to break down stored glycogen;
to release glucose
What occurs when transferring receptors are bound?
receptor iron complex enter cell and iron is either incorporated into heme/ or transferred to a storage molecule called ferritin
What do developing red blood cell have high levels of?
transferrin receptors
What is transferrin?
protein bound to iron
What happens iron is absorbed by small intestine?
tranferred to blood bound to a protein
Where is hemoglobin synthesized in?
red blood cells
When are iron/vitamin A/ vitamin D released into blood when stored in lover?
deficit in blood
What nutrients can be stored in excess in the liver?
glucose, when high causes insulin to stimulate hepatocytes to take up glucose and store as glycogen;
iron; Vitamin A; Vitamin D; vitamins are fat soluble
What happens to excess amino acids?
deaminated in the liver; organic acid part is removed/respired or converted to fat/carbohydrate
can the body store amino acids if in excess?
No
When proteins are broken down what do they contribute to?
pool of amino acids in blood plasma for new synthesis
What are examples of proteins that are produced for export from liver cells?
fibrinogen, globulins, albumin, prothrombin
What is the effect of having the liver adjust level of amino acids?
regulated to support the constant synthesis of proteins that can function as enzymes/components of membranes /structural components
What does the liver cell adjust as blood passes the sinusoids (supplies daily demand for protein)?
amino acids
What happens to components of red blood cells by liver?
broke down when old and recycled
What is bile used for?
break down fats into droplets that disperse for effective breakdown by digestive enzymes in duodenum
What is surplus cholesterol from the liver converted into?
bile salts (emulsifies the bile)
What does the liver produce other than bile?
cholesterol
Explain the role of liver in hemoglobin breakdown
Kupffer cells take up erythrocytes through phagocytosis;
hemoglobin is broken into globin and heme;
globin is hydrolysed;
breakdown of heme causes iron to attach to carrier protein;
iron stored or exported to bone marrow (via blood plasma) for new red blood cell;
heme converted into bile pigments
What are erythrocytes?
red blood cells
What are Kupffer cells?
phagocytes attached to walls of sinusoids that take up old red blood cells; contain many lysosome; specialized leucocyte
What are lovules?
rows of hepatocytes
Give an example of how the liver removes toxins
alcohol is oxidized to become carboxylic acid; becomes part of metabolites; oxidized to CO2 and water
What are bile channels?
bile from liver flows through (between liver cell rows but isolated from blood supply); merge into bile ducts to carry to gall bladder
What is one of the major functions of the liver?
remove toxin;
break down of red blood cells;
Wstabilization of quantity of nutrients circulating blood; regulation through storage and release of nutrients when needed
How does the blood from the heptic portal vein differ from normal blood?
- are wider
- is low pressure , deoxygenated blood
- varies in quantity of nutrients depending on food and timing
- contain kuppfer cells (brekadown haemoglobin for recycling)
After arterioles join with sunsoids what occurs?
Sinusoids merge with velues that lead to hepatic vein
How do sinuiods differ from liver cells?
sinuids do not have walls separating blood from liver cells (blood and liver cells are in direct contact); allows proteins to enter /leave blood
What are hepatocytes?
liver cells
What are sinuiods?
blood filled channels (like capillaris)where arterial blood mixed with blood from heptic portal flows through
What is a helptic portal vein?
bring blood to the liver directly from small intestine
How is the liver supplied with blood?
supplied by HEPTIC artery; drains deoxygenated blood through HEPTIC vein
What happens to fatty acids that reach the liver?
combine to form triclycerides; and proteins to be stored; transported to blood plasma; LDLs to tissues;
What does an excess of LDLs result to?
blocking of receptor sites of cell membrane that metabolize/store lipids; causes more LDL in blood;
How can monosaturated fats and polysaturated fats help?
help remove circulating LDL;
increase efficiency of receptor sites at removal of bad cholesterol
What are the primary effects of long-term alcohol abuse?
- cirrhosis - scar tissues damaged from exposure to alcohol;
- fat accumulation - damaged area build up fat instead of tissue / obesity
- gastritis - irritates stomach mucosa
- malnutrition - excess alcohol affects appetite
- dementia - destroys neurons
- weakened heart muscles
What are the key events of the break down of hemoglobin?
Occurs inside kupffer cell;
- four globin proteins are hydrolised into amino acid
- amino acids released into bloodstream (available for more protein synthesis)
- iron released can be stored within liver; some iron is sent to bone marrow (used in production of erythrocytes)
- bile pigment bilirubin (iron removed from haem group) is absorbed by hepatocytes (becomes bile)
What is bile used for?
added when fatty acids are being digested;
emulsification of clump formed by lipids;
does NOT chemically change lipids;
breaks down coalesced clumps/increases surface area for catalisation
How do hepatocytes produce bile in liver?
converts surplus cholesterol into bile salt
What examples plasma proteins do hepatocytes release?
albumin: helps regulate blood pressure, acts as carrier for bile salts and other fat soluble substances;
fibrinogen: converts to fibrin to form mesh of blood clot
What is bilirubin?
bile salt, heme part of hemoglobin without iron
What is jaundice?
condition where skin and whites of eyes develop yellow tinge; severe conditions are toxic to brain cells
What is the immediate cause of discolouration of jaundice?
build up of bile pigment bilirubin in blood and tissues
What are predicted causes of Jaundice?
any condition that disrupts movement of bilirubin;
- breakdown of red blood cells at an abnormal rate (increased bile rubin in blood)
- damage to liver (typically by alcohol-induced cirrhosis/malaria) cannot process bilirubin
- blocked bile duct (cannot send bile to digestive system)
Why do newborns sometimes suffer from Jaundice?
hemoglobin of fetus is different from hemoglobin our body forms after birth;
after birth breakdown of fetal hemoglobin occurs at accelerated rate;
bilirubin formed quicker than broken down;
self-corrects;
What is a common treatment for infants suffering from jaundice?
exposure to blue/green portion of light spectrum;
causes change in shape/structure of bilirubin
What is pre-hepatic jaundice caused by?
malaria, sickle cell anemia, thalassemia
What is intra hepatic jaundice caused by?
infection like hepatitis, leptospirosis or glandular fever; harmful substances (alcohol and drugs), also ecstasy overdose of paracetamol
What is post hepatic jaundice caused by?
gallstones can cause
Is alcohol considered as a drug?
Yes because of strong effects on central nervous system
What happens once alcohol is consumed?
absorbed into blood; distributed through out body; can cross blood bain barrier; metabolised in liver
What is cirrhosis?
a chronic inflammation of liver in which liver cells are destroyed and replaced by fibrous or adipose connective tissue
