liver
Meaning of liver: Blood leaving the gut reaches the liver before the rest of the body, which is why it handles nutrients and toxins first.
Definition of liver
The liver is the largest internal organ, sitting under the ribs on the upper right side of the abdomen. It filters blood arriving from the digestive tract, processes nutrients, breaks down drugs and waste products, stores glycogen and several vitamins, makes most clotting proteins and the blood protein albumin, and produces bile for digesting fat.
What does the liver actually do?
It is less an organ with one function than a chemical works handling several unrelated jobs at once. It converts absorbed sugars into glycogen for storage and releases them again between meals. It builds albumin, which holds fluid inside blood vessels, and nearly all the clotting factors. It breaks down old red blood cells, turning their pigment into bile. It converts ammonia from protein breakdown into urea the kidneys can excrete. It stores iron, copper and vitamins A, D, B12 and K. It also performs most of the body's drug metabolism, which is why liver disease alters how many medications behave.
Why does its blood supply matter?
The liver has two inflows. The hepatic artery brings oxygen-rich blood from the heart, and the portal vein brings nutrient-rich blood straight from the stomach and intestines, supplying the larger share of the total. Everything absorbed from food therefore passes the liver before reaching the general circulation. That arrangement lets the organ store or convert nutrients immediately and neutralize many swallowed toxins, and it is the reason a drug taken by mouth can lose much of its dose before it ever reaches the bloodstream at large.
What happens when it is damaged?
The liver regenerates unusually well, and a large share of it can be removed or injured with the remainder growing back. Repeated or continuous injury is different: each round of healing lays down scar tissue, and once enough accumulates the architecture is permanently distorted, a state called cirrhosis. Common drivers are chronic viral hepatitis, sustained heavy alcohol use, and fat accumulation linked to metabolic conditions, now generally named metabolic dysfunction-associated steatotic liver disease. A liver function test panel is something of a misnomer, since most of the values on it are enzymes released by injured liver cells rather than measures of how well the organ is working; albumin and clotting times come closer to that.
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Used in a sentence
Blood tests were ordered to evaluate the patient's liver function.
Good to know
The liver can regenerate a substantial amount of damaged tissue, which distinguishes acute and reversible injury from cirrhosis, the lasting scarring that follows prolonged or repeated damage.