L43: Metabolism and the Many Roles of the Liver

What is the liver attached to the diaphragm by?

Peritoneum

How heavy is a healthy adult liver?

1.5kg

What is the liver anchored to the stomach by?

Mesentery

What forms the hepatic ligaments and divide the liver into lobes?

Folds of the mesentery

What does a vessel do?

Carries a fluid connective tissue

What does a duct do?

Transports an exocrine secretion to a surface

Where does the majority of vessels and ducts converge?

Porta hepatis (door to the liver)

Which abdominal organs does the hepatic portal vein drains the capillaries of?

Small intestine, large intestine, rectum, stomach, pancreas, and spleen

Liver tissue is highly vascularized and consists of … which are organized into lobules

hepatocytes

What are liver capillaries also known as?

Sinusoids

What are the sinusoids notable for?

Their discontinuous endothelium

Liver sinusoids are also home to a special resident population of … macrophages

stellate

What is function #A1 of the liver?

Secretes bile, which is important or both digestion and excretion

What is function #A2 of the liver?

Glucose processing and storage in the absorptive state

What is function #A3 of the liver?

Acts as a store for certain key minerals (especially Cu and Fe) and vitamins (especially A and B12)

What is function #A4 of the liver?

Gluconeogenesis in the post-absorptive state

What is function #A5 of the liver?

Detoxification (breakdown) of alcohol and many other drugs and toxins

What are the enzymes that break down alcohols into ATP-generating substrates in the liver?

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH)

Liver biochemistry processes … — either because they require the same co-factors, or because they downregulate each other

compete

Ethanol metabolism leads to biochemical signalling changes that … fatty acid synthesis but … gluconeogenesis

enhance, inhibit

Why is alcohol processing and gluconeogenesis not compatible?

Alcohol-processing inhibits gluconeogenesis because the liver is prioritizing the alcohol breakdown

What is a critical function of liver that is not directly related to metabolism?

Storage of blood

What percent of cardiac output does the liver receive at rest?

25%

Hepatocytes are responsible for inactivating …. so that it can be safely excreted

acetaminophen

The liver can inactivate and breakdown many drugs and toxins beyond alcohol, including ones that are …, rather than used to generate ATP

excreted

What is function C of the liver?

Synthesizing most soluble proteins found in plasma

What is function liver/stellate macrophages?

Recycling red blood cells

The liver is a … endocrine organ which secretes at least 4 hormones or pro-hormones

secondary

What are the 4 main hormones/pro-hormones secreted by the liver?

Somatomedins, angiotensinogen, thrombopoietin, and hepcidin

Somatomedins (especially IGF) are secreted in response to what?

GH release from the anterior pituitary gland

Angiotensinogen is converted to the hormone angiotensin by what?

Renin when BP is low

What does thrombopoietin stimulate?

Platelet formation

What is hepcidin important for?

Iron homeostasis

The liver contributes to the activation or inactivation of … hormones by other endocrine organs

Steroid

The liver also plays an essential immediate step in the synthesis of what hormone from Vitamin D?

Calcitriol

When the liver cells are stressed or damaged, what do they do?

First accumulate fat, then collagenous scar tissue

What is the end-stage of liver disease (when scar tissue has replaced functional liver tissue) called?

Cirrhosis

What liver function is disrupted in jaundice?

Lack of bile production

Where is the yellow colour/pigment of jaundice from?

Bilirubin, which is excreted in bile (no bile = bilirubin cannot be excreted out = accumulation)