Exam 1 - Liver Anatomy and Physiology

What is the largest gland in the body?

liver

What are the four lobes of the liver?

Right, left, caudate, and quadrate

Where is the caudate lobe located?

Posterior to the right lobe

Where is the quadrate lobe located?

Inferior to the left lobe

What is the function of the falciform ligament?

It suspends the liver from the diaphragm and anterior abdominal wall

What major blood vessels enter the liver?

hepatic artery and hepatic portal vein

What major structures leave the liver?

hepatic veins and common bile duct

What is the structural and functional unit of the liver?

liver lobule

What shape is a typical liver lobule?

hexagonal cylindrical structure

What are the major components of a liver lobule?

Plates of hepatocytes, a central vein, portal triads, and sinusoids

Where are the portal triads located?

At each of the six corners of the hexagonal lobule

What three structures make up the portal triad?

• Branch of the hepatic artery

• Branch of the hepatic portal vein

• Bile duct

What are hepatic sinusoids?

Blood-filled spaces between plates of hepatocytes

What is the direction of blood flow through the liver lobule?

branches of the hepatic portal vein and hepatic artery → sinusoids → central vein

What is the direction of bile flow?

opposite direction of blood, through bile canaliculi toward the bile duct in the portal triad

What are Kupffer cells?

Phagocytic cells lining the sinusoids that remove debris such as bacteria from the blood

What is the high-yield relationship between blood flow and bile flow in the liver?

Blood flows toward the central vein; bile flows toward the bile duct. They move in opposite directions

What are the major overall functions of the liver?

• Metabolism

• digestion

• biotransformation

• immune function

• vitamin/mineral storage

• endocrine functions

What is the liver's role in metabolism?

converts nutrients into substances the body can use, stores substances, and supplies cells when needed

What is the liver's major role in carbohydrate metabolism?

Maintaining blood glucose homeostasis

How does the liver store glucose?

As glycogen.

What is glycogenolysis?

The process of releasing glucose from glycogen when blood glucose levels fall.

What is gluconeogenesis?

Production of glucose from amino acids and glycerol when glycogen stores are depleted and blood glucose is low

What can the liver do with excess glucose?

Convert it into fatty acids and triglycerides for storage

What is the liver's role in fat metabolism?

primary site of fat metabolism

What can acetyl-CoA be converted into by the liver?

Ketone bodies for use by tissues

What are lipoproteins used for?

Transporting fatty acids and cholesterol to and from tissues

What does LDL transport?

Cholesterol to tissues

What does HDL transport?

Cholesterol from tissues to the liver

What does the liver do with cholesterol?

It synthesizes cholesterol and breaks it down into bile salts

What plasma proteins does the liver synthesize?

Albumin, globulins, fibrinogen, prothrombin, and various hormone-binding proteins.

What is albumin?

most abundant plasma protein

Why are fibrinogen and prothrombin important?

important for blood clotting

What is deamination?

Removal of the amino group from amino acids, allowing the resulting products to be used to make ATP or convert to glucose

What does the liver do with ammonia produced during amino acid deamination?

Converts ammonia into urea for excretion

What happens if the liver cannot convert ammonia into urea?

Ammonia builds up, potentially causing hepatic coma

What is biotransformation?

The liver's metabolic alteration of foreign chemicals.

Why does the liver biotransform foreign chemicals?

It can convert substances into more polar/less lipid-soluble substances, making renal or biliary excretion easier

Does biotransformation always make a chemical less toxic?

No. Sometimes liver metabolism can make a substance more toxic.

What enzyme system is important for liver biotransformation?

The microsomal enzyme system (MES)

What is an example of an important MES enzyme?

Cytochrome P450

What happens to microsomal enzymes with repeated exposure to certain substances?

The enzyme system is inducible, so the number of enzymes can increase with exposure.

What is an example of enzyme induction?

Chronic alcohol use can increase enzyme activity and contribute to tolerance.

What role does the liver play in immunity?

It has a major immune role and contains a large number of phagocytic cells

What percentage of innate immunity proteins are produced by hepatocytes80–90%?

80–90%

What immune-related substances do hepatocytes produce?

Cytokines and chemokines.

What other immune function do hepatocytes perform?

Antigen presentation

What vitamins can the liver store?

Vitamin A, vitamin D, and vitamin B12

Approximately how much Vitamin A can the liver store?

1–2 year supply

Approximately how much Vitamin D and B12 can the liver store?

1–4 month supply

How does the liver store iron?

As ferritin

What happens when blood iron levels fall?

liver can release stored iron into the bloodstream

What are some endocrine functions of the liver?

t secretes substances involved in regulation of body systems, including IGF-1 and angiotensinogen, assists with vitamin D activation, and metabolizes hormones.

What is the function of IGF-1?

It promotes cell division

What does the liver produce that participates in the RAAS?

Angiotensinogen, which is converted to angiotensin I

What are the three structures of the portal triad?

Hepatic artery + hepatic portal vein + bile duct.

Blood or bile—which flows toward the central vein?

Blood

Blood or bile—which flows toward the bile duct?

Bile

What cells remove bacteria/debris from blood in hepatic sinusoids?

Kupffer cells.

What is the liver's role in blood glucose?

Stores glucose as glycogen, releases glucose through glycogenolysis, and produces glucose through gluconeogenesis when needed.

What is the liver's role in clotting?

It synthesizes fibrinogen and prothrombin.

What is the liver's role in ammonia?

Ammonia → urea → excretion.

What happens if ammonia accumulates because the liver cannot process it?

It can lead to hepatic coma.

What are the six major categories of liver function?

Metabolism, digestion, biotransformation, immune function, storage, and endocrine function.

What is the single most important microscopic structure to understand for the liver exam?

The liver lobule, especially the relationship among the portal triad → sinusoids → central vein and the opposite direction of bile flow