Liver structure and function Flashcards
What is the primary role of the liver in the body?
The liver is the largest gland in the body and the second largest organ. Its primary role is to secrete various substances into the bloodstream that impact different body systems. It performs a wide range of functions including metabolism, detoxification, and bile production.
How is blood supplied to the liver, and what is the significance of this dual blood supply?
The liver has two separate blood supplies:
75% of the blood comes from the portal vein, which carries nutrient-rich blood from the gastrointestinal tract (after digestion of food).
25% comes from the proper hepatic artery, which carries oxygenated blood from the aorta. This dual blood supply ensures that the liver receives both oxygen and nutrients required for its metabolic functions.
What role does the liver play in nutrient absorption after a meal?
After a large meal, the liver plays a crucial role in absorbing and processing nutrients like fats, glucose, and other substances from the gastrointestinal tract. The first place these nutrients go after being absorbed is the liver, where they are metabolized and distributed as needed by the body.
What are the two main cell types found in the liver, and what are their functions?
Hepatocytes (60% of liver cells): These are the main cells responsible for performing most of the liver’s metabolic functions, including bile production.
Kupffer cells (30% of liver cells): These are specialized macrophages that form a protective barrier and help in the immune response by removing pathogens and debris from the blood.
What is the biliary system, and how does it function in the liver?
The biliary system is responsible for bile production and transport. The liver’s hepatocytes secrete bile, which travels through the hepatic ducts, then the common bile duct, and is stored in the gallbladder. When food, particularly fats, enters the duodenum, cholecystokinin (CCK) signals the gallbladder to contract and release bile into the duodenum for fat digestion and absorption.
What is the composition of bile, and how does it contribute to digestion?
Bile is made up of water, electrolytes, bilirubin, cholesterol, and bile salts. It plays a key role in fat digestion and absorption by emulsifying fats in the duodenum. Bile also helps eliminate waste products like bilirubin and cholesterol from the body.
What is the significance of the sinusoids in the liver?
The liver’s sinusoids are specialized blood vessels that have a unique structure allowing for the exchange of large solutes between the blood and the liver cells. They facilitate the transfer of nutrients and waste products, and the Kupffer cells lining the sinusoids act as a protective barrier, filtering out harmful substances from the blood.
How does cholecystokinin (CCK) regulate bile release?
When fat or cholesterol enters the duodenum, cholecystokinin (CCK) is released, causing the gallbladder to contract. This contraction leads to the ejection of bile into the duodenum, aiding in the digestion and absorption of fats.
What is the structure of the liver, and how is it organized for efficient function?
The liver is made up of functional units called lobules, which are composed of hepatocytes arranged in a radial pattern. Blood flows through the lobules, starting from the hepatic artery and portal vein, and drains into the central vein of each lobule. This structural organization allows efficient blood flow and nutrient exchange, supporting the liver’s metabolic functions.
How does the liver contribute to detoxification in the body?
The liver plays a critical role in detoxifying harmful substances in the body. It processes toxins, drugs, and metabolic by-products, either by converting them into water-soluble compounds or by secreting them into bile for excretion. Hepatocytes perform this function by metabolizing these substances through phase 1 and phase 2 enzymatic processes.
What is the role of the Kupffer cells in the liver?
Kupffer cells are specialized macrophages in the liver that help protect the body by phagocytizing pathogens, dead cells, and debris in the blood. They form part of the liver’s immune defence system, filtering the blood that passes through the liver’s sinusoids and helping maintain overall body health.
How does bile contribute to the digestion of fats?
Bile, produced by hepatocytes in the liver and stored in the gallbladder, is essential for fat digestion. The bile salts in bile emulsify dietary fats in the small intestine, breaking them down into smaller droplets. This increases the surface area for pancreatic enzymes to further digest the fats, allowing them to be absorbed by the body.
What happens to the liver’s blood supply after digestion of food?
After digestion, nutrient-rich blood from the gastrointestinal tract enters the liver through the portal vein, carrying absorbed nutrients such as glucose and fatty acids. The liver processes these nutrients and distributes them as needed. The oxygenated blood enters the liver through the hepatic artery. Once processed, the blood exits the liver through the hepatic vein and returns to the vena cava.
What is the significance of the liver’s role in processing glucose and fatty acids after a meal?
After a meal, the liver helps regulate blood glucose levels by either storing excess glucose as glycogen or converting it into fatty acids for storage. It also processes dietary fats by converting them into triglycerides or lipoproteins. This ensures that the body has a steady supply of energy and helps maintain metabolic balance.
How is the liver involved in the synthesis of important proteins?
he liver is responsible for synthesizing many crucial proteins, including albumin (which helps maintain blood volume and pressure), clotting factors (important for blood coagulation), and enzymes involved in metabolism. Hepatocytes are the primary cells responsible for these synthetic processes, contributing to both metabolic function and immune response.
