H.4.1 Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein.
hepatic artery from aorta brings blood to liver;
hepatic portal vein (from gut) brings blood to the liver;
incoming blood flows merge in sinusoids of liver;
sinusoids are liver capillaries;
sinusoids merge to form hepatic vein;
hepatic vein carries blood
H.4.2 Explain the role of the liver in regulating levels of nutrients in the blood.
Carbohydrates
The normal level of blood glucose in humans is about 90 mg/100 ml of blood.
In the sinusoids, excess glucose is withdrawn from the plasma solution and used in metabolism or stored as glycogen.
Glycogen reserves are also stored elsewhere in the body, parti
H.4.3 Outline the role of the liver in the storage of nutrients, including carbohydrate, iron, vitamin A and vitamin D.
liver stores excess glucose as glycogen;
as levels drop, liver releases glucose from glycogen
liver breaks down red blood cells and stores iron;
liver stores fat soluble vitamins: i.e vitamin A (retinol), vitamin D (calciferol), vitamin B12, vitamin B9 (f
H.4.4 State that the liver synthesizes plasma proteins and cholesterol.
Plasma Proteins
The RER of hepatocyes (liver cells) produces 90% of the proteins in blood plasma, including all of the albumin (blood viscosity), globulin (antibodies production) and fibrinogen (blood clotting).
Those proteins are also important for the v
H.4.5 State that the liver has a role in detoxification.
Hepatocytes absorb toxic substances form blood and convert them by chemical reactions into non-toxic or less toxic substances.
H.4.6 Describe the process of erythrocyte and hemoglobin breakdown in the liver, including phagocytosis, digestion of globin and bile pigment formation.
erythrocytes rupture after 120 days;
absorbed by Kupffer cells (WBC called phagocytosis) in liver from blood;
hemoglobin split into globin and heme groups;
iron removed from heme leaving bile pigment called bilirubin;
bilirubin released into alimentary ca
H.4.7 Explain the liver damage caused by excessive alcohol consumption.
Hepatocytes absorb alcohol and convert it into other substances to detoxify it.
Excessive consumption of alcohol damages hepatocytes more than most other parts of the body.
Fatty deposits build up, which can cause hepatitis (inflammation of the liver).
Wi
H.4.2 Explain the role of the liver in regulating levels of nutrients in the blood.
Proteins
The liver cells also adjust the level of amino acids as the blood passes along the liver sinusoids.
A pool of amino acids is maintained in the plasma, in the liver and in other tissues undergoing rapid protein synthesis.
Amino acids are constantly being b
H.4.2 Explain the role of the liver in regulating levels of nutrients in the blood.
Lipids
The fatty acids (and glycerol) that reach the liver are combined to form triglycerides.
These are combined with proteins in the liver, and may be stored there.
Here lipids may be stored as food reserves (fat), or immediately broken down and respired as a