Final answer:
The two main ways to increase cholesterol concentration are through endogenous synthesis (primarily in the liver) and dietary intake from food. The synthesis is tightly regulated in the body by feedback mechanisms, and both endogenous and dietary cholesterol are transported through the blood by lipoproteins.
Step-by-step explanation:
The two main ways to synthesize/increase the concentration of cholesterol are through endogenous synthesis and dietary intake. Endogenous synthesis occurs in the body, with the liver being the main site. The liver uses fats, proteins, and carbohydrates to synthesize about 1 gram of cholesterol daily. Cholesterol biosynthesis is regulated at the HMG-CoA reductase step and can be influenced by cholesterol levels already present in the bloodstream, resulting in feedback inhibition.
On the other hand, dietary intake refers to the cholesterol that is consumed through food, mostly from animal products. The average American diet provides approximately 0.3 grams of cholesterol per day, which can contribute to the total cholesterol level. The absorbed dietary cholesterol and the endogenously synthesized cholesterol are then carried through the blood by lipoproteins such as LDL and HDL.
The correct answer to the synthesized/increased concentration of cholesterol through lipid transport is: 1) Endogenous synthesis and dietary intake.