Ch. 24 Nutrition, Metabolism, and Energy Balance

Marieb - Human Anatomy & Physiology 7th Edition

Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook

Marieb, Hoehn 7th Edition

Ch. 24 Nutrition, Metabolism, and Energy Balance

Problem 18

Chapter 23, Problem 18

Distinguish between the role of HDLs and that of LDLs.

Verified step by step guidance

Understand the acronyms: HDLs stand for High-Density Lipoproteins, and LDLs stand for Low-Density Lipoproteins. Both are types of lipoproteins that transport cholesterol in the bloodstream, but they have different roles and effects on health.

Explain the role of HDLs: HDLs are often referred to as 'good cholesterol' because they help remove excess cholesterol from the bloodstream and transport it to the liver for excretion or recycling. This process helps reduce the risk of plaque buildup in arteries.

Explain the role of LDLs: LDLs are often called 'bad cholesterol' because they transport cholesterol from the liver to tissues throughout the body. Excess LDL cholesterol can deposit in the walls of arteries, leading to plaque formation and increasing the risk of atherosclerosis and cardiovascular diseases.

Compare their density and composition: HDLs are denser because they contain more protein and less cholesterol, while LDLs are less dense due to their higher cholesterol content relative to protein.

Summarize their health implications: High levels of HDLs are generally associated with a lower risk of heart disease, while high levels of LDLs are linked to an increased risk of cardiovascular problems. Maintaining a healthy balance between the two is crucial for cardiovascular health.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

HDLs (High-Density Lipoproteins)

HDLs are often referred to as 'good' cholesterol because they help transport cholesterol from the arteries and tissues back to the liver for excretion or recycling. This process reduces the risk of plaque buildup in the arteries, thereby lowering the chances of heart disease. Higher levels of HDLs are generally associated with a lower risk of cardiovascular problems.

LDLs (Low-Density Lipoproteins)

LDLs are known as 'bad' cholesterol because they carry cholesterol from the liver to the cells and tissues. When there is an excess of LDLs, they can deposit cholesterol in the arterial walls, leading to plaque formation and narrowing of the arteries. Elevated LDL levels are a significant risk factor for heart disease and stroke.

Cholesterol Transport Mechanism

The cholesterol transport mechanism involves the movement of cholesterol through the bloodstream via lipoproteins, which are complexes of lipids and proteins. This mechanism is crucial for maintaining cellular function and overall lipid balance in the body. Understanding how HDLs and LDLs function within this system helps clarify their contrasting roles in cardiovascular health.

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Related Practice

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Define glycogenesis, glycogenolysis, gluconeogenesis, and lipogenesis. What is (are) likely to be occurring:

a. Shortly after a carbohydrate-rich meal

b. Just before waking up in the morning?

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What is meant by 'body energy balance,' and what happens if the balance is not precise?

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Describe the site, major events, and outcomes of glycolysis.

Textbook Question

List some factors that influence plasma cholesterol levels. Also list the sources and fates of cholesterol in the body.

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What is the harmful result when excessive amounts of fats are burned for energy? Name two conditions that might lead to this result.

Textbook Question

Calculate the number of ATP molecules that can be harvested during the complete oxidation of an 18-carbon fatty acid.