Question

Yellow marrow has been identified as \(--1----1\) a. an area of fat storage b. a point of attachment for muscles c. the hard portion of bone d. the cause of kyphosis

Short answer

Answer: The main function of yellow marrow in long bones is to serve as an area of fat storage.

Step-by-step solution

Define Yellow Marrow

Yellow marrow is a soft, fatty tissue found in the hollow interior of long bones, like the femur and the humerus. It is also present in the medullary cavity of bones.

Evaluate the Options

Let's evaluate each option to determine if it correctly identifies the function of yellow marrow: a. an area of fat storage Yellow marrow stores fat in the body. It is composed mainly of adipose cells and is an energy reserve for the body. b. a point of attachment for muscles This statement is incorrect because yellow marrow is not involved in muscle attachment. Muscle attachments occur primarily at bone surfaces through tendons and ligaments. c. the hard portion of bone This statement is wrong because yellow marrow is a soft tissue and not a hard portion of the bone. The hard portion of bone is known as the cortex, which is made up of compact bone tissue. d. the cause of kyphosis Kyphosis is a spinal disorder characterized by an exaggerated curvature of the spine, and yellow marrow does not cause it.

Select the Correct Option

Based on our evaluation of the options, we can conclude that option a, "an area of fat storage," is the correct answer. Yellow marrow is indeed responsible for fat storage within the medullary cavity of bones.

Key concepts

Bone Marrow

Bone marrow is a crucial tissue found within the cavities of bones, playing critical roles in both hematopoiesis—the production of blood cells—and the storage of fats. In pediatric skeletons, bone marrow is initially red, due to its high density of hematopoietic cells which produce new red and white blood cells and platelets. As individuals age, some of this red marrow gets replaced by yellow marrow.

Yellow marrow, which is the focus of our exercise, differs from red marrow in function and appearance. Rich in fat cells, it serves as a storage site for energy reserves. While the red marrow works hard to replenish the body's blood cells, yellow marrow stands by as a reserve to potentially be converted back to red marrow if the body requires increased blood cell production, such as in cases of chronic anemia or hemorrhage. This reconversion can indicate the body's resilient response to high demands for blood cells.

Adipose Cells

Adipose cells, commonly known as fat cells, are the main cellular components of yellow marrow. They are specialized for the storage of fat, which the body can break down into energy during times of caloric necessity, such as fasting or heavy exercise. These cells are unique because they can significantly change their size depending on the body's energy storage status.

Understanding adipose cells in the context of the bone marrow exercise is essential in recognizing why option (a) from the problem provided was the correct answer. These adipose cells within yellow marrow provide a 'fuel tank' for the body, storing excess energy that can be mobilized when required. This function is distinct from that of red marrow cells, which are engaged in the continual cycle of blood cell production and do not primarily serve as an energy reserve.

Medullary Cavity

The medullary cavity, also known as the marrow cavity, is the central cavity of bone shafts where marrow is stored. In long bones, such as the femur, this cavity is the primary site of yellow marrow in adults. It is surrounded by the hard, dense cortical bone that constitutes the outer layer of the bone structure, providing stability and protection to the softer marrow inside.

The medullary cavity's presence within the hard components of the bone exemplifies the importance of having a protected area for energy storage and potential blood cell production. This cavity accommodates yellow marrow's fat-storing function without compromising the structural integrity of the bone, which is why options (b) and (c) in our initial exercise are inaccurate descriptions of the marrow's function or characteristics. Also, the medullary cavity's role is completely unrelated to diseases of the spine, such as kyphosis, invalidating option (d) and further supporting the correct answer: option (a), 'an area of fat storage'.