Problem 39 - Objective Biology for NEET

Question

Which of the following is not true? (a) Limb bones are long bones. (b) The function of long bones is weight bearing and bringing out movement. (c) Bone marrows in all such long bones are site of blood cells production. (d) All of these

Step-by-Step Solution

Answer

The statement that is not true is (d) 'All of these'.

Step 1: Analyze Statement (a)

Check whether limb bones qualify as long bones. Long bones are typically found in the limbs and include bones like the femur, humerus, ulna, radius, tibia, and fibula. Therefore, statement (a) that says 'Limb bones are long bones' is true.

Step 2: Analyze Statement (b)

Review the stated function of long bones. Long bones are indeed meant for weight-bearing and facilitating movement. So, statement (b) that says 'The function of long bones is weight bearing and bringing out movement' is also true.

Step 3: Analyze Statement (c)

Consult the given statement about bone marrow in long bones. Bone marrow in all such long bones is a site of blood cell production, particularly red and white blood cells and platelets. Therefore, statement (c) that says 'Bone marrows in all such long bones are site of blood cells production' is a fact.

Step 4: Final Conclusion

Analyze the claim in statement (d). After examining the veracity of statements (a), (b), and (c), it becomes clear that each one correctly describes an aspect of long bones. Consequently, statement (d) 'All of these' is not true since it implies that one of the previous statements is false.

Key Concepts

Limb Bones Anatomy

The human body is a marvel of engineering, and the anatomy of limb bones plays a crucial role in its structural integrity. The limbs, comprising the arms and legs, are predominantly constructed from long bones such as the femur in the thigh and the humerus in the upper arm. These long bones serve as rigid support systems, much like the beams of a building, providing leverage and facilitating movement.

Long bones are characterized by their elongated shape and typically consist of a diaphysis, or shaft, made up of dense cortical bone, as well as rounded ends called epiphyses, which are spongy and contain red bone marrow. A layer of compact bone provides strength, while the internal cavity is filled with marrow. The periosteum, a dense layer of vascular connective tissue, covers the bone surface and is essential for bone growth and repair.

Bone Marrow Hematopoiesis

Hematopoiesis is the complex process of blood cell formation, and it occurs within the spongy tissue of the bone marrow. Found within the cavities of long bones, bone marrow is a vital organ where all three types of blood cells—red blood cells, white blood cells, and platelets—are produced. It's fascinating to consider how the architecture of long bones accommodates this life-sustaining task.

The marrow contains a rich supply of stem cells. These are pluripotent, meaning that they have the potential to differentiate into any of the various blood cells needed by the body. Red blood cells carry oxygen, white blood cells fight infection, and platelets clot the blood. The interplay between the bone structure and the marrow exemplifies how our skeletal system is not just a framework for our bodies but also a dynamic site of critical biological processes.

Skeletal System Physiology

The skeletal system, comprising 206 bones in a typical adult human, is not simply a static support structure. It is dynamic, with physiology that includes protection of vital organs, mineral storage, and even endocrine functions. The physiology of long bones within the skeletal system is no exception to this level of activity.

These bones store minerals such as calcium and phosphorus, which can be released into the bloodstream to maintain critical levels necessary for various body functions. They also house the bone marrow, where hematopoiesis occurs, contributing to the body's immune response and oxygen transportation. Moreover, the skeletal system works in tandem with the muscular system, using the lever action of bones to create movement when muscles contract. Every time you walk, type, or wave, your long bones are instrumental in converting muscular actions into motion.