The structural and functional unit of skeletal muscle is called:

Raj. CHO -2024

Applied Physiology

Easy

Appeared in: Raj. CHO -2024

Explanation

The sarcomere is defined as the basic contractile unit of a muscle fiber.
It consists of the arrangement of thick (myosin) and thin (actin) filaments between two Z-lines.
The sliding of these filaments relative to each other causes muscle contraction and force generation.
The repeating pattern of sarcomeres gives skeletal and cardiac muscle their characteristic striated appearance.

Option A: A nephron is the structural and functional unit of the kidney, not skeletal muscle. Its primary function is to filter blood and produce urine.
Option C: A micromere is a term from embryology. It refers to the smaller cells formed during the cleavage of a fertilized egg, particularly in eggs with unequal yolk distribution. It is not related to muscle structure.
Option D: Similar to a micromere, a macromere is an embryological term for the larger cells formed during cleavage. It has no function in the structure of skeletal muscle.

Visual 1: Diagram of a Sarcomere. This visual should clearly label the Z-lines, A-band, I-band, H-zone, and the overlapping actin (thin) and myosin (thick) filaments. It helps to visualize the structural components mentioned in the explanation.
Visual 2: Animation of the Sliding Filament Model. An animation showing how the actin and myosin filaments slide past each other during muscle contraction and relaxation would effectively demonstrate the functional aspect of the sarcomere.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The concept tested is the identification of the basic structural and functional unit of skeletal muscle as background academic context rather than a clinical decision trigger.
Understanding the sarcomere is fundamental to comprehending muscle-related diseases (myopathies), such as muscular dystrophies, where proteins within the sarcomere are defective.
The principles of sarcomere function are crucial in sports medicine and physical therapy for designing effective exercise and rehabilitation programs that target muscle strengthening and recovery.
What if a patient has a genetic mutation affecting the protein dystrophin? This would lead to Duchenne muscular dystrophy, where the structural integrity of the sarcolemma is compromised during contraction, causing progressive muscle fiber damage and weakness, even though the basic sarcomere contraction mechanism is initially intact.

How to Approach the Question

This is a factual recall question that tests your knowledge of basic human physiology.
First, identify the key terms in the question: 'structural and functional unit' and 'skeletal muscle'.
Mentally define what a 'functional unit' is—the smallest component of an organ or system that can perform all of its functions.
Review the options provided and recall the functional units for different body systems.
Eliminate the incorrect options. 'Nephron' is for the kidney. 'Micromere' and 'Macromere' are related to embryology.
Select the option that correctly identifies the functional unit of skeletal muscle, which is the sarcomere.

Concept Tested & Keywords

Concept Tested: The concept tested is the identification of the basic structural and functional unit of skeletal muscle.
Stem keywords: structural and functional unit, skeletal muscle
Lead-in keywords: is called

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