Using the terms provided, fill in the blanks in the subsequent text passage such
ID: 58355 • Letter: U
Question
Using the terms provided, fill in the blanks in the subsequent text passage such that, when completed, the passage accurately details skeletal muscle structure from the tissue level to the cellular, and finally to the subcellular level.
Terms:
belly, bundles, myofibers, myofibrils, perimysium, sarcolemma, sarcomeres, thick, thin, Z-lines
Skeletal muscle is attached to the bones of our skeletons via tendons and the contraction and relaxation of these muscles allows for voluntary movement of the skeleton. In any given muscle, the 'beefy' part of the muscle, or the muscle __________ is surrounded by a layer of thick connective tissue called the epimysium. If this connective tissue sheath is peeled back or removed, the muscle below is seen to be divided into several distinct ___________, or fascicles.
Each fascicle is surround by and separated from other fascicles by another layer of connective tissue called the ____________. If this connective tissue layer is peeled away or removed, each fascicle can then be seen to be made up of a number of even smaller-diameter subunits called ____________ - each of which is a single skeletal muscle cell. Each muscle cell is individually wrapped in its own layer of connective tissue - or endomysium. Lying just below the endomysium is the plasma membrane of the muscle cell, often referred to as the ________________.
At the sub-cellular level, each muscle cell is composed of even smaller diameter subunits called ____________ which are, themselves, filled with myofilaments composed of the contractile proteins present in the muscle cell. There are 2 types of myofilaments present: those composed of multiple molecules of actin, which are called the __________ filaments, and those that are composed of multiple molecules of myosin, called the __________ filaments. These myofilaments are arranged in specific fashion in repetitive units called _____________ that are bordered by and separated from one another by bands of non-contractile protein called ___________.
Explanation / Answer
Skeletal muscle is attached to the bones of our skeletons via tendons and the contraction and relaxation of these muscles allows for voluntary movement of the skeleton. In any given muscle, the 'beefy' part of the muscle, or the muscle belly is surrounded by a layer of thick connective tissue called the epimysium. If this connective tissue sheath is peeled back or removed, the muscle below is seen to be divided into several distinct bundles, or fascicles.
Each fascicle is surround by and separated from other fascicles by another layer of connective tissue called the perimysium. If this connective tissue layer is peeled away or removed, each fascicle can then be seen to be made up of a number of even smaller-diameter subunits called myofibers - each of which is a single skeletal muscle cell. Each muscle cell is individually wrapped in its own layer of connective tissue - or endomysium. Lying just below the endomysium is the plasma membrane of the muscle cell, often referred to as the Sarcolemma.
At the sub-cellular level, each muscle cell is composed of even smaller diameter subunits called myofibrils which are, themselves, filled with myofilaments composed of the contractile proteins present in the muscle cell. There are 2 types of myofilaments present: those composed of multiple molecules of actin, which are called the ___thin_______ filaments, and those that are composed of multiple molecules of myosin, called the thick filaments. These myofilaments are arranged in specific fashion in repetitive units called sarcomeres that are bordered by and separated from one another by bands of non-contractile protein called Z-lines.
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