Muscular Physiology Warm Up 2

Structure number 2 in the image is pointing towards the nuclei. Nuclei are typically found in the center of cells and contain the genetic material of the cell. In this context, it is likely referring to the nuclei of muscle cells.

The T tubule is indeed found sandwiched between the sacs of the sarcoplasmic reticulum. This arrangement allows for efficient communication and coordination between the T tubule and the sarcoplasmic reticulum, which are both important for muscle contraction. The T tubule carries the action potential deep into the muscle fiber, while the sarcoplasmic reticulum stores and releases calcium ions, which are crucial for muscle contraction. This close proximity allows for quick and effective communication between these two structures during the process of muscle contraction.

Titin is a protein that is found in elastic filaments and it acts as a molecular spring. It is responsible for connecting the ends of thick filaments to the Z line, which helps in maintaining the structural integrity of the sarcomere. Titin is the largest known protein and it plays a crucial role in muscle contraction and elasticity.

The four correct kinds of protein molecules that make up myofilaments are myosin, actin, tropomyosin, and troponin. These proteins are essential for muscle contraction. Myosin is responsible for generating the force during muscle contraction, while actin provides the structure for muscle fibers. Tropomyosin regulates the interaction between myosin and actin, preventing them from binding when the muscle is at rest. Troponin works in conjunction with tropomyosin to control muscle contraction by regulating the availability of binding sites on actin for myosin. Glyocomyosin and Sarcomere troponin are not correct answers as they are not proteins involved in myofilament formation.

The correct answer is cardiac because the image shows muscle tissue that has striations and branching fibers, which are characteristic features of cardiac muscle. Cardiac muscle is found in the walls of the heart and is responsible for the contraction and pumping of blood.

The structure number 3 in the image is pointing towards intercalated discs. Intercalated discs are specialized cell junctions found in cardiac muscle tissue. They connect adjacent cardiac muscle cells and allow for coordinated contraction of the heart. These discs contain gap junctions, which facilitate the flow of ions between cells, allowing for rapid electrical communication. The presence of intercalated discs is a unique feature of cardiac muscle and helps in its efficient functioning.

In the image, number 1 is pointing towards skeletal striated voluntary muscles. This is indicated by the fact that the other options, such as myofibrils, multinucleated, and T tubules, do not accurately represent the structure being pointed at. The term "skeletal striated voluntary muscles" specifically refers to the type of muscles that are attached to the skeleton, have a striped or striated appearance, and are under voluntary control. Therefore, it is clear that number 1 is indicating skeletal striated voluntary muscles in the image.

The correct answer is "Cardiac muscle cell" because the question asks about the structure that number 1 is pointing toward in the image. Based on the options provided, the most appropriate structure that can be identified is a cardiac muscle cell.

The correct answer is Multinucleated because in the image, number 2 is pointing towards a structure that contains multiple nuclei. This is a characteristic feature of multinucleated cells, such as skeletal striated voluntary muscles. The other options, Myofibrils and Sarcomere, do not specifically refer to the presence of multiple nuclei.

Myofibrils are bundles of fine fibers that extend lengthwise along muscle fibers. These fibers are responsible for muscle contraction and contain the contractile proteins actin and myosin. The sarcolemma is the cell membrane of a muscle fiber, sarcoplasm is the cytoplasm of a muscle fiber, and sarcomere is the basic unit of a muscle fiber. However, none of these options describe the bundles of fine fibers along muscle fibers, making myofibril the correct answer.