Skeletal Muscle: Levels of Organization (Nursing)

by Jasmine Clark

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    00:01 Greetings.

    00:01 In this lecture we will be discussing the muscular system.

    00:07 So first let's talk about the different types of muscles that are found in the body.

    00:11 We have skeletal muscle tissue, cardiac muscle tissue, and smooth muscle tissue.

    00:19 Of these three types of muscle tissue, we will focus mainly on the skeletal muscles for this lecture.

    00:26 We will talk briefly about cardiac muscles and smooth muscles But we will talk more extensively about those in other lectures.

    00:36 So, first let's discuss the functions of the muscular tissue.

    00:40 The muscle tissue is involved in producing body movements, stabilizing the body's position, storing and mobilizing substances within the body, and also generating heat.

    00:55 Other properties as a muscular tissue include electrical excitability, the ability to contract, the ability to extend, and finally, the ability to return back to its normal size or elasticity.

    01:13 So now let's look at the structural organization of our skeletal muscles.

    01:19 Starting with the largest part, the actual muscle itself.

    01:24 This organ is made up of vesicles that are going to contain muscle fibers as well as blood vessels, nerves, and all of this is wrapped in a connective tissue layer known as the epimysium.

    01:38 If we go inside or the next smallest unit of the muscle, we have the fascicles.

    01:45 This is going to be a bundle of muscle fibers that are wrapped in a connective tissue layer known as the perimysium.

    01:52 If you like pulled pork, you are actually looking at the individual fascicles of the muscle.

    02:01 The third level or the next smallest level is going to be the muscle fiber itself.

    02:07 We actually refer to muscle cells as muscle fibers.

    02:12 And this is because of the shape and the organization of the cells.

    02:17 In the muscle fiber we start out with a connective tissue layer known as the endomysium.

    02:24 Inside of that we have the sarcolemma.

    02:27 The sarcolemma would be synonymous with the plasma membrane of a regular cell.

    02:34 Inside of the sarcolemma, we have the sarcoplasm, which is synonymous with the cytoplasm of a regular cell.

    02:42 Also inside of the cell, we have myofibrils, which are the contractile units of the muscle, as well as multiple nuclei, which is unique to muscle cells.

    02:53 We also have mitochondria which are very important for allowing us to have the energy for our muscles to contract.

    03:00 And other structures include transverse tubules, the sarcoplasmic reticulum, and the terminal cisterns, which are going to be very important for bringing in calcium so that we can undergo a muscle contraction.

    03:14 When you look at a muscle fiber, it has a striated or striped appearance.

    03:19 We'll discuss why this is later.

    03:23 The final and smallest unit of the muscle is going to be the myofibril.

    03:28 As I said, this is a contractile unit of the muscle.

    03:32 This threadlike contractile element is going to be found within the sarcoplasm of the muscle fiber and it's going to extend the entire length of the fiber.

    03:42 Within the myofibril.

    03:44 We have several different filaments including thick and thin filaments.

    03:49 We'll discuss these in more detail shortly.

    03:54 So speaking of the filaments of the muscle, we have the thick filaments which are going to be composed of a protien known as myosin, and then the thin filaments which are composed of a protein known as actin.

    04:07 There are also several regulatory proteins including tropomyosin and troponin.

    04:14 This part of the myofibril these filaments are going to be what we use in order for our muscles to contract or shorten.

    About the Lecture

    The lecture Skeletal Muscle: Levels of Organization (Nursing) by Jasmine Clark is from the course Musculoskeletal System – Physiology (Nursing).

    Included Quiz Questions

    1. Produce body movements
    2. Stabilize body positions
    3. Generate heat
    4. Aid in peristalsis
    5. Produce cardiac contractions
    1. Endomysium
    2. Fascia
    3. Perimysium
    4. Sarcomere

    Author of lecture Skeletal Muscle: Levels of Organization (Nursing)

     Jasmine Clark

    Jasmine Clark

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