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.
The lecture Skeletal Muscle: Levels of Organization (Nursing) by Jasmine Clark, PhD is from the course Musculoskeletal System – Physiology (Nursing).
What is the function of skeletal muscle tissue? Select all that apply
What is the layer of connective tissue that surrounds a single muscle fiber?
5 Stars |
|
5 |
4 Stars |
|
0 |
3 Stars |
|
0 |
2 Stars |
|
0 |
1 Star |
|
0 |