This is because of the high metabolic demands of these cells. There is a constant need for protein production and repairs to maintain muscle tissue, processes which originate in the nucleus. It makes sense that skeletal muscle, which is most active and has the highest energy demands, has the greatest number of nuclei. Skeletal muscle is the only type of muscle that can be controlled voluntarily. Skeletal muscle is the muscle type used to control the movement of our bones and therefore our bodies.
An exception to this rule is that smooth muscle can be controlled by some individuals, but to a extremely limited capacity. The only type of muscle tissue that can be controlled voluntarily is skeletal muscle tissue. Both skeletal and cardiac muscle tissue have the sarcomere as the functional unit, and only skeletal muscle has multinucleated cells.
Smooth muscle does not have troponin, and therefore does not require calcium in order to contract. The first requirement of this question is that the muscle type be striated. Striated muscle can be identified by the presence of alternating dark and light bands, caused by the repetition of sarcomeres, the basic muscle units composed of actin and myosin. Both cardiac and skeletal muscle types are striated. The second requirement is that the muscle type must be multinucleate, meaning that individual cells have fused to form larger units with more than one nucleus.
The only muscles with multinucleate cells are skeletal muscles, so that is our solution. Cardiac muscle and skeletal muscle are both composed of sarcomeres. This layout gives both muscle types a striated appearance, alternating dark bands of myosin with lighter bands of actin. Only cardiac muscle has intercalated discs and skeletal muscle is the only type that is multinucleated. No muscle type is attached directly to bone, but skeletal muscle is linked to bone via tendons.
Cardiac muscle is organized into sarcomeres, giving it a striated appearance, and cardiac contraction is strongly dependent on calcium concentrations and release. While the heart is capable of beating without nervous innervation, autonomic regulation via the parasympathetic nervous system mediates the frequency of cardiac stimulation from the sinoatrial SA node.
Signals from the parasympathetic nervous system travel to the cardiac muscle via chemical synapses, by use of a neurotransmitter. Signals from one cardiac fiber to another are transmitted via electrical synapses, or gap junctions, the allow proliferation of the signal without a chemical intermediate.
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Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney. Hanley Rd, Suite St. There are two types of muscle based on the morphological classification system.
There are two types of muscle based on a functional classification system. Types of muscle: there are generally considered to be three types of muscle in the human body. Skeletal muscle: which is striated and voluntary. Cardiac muscle: which is striated and involuntary. Smooth muscle: which is non striated and involuntary. Skeletal muscle cells are elongated or tubular.
They have multiple nuclei and these nuclei are located on the periphery of the cell. Skeletal muscle is striated. That is, it has an alternating pattern of light and darks bands that will be described later. Cardiac muscle cells are not as long as skeletal muscles cells and often are branched cells. Cardiac muscle cells may be mononucleated or binucleated.
In either case the nuclei are located centrally in the cell. Cardiac muscle is also striated. In addition cardiac muscle contains intercalated discs. Smooth muscle cell are described as spindle shaped. That is they are wide in the middle and narrow to almost a point at both ends. Smooth muscle cells have a single centrally located nucleus. Smooth muscle cells do not have visible striations although they do contain the same contractile proteins as skeletal and cardiac muscle, these proteins are just laid out in a different pattern.
Parallel or fusiform: as their name implies their fibers run parallel to each other. These muscles contract over a great distance and usually have good endurance but are not very strong.
Examples: Sartorius muscle and rectus abdominus muscle. Convergent: the muscle fibers converge on the insertion to maximize the force of muscle contraction.
Examples: Deltoideus muscle and Pectoralis Major muscle. These types of muscles are strong but they tie or quickly. There are three types of pennate muscle. Circular: the muscle fibers surrounded opening to act as a sphincter.
No striations are evident because the actin and myosin filaments do not align in the cytoplasm. You are watching cells in a dish spontaneously contract. They are all contracting at different rates, some fast, some slow. After a while, several cells link up and they begin contracting in synchrony. Discuss what is going on and what type of cells you are looking at.
The cells in the dish are cardiomyocytes, cardiac muscle cells. They have an intrinsic ability to contract. When they link up, they form intercalating discs that allow the cells to communicate with each other and begin contracting in synchrony. Under the light microscope, cells appear striated due to the arrangement of the contractile proteins actin and myosin. Skip to content Learning Objectives Describe the characteristics of muscle tissue and how these dictate muscle function.
By the end of this section, you will be able to: Identify the three types of muscle tissue Compare and contrast the functions of each muscle tissue type. External Website. Chapter Review The three types of muscle cells are skeletal, cardiac, and smooth. Interactive Link Questions Watch this video to learn more about muscle tissue. Skeletal muscle cells are striated. Review Questions. The following section will explore the structure of the nucleus and its contents, as well as the process of DNA replication.
Like most other cellular organelles, the nucleus is surrounded by a membrane called the nuclear envelope. This membranous covering consists of two adjacent lipid bilayers with a thin fluid space in between them. Spanning these two bilayers are nuclear pores. A nuclear pore is a tiny passageway for the passage of proteins, RNA, and solutes between the nucleus and the cytoplasm. Proteins called pore complexes lining the nuclear pores regulate the passage of materials into and out of the nucleus.
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