Ch 21 Review Which of the Following Types of Muscle Is a Voluntary Muscle
iv.4 Muscle Tissue
Learning Objectives
Describe the characteristics of muscle tissue and how these dictate musculus function.
By the end of this section, you will be able to:
- Place the iii types of muscle tissue
- Compare and contrast the functions of each muscle tissue blazon
Muscle tissue is characterized past properties that let movement. Muscle cells are excitable; they respond to a stimulus. They are contractile, significant they can shorten and generate a pulling force. When attached between 2 movable objects, such every bit two bones, contraction of the muscles cause the bones to move. Some muscle move is voluntary, which means it is under conscious command. For case, a person decides to open a volume and read a chapter on anatomy. Other movements are involuntary, meaning they are not under conscious command, such equally the wrinkle of your pupil in bright light. Muscle tissue is classified into 3 types according to structure and function: skeletal, cardiac, and polish (Table iv.2).
| Musculus blazon | Structural elements | Function | Location |
| Skeletal | Long cylindrical fiber, striated, many peripherally located nuclei | Voluntary motility, produces heat, protects organs | Fastened to basic and around entry & exit sites of body (e.g., mouth, anus) |
| Cardiac | Short, branched, striated, single central nucleus | Contracts to pump blood | Heart |
| Smoothen | Short, spindle-shaped, no evident striation, unmarried nucleus in each cobweb | Involuntary motion, moves food, involuntary control of respiration, moves secretions, regulates flow of blood in arteries by contraction | Walls of major organs and passageways |
Skeletal muscle is attached to basic and its contraction makes possible locomotion, facial expressions, posture, and other voluntary movements of the torso. Twoscore per centum of your body mass is made upwards of skeletal muscle. Skeletal muscles generate rut as a byproduct of their contraction and thus participate in thermal homeostasis. Shivering is an involuntary contraction of skeletal muscles in response to lower than normal body temperature. The muscle prison cell, or myocyte, develops from myoblasts derived from the mesoderm. Myocytes and their numbers remain relatively constant throughout life. Skeletal muscle tissue is arranged in bundles surrounded by connective tissue. Under the light microscope, muscle cells announced striated with many nuclei squeezed along the membranes. The striation is due to the regular alternation of the contractile proteins actin and myosin, along with the structural proteins that couple the contractile proteins to connective tissues. The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to grade each long muscle fiber.
Cardiac muscle forms the contractile walls of the centre. The cells of cardiac muscle, known as cardiomyocytes, also appear striated under the microscope. Unlike skeletal musculus fibers, cardiomyocytes are single cells with a single centrally located nucleus. A main characteristic of cardiomyocytes is that they contract on their own intrinsic rhythm without external stimulation. Cardiomyocytes adhere to one some other with specialized cell junctions called intercalated discs. Intercalated discs have both anchoring junctions and gap junctions. Attached cells class long, branching cardiac muscle fibers that human action equally a syncytium, allowing the cells to synchronize their actions. The cardiac muscle pumps blood through the body and is under involuntary control.
Polish muscle tissue contraction is responsible for involuntary movements in the internal organs. Information technology forms the contractile component of the digestive, urinary, and reproductive systems likewise as the airways and blood vessels. Each cell is spindle shaped with a single nucleus and no visible striations (Figure iv.4.1 – Musculus Tissue).
External Website
Watch this video to learn more than most muscle tissue. In looking through a microscope how could you distinguish skeletal muscle tissue from polish muscle?
Affiliate Review
The iii types of musculus cells are skeletal, cardiac, and smoothen. Their morphologies lucifer their specific functions in the body. Skeletal muscle is voluntary and responds to witting stimuli. The cells are striated and multinucleated actualization as long, unbranched cylinders. Cardiac muscle is involuntary and institute only in the middle. Each jail cell is striated with a single nucleus and they adhere to one another to form long fibers. Cells are fastened to one another at intercalated disks. The cells are interconnected physically and electrochemically to human action as a syncytium. Cardiac muscle cells contract autonomously and involuntarily. Smooth musculus is involuntary. Each cell is a spindle-shaped fiber and contains a single nucleus. No striations are axiomatic because the actin and myosin filaments do not marshal in the cytoplasm.
Interactive Link Questions
Watch this video to learn more than almost muscle tissue. In looking through a microscope how could you distinguish skeletal muscle tissue from smooth muscle?
Skeletal muscle cells are striated.
Review Questions
Disquisitional Thinking Questions
You are watching cells in a dish spontaneously contract. They are all contracting at unlike rates, some fast, some slow. After a while, several cells link upwards and they begin contracting in synchrony. Discuss what is going on and what type of cells you lot 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 permit the cells to communicate with each other and begin contracting in synchrony.
Why does skeletal muscle await striated?
Nether the low-cal microscope, cells appear striated due to the arrangement of the contractile proteins actin and myosin.
Source: https://open.oregonstate.education/aandp/chapter/4-4-muscle-tissue/
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