Can too much physical exercise be harmful? The arm would straighten out. Motor neurons are clustered in columnar, spinal nuclei called motor neuron pools (or motor nuclei). Both muscle fibres and myocytes are muscle cells. The motor commands that work to raise the hand of an infant would fail completely to raise the hand of an adult. A strained muscle is caused by the tearing of muscle fibres. Finally, fast-twitch, fatigable fibers are recruited when the largest motor neurons are activated. C. Rate code This answer is CORRECT! Other organ systems rely on this calcium for action (specifically, muscle contraction and neural signaling). Muscular system worksheet answer key. Define flexibility exercise, and state its benefits. Skeletal muscle is attached to bones, cardiac muscle makes up the walls of the heart, and smooth muscle is found in the walls of internal organs and other internal structures. The muscular system is the organ system that consists of all the muscles in the body.
This contraction keeps the spindle taut at all times and maintains its sensitivity to changes in the length of the muscle. The muscle spindle signals the length of a muscle and changes in the length of a muscle. Skeletal muscles also have connective tissue supporting and protecting the muscle tissue. Fast-twitch, fatigue-resistant fibers are recruited when the input onto motor neurons is large enough to recruit intermediate-sized motor neurons. Muscular system questions and answers pdf. Genetic differences in proportions of slow-twitch and fast-twitch skeletal muscle fibres may influence how people respond to physical exercise. This entire process falls under the subject of motor control.
Sample answer: The skeletal system and the nervous system. They contain protein filaments that slide over one another using energy in ATP. These fibers are so-named because their nuclei are collected in a bundle in the middle of the fiber. Group Ia afferents (also called primary afferents) wrap around the central portion of all 3 types of intrafusal fibers; these specialized endings are called annulospiral endings. Identify several other health benefits of physical exercise. One of the key questions of research on motor control is to understand the functional roles played by each area. Chapter 6 the muscular system answer key. Describe the structure of a skeletal muscle. Alpha motor neurons (also called lower motor neurons) innervate skeletal muscle and cause the muscle contractions that generate movement.
If a resting muscle is stretched, the muscle spindle becomes stretched in parallel, sending signals through the primary and secondary afferents. Most muscles contain both fast- and slow-twitch fibers, but in different proportions. Many people who overwork their muscles develop delayed onset muscle soreness (DOMS), which may be caused by tiny tears in muscle fibres. Two terms are used to describe the anatomical relationship between motor neurons and muscles: the motor neuron pool and the motor unit. Because this low level of the hierarchy takes care of these basic functions, higher levels (such as the motor cortex) can process information related to the planning of movements, the construction of adaptive sequences of movements, and the coordination of whole-body movements, without having to encode the precise details of each muscle contraction. In addition to the use of proprioception to sense the position of the body before a movement, the motor system must use other sensory information in order to perform the movement accurately. Padding of a strained muscle protects it from further impact. Attribute specific functions of the skeletal system to specific components or structures. If the triceps were to then contract, which way would the arm move? How do muscles change when they increase or decrease in size? Without these automatic adjustments, the simple act of reaching for a cup would cause us to fall, as the body's center of mass shifts to a location in front of the body axis. Primary Parkinson's disease occurs mostly in older people, for no known reason. A skeletal muscle contraction is an increase in the tension or a decrease in the length of a skeletal muscle. Compensation for the physical characteristics of the body and muscles.
Describe muscle cells and their function. Part 1: Muscle Basics. Gamma motor neurons innervate intrafusal fibers, which do not contribute significantly to muscle force.