Sliding filament theory describes how actin and myosin filaments slide past each other during muscle contraction. These unconscious processes allow higher-order brain areas to concern themselves with broad desires and goals, rather than low-level implementations of movements. When does anaerobic respiration typically occur in human muscle cells? A dense connective tissue that connect one whole bone to another whole bone. 3 Types of Muscle Tissue: Review Questions and Answers. Chapter 10 anatomy of the muscular system. During muscle contraction, the sliding of the actin and myosin filaments pulls the Z discs closer together, shortening the sarcomere.
When muscles increase or decrease in size, the individual muscle fibres grow wider or narrower, respectively. Flexibility exercise is any physical activity that stretches and lengthens muscles. List four characteristic signs of the disorder. During the stretch, the two types differ in their responses. Muscular system worksheet pdf answer key. Instead, many motor tasks are performed in an automatic fashion that does not require conscious processing. Part 1: Muscle Basics. Because of Ohm's Law, a small amount of synaptic current will be sufficient to cause the membrane potential of a small motor neuron to reach firing threshold, while the large motor neuron stays below threshold. Most muscles contain both fast- and slow-twitch fibers, but in different proportions. This elaborate processing would be of limited value, however, unless we had a way to act upon the environment that we are sensing, whether that action consist of running away from a predator; seeking shelter against the rain; searching for food when one is hungry; moving one's lips and vocal cords in order to communicate with others; or performing the countless other varieties of actions that make up our daily lives.
When the acetylcholine binds to acetylcholine receptors on the muscle fiber, an action potential is propagated along the muscle fiber in both directions (see Chapter 4 of Section I for review). It is characterized by fluctuating muscle weakness and fatigue, with more muscles becoming affected and muscles becoming increasingly weakened as the disorder progresses. Myokines are endocrine hormones that promote tissue repair and growth and have anti-inflammatory effects. Chapter 6 the muscular system answers key. A muscle strain occurs when muscle fibres tear as a result of overstretching. 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. The bones and muscles have mass that must be considered when moving a joint, and the muscles themselves have a certain degree of resistance to movement. Therefore, an increase in muscle size generally causes an increase in strength, and a decrease in muscle size generally causes a decrease in strength. As people age, accumulated spinal column injuries and diseases like osteoporosis can also lead to curvatures of the spine, hence the stooping you sometimes see in the elderly. If the triceps were to then contract, which way would the arm move?
Mineral and Fat Storage, Blood Cell Formation. In the areas of the skeleton where whole bones move against each other (for example, joints like the shoulder or between the bones of the spine), cartilages, a semi-rigid form of connective tissue, provide flexibility and smooth surfaces for movement. The filaments are arranged in repeating units called sarcomeres, which are the basic functional units of skeletal muscles. Instead, they are controlled by the autonomic nervous system, hormones, and other substances. What mechanism may underlie many of the general health benefits of physical exercise?
7 Case Study Conclusion and Chapter Summary: Review Questions and Answers. The motor commands that work to raise the hand of an infant would fail completely to raise the hand of an adult. Give three reasons that muscle atrophy may occur. The large majority of muscle fibers that allow the muscle to do work are termed extrafusal fibers. 12 illustrates the difference in information conveyed by muscle spindles and Golgi tendon organs. The system must adapt over time to change its output to accomplish the same goals. A strained muscle is caused by the tearing of muscle fibres. Bone (osseous) tissue.
Skeletal muscle is attached to bones by tendons. Is the situation described in part (a) more likely to be an isometric or isotonic contraction? Describe the structure of a skeletal muscle. If a muscle is required for fine control or for delicate movements (e. g., movement of the fingers or hands), its motor units will tend to have small innervation ratios. What is Parkinson's disease? What is muscle tissue? Sample answer: ATP is required to move the myosin head into the cocked position. Attribute specific functions of the skeletal system to specific components or structures.
Without the skeletal system, you would be a limp mass of organs, muscle, and skin. The motor system hierarchy consists of 4 levels (Figure 1. Motor neurons are clustered in columnar, spinal nuclei called motor neuron pools (or motor nuclei). 2 Some Necessary Components of Proper Motor Control. One of the major principles of the motor system is that motor control requires sensory input to accurately plan and execute movements.