Chapter 6 The Muscular System Answer Key
Through vision, audition, somatosensation, and the other senses, we perceive the world and our relationship to it. Its firing rate does not depend on the rate of change of the muscle; rather, its firing rate depends only on the immediate length of the muscle. Crossbridge cycling is the specific mechanism by which the filaments slide past each other, which involves the use of ATP.
- Chapter 6 muscular system answer key
- The muscular system answer key
- Chapter 10 anatomy of the muscular system
Chapter 6 Muscular System Answer Key
In summary, - Muscle spindles signal information about the length and velocity of a muscle. The different areas of the motor system are organized in a hierarchical fashion. This conserves body heat or dissipates it, respectively. They signal information about the static length of the muscle. Neuromuscular disorders are systemic disorders that occur because of problems with the nervous control of muscle contractions or with the muscle cells themselves. If the muscle shortens against no resistance, the contraction results in constant force (isotonic contraction). 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. Chapter 10 anatomy of the muscular system. Why is padding of a strained muscle part of the typical treatment?
When muscles increase or decrease in size, the individual muscle fibres grow wider or narrower, respectively. Alpha motor neurons innervate extrafusal fibers, the highly contracting fibers that supply the muscle with its power. 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. If the triceps were to then contract, which way would the arm move? Sliding filament theory describes how actin and myosin filaments slide past each other during muscle contraction. Skeletal muscles also have connective tissue supporting and protecting the muscle tissue. The muscular system answer key. The ease with which we make most of our movements belies the enormous sophistication and complexity of the motor system. 10 Sensory Innervation of Muscle Spindles. This is because the neurotransmitter acetylcholine is necessary to trigger muscle contractions at the neuromuscular junction by binding to its receptors on the muscle fibres. As we shall see throughout this material on the motor system, our abilities to make movements that are accurate, properly timed, and with proper force depend critically on the sensory input that is ubiquitous at all levels of the motor system hierarchy. The motor system must perform many procedures in an automatic fashion, without the need for high-order control. Why is the heart the muscle that performs the greatest amount of physical work in the course of a lifetime?
The Muscular System Answer Key
These unconscious processes allow higher-order brain areas to concern themselves with broad desires and goals, rather than low-level implementations of movements. What may explain the positive benefits of physical exercise on cognition? If this does not occur, the myosin head cannot attach to the actin filament and the "power stroke" cannot occur. Carpal tunnel syndrome may be treated by wearing a wrist splint, receiving corticosteroid injections, or undergoing surgery to cut the carpal ligament and reduce pressure on the median nerve. Chapter 6 muscular system answer key. These fibers are used for maintaining posture and making other low-force movements. Its general function is to power voluntary body movements. 3 Motor Control Requires Sensory Input. Other organ systems rely on this calcium for action (specifically, muscle contraction and neural signaling). Instead, many motor tasks are performed in an automatic fashion that does not require conscious processing. At the resting position, the Ia afferents of spindles in the triceps muscle fire at a steady rate to encode the present length of the muscle, and the Ib afferents of the Golgi tendon organs of the biceps muscle fire at a low rate. If the ends of the muscle are fixed, keeping the muscle at the same length, then the contraction results on an increased force on the supports (isometric contraction).
Because of their patterns of innervation onto the three types of intrafusal fibers, Group Ia and Group II afferents respond differently to different types of muscle movements. A skeletal muscle consists of bundles of muscle fascicles, each of which in turn consists of bundles of muscle fibres. The function of intrafusal fiber contraction is not to provide force to the muscle; rather, gamma activation of the intrafusal fiber is necessary to keep the muscle spindle taut, and therefore sensitive to stretch, over a wide range of muscle lengths. Answers for Critical Thinking Questions. Activation of gamma motor neurons prevents this temporary insensitivity by causing a weak contraction of the intrafusal fibers, in parallel with the contraction of the muscle. 4 Muscle Contraction: Review Questions and Answers.
Chapter 10 Anatomy Of The Muscular System
Why do many skeletal muscles work in pairs? Cat Muscles Lab Guide - checklist of the muscles you need to identify on the cat. Skeletal muscle is attached to bones by tendons. Although many of the details are not understood, two broad principles appear to be key concepts toward understanding motor control: - Functional Segregation. Myasthenia gravis is a genetic neuromuscular disorder most often caused by immune system antibodies blocking acetylcholine receptors on muscle cells and the actual loss of acetylcholine receptors. To report a technical problem with this Web site, please contact the.
The organ is innervated by primary afferents called Group Ib fibers, which have specialized endings that weave in between the collagen fibers. With increasing firing rates, the summation grows stronger, up to a limit. Bones also protect internal organs from injury by covering or surrounding them. If the motor neuron fires after the muscle has returned to baseline, then the magnitude of the next muscle twitch will be the same as the first twitch.