Involuntary muscle control

There is probably no biological phenomenon that has excited more interest among biochemists than the movement caused by the contractile fibers of muscles. Unlike the motion of bacterial flagella, the movement of muscle is directly dependent on the hydrolysis of ATP as its source of energy. Several types of muscle exist within our bodies. Striated (striped) skeletal muscles act under voluntary control. Closely related are the involuntary striated heart muscles, while smooth involuntary muscles constitute a third type. Further distinctions are made between fast-twitch and slow-twitch fibers. Fast-twitch fibers have short isometric contraction times, high maximal velocities for shortening, and high rates of ATP hydrolysis. 

SLE systemic lupus erythrematosus. smooth muscle (involuntary muscle plain muscle) Unlike striated muscle, smooth muscle has no cross-striations under the microscope, indicating an organization characteristic of muscle controlled by the autonomic nervous system, and reacts more slowly to neurotransmitters than striated muscle (skeletal muscle) of the voluntary nervous system. 

Smooth or involuntary muscle is found within the wall of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder and blood vessels. Unlike skeletal muscle, smooth muscle is not under conscious control. 

Movement disorders refer to those clinical syndromes involving (a) a deficit in non- or extrapyramidal function and (b) at least one non-epileptic abnormal movement. Typical symptoms include akinesia or bradykinesia, ataxia, catalepsy, chorea, spasm, tremor and dystonia (slow involuntary muscle contractions producing abnormal posture or position), either focal or generalized. Many movement disorders are poorly controlled with current therapies, especially those with dystonia, spasticity and iatrogenic dyskinesia, and better drug therapies are clearly indicated. 

The same cardiovascular control system regulates blood distribution and blood pressure by affecting the small arterioles of the peripheral blood vasculature. The entrance to each of these vessels is surrounded by a sphincter muscle (a ring of involuntary muscle that surrounds the arteriolar aperture) with sympathetic, and in some cases, parasympathetic, nerve fibers. The sphincter is usually contracted. When the signal comes for the muscle to relax, the neuron produces nitric oxide at the neuromuscular junction, and this gas relaxes the sphincter. When the sphincter muscle expands, it increases the area through which blood flows and decreases its resistance. With decreased resistance, blood pressure falls. 

Muscle whose activity is not under the control of the will It Is supplied by the autonomic nervous system. Involuntary muscle comprises long spindle-shaped cells without striations. These cells occur singly, in groups, or as sheets in the skin, around hair follicles, and in the digestive tract, respiratory tract, urinogenital tract, and the circulatory system. The cells contract slowly in spontaneous rhythms or when stretched they may show sustained contraction (tonus) for long periods without fatigue. Compare cardiac muscle voluntary muscle. 

Involuntary muscle does not have the characteristic striped appearance of voluntary muscle. It exists in the digestive tract, the walls of the blood vessels and in the respiratory and genito-urinary apparatus. Involuntary muscle is controlled automatically by the autonomic nervous system. 

The microorganism makes spinosyns, unique macrocyclic lactones, containing a tetracyclic core to which two sugars are attached. Most of the insecticidal activity is due to a mixture of spinosyns A and D, commonly referred to as spinosad. Products such as Tracer Naturalyte Insect Control, and Precise contain spinosad as the active ingredient. Insects exposed to spinosad exhibit classical symptoms of neurotoxicity lack of coordination, prostration, tremors, and other involuntary muscle contractions leading to paralysis and death. Although the mode of action of spinosad is not fully understood, it appears to affect nicotinic and -aminobutyric acid receptor function through a novel mechanism. 

This chapter discusses drug s used to treat urinary tract infections (UTIs) and certain miscellaneous drag > used to relieve the symptoms associated with an overactive bladder (involuntary contractions of the detrusor or bladder muscle). Structures of the urinary system that may be affected include the bladder (cystitis), prostate gland (prostatitis), the kidney, or the urethra (see Pig. 47-1). These drug s also help control the discomfort associated with irritation of the lower urinary tract mucosa caused by infection, trauma, surgery, and endoscopic procedures. 

Unconscious control involuntary All innervated structures except skeletal muscle (e.g., cardiac and smooth muscles glands)... 

Skeletal muscle, also known as striated muscle because of the microscopic appearance, is responsible for locomotion and those fine, voluntary movements of the body which are under conscious control. Smooth muscle exerts automatic, involuntary... 

There are two classes of movements in the human body voluntary and involuntary. Voluntary movements are pretty clear they are the movements that we can control. Reaching for the French fries, swinging a baseball bat, turning on the TV, and typing at a computer keyboard provide obvious examples. Involuntary movements include those movements that we cannot readily control such as heart beats, vascular contraction, and movement of the gut muscles, and they basically control the internal environment of the body. Voluntary movements are controlled by the somatic nervous system. Involuntary movements are controlled by the autonomic nervous system, to which we now turn. 

The first is transport. The air, with its variable components, requires the inspiratory activity of the respiratory muscles—namely, the diaphragm and intercostals (the muscle between the ribs). The action of these muscles is under both voluntary and involuntary central nervous system control thus, gas flow can be adjusted to maintain a steady state of gas exchange. Air must also be provided to the upper airway for speech. 

The dystonias are involuntary contractions of major muscle groups and are characterized by symptoms such as torticollis, retrocollis, oculogyric crisis, and opisthotonos. Akathisia is a motor restlessness manifested by the urge to move about and/or an inability to sit still. This can be confused with psychotic agitation because patients are driven by a restlessness which is primarily motor and cannot be controlled by their own volition. Unlike psychotic agitation, however, akathisia is... 

In addition to the somatic motor system that operates the voluntary (striated) muscles via the pyramidal tract, there is the autonomic system, which controls the involuntary (smooth) muscles, glands, heartbeat, blood pressure, and body temperature. This system has its origins in both the cerebral cortex and... 

The nervous and endocrine systems control an extensive number of functions in the body. The nervous system is divided into the central nervous system and the peripheral nervous system. The peripheral nervous system is further divided into the somatic nervous system (a voluntary system innervating skeletal muscles) and the autonomic nervous system (an involuntary system innervating smooth muscle, cardiac muscle, and glands). 

The basal ganglia are part of what is referred to as the brain s extrapyra-midal system of motor control, so called to distinguish it from the pyramidal nerve tracts that control voluntary movement. The extrapyra-midal system is most directly associated with involuntary aspects of movement such as muscle tone and posture. However it has extensive connections with other parts of the brain, especially the frontal cortex, the seat of personality and rationality. This functional network... mediates volitional motor activity, saccadic eye movements, emotion, motivation, cognition and social behaviour (Wonodi, Hong, Thaker 2005, p. 340). Thus conditions that effect neurotransmission in the basal ganglia can be expected to have far-reaching functional consequences. 

The efferent somatic nervous system differs from the autonomic system in that a single myelinated motor neuron, originating in the CNS, travels directly to skeletal muscle without the mediation of ganglia. As noted earlier, the somatic nervous system is under voluntary control, whereas the autonomic is an involuntary system. 

Muscles can be divided into two classes, the voluntary or skeletal muscles and the involuntary or smooth muscles. The heart muscle, the myocardium, is a unique type of muscle that does not fit into either category. Skeletal muscles are those that are under voluntary control. The muscles that move the arms, that move the legs when you walk or run, or those that are involved in chewing are all skeletal muscles. They come into play only when you will them. Smooth muscles are those that are not under conscious control. The muscles in the digestive organs are smooth muscles. 

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