Control of muscle activity

Fig. 9.20. Muscular actuators in feedback systems. Control of muscle activity via...

Veraart C., Grill W.M., and Mortimer J.T. Selective control of muscle activation with a multipolar nerve cuff electrode. IEEE Trans. Biomed. Eng. 37 688-698,1990. 

Hormones have a profound effect on carbohydrate metabolism. Great interest has been aroused by reports of hormonal control of hexokinase activity by specific proteins in animal tissues.99- 100 Hexokinase action is the rate-limiting step in the uptake of D-glucose by muscle. Hexokinase is inhibited in diabetic muscle, but the inhibition can be partially reversed by insulin. A protein fraction from the anterior pituitary gland will inhibit the hexokinase of extracts of brain and muscle, and the effect of this... 

Neural control of the activity of phosphorylase kinase. The electrical stimulation of muscle is mediated by the release of Ca2+ ions. These ions also... 

It is believed that fine cytoplasmic arms connect the nuclei-containing portion of the myocytons with the contractile components such that many parenchymal cells are in fact myocytons (Lumsden and Hildreth, 1983). Also, some cytoplasmic arms are believed to form multiple neuromuscular junctions that provide for neuronal control/modulation of muscle activity. Limited information is available on the functional relationship of trematode nerve and muscle although the situation in ces-todes has been described as polyneuronal and polyterminal in that each neuron can form synapse-like contacts with multiple myocytons and each myocyton can synapse with several neurons (Webb, 1987). Morphologically atypical synapses and paracrine release sites have been described in the relationship between muscle and nerve in flatworms details on the role they play are not available, although they are believed to facilitate nerve-muscle communication. 

The control of the activity of the respiratory muscles the process by which a pattern of activation (tidal volume, frequency of breathing) of the respiratory muscles is selected in which the average expenditure of energy is kept at a minimum for any level of ventilation demanded. 

Tliese developments will provide amputees and patients with a variety of motor disorders such as paralysis, amyotropic lateral sclerosis with the means to act and communicate by replacing tlie control of muscles with the control of artificial devices by brain activity. 

In our work, the tip of a catheter is equipped with an IPMC artificial muscle as a stirrer. A schematic of an attached IPMC stirrer to the tip of a catheter is depicted in Fig. 2.4. Bi-directional bending of the catheter, along with the manual twisting motion of the wire, enables 3D orientation control of the active catheter. Successful actuation is achieved in a fluidic environment as shown in Fig. 2.5. The tip of the actuator is easily bent about 90°, which is sufficient to maneuver through the endovascular branches. 

The muscle activity and the EMG signal associated may vary according to the number of Motor Units (MU) recruited and their activation frequency. A MU is the smallest functional unit, which describes the neural control of muscle contraction. During voluntary muscle contraction, two independent parameters modulates the force applied the first one represents the number of recruited MUs and the second one is MU activation frequency. Considering an experiment, which involves the same muscle activity and the same applied force, is unlikely to observe the same pattern signal. The main parameters that influences EMG signals are ... 

F. Meyer, L. M. Heilmeyer, Jr., R. H. Haschke, E. H. Fischer, Control of phosphorylase activity in a muscle glycogen particle. I. Isolation and characterization of the protein-glycogen complex J. Biol Chem. 245 1970, 6642-8. 

The posterior lobe of the pituitary, ie, the neurohypophysis, is under direct nervous control (1), unlike most other endocrine organs. The hormones stored in this gland are formed in hypothalamic nerve cells but pass through nerve stalks into the posterior pituitary. As early as 1895 it was found that pituitrin [50-57-7] an extract of the posterior lobe, raises blood pressure when injected (2), and that Pitocin [50-56-6] (Parke-Davis) causes contractions of smooth muscle, especially in the utems (3). Isolation of the active materials involved in these extracts is the result of work from several laboratories. Several highly active posterior pituitary extracts have been discovered (4), and it has been deterrnined that their biological activities result from peptide hormones, ie, low molecular weight substances not covalendy linked to proteins (qv) (5). 

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