The action potentials of smooth muscles are unique in that the membrane potential initiates or modulates contraction. Therefore, a graduated membrane response can be stimulated by several factors, including local humoral factors, circulating hormones, or mechanical stimulation such as cell stretching. Action potentials in smooth muscle cells are slower than skeletal action potentials and can last nearly fifty times longer. This property seems to occur because the calcium channels in smooth muscle cells open more slowly than skeletal muscle, resulting in slow repolarization of smooth muscle, as potassium channels also react slowly. Sodium channels can also be present on the membrane and smooth muscle function by increasing the rate of depolarization and thus helping in the activation of calcium channels. When an event changes the permeability of the membrane for Na+ ions, they enter the cell. It changes the tension. This is an electrical event called action potential that can be used as a cellular signal. Communication between nerves and muscles is via neurotransmitters. The action potentials of neurons cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can then diffuse through the synaptic cleft and bind to a receptor molecule on the motor end plate. The end plate of the motor has connecting folds – folds in the sarcolemma that create a large area for the neurotransmitter to bind to the receptors. Receptors are actually sodium channels that open to allow Na+ to pass into the cell when they receive a neurotransmitter signal. 1.

Why can smooth muscle contract over a wider range of rest periods than skeletal and cardiac muscles? In the genital system, smooth muscles are often at the center of their role in childbirth. Smooth muscles line the uterus, which creates contractile strength during childbirth. Many medications exist specifically to improve smooth muscle contraction at the time of birth. Although this may not be an actual pathology, it is important to realize that doctors can use knowledge of the physiology of smooth muscles to prevent the appearance of pathologies. In men, fertility is also a function of smooth muscle contractions in the epididymis and vas deferens. Without the contractile nature of smooth muscle, sperm would never be able to aid in fertilization; This becomes important due to the obvious lack of information about the possible pathological effects of smooth muscle and infertility. For example, many drugs commonly used by men affect the contractility of smooth muscles and therefore can also affect fertility. Examples include nonsteroidal anti-inflammatory drugs, phosphodiesterase inhibitors (PDEs), nitrates, adrenergic receptor antagonists and agonists, psychotropic drugs, anticholinergics, calcium antagonists, and ace inhibitors. [13] Another important clinical aspect of smooth muscle relaxation is the nitric oxide mechanism.

Nitric oxide is formed by nitric oxide synthase in endothelial cells; It is then able to diffuse endothelium into smooth muscle cells. Nitric oxide then induces the conversion of guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP) by binding and activating the enzyme guanylyl cyclase. In smooth muscle cells, increased cGMP leads to stimulation of cGMP-dependent protein kinase, which in turn activates MLCP, resulting in the dephosphorylation of myosin light chains and eventually smooth muscle relaxation. From a functional point of view, the physiology of smooth muscles is responsible for maintaining and maintaining every vital sign. Whether a patient has an emerging acute disease or a chronic disease, it is likely that smooth muscle played a role in their development. In an acute environment, many life-saving therapies are aimed directly at smooth muscles. In these situations, a solid foundation and understanding of smooth muscle helps healthcare professionals save lives. An even broader understanding of smooth muscle will help clinicians improve the quality of life of their patients. As part of the biopsychosocial model, it is also important to take into account psychosocial factors that can be overlooked in smooth muscle diseases; For example, a patient diagnosed with neurogenic bladder disease may be socially isolated to avoid the embarrassment associated with their medical condition. As smooth muscle dysfunction approaches, healthcare providers need to appreciate the many facets of how the disease will affect their patients.

Excitation-contraction coupling is the link (transduction) between the action potential generated in the sarkolemma and the onset of muscle contraction. The trigger for the release of calcium from the sarcoplasmic reticulum into the sarcoplasm is a neural signal. .