no, the muscle does not begin to contract the instant it is stimulated, rather a fraction of a second later!
muscle fibers contract the muscles when stimulated.
cardiac muscle tissue
Repolarization
When a muscle is stimulated not all motor units in the nerve are fired. More muscle fibers are stimulated, however and smaller nerves are stimulated before larger ones.
You call it as cardiac muscles. The muscle fibers contract rhythmically. The muscle fibers are attached to each other end to end. This facilitates the conduction of the impulse. The muscle fiber can be stimulated to give you contraction of the the same.
Cardiac muscle. Unlike skeletal and smooth muscle, the contraction of cardiac muscle is involuntary and requires stimulation from the nervous system. This ensures that the contractions of the heart are synchronized and coordinated.
smooth muscle
Yes! Although we have total control over these muscles, they still need stimulation to contract. The difference with muscles that we don't control is that we decide if we want to make this stimulation.
Generally, voluntary muscles are striated and skeletal muscles, while involuntary muscles are smooth muscles and are visceral (located in organs). Voluntary muscles are muscles that can be consciously contracted, while involuntary muscles are muscles that are contracted at certain times or at all times without the conscious consent of the brain.
When the eye is stimulated by bright light, the circular muscle of the iris contracts, decreasing the size of the pupil.
Here you have a special kind of muscle called as cardiac muscles. Cardiac muscle has got fallowing properties. They are automaticity, excitability, conductivity, contractility, rhythmicity, and refractoriness. That means it contracts. It contracts rhythmically. It contracts automatically of it's own. It can be stimulated. It conducts the impulse across the length. Once it contracts, it will not contract for some time again. These properties have many implications. The different types of heart cells contract at different pace. The cells from SA node contract at the rate of about 76 per minute. That of AV node contract at the speed of about 60 per minute. The cells of atrium contract with the speed of in between the both types of cells. The cells of ventricle contract at the speed of about 36 per minute. So the final rate of contraction of the heart is decided by SA node. it is called as pace maker. The impulse has to be conducted across the heart in synchronized manner. For that the heart muscle is designed to conduct the electrical impulse. Once stimulated, the muscle fiber takes some rest. That is needed so that the muscle can function non-stop for years together. The property of excitability is needed so that the muscle can be stimulated by a stimulus.
the Z lines abut against the thick filaments and cannot go any further