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A muscle is stimulated and exhibits a contraction twitch Before this twitch is over it is stimulated again and a second twitch occurs piggyback on the first one and causes a higher contraction?
summation
What muscle that makes up the heart?
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.
Can the heart tetanize?
The cardiac muscle fiber absolute refractory is a long period of time (longer then skeletal muscles), so you cannot tetanize cardiac muscle fibers because it has to relax before it is able to contract again.
How long is absolute refractory period for skeletal muscles?
The absolute refractory period for skeletal muscles is about 1 to 2 milliseconds. During this time, the muscle fiber is unable to respond to a new stimulus, no matter how strong it is. This period ensures the muscle has enough time to recover before being stimulated again.
What is a refactory period?
Refractory period is the period after a stimulus is given when something needs to recover in a resting state before it can respond to stimulus again. It is a term used in both physiology and psychology.
Can an axon be stimulated during the refractory period?
No, the axon cannot be stimulated during the refractory period. This period is where the axon is temporarily unable to generate another action potential, ensuring that nerve impulses travel in one direction and allowing the neuron to recover before firing again.
What is post-systolic potentiation?
Because the PVC (premature ventricular contraction) comes early, there is more time before the next beat, meaning that there is more time for the heart to fill. Because of more filling, there is more initial tension on the cardiac muscle, eliciting a stronger contraction from the heart. Also, the PVC is a weak contraction, so the heart does not fully empty, and there is more residual blood in the heart even before it starts filling again.
Why does our muscles became bigger when we are lifting heavy objects?
As you lift weights, your muscle's fibers are being ripped apart. After that, the muscle grows in order to be "normal" again and not ripped apart, making it bigger.
Does one should push ups everyday?
No, you should rest your muscle for AT LEAST 24 hours before exercising it again.
What muscle in the lungs which contract and releases changing the volume of the lungs?
I believe that answer is the diaphragm. As the diaphragm moves up and down, it expands the lungs, and when the diaphragm goes up, the lungs release the air out again.
Can the front part of the brain be stimulated to get it active again?
If the frontal area is death, you can stimulate it but will not get any response.
What is maximal tetanic tension?
When a muscle is applying a little bit of force, action potentials are triggering twitches in the muscle fibers. A skeletal muscle has many many muscle fibers, and a single fiber (cell) is either contracted or relaxed, it cannot get stronger or apply a fraction of its force. A muscle fiber and its connected neuron are called a motor unit When a muscle is applying a lot of force it is sending many action potentials at once, such that most of the fibers in a muscle are contracting at once. This effect is called motor unit recruitment When a muscle is "maxing out," it is sending waves of many action potentials in rapid succession, such that the whole muscle is stimulated again while the stimulated cells are still in the relaxing phase. This has the effect of not only reactivating the fibers in the relaxing phase, but also engaging more of the few cells that were left so that more total fibers contract. When the signals are received in rapid enough succession the total force of the muscle will eventually plateau. This is called unfused tetanus. If applied at an even greater frequency the fibers that are activated will stay activated so that no lag is seen between single fiber twitches. It is at this point that the fibers are all fused and the muscle has reached maximum tetanic tension (This can occur as an effect in patients with tetanus, hence the name)
