0
What else can I help you with?
When a single neuron sends a strong enough impulse to a muscle that how many muscle fibers does it cause to contract?
When a single neuron sends a strong enough impulse to a muscle, it can cause multiple muscle fibers within that muscle to contract. The specific number of muscle fibers that contract will depend on factors like the size of the motor unit and the intensity of the signal from the neuron.
How does the impulse to contract slow down slightly before it is transferred into the ventricles?
junctional fibers leading into the AV node have very small diameters
What law states that muscle fiber cannot partially contract?
The all-or-none law states that muscle fibers cannot partially contract; instead, they either fully contract or remain relaxed. When a muscle fiber is stimulated by a nerve impulse that reaches a certain threshold, it will contract maximally. This law applies to individual muscle fibers, while whole muscles can exhibit varying degrees of contraction through the recruitment of multiple fibers.
What are junctional fibers?
On the Net, you can find different things being said about the cardiac "junctional fibers". I am going to offer what I understand makes the most sense. The junctional fibers are cardiac muscle cells which are specialized for slowing down the cardiac impulse just before it goes into the atrioventricular node. This delay gives the atria time to empty their blood into the ventricles before the cardiac impulse goes on to stimulate the ventricles to contract. Notes: (1) These junctional fibers are not nerve cells, but are muscle cells which are specialized for conducting the cardiac impulse. You may know how more-narrow nerve axons are slower at passing on an action potential, while wider axons can pass on an action potential faster. Well, these junctional fibers are like nerve fibers, in this way > because these junctional fibers are very narrow, they can slow down the cardiac impulse. (2) So, where do you think these narrow junctional fibers need to be, in order to slow down the cardiac impulse at the right place and time? If the cardiac impulse were to go from the atria right on to to the ventricles, then the ventricles would be stimulated to contract while the atria were still trying to empty blood into the ventricles. And so, the ventricular blood pressure would be pushing back against the blood that was trying to get from the atria into the ventricles. This would not be good. So . . . the heart needs to slow that impulse, just after it leaves the atria . . . slowing it long enough so the ventricles stay relaxed while they receive blood from the atria. (3) And, lo and behold . . . the junctional fibers are located right after the atria; and they receive the impulse which comes from the atrial muscles; then it delays the impulse before letting it go into the atrioventricular node. This slow-down gives the atrial muscles just enough time to finish contracting before the atrioventricular node sends on the cardiac impulse to stimulate the ventricles to contract. (4) You might notice on an EKG how there is the P wave showing atrial depolarization. Then the line goes flat for a little bit before the QRS complex. At the beginning of that flat time at the end of the atrial depolarization, this is where the junctional fibers are slowing down the cardiac impulse before it shows as the QRS which shows the impulse being fired by the atrioventricular node to the ventricles, I understand.
What kind of muscle makes your heart?
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.
How is the cardiac impulse transmitted from the right atrium to the other heart chambers?
The electrical impulse in the heart begins in the sinoatrial (SA) node and travels across the walls of the right atrium to the atrioventricular (AV) node. WHie the impulse travels the atria have time to contract. Once the impulse hits the AV node the signal is transmitted to the Bundle of His (AV bundle) and then on the the intraventricular fibers (purkinje fibers) in the septum and the outer chamber walls of the heart . This results in a simultaneous ventricular contraction.
Which of the following types of nerve fiber possesses the fastest speed of impulse propagation?
Myelinated A fibers have the fastest speed of impulse propagation among nerve fibers.
Does Electricity causes your muscles to contract?
Yes, electricity can cause your muscles to contract. This occurs because muscle contractions are triggered by electrical signals from the nervous system, which stimulate muscle fibers. When an electrical impulse reaches a muscle, it leads to the release of calcium ions, allowing the muscle fibers to contract. This principle is also utilized in medical therapies and devices, such as electrical stimulation for muscle rehabilitation.
What is the point in the purkinje system where the impulse is temporarily delayed?
The point in the Purkinje system where the impulse is temporarily delayed is at the atrioventricular (AV) node. This delay allows the atria to fully contract and pump blood into the ventricles before the impulse is transmitted to the ventricles, ensuring efficient blood flow through the heart.
What happens after the SA node stimulates the atria to contract in the heart cycle?
After the SA node stimulates the atria to contract, the electrical impulse travels to the atrioventricular (AV) node, where it is briefly delayed. This delay allows the atria to fully contract and push blood into the ventricles. Following this, the impulse proceeds down the bundle of His and into the Purkinje fibers, causing the ventricles to contract and pump blood to the lungs and the rest of the body. This sequence ensures coordinated heartbeats and efficient blood flow.
If enough muscle fibers contract to make the muscle as a whole shorten in length the muscle is said to exhibit contractions?
concentric
What fibers in the heart cause the ventricles to contract?
pukinje fibers
