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Depolarization refers to the change in electrical charge across a cell membrane, where the inside becomes less negative. Repolarization is the return to the cell's resting membrane potential after depolarization. These processes are essential for transmitting electrical impulses in nerve and muscle cells.
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Why T wave is in same direction of QRS wave in ECG?
The T wave in an ECG is typically in the same direction as the QRS complex because both represent ventricular depolarization and repolarization, respectively. During the QRS complex, the ventricles depolarize, and then during the T wave, they repolarize, leading to the similar orientation of the waves.
How does threshold change during the relative refractory period?
During the relative refractory period, the threshold for excitation is increased compared to the resting threshold. This is because the membrane potential is closer to its resting state, making it more difficult to depolarize the cell and generate an action potential. It requires a stronger stimulus to overcome this increased threshold and trigger another action potential.
How does the nervous stimulus pass to the motor end plate?
An activated neuron will send an action potential from upper motor neurons to lower motor neurons to effector organs. It is able to propagate the action potential to the motor end plate by release of neurotransmitters, chiefly acetylcholine. On the terminal bouton the action potential opens voltage gated calcium channels. There is an influx of calcium in the pre-synaptic cell and it pushes the vesicles that contain acetylcholine. These vesicles will pass through the synaptic cleft and bind to cholinergic receptors on the post synaptic neuron. Each vesicle has a miniature end plate potential of 0.5mV. In a normal action potential, it will depolarize the post synaptic motor neuron from -85mV to approximately 0-15mV. So that's approximately 180 vesicles.* The influx of neurotransmitters (primarily acetylcholine) will depolarize the motor end plate and propagate the action potential. *Threshold of an action potential is approximately -55mV so technically the minimum required to continue an action potential is around 60 vesicles.
What does the word struck mean?
"Struck" is the past tense of the verb "strike," which can mean to hit, collide with, or make contact with forcefully. It can also mean to be affected by a particular situation or emotion.
What is the significance of Mean square distance?
Mean square distance is a statistical measure that provides information about the dispersion of data points from the mean. It is commonly used in various fields such as physics, engineering, and finance to quantify the variability of a dataset. A smaller mean square distance indicates that data points are closer to the mean, while a larger mean square distance suggests more variability in the data.
What is the correct order that information passes through in a neuron?
The flow of information across nerve cells is called a nerve impulse in which the axons of the cell must depolarize, repolarize and go through a refractory period before reaching the resting potential. At this point, another impulse can occur.
The stage of the heart cycle in which the heart muscle contacts and the chambers pump blood?
The sinoatrial node depolarizes the atria and causes them to contract which tops up the ventricles with blood, the signal then moves through the atrioventricular node and then the atrioventricular bundle and into the purkinje fibres which causes the ventricles to depolarize and contract sending blood from the right ventricle to the lungs and from the left ventricle. The Atria repolarizes at the same time as the ventricles depolarize and then a fraction of a second later the ventricles repolarize and the cycle begins again.
Why T wave is in same direction of QRS wave in ECG?
The T wave in an ECG is typically in the same direction as the QRS complex because both represent ventricular depolarization and repolarization, respectively. During the QRS complex, the ventricles depolarize, and then during the T wave, they repolarize, leading to the similar orientation of the waves.
What chemicals enter and leave the axon at the Nodes of Ranvier?
Sodium and potassium ions enter and leave the axon at the nodes of Ranvier. Sodium ions enter the axon to depolarize the cell, while potassium ions leave the axon to repolarize the cell and reset its resting potential.
When does a QRS complex occurs?
When ventricles depolarize
What do node cells of the heart depolarize?
purkinje fibers
The ventricles should depolarize in?
less than 0.08 seconds
Is the left ventricle the first to depolarize?
No, the right ventricle is first to depolarize, that is if you're talking about ventricular depolarization (the QRS complex). If not, then it's the right atrium (atrial depolarization, P wave).
Does calcium depolarize or hyperpolarize cell membranes?
Calcium depolarizes cell membranes.
What happens to the size of an action potential as it continues down the axon?
I belive the size of the axon potential remains constant at a depolarisation of +40 mv and a resting potential of -70mv for most nerves. The frenquency of action potentials is the factor that determines the strength of the nerve impulse.
What causes the ability of cardiac cells to spontaneously depolarize without being stimulated by a nerve?
Automaticity
Which cells cause resting membrane potentials to continually depolarize?
Cells with unstable resting membrane potentials, such as pacemaker cells in the heart or neurons in the brain, can continually depolarize due to the presence of a "funny" current (If) that slowly depolarizes the cell until it reaches the threshold for an action potential to be generated.
