Atrial depolarization is the first part of the cardiac cycle.
Cardiac (and skeletal) muscle is made up of bundled stands of functional units called sarcomeres. Each sarcomere consists of two Z-disks, which mark the ends of each sarcomere, and alternating dark and light bands called A-bands and I-bands respectively. The I-band contains only actin (the main cytoskeletal protein in most cells) filaments whereas the A-band contains overlapping myosin (a "molecular motor" protein) and actin filaments in its periphery and only myosin filaments in the central region called the H-zone. The center of the H-zone is marked by an imaginary line (called the M-line) in which myosin extends in both directions. The sarcomere contracts inward toward the M-line. "Depolarization" occurs when an electrochemical event causes calcium cations to be released from a membranous network (similar to the the endoplasmic reticulum) called the sarcoplasmic reticulum and creates an action potential. The free Ca2+ binds to a specific troponin protein shifting a troponin/tropomyosin protein complex allowing the myosin head groups to bind to the actin filament. ATP hydrolysis causes conformational changes of the myosin filament which in effect "pulls" the actin filament toward the M-line of the sarcomere. The sarcomere can return to its resting potential by allowing potassium (K+) ions to flow out.
A P wave reflects atrial depolarization.
The electrical milestone event that occurs at the P wave of the cardiac cycle of the EKG is atrial depolarization. The upward stroke is right atrial depolarization, and the downward stroke is left atrial depolarization. Normally, this lasts for no more than 0.11 sec.
It is on page 374 of your lab book assuming this is the same question that came out Lab 28 in the Ninth Edition of Seeley's Anatomy & Physiology. The atrial repolarization occurs during ventricualr depolarization and is masked by the larger QRS complex. I actually did my homework :)
Depolarization stimulates the release of the neuro-transmitter from the terminal end of the neuron.
Sodium ions cause depolarization and potassium ions cause repolarization.
No it does not. Atrial repolarization is generally not visible on the telemetry strip because it happens at the same time as ventricular depolarization (QRS complex). The P wave represents atrial DEpolarization (and atrial systole). Atrial repolarization happens during atrial diastole (and ventricular systole).
The portion of the ECG that corresponds to atrial depolarization is called the P wave. The P wave is the first wave on the ECG.
Atrial Depolarization.
The atrial repolarization occurs during the QRS complex of the ECG but is obscured by the ventricle depolarization.
Atrial depolarization occurs at the P wave. The atrial contraction occurs at the peak of the wave at the influx of calcium ions to prolong depolarization.
The P wave.
A P wave reflects atrial depolarization.
Qrs complex
depolarization of atrial muscle fibers
On the EKG readout the P Wave represents atrial depolarization. For a healthy person it should be smooth, round and upright, and preceding the QRS complex.
An Electrocardiogram of a single heart beat shows three distinct waves. These are the P, QRS and T Waves. The QRS wave (normally the largest spike) in the electrocardiogram, is that of the ventricles depolarizing and contracting.
Atrial Flutter is characterized by rapid depolarization of a single atrial focus at a rate of 250-350 BMP