PHASE0(RAPID DEPOLARIZATION)
due to opening of fast voltage gated sodium channels
PHASE1(INITIAL REPOLARIZATION)
due to closure of sodium channels while loss of potassium is goingon ,making the cell polarized.
PHASE2(PLATEAU)
due to opening of calcium channels. influx of calcium neutralizes the effect of out going potassium so prolonged plateau is achieved.
PHASE3(FINAL RE POLARIZATION)
due to closure of calcium channels and continue loss of potassium makes the inside of cell more negative resulting in polarization.
PHASE4(RMP)
eventually cell returns to resting membrane potential due to K efflux and cell is ready for next cycle
Cardiac Cycle
The diastolic phase of the cardiac cycle shortens the most in response to tachycardia. This includes the time spent in ventricular filling (diastasis) and atrial contraction (atrial systole), as these phases are compressed to accommodate the faster heart rate.
Diastole is the relaxation phase. Systole is the contraction phase. If you put these phases together you have the Cardiac Cycle...
The concentration of sodium (Na⁺) and potassium (K⁺) ions significantly influences resting membrane potentials and their hyperpolarization/depolarization phases. An increase in extracellular Na⁺ can lead to depolarization, as more Na⁺ enters the cell when sodium channels open, making the interior more positive. Conversely, higher intracellular K⁺ concentrations promote hyperpolarization when K⁺ channels open, allowing K⁺ to exit the cell and making the interior more negative. Thus, the balance of these ion concentrations is crucial for maintaining the resting membrane potential and regulating excitability in neurons and muscle cells.
we get different phases of the moon
The period of time between the beginning of one heartbeat and the start of the next is known as the cardiac cycle. It consists of two phases: systole (contraction of the heart muscles) and diastole (relaxation of the heart muscles).
The four phases of the cardiac cycle are diastole, isovolumetric contraction, systole, and isovolumetric relaxation. During diastole, the heart muscles relax and the chambers fill with blood. In isovolumetric contraction, the heart muscles contract but the chambers do not change volume. Systole is when the chambers contract and blood is ejected. Finally, isovolumetric relaxation is when the heart relaxes but the chambers do not change volume.
The phases are: 1) Warm-Up, 2) Conditioning, and 3) Cool Down. This can be found in more detail at the Clevend Clinics' Cardiac Rehab exercise page. Hope this helps you...Regards, Ray Siegel, MCP,LP
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Complete tetani
Mid-to-late diastole, ventricular systole and early diastole