1. beginning with all chambers of the heart in the "relaxed" phase, describe the cardiac cycle in mammals, with systole and diastole of the atria and ventricles. for each time point in the cycle you select, state the following: • whether the atria and ventricles are contracting or relaxing • whether the av valves and semilunar valves are closed or open • whether the pressure in the atria and ventricles is high or low



The semilunar valves are the pulmomic and aortic values.
the mitral and tricuspid valves prevent back flow of blood into the atria.

The second one


I think the answer is B.

if it is correct.plz mark as brainliest...

I know it will decrease. The venticles are filling with less blood between beats most likely since the heart is beating faster. (I hope this helps!)


B)the ventricles are contracting and pushing blood out of the heart to the lungs and body

Answer and Explanation:

The cardiac cycle throughout mammals consists of four main different steps of activity:

Isovolumic relaxation: During which the AV valve is locked, the Semi-Lunar valves are closed. One such stage consists of a ventricular contraction.Inflow Stage: And the same for atrial systole, and during that blood going back to the heart circulates via the atria to comfortable ventricles (left or right). AV valve remains located as well as the semi-lunar valve does seem to be inaccessible. The whole stage is known as the ventricular filling venue.Isovolumic contraction: Both the AV valve as well as the Semi-lunar valve remain sealed or disabled. AV Valve decides to close at either the final moment including its ventricular, this same blood circulation slows down the ventricle from contracting.Ventricular Ejection stage: This valve seems to be closed as well as the Semi-lunar valve is accessible. Ventricles or even blood need to circulates from the heart and lungs to the tissues as well as to the surrounding tissue or human body.

A. The atria are contracting and pushing blood into the bottom ventricles of the heart.

mark me brainliyeast

A or B

i think not a 100% sure

1 makes the most sense


There is no way blood pressure will be decreased especially if your ventricles are erratically contracting for a long period of time. So 3 and 4 are out. And you said number 2 is wrong so my finally answer is 1.

Which statement describes the condition of the heart at the point indicated in the electrocardiogram?

The atria are contracting and pushing blood into the bottom ventricles of the heart.


The electrocardiogram is a test that records the electrical activity of the heart. Each beat produces an electrical activity and with an electrocardiograph we can see how that activity is and if there are alterations of the heart rhythm.

The P wave is the first wave of the cardiac cycle. It represents the depolarization of the atria. It is composed of the superposition of the electrical activity of both atria.

Its initial part corresponds to the depolarization of the right atrium and its final part to that of the left atrium.

Do you know the answer?

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