Question

Arteries are thick walled, because
A. They are without valves
B. They have to pump blood
C. The blood flows with jerks in them
D. They have oxygenated blood

Answer 1

Hint: Outer tunica adventitia, middle tunica media and inner tunica intima are the part of veins and arteries that are made up of three layers. The blood flows with jerks in the arteries because of thick walls and carry much higher blood pressure.

Complete answer:
In the systole there are two events occurring diastole and systole representative during the left and right ventricle contract and ejecting blood into the pulmonary artery and aorta. During the process occurred in the systole the pulmonary valves and aortic Valve opens to permit ejection into the pulmonary and aorta artery. During the systole atrioventricular valves are closed and no blood enters the ventricles but the process of entering the continuous blood into the atria through the vena. It is also called atrial systole and cardiac cycle is initiated by auricular systole and duration of the auricular systole is 0.1 second.
One beat is repeated in the same order in the next beat during the change that occurred in the heart. And cyclic repetition during this process is known as cardiac cycle and the normal human heart rate is 0.8 second per minute. Diastole and systole are the two cycles of the cardiac activity.

Therefore the correct option is (C).

Note: Aortic and pulmonic valves open and permit ejection into the pulmonary artery and aorta during the systole process. But during systole no blood enters the ventricles and continues into the pulmonary veins, cavae and vena because of that atrioventricular valves are closed.