Explanation: there are two processes that takes place in cardiac cycle. These procesesss comprises of complete relaxation and contraction of both the atria and ventricles which usually last for about 0.8 seconds. Starting with the chambers in the diastole, blood flows passively from the veins into the atria and past the atrioventicular valves into the ventricles. Contraction begins in the atria following the depolarization of the atria and blood is pumped into the ventricles. The ventricles begins contraction by raising pressure within the ventricles.
A. depolarization of the atria and pump blood into the ventricles.
Explanation:
Contraction of atria is also called atrial systole which is responsible for the pumping of blood into the ventricles. The blood moves from the atria into the ventricles, opening the atrioventricular valves and completed one heart cycle. Contraction of ventricle is known as ventricle systole. During contraction of ventricle, blood is transported to two regions, one is the lung for cleaning and other is all parts of the body.
First, the yellow fever virus is phagocytosed by white blood cells. The phagocytosed white blood cell then travel through the lymph vessel. Since lymph node contain white blood and filter lymph, the yellow fever phagocytosed with white blood cell establish in the lymph node.
Rigid skeletons are formed from materials including chitin (in arthropods), calcium compounds such as calcium carbonate (in stony corals and mollusks) and silicate (for diatoms and radiolarians).
