Select the correct statement about blood flow. A) It is relatively constant through all body organs. B) It is measured in mm Hg. C) It is greatest where resistance is highest. D) Blood flow through the entire vascular system is proportional to cardiac output.

The correct option is (D). The value of cardiac output in the case of the human heart is approx. 5 liters in a minute. The multiplication product of heart rate and stroke volume gives the cardiac output.  

Explanation:

The blood flow serves as the parameter for the calculation of cardiac output. For the restoration of homeostasis, increase or decrease in the cardiac output leads to the simultaneous increase and decrease in the blood flow and pressure respectively. Also, the reduction of cardiac output and venous return signifies the higher value of the tidal volume. The associated parameters namely stroke volume and  heart rate is also affected by certain factors. Some of them includes age, gender, contractility, heart size and duration of contraction.  

Besides the flow of blood in the body depends on the oxygen requirement of the target cell.

Very necessary for its survival.

Explanation:

Movement of molecules is very important to maintain a healthy cell environment because some molecules are required by the cell for its growth and development. Some molecules moves inside the cell environment through a semi-permeable membrane such as glucose, oxygen, potassium etc while on the other hand, some molecules are removed from the cell which are waste materials such as carbondioxide etc. If these waste materials are not removed from the cell, it greatly damaged the cell.