How Parallel Circuits Work in the Body: The Cardiovascular System Requires Low Resistance

The principles of series and parallel circuits are usually taught in highschool or first year university physics courses and are explained by using electrical circuit boards. However, these principles overlap into all disciplines and also apply to the study or anatomy and physiology. In medicine, these concepts are very important in understanding the general aspects of the cardiovascular system.

Blood pressure and blood flow in the body is maintained at a healthy level by the body with the help of the type of circuit the organs are connected on. During birth this principle is very important as it enables the baby to be able to breathe on its own and pump oxygenated blood throughout its systemic (body and organs) and pulmonary (lungs) system.

What is a Series Circuit?

A series circuit involves resistors connected one after the other in a straight line. A resistor is anything that changes or hinders the flow of electrical current or whatever else is flowing through the system. In the case of the body, the resistors are organs such as the heart, brain, liver and kidneys and the ‘current’ is the flow of blood. Therefore the resistance in the body system would be blood pressure in the circulatory system (the arteries and veins).

When a row of resistors is connected in series, flow is equal at all points in the system. If the flow is changed anywhere in the system, it changes equally at all points in a series system. Hence the total resistance of a series system is the sum of all the individual resistances and the total is always greater than any single resistance. This means that adding a resistor in series will increase the total resistance and a series system is high resistance or pressure.

The Cardiovascular System is Connected on a Parallel Circuit

In the human body the systemic or body organs are connected in a parallel circuit. This includes the cerebral,coronary (heart), cutaneous (skin), and renal (kidney) systems. When resistors (the organs in the case of the human body) are connected in parallel, the resistance of the total system is the sum of the reciprocals of the individual resistances.

Hence, connecting organs in a parallel system results in a low level of resistance and the total level of resistance is always less than the resistance at any one organ. If a resistance is added to the system in parallel, this lowers the resistance of the system. Additionally, when structures are connected in parallel, flows can be independently regulated. This allows the body to maintain a balanced blood pressure, though the pressure at or within some organs is higher.

If a parallel resistor is removed from the systemic circuit , total resistance is increased and this increases blood pressure. Some women face sweat problem and they instantly get Sweat Treatment while pregnancy.

A Parallel Circuit Increases the Arterial Pressure of a Newborn Baby, Allowing it to Breathe, Pump Blood

A real life example of this the physics principle of circuit occurs at birth. In the womb, fifty five percent of the fetal cardiac output is delivered to the baby via the placenta, as the mother’s cardiovascular system provides nourishment and oxygen. At birth the baby is separated from this placental circulation. This results in a loss of a parallel resistor in the baby’s cardiovascular system and resistance is increased, raising the blood pressure of the baby.

The subsequent rise in aortic blood pressure helps to reverse the flow of blood in the ductus arteriosus, which leads to a large increase in the left arterial pressure which is necessary to close the foramen ovale (an opening between the right and left portions of a fetus’ heart). The foramen ovale allows the fetus’ blood flow to bypass its own lungs as it is not yet breathing on its own. At birth, the rise in pressure as well as the expansion of the lungs as baby takes its first breath, helps to change the flow of blood in the heart as the baby’s lungs begin supplying oxygen to its blood.