Frequency of heart Pulsation,dependence of diastolic pressure on G-load,simulate and obtain by 1D blood flow model

1.    Frequency of heart pulsation, systolic and diastolic pressure

Frequency of heart pulsation:

The heart is an organic tissue and plays a vital role in life. It's size about the first of the average adult and weight 11 ounces (310 grams). The sympathetic and parasympathetic system control the speed of heart beat. Sympathetic system speed up the heart beat but pare sympathetic slow it down the whole system known as the autonomic nervous system. Frequency is defined as the continuously recurring process that occurs in 1 sec. We want to calculate the frequency of heart beats so the total number of the heart beat in 1 minute divided by 60 sec finally the frequency is obtained in hertz. After a research, the approximately 70 Hz frequency calculated for a normal human.

Systolic Blood Pressure

Due to contracts of the heart the blood in the heart push through the arteries. The heart beat generates pressure on the arteries this phenomenon is known as systolic pressure. The ideal systolic blood pressure is about 120 mmHg or below. Increasing the pressure like 120-139 mmHg range are the borderline of higher pressure and have more chances of heart diseases. When the systolic bold pressure is 140 or greater after average calculation then you have hypertension.

Diastolic blood Pressure

When the heart rests the amount of pressure or force which is exerted on the arteries between the beats is well known is diastolic. The ideal diastolic blood pressure is 80 or minimum less than 80 but if the diastolic blood pressure about 80 to 89 is considered to be normal but greater than ideal and if the diastolic blood pressure is greater than 90 then you have hypertension.

2.    The dependence of diastolic pressure on G-load

The term G is the calculation of mechanical force on the body with respect to the gravitational force exerted on the body on the surface of the earth. We calculate the G by “a/g” which is the ratio of applied acceleration and the amount of acceleration produced by the gravity effect. On the surface of earth a=g so the human body is subject as 1 G.

According to the definition of weightless stated that when an object put under the gravitational forces and not effected by the external forces is weightless. When a body in weightlessness mean a very few amount of mechanical force is exerted on it. There are three properties when the body in the weightless which is stated below

1 The only external force present is the force of gravity.

2 This is uniform throughout the entire system.

3 The system is free of internal gravity.

Diastolic pressure on G-load diastolic blood pressure of arterial and heart beat decreased but the systolic and arterial pressure not decreased. The amount of decrease blood pressure shown in the figure about 5 mmHg

3.    The dependence of diastolic and systolic pressure on G-load in human extremities.

The first research since 1996 conducted about the ambulatory brachial blood pressure monitoring in 24 h in space by Fritsch-Yelle et al to observe the behavior of the blood pressure in the (5-10days) shuttle mission the body would be weightlessness. His observation calculation was that the diastolic blood pressure of arterial and heart beat decreased but the systolic and arterial pressure not decreased. The amount of decrease blood pressure shown in the figure about 5 mmHg

4.    What physiological consequence of G-loading can we simulate and obtain by 1D blood flow model?

The shape of the human body is elongate and human body consist of bipeds so the flow of blood in horizontal laying position is pronounced in the upper half that’s  why the G-force which is effected on the body is explained according to the body human anatomy. The direction of G forces is opposite to the applied mechanical forces due to this reason the G forces follow the inertial movement direction and indicate the direction we use algebraic sings with gravitational forces denoted by G.(+Gz) indicate head to foot or (-Gz) foot to head,(+Gx) front to back (-Gx) back to front, (+Gy) right to left or (-Gy)left to right displacement. There are two simulation models which used widely for the weightlessness on human physiology like head-out water immersion and head down bed rest 6 º. The water immersion model used for short time simulation few hours per day but as well as the head down bed rest model used for simulation of several months. In the water immersion model water level up to the neck of the subjected which is seated upright position. The head down bed rest model is used to terminate the blood or fluid at the upper part of fluid.

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5.     1D or 0D simulation (or any simulation at all) of blood flow under G-load

The 0D model used to measure the hemodynamics in the circulation system. In this model, the main idea of hydraulics analog is used. The flow of blood are similar to the flow of current but the difference is blood flow in the circulatory system and current flow in the circuit. All the friction loss explain completely hydraulic impedance and also vessel wall elasticity, the inertia of blood flow. Mass conservation equation completely explain the blood flow

Zero-dimensional model used simultaneous differential equations to explain the vasculature. There is 2 equation to explain a single part, conservation of mass and conservation of momentum. The valuable part of the system like that heart valves, different parts of the vasculature which are perfect for investigating the global distribution pressure, blood volume exceeded by the range of physiological conditions and flow and also consist the theory of interaction between the component of system model formed by the 0D components.