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Human Heart

Heart Diagram
Human Heart Drawing

by Vaughn Aubuchon

Here is a brief simplified drawing of the human heart, showing arterial and venous blood circulation, and the relationship between the heart and the lungs.


This is a simplified, two-dimensional Human Heart Diagram, including the surrounding cardiovascular system.
The illustration shows the four heart chambers and the four heart valves, in addition to the electrical activity of the heart. Blood flow throughout the body is summarized.



Human Heart Diagram
Human Heart Mechanical Diagram


RED = Oxygenated blood from the lungs.
BLUE = Oxygen depleted blood arriving from the body.
The relationship between the heart and lungs is shown.
The relationship between venules, arterioles and capillaries is shown.



Heart Valves
The tricuspid and mitral valves open and close simultaneously - the pulmonic and aortic valves close and open simultaneously.

Systole (contraction) = When the Tricuspid Valve and the Mitral Valve are closed, and the Pulmonic Valve and Aortic Valve are open (systolic pressure).

Diastole (relaxation) = When the Tricuspid Valve and the Mitral Valve are open, and the Pulmonic Valve and Aortic Valve are closed (diastolic pressure).


Heart Strength
Ejection fraction represents the ability of the left ventricle to pump blood. An ejection fraction of >55% is considered normal. If the right ventricle fails, blood pools in systemic circulation, leading to fluid buildup in parts of body most affected by gravity, usually feet and lower legs. A weak left ventricle can result in systolic failure. For more information on BP, visit my Blood Pressure Range page. I was not able to find a simplified heart and blood circulation drawing on the web, so I made this page.

Heart Electrical Activity
Electrical activity of the heart is regulated by the Sinus node, the AV Node, the bundle of His, the right and left bundle branches, and finally the Purkinje Fibers, in that order. Then the heart muscle contracts, producing the systolic BP. When the heart is relaxed, the diastolic pressure is produced.

Heart Innervation
10th Cranial Nerve - Vagus Nerve

Parasympathetic stimulation - decreases heart rate, which reduces blood pressure
The right Vagus nerve is said to operate on the SN, and the left Vagus nerve upon the AV Node.
Motor = efferent (slows down the heart)

Thoracic Spinal Nerves - T1-T5
Sympathetic Stimulation - increases heart rate - vasoconstriction, which increases blood pressure
Sensory = afferent (speeds up the heart)

Heart Electrolyte Minerals
K (potassium) for heart muscle relaxation (diastole)
Mg (magnesium) and Ca (calcium) for heart muscle constriction (systole)


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Human Heart Diagram


The author has no medical training. No advice is intended.
Although the author has tried to be as accurate as possible, errors and misstatements are possible. Consult your doctor for personal advice. I could not find a human heart diagram like the above. So, I drew this schematic diagram of the human heart, to help myself understand the inner workings of the human cardiovascular system. I hope that it helps you. Understanding how the heart works can help you to reduce your blood pressure.


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Tags: heart diagram, diagram of the heart, human heart drawing, heart diagram blood flow, cardiovascular system diagram

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This Vaughns Simple Human Heart
Diagram was last updated on 2020-11-25.