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).
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
page. I was not able to find a simplified heart and blood
circulation drawing on the web, so I made this
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.
10th Cranial Nerve - Vagus
stimulation - decreases heart rate, which reduces blood
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
Spinal Nerves - T1-T5
Stimulation - increases heart rate - vasoconstriction, which
increases blood pressure
Sensory = afferent (speeds up the
K (potassium) for
heart muscle relaxation (diastole)
Mg (magnesium) and Ca (calcium) for heart muscle