More on The Heart

Generator

(These are notes derived from my Grade 11 biology teacher)

Sinoatrial Node

The sinoatrial node is the impulse generator, a bundle of neuron tissue located in the right atrium. Many different sources call it the natural pacemaker. The function is to,  as is interpreted by the "pacemaker", sets the rate of contraction (muscle becomes or/is made shorter and tighter) for the heart. The atrioventricular node produces a "wave" of electrical activity over the atria (plural of Atrium) causing them to contract.

Atrioventricular  Node

 The atrioventricular node is part of the "electrical control system" of the heart. Its function is to controls/coordinates the top of the heart. It picks up part of the impulses and conducts it through the purkinje fibers.

Purkinje Fibers

Purkinje fiber branch off the atrioventricular node and is located in the septum. Its function is to conducts signals to the bottom of the ventricles this causes them to contract. In the purkinje fibers the impulse is conducted to the left and right ventricles.

Heart Sounds

The sound that your heart makes are due to the opening and closing of valves. The classic "Lubb-Dubb" sound.

Lubb

This is the first sound and is made when the atriolventricular valve closes during a ventricular contraction. The first sound lub, occurs when the atrioventricular valves close.

Dubb

 This is when the blood is forced out of the ventricles during a contraction. At the end of the contraction the blood pressure begins to drop within the heart. The semilunar valve prevent the blood that wants to flow backwards into the ventricles. The second sound occurs when the semilunar valves close.


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