Vascular System of Heart
The heart of mammal, conical is completely enclosed in a membrane called Pericardium. Heart of mammal is four chambered.
The two auricles are separated by an inter auricular septum and the two ventricles by 2 ventricular septum.
The right auricle receives venous blood (blood through vein) from all parts of the body, except the lungs, Left auricle receives oxygenated bloods from the lungs through Pulmonary veins.
Right auricle leads into the right ventricle by an opening guarded by Tricuspid valve; his valve allows the flow of blood in one direction only.
i.e. from auricle to ventricle. Similarly, the left auricle which received oxygenated blood coming from lungs, opens into left ventricle by an opening guarded by a valve called Bicuspid Valve or Mitral Valve.
The valves between auricles and ventricles are membranous in mammals while in frog, they are muscular.
For the Pumping Action of Heart, the wave of contraction originated from a Pacemaker or Contraction called the Sinu Auricular Node.
Any interference in the conducting system of wave of contraction from a ‘pacemaker’, either by mechanical obstruction or degeneration due to disease affects the heart beat. The defect is called Heart Block.
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