Question

describe the role role of the heart sending blood to the brain. Please include the separate chambers, valve and autorhythmic fibers in your description.

Answer 1

Human Heart

Human heart is made up of 4 chambers .Two chambers on right side Right atrium and Right ventricle.Two chambers on left side Left atrium and left ventricle. Atrium is separted from Ventricle by Atrioventicular valve. Right atrium is separated from right ventricle by Tricuspid and Left atrium and left ventricle by Mitral valve.

During Left Ventricular systole the blood moves from left ventricle into the aorta. Valve in between LV and aorta is semilunar valve. The arch of aorta gives three branches, Right Brachiocephalic, left common carotid and left subclavian. Right Brachiocephalic artery fruther divides and forms Right cammon carotid and right subclavian artery. Both left and right common carotid further divides into External and Internal carotid artery. Internal carotid artery continue as middle cerebral artery and supply the brain. Inside the brain Middle cerebral artery anastomose with Anterior and Posterior cerebral artery via Anterion and Posterior communicating artery.

Autorhythmic Fibers are the conducting system of heart.

The wave of depolarisation (impulse) generated in SA node situated on Right Atrial wall and thn flow in the direction shown below..

SA node ----> three internodal pathway----> Av node ----> Bundle of Hiss -----> right and left bundle branch -----> Purkinje Fibers -----> Ventricular muscle

The Diretion of blood flow from heart to brain can be summarised as follows :

IVC and SVC ----> Right Atrium ---->Tricuspid Valve ----> Right Ventricle -----> Pulmonary valve ----> Pulmonary artery -----> Pulmonary capillary ----->Pulmonary vein ----- > Left atrium ----> Mitral Valve-----> Left ventricle ------> Aortic semilunar valves ---> Aorta ----> arch of aorta gives following branch,

1) On right side Right Brachiocephalic followed by right common carotid -----> Right Internal carotid -----> Right middle cerebral artery

2) On left side -----> Left common carotid -----> Left internal carotid ----> Left middle cerebral artery

Both internal carotid enter the brain & give middle cerebral artey which anastomose with Anterior and Posterial Cerebral Artery and forms Circle of Willis, which supply the brain.