Thursday, August 18, 2011


The circulatory system is the transport system of the body,it  transports various substances  from tissues to tissues .Besides ,it maintains the chemical composition  and physical environment  of the body fluids ,essential  for the metabolic reactions on which the life wheels on smoothly .Moreover , in certain animals such as birds and mammals ,it also it also maintains a body temperature  to a constant level.                                                                                The  circulatory system of vertebrates , including mammal fall under two categories ,[1]  blood vascular system  and [2]  lymphatic system .These  are distinguishable  on the basis of  the circulatory or transporting medium; it  is blood in the blood vascular system  and lymph  in the lymphatic system .However , the remarkable  fact about the circulatory system  of mammals is that it is of closed type i.e.,  the circulatory  medium  flows in vessels; even the lymph  does not flow in  open spaces within the body.                                            1.BLOOD VASCULAR SYSTEM       ;The blood vascular system  of the rabbit or any other mammal ,like that of other vertebrates , consists of the rabbit of higher muscular  and highly contractile heart ,blood vessels,pervading every  part of the body and blood vessels due to the pumping  action of the heart .                                                                                                                                                                                          HEART                                                                                                        The heart of the rabbit and other mammals, including man ,lies in the mediastinal space between the lungs ,inclined slightly to the left,.It is somewhat pear -shaped with broad -base ,lying toward the trachea ,and a narrow apex ,lying toward the diaph ragm .The heart  is covered by the pericardium  which is composed of two thin membranes  between which is present  a lymph like  fluid called pericardial fluid .This fluid ensures  free movement of the heart and absorbs shocks  which oterwise may hurt the heart .                                        External  Structure ; The heart is  extenally distinguishable  into a broad  anterior  part called  atrial  or auricular part  and a poterior  narrow part called ventricular part   .These two parts are demarcated  by a transverse  shallow groove like  coronary sulcus  which is placed far forward ,making the auricular part smaller than the ventricular part .The  auricular part consists of the right  and left auricles .Like wise , the ventri cular  is also  divided  into the right and left  auricles .Likewise , the  ventricular part  is also divided into the   left and right ventricles  by a logitudinal  sulcus  which starts from the base of the  ventricular part , almost  medially and extends  backward obliquely toward the right not reaching the apex and therefore the  left ventricle is large than the right ventricle .                                                                                                                                                         The sinus venosus and trunkus arteriosus  are not found in the heart of the rabbit or any other mammal .The sinus venosus is merged into the right  auricle and is represanted only  by the sinu - auricular  node[sanode] . Likewise , the trunkus arteriosus  is completely merged  in the left ventricle .The right auricle recieves   venous or deoxygeneted  blood from all parts of the body , except lungs by two superior vena cavae [anteroir vaena cavae or precavals ] and  an inferior vena cava [= posterior vena cavae or postcaval ], whereas the left auricles recieves ithe oxygeneted blood  from lung by two pulmanary veins The aorotid arches arise from the ventricles ; the pulmonary aorta  arises from the right ventricle and the caratico- systemic  aorta from the left ventricle .The pulmonary aorta  and caratico -systemic aorta are joined  by a liga ment  called  ligamentum arteriosus . The blood supply of the heart is  maintain by acoronary  artery and a coronery vein .        

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