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Circulatory System (Circulation through mammalian heart and body (Process…

- - - - Blood is oxygenated in the lungs (capillaries) and returns to the heart (Pulmonary circuit) - entering into the left atrium, entering the left atrioventricular valve, the left ventricle, the systemic semilunar valve, and the aortic artery (upper and lower)
        
        In the aortic artery. oxygenated blood is distributed throughout the body (body capillaries)
        
        Deoxygenated blood returns to the heart in the inferior and superior vena cava into the right atrium (this part is called the systemic circuit)
- - - - Contractions and Blood pressure:
        
        force directed lengthwise in artery causes blood to flow away
        
        force directed against artery wall causes the wall to stretch (the wall recoils in order to maintain blood pressure and blood flow)
        
        before pressure in the arteries is completely relieved during relaxation, the heart contractions again (ARTERIES REMAIN PRESSURIZED)
- - - - Ventricular systole and atrial diastole:
        during the remainder of cycle, ventricular contraction pumps blood into large arteries through semilunar valves
- - - - Lost plasma is regained at the venule end of the capillary bed. Interstitial fluid osmotic pressure is higher than capillary blood pressure.
        
        Two previous forces are continually fighting against one another but more fluid leaves the capillaries (blood pressure is the greater force)
        Note also that these forces are subject to regulation by the body;s endocrine and nervous systems.
        
        Purpose: to remain living and to conduct physiological processes, a cell must obtain - fuel, raw materials, nutrients, and oxygen
        
        every cell in the body must obtain these materials
        
        a transport system is required to sustain those cells that are NOT IN DIRECT CONTACT WITH THESE REQUIREMENTS (this is WHY we need this exchange - to get nutrients to the other cells that are not attached
        -Also we NEED to get rid of wastes (two direction transport)
- - - - Four Main Steps:
        
        Signals, electrical impulses- from SA node (pacemaker) spread through atria and cause the walls of atria to contract in unison
        
        Signals are delayed at AV node - delay allows atria to empty completely before ventricles contract
        
        Bundle Branches pass signals to the heart apex -
        
        Signals spread throughout ventricles - the signals finally cause these to contract in unison
        
        Note that Purkinje fibers carry the contraction impulse from both the left and the right bundle branch to the myocardium of the vetricles
        
        We can detect the electricl impulses in the heart by electrocardiogram (ECG or EKG) which displays as a graph of current against time showing the stages in the cardiac cycle