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Circulatory System (Structures and functions of arteries, capillaries and…
Circulatory System
Structures and functions of arteries, capillaries and veins. Blood pressure and vasoconstriction and vasodilation
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When blood is pumped Away from the heart (it is in arteries, leaving ventricles ) the pressure is High
When blood is traveling towards the heart after it has finished traveling through the capillaries and reenters the veins the blood pressure is Low(Traveling towards atria
and it is In the veins)
Vasodilation increased blood flow but decreasesed blood pressure, vasoconstriction decrease blood flow but increased blood pressure
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3 steps of Cardiac Cycle
2.Atrial systole and ventricular diastole: Atrial contraction that is very brief which forces all the blood remaining in the atria into the ventricles
3.Ventricular systole and atrial diastole: In the remainder of the cycle ventricular contraction pumps blood into the arge arteries through semilunar valves
1. Atrial and ventricular diastole:
This is during the relaxation phase, the blood returns from large veins and flows into atria and then into ventricles through AV valves
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Heart Rhythm
1.Electrical impulse spreads to the walls of atria which cause them to contract together. 2.During atrial contraction, electrical impulses reach atrioventricular (AV) node, which delays the electrical impulse for about 0.1 second so the atria has enough time to empty completely before the ventricles contract. 3.Then the electrical impulses spread to the heart apex.4. Then to the ventricles, which causes them to contract together, purkinje fibers help spread the electrical signal throughout the ventricular wall.We use electrocardiogram (ECG or EKG) to detect the electrical impulses in the heart .
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Heart rhythm is determined by pacemaker cells in the SA node,pacemaker cells set the timing and rate of contraction for all other cardiac cells
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