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Open Circulatory System
blood leaves vessels and flows around the cells of the animal’s body before re-entering blood vessels again
Closed Circulatory System
blood remains in a continuous system of blood vessels
Arteries
carry blood away from the heart
Veins
carry blood to the heart
Capillaries
tiny vessels that link arteries and veins
Arteries
carry blood away from the heart
blood under high pressure
thick wall
small lumen
blood flows in pulses
valves absent
blood high in oxygen (except pulmonary artery)
Veins
carry blood to the heart
blood under low pressure
thin wall
large lumen
blood flows smoothly (no pulses)
valves present
blood low in oxygen (except pulmonary vein)
Blood Pressure
the force the blood exerts against the wall of a blood vessel
Valves
control the direction of blood flow
Septum
divides the heart in two
Atria
the upper chambers of the heart
Ventricles
pump blood out of the heart
Tricuspid Valve
valve on the right-hand side of the heart
Bicuspid Valve
valve on the left-hand side of the heart
Semilunar Valves
allow blood to flow out of the heart into the two main arteries
Vena Cava
through where deoxygenated blood enters the heart
Pulmonary Vein
through where oxygenated blood enters the heart
Pulmonary Artery
an artery that is low in oxygen
Pulmonary Vein
a vein that is high in oxygen
Pulmonary Circuit
heart → lungs → heart
Systemic Circuit
heart → body → heart
Double Circulation System
allows oxygen-rich and oxygen-poor blood to be kept separate
ensures that the blood pressure is high enough to reach all parts of the body
Portal System
a blood pathway that begins and ends in capillaries
Hepatic Portal Vein
example of a portal system, connects the stomach and intestines to the liver
Heartbeat
SA node causes atria to contract
Electrical impulse from SA node stimulates the AV node
AV node sends an impulse down special muscle fibres located in the septum
Impulses cause the ventricles to contract
Atrioventricular Node
sends electrical impulses down the septum
Sinoatrial Node
causes the atria to contract
Atrioventricular Node
located between the septum / between the ventricles
Sinoatrial Node
located in the right atrium
Diastole
when the heart chambers relax
Systole
when the heart chambers contract
Cardiac Cycle
diastole: blood enters the atria
atrial systole: blood is pumped to the ventricles
ventricular systole: blood is pumped out of the heart
Pulse
the alternate expansion and contraction of the arteries
Blood Pressure
the force exerted by the blood against the walls of the blood vessels (mainly the arteries)
Pulmonary Vein
carries blood richest in oxygen
Hepatic Portal Vein
carries blood between the intestine and liver
Renal Vein
carries blood lowest in metabolic waste
Vena Cava
carries blood into the right atrium of the heart
Cardiac Muscle
specialised muscle of the heart, never tires
Note 
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