Found in insects, interconnecting vessels aren't in a closed system
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What is a closed system?
Closed circuit, circulatory fluid continuously going around vessels
Humans and other vertebrates have this called the cardiovascular system
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Blood going around the cardiovascular system simplified
Arteries branch into arterioles and carry blood away from the heart to capillaries. Venules converge into veins and return blood from capillaries to the heart.
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Types of circulation
1) single circulation
2) double circulation- 4 heart chambers, in mammals, oxygen poor and rich blood pumped separately from right & left sides of heart
3) Incomplete double circulation- in amphibians, 3 heart chambers
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Blood vessel structures
Central lumen- middle
Endothelium- lines blood vessels
Artery, veins, capillaries
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Artery Function
Small lumen, arterioles, thicker connective tissue layer as the walls are under high pressure from the blood leaving the heart
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Vein functions
Large lumen, have valves to prevent backflow, have venules, blood to the heart
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Capillaries functions
Smallest vessels, 1 cell thick, narrow lumen, thin walls to enable exchange of materials, exchange blood and interstitial fluid
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The heart process
heart contracts & relaxes (cardiac cycle)
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What is the phase called when the heart is contracting
Systole
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What is the phase called when the heart is relaxing
Diastole
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What is the stroke volume?
amount of blood pumped in a single contraction
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What is the cardiac output?
volume of blood pumped into system per minute
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How many valves are there to prevent backflow of blood back into the heart
4
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What is the function of the atrioventricular (AV) valves?
Separate each atrium and ventricle
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What is the function of the semilunar valves
Control blood flow to aorta and pulmonary artery
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Maintaining the hearts rhythmic beat
Some cardiac cells are auto rhythmic (contract without a signal)
Sinoatrial (SA) node sets the rate and timing at which cardiac muscle cells contract
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Blood composition is vertebrates
Connective tissue of cells suspended in plasma
Plasma- 55% of blood
Cellular elements-45% of blood: Leukocytes, platelets, erythrocytes
Haemoglobin
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what are leukocytes?
White blood cells
defence, immunity
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What are Platelets for?
Blood clotting
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What are erythrocytes?
Red blood cells
Transport oxygen and some carbon dioxide
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