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8 Cards in this Set
- Front
- Back
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State three reasons why larger organisms need transport systems |
Higher metabolic rate Small surface area to volume ratio Cells too deep in the body - too large diffusion path |
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State the functions of the 4 blood vessels attached to the heart. |
Vena cava - carries deoxygenated blood from the body back to the heart Pulmonary artery - Carries deoxygenated blood from the heart to the lungs Pulmonary vein - Carries oxygenated blood from the lungs back to the body Aorta - Carries oxygenated blood from the heart to the body |
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Describe the main stages of diastole. |
Walls of atria and ventricles relax Blood flows through atria and into ventricle AV valves open Semi lunar valves shut |
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Describe the main stages of atrial systole. |
Walls of atria contract AV valves open Blood flows through AV valve into ventricle Semi lunar valves shut |
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Describe the main stages of ventricular systole |
Walls of ventricles contract Semi lunar valves open Blood flows through semi lunar valves into arteries AV valves shut |
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Explain why the AV valves are open during atrial systole |
The pressure in the atria is higher than the pressure in the ventricles The AV valves are forced open |
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Explain why the AV vales are closed during ventricular systole |
The pressure in the ventricles is higher than atria The AV vales are forced closed |
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Describe how the heart beat is regulated and controlled |
The sino atrial node (SAN) send out a wave of excitation. This cause the cardiac muscle in the walls of the atria to contract. The wave of excitation hits the atrio ventricular node (AVN). The wave of excitation is delayed, to allow time for the blood to flow out of the atria. The bundle of His carries the wave of excitation down the septum. The wave of excitation travels up the Purkyne tissue. The ventricles contract bottom to top, to ensure all the blood is pushed upwards into the arteries |
