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Heart consists of 4 chambers
o Right atrium (RA)
o Right ventricle (RV)
o Left atrium (LA)
o Left ventricle (LV)
Blood flow
o Right atrium receives blood from
Superior vena cava (SVC) - carries blood from upper body (head, arms)
Inferior vena cava (IVC) - carries blood from…

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Diastole: period of relaxation by heart muscle
Atrial systole
o Both atria contract and move blood across AV valves into ventricles
o This reduces volume of atria but increases pressure
Pressure of RA > RV - forces tricuspid valve to open
Pressure of LA > LV - forces mitral valve…

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o Fibres that branch out to distant ventricles are called Purkinje Fibers
o Cause contraction of ventricles

Pressure Changes

Isovolumetric contraction
o Ventricles start to contract
o Intraventricular pressure rises and causes AV valves to close
o Ventricles are no longer filled with blood and volume says the same

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o Muscular arteries branch into smaller arterioles (smallest arteries)
o Arterioles regulate blood flow into tissue capillaries
Made up of 3 layers:
o Tunica intima (innermost layer)
Simple squamous epithelium
Surrounded by a connective tissue basement membrane with elastic fibres
o Tunica media (middle layer)
Smooth muscle and usually thickest…

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Enters through the vena cava into the right atrium
It's then pumped through a valve into the right ventricle chamber
And then up through the pulmonary valve into the pulmonary artery towards the lungs
Oxygenated blood
Enters through the pulmonary veins into the left atrium
It's then pumped through a…

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Ventricular Systole
Electrical impulse passes to ventricles via atrioventricular node, bundle of His and Purkinje fibres.
Fibres do not contract, but pass impulse to base of ventricles.
Ventricle contract shortly after atria, squeezing blood upwards into arteries
Atria and ventricles relax > atria filll with blood
Cardiac output: blood…


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