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BIO CLASS Recording-2025-02-17T16:00:03.468Z

Blood Flow Through the Heart

  • Superior and Inferior Venacava:

    • Superior drain brings blood from above

    • Inferior drain brings blood from below

    • Both drains lead to the heart

Right Atrium

  • Blood enters the right atrium

  • Right atrium is not very muscular

  • Pumps blood down to the right ventricle

  • Valve:

    • Known as the Tricuspid Valve or Right AV Valve

    • Tricuspid valve has three flaps

Right Ventricle

  • The right ventricle has more muscle than the right atrium but less than the left ventricle

  • Pumps deoxygenated blood to the lungs

  • Valve:

    • Pulmonary Semilunar Valve

    • Blood then goes to the Pulmonary Artery

Pulmonary Circuit

  • Blood on this circuit is deoxygenated and travels to the lungs

  • In the lungs, gas exchange occurs across simple squamous epithelium in alveoli and capillaries

  • Blood returning from lungs is now oxygenated

Pulmonary Vein

  • Blood returns to the heart via the Pulmonary Veins

  • Carries oxygenated blood to the left atrium

Left Atrium

  • The left atrium pumps blood down to the left ventricle

  • Valve:

    • Known as Bicuspid Valve, Mitral Valve, or Left AV Valve

    • Takes blood from the left atrium to the left ventricle

Left Ventricle

  • The left ventricle has the thickest walls

  • Pumps oxygenated blood into the body

  • Valve:

    • Aortic Semilunar Valve

    • Blood then enters the Aorta to be distributed throughout the body

Cardiac Circuits

  • Right side of the heart

    • Pulmonary Circuit: Only goes to the lungs

  • Left side of the heart

    • Systemic Circuit: Supplies oxygenated blood to the rest of the body

Electrical Pathway of the Heart

  • Starts in the Sinoatrial (SA) Node located in the right atrium

  • Signal spreads through intercalated discs to allow for simultaneous contraction of the atria

  • Atrioventricular (AV) Node located on the medial floor of the right atrium fires next

  • The signal progresses through the Bundle of His (AV bundle) down the septum

  • Runs through Purkinje Fibers to contract the ventricles

ECG and Heart Activity

  • QRS Complex: Indicates ventricular contraction

    • Q = bottom, R = top, S = bottom

  • After QRS, ventricular relaxation occurs

  • ECG amplitude and spacing are crucial for determining normal cardiac rhythm

  • Bradycardia: Slow rhythm (lower heart rate)

  • Tachycardia: Fast rhythm (higher heart rate)

White Blood Cells

  • Neutrophils:

    • Most numerous white blood cells (70%)

    • Function as macrophages, engulfing pathogens and debris