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Overview of Cardiovascular System

  • Focus on cardiovascular system due to its impact on mortality rates.

  • Significance of understanding blood vessels and blood pressure.

Anatomy of the Heart

  • Structure: Heart is divided into chambers.

    • Atria: Top chambers of the heart.

      • Left atrium (labeled).

      • Right atrium (located on the opposite side).

    • Ventricles: Bottom chambers of the heart.

      • Left ventricle.

      • Right ventricle.

  • Heart dissection: Front of the heart removed for internal view, essential for lab work.

Electrical Conducting System

  • Representation in diagrams: Yellow elements show the electrical conducting system.

  • Sinoatrial (SA) Node:

    • The pacemaker of the heart where electrical excitation begins.

    • Generates action potentials independently without external nervous system input.

  • Atrioventricular (AV) Node:

    • Located between atria, situated at the bottom of the right atrium.

    • Receives signals from the SA node; embedded within the atrial wall.

  • AV Bundle (Bundle of His):

    • Takes signals from the AV node.

    • Thin structure that runs down the septum between the ventricles.

  • Bundle Branches:

    • Two branches (left and right) extending down each side of the septum.

  • Purkinje Fibers:

    • Spread electrical signals throughout the ventricles, facilitating contraction.

    • The contraction begins at the apex of the heart and moves upward toward the atria.

Contraction Mechanism

  • Directional Flow of Blood:

    • Ventricles push blood upwards (to aorta and pulmonary trunk), atria push it downwards.

    • This process resembles squeezing a tube of toothpaste.

  • The contraction sequence is crucial for effective blood circulation.

Electrocardiogram (ECG/EKG)

  • Used to study heart's electrical activity.

  • Origin of terms:

    • EKG comes from "Kardiogramm" in German; ECG is the English equivalent.

  • Key Components of ECG:

    • P Wave: Atrial electrical excitation (smallest wave).

    • QRS Complex: Signifies ventricular excitation and is the most significant part of the ECG.

    • T Wave: Indicates ventricular repolarization.

  • Importance of recording good quality waveform for practical understanding in lab sessions.

Cardiac Cycle and Electrical Excitation

  • Cycle Overview:

    • Sequence of electrical excitation and subsequent contraction.

    • P wave (atrial excitation) leads to contraction.

    • QRS complex (beginning of ventricular excitation) observed next.

    • T wave indicates return to resting state after ventricular contraction.

  • The entire process repeats continuously in the cardiac cycle.

Blood Flow Pathway Through the Heart

  • Systematic Flow:

    • Blood flows from the body into the right atrium via the vena cava.

    • Moves through the right atrium, passes through the tricuspid valve (right AV valve) into the right ventricle.

    • Exit to lungs through the pulmonary valve into the pulmonary trunk.

  • Oxygenation Process:

    • Blood becomes oxygenated in lungs, returns to the left atrium via pulmonary veins.

    • Passes to the left ventricle via the mitral valve (left AV valve) and exits through the aortic valve into the aorta.

Coronary Circulation

  • Supplies blood to the heart tissue itself.

  • Coronary Arteries:

    • First branches off the aorta, responsible for heart muscle perfusion.

  • Importance of coronary circulation in overall heart health.