KD

Heart Lab

Overview of the Heart and Circulatory System

Basic Structure

  • Lungs

  • Diaphragm

  • Base

  • Apex

Heart Anatomy

Chambers of the Heart

  • Right Side

    • Right Atrium: Receives deoxygenated blood from the body via the superior and inferior vena cavae.

    • Right Ventricle: Pumps deoxygenated blood to the lungs through the pulmonary trunk.

  • Left Side

    • Left Atrium: Receives oxygenated blood from the lungs through the pulmonary veins.

    • Left Ventricle: Pumps oxygenated blood to the rest of the body via the aorta.

Anatomy Details

  • Auricles: Extensions of the atria that increase capacity.

  • Ventricles: Larger chambers that pump blood out of the heart.

    • Anterior Ventricle: Refers to the left ventricle.

    • Posterior Ventricle: Refers to the right ventricle.

Major Blood Vessels

Blood Flow Pathways

  1. Aorta: Major artery supplying oxygenated blood to the body.

  2. Superior Vena Cava: Brings deoxygenated blood from the upper body to the right atrium.

  3. Inferior Vena Cava: Carries deoxygenated blood from the lower body to the right atrium.

  4. Pulmonary Trunk: Divides into the right and left pulmonary arteries; carries deoxygenated blood to lungs.

  5. Pulmonary Veins: Bring oxygenated blood from the lungs to the left atrium.

  6. Coronary Arteries: Supply blood to the heart muscle itself.

Coronary Circulation

  • Right Coronary Artery: Supplies blood to the right side of the heart.

  • Left Coronary Artery: Supplies blood to the left side of the heart.

  • Cardiac Veins: Drain into the coronary sinus and then into the right atrium.

Heart Valves

Function and Types

  • Tricuspid Valve: Between right atrium and right ventricle.

  • Pulmonary Semilunar Valve: Between right ventricle and pulmonary trunk.

  • Bicuspid (Mitral) Valve: Between left atrium and left ventricle.

  • Aortic Semilunar Valve: Between left ventricle and aorta.

Intrinsic Conduction System

  1. Sinoatrial (SA) Node: Natural pacemaker of the heart.

  2. Atrioventricular (AV) Node: Receives impulses from SA node and transmits them to ventricles.

  3. AV Bundle (Bundle of His): Pathway from AV node to bundle branches.

  4. Right & Left Bundle Branches: Conduct impulses through the ventricles.

  5. Purkinje Fibers: Spread electrical impulses throughout the ventricles causing contraction.

Blood Flow Pathway

Pulmonary Circuit

  • Right atrium → Tricuspid valve → Right ventricle → Pulmonary semilunar valve → Pulmonary trunk → Lungs → Left atrium.

Systemic Circuit

  • Left atrium → Bicuspid valve → Left ventricle → Aortic semilunar valve → Aorta → Body → Returns via SVC and IVC to Right atrium.

Fetal Circulation vs. Newborn Circulation

  • Fetal Circulation: Oxygen and nutrients from the placenta; lungs nonfunctional; shunts like foramen ovale and ductus arteriosus bypassed.

  • Newborn Circulation: Independent cardiovascular system; fetal shunts close to reroute blood.

Postnatal Changes in Circulation

  • Ligamentum Arteriosum: Remnant of ductus arteriosus.

  • Fossa Ovalis: Remnant of foramen ovale.

  • Medial Umbilical Ligaments: Remnants of umbilical arteries.

  • Ligamentum Teres: Remnant of umbilical vein (round ligament of the liver).