Circulatory System Overview

Study Notes

The heart consists of two muscular pumps (right and left heart) for pulmonary and systemic circulations, forming a continuous loop.
Systemic circulation comprises many parallel circuits serving various organs and body regions.

The heart is cone-shaped with:
- Apex: Directed downward, forward, and left; formed by the left ventricle; located 9 cm from midline, opposite the 5th intercostal space.
- Base: Directed upward, backward, and right; formed mainly by the left atrium; positioned in front of the middle four thoracic vertebrae.

Sterno-costal surface: Not specified in detail, but relevant for external anatomy.
Heart borders include:
- Upper: formed by both atria
- Lower: formed by the right ventricle and part of the left ventricle
- Right: formed by the right atrium
- Left: formed by the left ventricle and left auricle

Right Atrium: Receives non-oxygenated blood from the body via:
- Superior vena cava
- Inferior vena cava
- Coronary sinus
Blood flows to the right ventricle through the tricuspid valve (right atrioventricular orifice).
Right Ventricle: Pumps blood to lungs via pulmonary trunk; valves prevent backflow during contraction.
Left Atrium: Receives oxygenated blood from lungs through four pulmonary veins; blood moves to left ventricle via mitral valve (left atrioventricular orifice).
Left Ventricle: Pumps oxygenated blood to the body through the aorta; mitral valve closes to prevent backflow during contraction.

Tricuspid Valve: Between right atrium and right ventricle.
Mitral Valve: Between left atrium and left ventricle.
Pulmonary Valve: Between right ventricle and pulmonary trunk.
Aortic Valve: Between left ventricle and aorta.
Atrioventricular valves open during atrial contractions and close during ventricular contractions to prevent backflow.
Semilunar valves open during ventricular contractions and close post-contraction.

Right Atrium:
- Smooth posterior wall with openings for SVC, IVC, and coronary sinus; features a rough anterior wall and a “crista terminalis.”
- Septal wall has a depression called “fossa ovalis.”
Left Atrium: Smooth walls, receiving four pulmonary veins.
Right Ventricle: Thin-walled and large lumen; contains muscular projections (trabeculae carneae) and 3 papillary muscles; smooth outflowing part leads to pulmonary trunk.
Left Ventricle: Thick-walled and smaller, circular lumen; includes trabeculae carneae and 2 papillary muscles; smooth outflowing part leads to aorta.

Right Coronary Artery: Originates from the ascending aorta and runs in the coronary groove.

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