11+heart

The cardiovascular system includes the heart, blood vessels, and blood functioning to circulate oxygen and nutrients throughout the body.

Mediastinum: The central compartment of the thoracic cavity that contains the heart, major blood vessels, trachea, esophagus, and more.
Maximal Point of Vena Cava Intensity (PMI): Location where the heartbeat can be maximally detected, generally corresponds to the apex of the heart.
Heart Orientation: The heart can be positioned leftward (left axis deviation), be displaced due to obesity/pregnancy, or be centrally located in tall individuals.

The heart has four chambers:
- Right and Left Atria (plural of atrium)
- Right and Left Ventricles

Deoxygenated Blood enters the Right Atrium via the superior and inferior vena cava, meaning it has less than 50% oxygen saturation.
Blood flows through the tricuspid valve to the right ventricle, where it is pumped into the pulmonary trunk.
Oxygenated Blood returns to the left atrium via the pulmonary veins, flows through the bicuspid (mitral) valve into the left ventricle, and is then pumped into the aorta.
Key Heart Sounds: The closure of AV valves produces the "Lub" sound, while closure of the semilunar valves produces the "Dup" sound.

The heart muscle, or myocardium, is responsible for the heart's contractions.
Composed mostly of contractile myocytes with a small percentage of pacemaker (autorhythmic) cells, which initiate action potentials.

Atrioventricular (AV) Valves: Tricuspid (Right) and Mitral (Left) valves regulate blood flow between atria and ventricles.
Chordae Tendineae and Papillary Muscles: Prevent valve prolapse and regulate blood flow during contractions.

Diastole: Heart at rest, atria fill with blood from the veins, AV valves open due to gravity.
Systole: Ventricles contract, forcing blood into arteries; this includes isovolumetric contraction where all valves are temporarily closed.

Heartbeat initiated by pacemaker cells located primarily in the sinoatrial (SA) node, followed by atrioventricular (AV) node firing.
Action potentials propagate through the heart muscle via specialized conduction pathways (Bundle of His, Purkinje fibers).

Electrocardiogram (ECG): Reflects the heart's electrical activity, crucially showing depolarization of the atria (P wave) and ventricles (QRS complex).
Waveforms indicate cardiac rhythm and can reveal conditions like myocardial infarctions or arrhythmias.

Caused by plaque buildup in coronary arteries, severely decreasing blood flow.
Leads to muscle damage as the lack of oxygenated blood prevents normal electrical activity.

Characterized by the buildup of cholesterol plaques in arteries, with differing impacts based on the type of lipoproteins involved (HDL vs. LDL).

Governed by pressure gradients (blood flows from high to low pressure), resistance, and vessel diameter (Poiseuille’s law).
Hydrostatic Pressure: Key driving force for blood flow, measured in mmHg.