Heart Anatomy and Circulation

Aorta

Largest artery in the body; pumps oxygenated blood from left ventricle to body.

Inferior Vena Cava

Vein transporting deoxygenated blood from lower body and abdomen to right atrium.

Left Atrium

Heart chamber receiving oxygen-rich blood from lungs and emptying into left ventricle.

Left Ventricle

Heart chamber pumping oxygen-rich blood out to the rest of the body.

Mitral Valve

Valve regulating blood flow between the left atrium and left ventricle.

Pulmonary Artery

Artery carrying deoxygenated blood from right side of heart to lungs.

Pulmonary System

Closed circuit circulating blood from heart to lungs and back to heart.

Pulmonary Valve

One-way valve allowing blood to flow from right ventricle into pulmonary artery.

Right Atrium

Heart chamber receiving oxygen-poor blood from body and emptying into right ventricle.

Right Ventricle

Heart chamber pumping oxygen-poor blood to the lungs through pulmonary valve.

Superior Vena Cava

Vein carrying deoxygenated blood from head, neck, arms, and chest to right atrium.

Systemic System

Circulation moving blood from heart to body (except lungs) and back.

Tricuspid Valve

Three-flap valve controlling blood flow between right atrium and right ventricle.

Mediastinum

Thoracic cavity region containing the heart, esophagus, trachea, and major vessels.

Parietal Pericardium

Outer membrane enclosing and protecting the heart within the mediastinum.

Apex of the Heart

Inferior, pointed tip of the heart pointing downward and to the left.

Fossa Ovalis

Indentation in interatrial septum; remnant of the fetal foramen ovale.

Foramen Ovale

Fetal interatrial passageway allowing blood to bypass lungs before birth.

Coronary Sulcus

Surface groove separating the atria from the ventricles.

Chordae Tendineae

Fibrous cords connecting AV valve cusps to papillary muscles.

Papillary Muscles

Ventricle wall projections anchored to valve cusps via chordae tendineae.

Right Coronary Artery

Artery supplying oxygenated blood to right atrium and both ventricles.

Left Coronary Artery

Artery supplying anterior/posterior cardiac walls and left ventricle.

Coronary Sinus

Vein receiving cardiac venous blood and emptying into the right atrium.

Arteries

Blood vessels that carry blood away from the heart to tissues and organs.

Veins

Blood vessels that carry blood back to the heart from tissues and organs.

Capillaries

Tiny blood vessels where oxygen, nutrients, and waste products are exchanged with tissues.

Circulatory System

Closed system of blood vessels transporting blood between heart, lungs, and tissues.

Tunica Media

Smooth muscle layer in blood vessels, thicker in arteries to regulate blood pressure.

Vein Valves

Special structures in veins that prevent backflow and ensure blood flows toward heart.

Capillary Structure

Single layer of simple squamous epithelium enabling efficient substance exchange.

Blood Vessel Layers

Three tunics surrounding vessels: externa (outer), media (middle), and interna (inner).

Aortic Arch Branches

Right brachiocephalic, left common carotid, and left subclavian arteries.

Brachiocephalic Artery Division

Divides into the right common carotid and right subclavian arteries.

Internal Carotid Artery

Branch of common carotid supplying blood to the brain.

External Carotid Artery

Branch of common carotid supplying blood to the facial area.

Vertebral Artery

Passes through vertebral transverse foramina to supply blood to the brain.

Upper Extremity Arterial Pathway

Subclavian becomes axillary, then brachial, which divides into radial and ulnar.

Abdominal Aorta

Continuation of thoracic aorta past diaphragm, dividing into common iliac arteries.

Abdominal Aorta Major Branches

Inferior phrenic, celiac trunk, superior/inferior mesenteric, and renal arteries.

Common Iliac Artery Division

Divides into internal and external iliac arteries.

Lower Extremity Arterial Pathway

External iliac becomes femoral, then popliteal, dividing into anterior/posterior tibial.

Venous System Divisions

Composed of deep veins (often matching arterial names) and superficial veins.

Superior Vena Cava Branches

Branches into the right and left brachiocephalic veins.

Jugular Veins

Includes internal and external jugular veins draining the head and neck.

Upper Extremity Deep Venous Pathway

Subclavian becomes axillary, then brachial, dividing into radial and ulnar veins.

Upper Extremity Superficial Veins

Includes the cephalic and basilic veins.

Inferior Vena Cava Branches

Includes renal, gonadal, and lumbar veins.

Lower Extremity Deep Venous Pathway

Common iliac divides into internal/external iliac; external becomes femoral, popliteal, and tibial.

Great Saphenous Vein

Important superficial vein located in the lower extremity.

Cardiac Cycle

Sequence of events occurring in the heart during one complete heartbeat.

Diastole

Relaxation phase of the heart chambers.

Systole

Contraction phase of the heart chambers.

Rest Phase (Phase 1)

Heart is in diastole, allowing passive blood flow into atria and ventricles.

Passive Ventricular Filling

About 70% of blood flows into ventricles before atria contract.

Phase 1 Valve Status

AV valves open due to higher atrial pressure; semilunar valves closed.

Phase 2 (Atrial Systole)

Atria contract, pushing the remaining 30% of blood into ventricles.

Phase 3 (Ventricular Systole)

Ventricles contract, causing AV valves to close and semilunar valves to open.

Auscultation

Procedure of listening to heart sounds using a stethoscope.

First Heart Sound (S1)

"Lubb" sound produced by closure of AV valves during ventricular systole.

Second Heart Sound (S2)

"Dub" sound produced by closure of semilunar valves during ventricular diastole.

Third Heart Sound (S3)

Sound caused by ventricular filling; heard in children, athletes, or heart failure.

Electrocardiogram (ECG)

Representation of the electrical events occurring in the heart.

Cardiac Node

Specialized area of cardiac muscle that generates action potentials.

Sinoatrial (SA) Node Location

Posterior wall of the right atrium.

Sinoatrial (SA) Node Function

Primary pacemaker generating action potentials at 60-100 beats per minute.

Atrioventricular (AV) Node Location

Floor of the right atrium.

AV Node Delay

Delays impulse by ~100 ms, allowing atrial contraction before ventricular contraction.

AV Node Intrinsic Rate

Generates action potentials at 40-60 bpm if SA node is damaged.

Heart Pumping Efficiency Threshold

Pumping efficiency begins to decrease at heart rates above ~180 bpm.

Bundle of His (AV Bundle)

Conduction pathway connecting atria and ventricles; intrinsic rate of 20-40 bpm.

Moderator Bands Function

Distribute impulses to papillary muscles so they contract before ventricles.

Purkinje Fibers

Fast-conducting cells distributing impulses throughout ventricles for even emptying.

P Wave

ECG wave representing atrial depolarization occurring just before atrial contraction.

QRS Complex

ECG wave representing ventricular depolarization; overshadows simultaneous atrial repolarization.

T Wave

ECG wave resulting from ventricular repolarization.

P-R Interval

Extends from start of P wave to start of QRS complex; indicates conduction problems if prolonged.

Q-T Interval

Extends from end of P-R interval to end of T wave; represents ventricular systole.

Maximum AV Node Conduction Rate

Maximum rate of 230 bpm for impulse conduction through the AV node.

Maximal Ventricular Contraction Rate

About 300-400 bpm, though contractions at these rates are very inefficient.

Primary Goal of Cardiovascular System

Maintain the flow of oxygenated blood to tissues.

Cardiac Output (CO)

Amount of blood pumped by each ventricle in one minute.

Stroke Volume (SV)

Amount of blood pumped out of the ventricle during one contraction.

Cardiac Output Formula

CO = SV × HR

Typical Rest Stroke Volume

Approximately 70 to 80 mL per beat.

End Diastolic Volume (EDV)

Amount of blood in the ventricle just before contraction.

End Systolic Volume (ESV)

Amount of blood remaining in the ventricle after contraction.

Stroke Volume Formula

SV = EDV - ESV

Athlete vs. Heart Failure Resting Heart Rate

Athletes have higher SV and lower HR; CHF patients have lower SV and higher HR.

Starling's Law of the Heart

Relates the degree of ventricular wall stretch directly to stroke volume.

Preload

The degree of stretch of the ventricular walls prior to contraction.

Effect of Increased Preload

Increases stroke volume, which increases cardiac output.

Venous Return Range

Varies from about 2 L/min at rest to 24 L/min during exertion.

Hypertension

Chronically elevated blood pressure of 140/90 mm Hg or above.

Hypertension Presentation

Typically a silent disorder, causing patients to miss its seriousness and treatment.

Complications of Hypertension

Includes heart attack, kidney failure, stroke, and aneurysm.

Stroke

Medical emergency caused by inadequate or interrupted blood supply to the brain.

Two Main Causes of Stroke

Blocked artery (ischemic) or leaking/bursting blood vessel (hemorrhagic).

Transient Ischemic Attack (TIA)

Temporary disruption of brain blood flow that produces no lasting symptoms.

Ischemic Stroke Cause

Narrowed or blocked brain arteries due to fatty deposits or blood clots.