Unit 4 Health Science: Heart Structures and EKG

endo-

Within

peri-

Around

Coronary

Heart's blood vessels

Location of the heart

In the thoracic cavity, behind the sternum, between the lungs, slightly left of center

Atrium

Upper heart chamber that receives blood

Ventricle

Lower heart chamber that pumps blood out of the heart

Septum

Muscular wall separating the right and left sides of the heart

Purpose of heart valves

Prevent backflow and keep blood moving in one direction

Right atrium (RA)

Receives deoxygenated blood from the SVC and IVC

Right ventricle (RV)

Pumps deoxygenated blood to the lungs through the pulmonary artery

Left atrium (LA)

Receives oxygenated blood from the lungs through the pulmonary veins

Left ventricle (LV)

Pumps oxygenated blood to the body through the aorta

Superior and inferior vena cava (SVC/IVC)

Large veins returning deoxygenated blood from the upper and lower body to the right atrium

Pulmonary artery

Carries deoxygenated blood from the right ventricle to the lungs

Pulmonary veins

Carry oxygenated blood from the lungs to the left atrium

Aorta

Largest artery; carries oxygenated blood from the left ventricle to the body

Tricuspid valve

Between the right atrium and right ventricle

Pulmonary valve

Between the right ventricle and pulmonary artery

Mitral (bicuspid) valve

Between the left atrium and left ventricle

Aortic valve

Between the left ventricle and aorta

Deoxygenated blood flow pathway

Body → SVC/IVC → RA → tricuspid valve → RV → pulmonary valve → pulmonary artery → lungs

Oxygenated blood flow pathway

Lungs → pulmonary veins → LA → mitral valve → LV → aortic valve → aorta → body

Sinoatrial (SA) node

Natural pacemaker; starts the electrical impulse and triggers atrial depolarization

Atrioventricular (AV) node

Briefly delays the electrical impulse so ventricles can fill before contracting

Bundle of His

Carries electrical impulses from the AV node toward the ventricles

Right and left bundle branches

Split the electrical pathway to conduct impulses down both sides of the ventricular septum

Purkinje fibers

Rapidly distribute electrical signals throughout the ventricles, activating ventricular depolarization

Electrical conduction pathway

SA node → AV node → Bundle of His → right/left bundle branches → Purkinje fibers

P wave on an EKG

Atrial depolarization (electrical activation before atrial contraction)

QRS complex on an EKG

Ventricular depolarization (electrical activation before ventricular contraction)

T wave on an EKG

Ventricular repolarization (electrical recovery)