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Electrocardiography Essentials Chapter 3

myocardium

the heart muscle

atrium

one of the two top chambers of the heart, that receives blood from the large veins and then pumps blood into the lower chambers of the heart

superior vena cava

the main vein that drains blood from the upper part of the body into the right atrium of the heart

inferior vena cava

the main vein that drains blood from the lower part of the body into the right atrium of the heart

pulmonary vein

one of the two large vessels that returns oxygenated blood from the lungs to the left atrium

ventricle

one of the two large muscular pumping chambers of the heart located inferior to the atria

aorta

the large artery that receives blood from the left side of the heart and distributes the blood to the rest of the body

6 steps of Pulmonary circulation

1a. superior vena cava
1b. inferior vena cava
2. right atrium
3. tricuspid valve
4. right ventricle
5. pulmonary valve (semilunar)
6a. right pulmonary arteries
6b. left pulmonary arteries

6 steps of systemic circulation

7a. left pulmonary veins
7b. right pulmonary veins
8. left atrium
9. bicuspid valve (mitral)
10. left ventricle
11. aortic valve
12. aortic arch

tricuspid valve

the three-cusp valve which controls the flow of blood between the right atrium and right ventricle

pulmonic valve

the valve that is in the right ventricle and which separates the ventricle from the pulmonary artery

mitral valve

the two-cusp valve separation the left atrium from the left ventricle

aortic valve

the valve on the left side of the heart that opens to allow blood to flow from the left ventricle into the aorta

pericardial sac

the fibrous covering which completely encloses and protects the heart

electrolyte

an ion or a small particle that is positively or negatively charged, such as sodium (Na+), potassium (K+), or chloride (Cl-)

extracellular

fluid and particles outside of and surrounding the cell

intracellular

within a cell

cellular membrane

a layer of protein that surrounds a cell and keeps it separated from the surrounding fluid and cells

sinoatrial node "SA Node"

the natural pacemaker of the heart, located in the upper part of the right atrium

polarization

the resting state, meaning that there is a balance between the electrical charges on both sides of the cellular membrane and no movement of ions across the membrane occurs. "ready for action"

depolarization

a current, or wave of electricity that is created when sodium and potassium trade places across the cellular membrane. "active"

repolarization

when sodium and potassium again change places across the cellular membrane returning to their original places. "recharging"

atrioventricular node "AV Node"

special conductive tissue located in the lower right atrium that conducts electrical impulses from the atria to the ventricles

bundle of His

special conductive tissue in the middle of the septum of the heart, or inter-ventricular septum, that allows smooth and rapid conduction of the electrical impulse from the AV node to the ventricle

bundle branches

special conductive tissue fibers that extend from the Bundle of His and into the left and right ventricle

purkinje fibers

conduction fibers that branch off from the bundle branches and deliver the electrical stimulus to the ventricles, causing the ventricles to contract

systole

the period of time in which the heart muscle is contracting

diastole

the period of time when the heart muscle is relaxed

5 steps of the conduction system

1. SA Node
2. AV Node
3. Bundle of His
4. bundle branches (left and right)
5. Purkinje fibers

vascular

relating to the system of blood vessels

vena cava

large vein returning deoxygenated blood to the right side of the heart

atria

the upper chambers

pulmonary

relating to the lungs

ventricles

lower chambers or main pumping chambers

ion

very small charged particle

cardiac cycle

the series of electrical and mechanical events that comprise each heart beat

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