EKG Interpretation Ch. 1

Anatomy & Physiology

Each time the heart contracts, about ___ milliliters are ejected and begin circulation

70

The average cardiac output is ___ liters per minute

5.25

The ventricles are ___ and ____ than the atria.

Larger and thicker

All blood exiting the heart leaves through an ____. All blood enters the heart through a ____.

Artery

Vein

The heart is kept in place and prevented from over-expanding by the _____.

Pericardium

Valleys are seen on the heart known as ___. Which are where coronary vessels can pass along the heart surface.

Sulci

The _____ _____ divides the atria and ventricles.

Coronary sulcus

The ______ ____ divides the left and right ventricles.

Interventricular Sulci

The myocardium is thickest in the _____ _____ and thinnest in the _____.

Left Ventricle

Atria

The _____ ____ houses the major electrical pathways of the heart.

Interventricular Septum

The ____ _____ is the receptacle for deoxygenated blood.

Right Atrium

Blood from the upper body enters through the ______ ___ ___ while the blood from the lower body enters through the _______ ____ ____.

Superior Vena Cava

Inferior Vena Cava

To match the leaflets of the valves, ____ ____ prevent them from relapsing.

Papillary muscles

The ___ ___ receives oxygenated blood from four pulmonary veins.

Left atrium

The AV valves include the _____ & _____ valves.

Tricuspid

Mitral (Bicuspid)

The semilunar valves include the _____ & _____ valves.

Pulmonary

Aortic

The AV & Semilunar valves both open and close _____ which is where the “Lub Dub” sounds come from.

Simultaneously

The two AV valves close when ____, or contraction of the ventricles, start.

Systole

The ____ prevent back-flow when blood has exited the heart.

Semilunar Valves

The _____ is the layer on the inside of the heart wall as well as the valves.

Endocardium

Some of the main conducting nerve fibers travel through the _____ which is a layer below the endocardium that connects to the myocardium.

Sub-endocardium

The ____ is very thick with involuntary muscle fibers specific to the heart called ____ linked through connections called intercalated discs.

Myocardium

Myocites

The _____ is the outer layer of the heart and produces the pericardial lubricating fluid

Epicardium

The ________ takes blood from the below the diaphragm back to the heart. Movement of the ___ muscles helps squeeze blood up to the heart.

Inferior Vena Cava

Leg

The _____ Takes blood from the upper body to the ____ atrium.

Superior Vena Cava

Right

Another word for oxygen deficit

Ischemia

¼ people have an extra branch off the left circumflex artery called the _______

Posterior Interventricular Artery

The ______ artery supplies the left atrium and left ventricle.

Left Circumflex Artery

The ______ supplies the right ventricle, left ventricle, and interventricular septum.

Left anterior descending artery

The ______ artery supplies the left ventricle.

Left marginal artery

The _____ artery supplies the right ventricle and the apex.

Right marginal artery

The ______ supplies the right atrium and the right ventricle.

Right Coronary Artery

If there is a blockage of blood flow in the coronary arteries the _____ heart layers are most likely to be short on oxygen as blood flows Outside —> Inside.

Inner Heart Layers (Endocardium/Sub-Endocardium)

The term _____ means all through the heart.

Transmural

_______ means pertaining to the inner heart layers.

Sub-endocardium

The ____ ____ of a cell means the difference of charge between the outside and inside.

Resting Potential

The sodium potassium ATPase pump sends out ____ sodium ions for every ___ potassium ions. Keeping the cell steadily negative.

3

2

The normal heart resting potential is about ___ mv.

-90

Phase 0 - Rapid _____

The cell becomes rapidly positive

____ rushes in.

____ channels open.

Charge change: -90mv —> +25mv

Depolarization

Na+

Na+

Phase 1 - Initial ______

Slight drop in voltage.

____ leaves the cell

____ channels close

____ channels briefly open

Charge Change: +25mv —> 0mv

Repolarization

K+

Na+

K+

Phase 2 - ____ Phase

Membrane potential stays steady

____ open and ___ remain open

____ enters the cell while ____ leaves

Charge Change: 0mv

Plateau

Ca 2+ K+

Ca 2+ K+

Phase 3 - Repolarization

The cell returns to its ______

____ continues leaving, ____ channels close

Charge Change: 0mv —> -90mv

Resting State

K+, Ca 2+

Phase 4 - ______ ______ _______

Cell is at rest and ready for the next beat

Na+/K+ ATPase pump maintains ion balance

Most channels close, leaky ____ channels keep resting potential

Charge: -90mv

Resting Membrane Potential

K+

Muscle cells are made up of strands called _____, which contain a unit _____ & _____

Sarcomeres

Actin & Myosin

The ______ has the fastest rate of autorhythmicity so it sets the other cells’ pace too. If it fails the other cells still can set the rate, however it is much ______.

SA Node

Slower

SA Node: ____ beats/min

AV Node: ____ beats/min

Bundle of His/Bundle Branches/ Purkinje Fibers: _____ beats/min

60-100

40-55

25-40

In ____ the ventricles contract.

_____ is the time of ventricular filling.

Systole

Diastole

Pressure changes in the ventricles occur in 4 phases.

Phase 1: _____ Relaxation Phase

Phase 2: _____ ______ Phase

Phase 3: _____ ______ Phase

Phase 4: Rapid _____ _____ Phase

Isovolumic

Ventricular Filling

Isovolumic Contraction

Ventricular Ejection

Isovolumic relaxation happens when the _____ & _____ valves are closed.

Aortic & Mitral

The Maximum & Minimum Pressures in each heart chamber:

Left Ventricle: ___to ___ mm Hg

Right Ventricle: ___ to ___ mm Hg

Aorta: ___ to ___ mm Hg

15 to 120

5 to 25

80 to 120

_____ or LVEDP (Left Ventricular End Diastolic Pressure) is a measure of how much the ventricle wall is stretched at the end of diastole.

Preload

______ is the resistance the left ventricle must overcome to circulate blood.

Afterload

Preload influences ____ ____ which is the amount of blood ejected from each ventricle during systole.

Stroke Volume

____ ____ is the amount of blood the heart pumps per minute.

____ ____ = HR x SV

____ ____ = HR x End diastolic volume - End systolic volume

Cardiac Output

The _____ _____ period is a pause button on the heart’s ability to be re-stimulated and contract again.

Also, when the cell membrane’s sodium and calcium channels are inactive.

Absolute Refractory

The paper used on an ECG is designed so that each tiny square is 1mm in width and equal to ___ seconds and each 1mm in height is equal to ___ milivolts.

0.04

0.1

The P wave represents _____ ______ and the electrical activity seen when the atria ______ or begin to contract.

Atrial Diastole

Depolarize

The T wave ends with ventricular _______ and _______.

Repolarization and Systole

The width of the ____ is typically narrow representing ventricular _____ and knowing if the _____ is working right.

QRS Complex

Depolarization

AV Node

The _____ nervous system (responsible for “fight or flight”) can rapidly increase the heart rate while the _____ nervous system can ____ it.

Sympathetic

Parasympathetic

Slow

It is called a “Vagal Brake” when the ______ from the parasympathetic nervous system influences the heart to reduce its pace.

Vagus Nerve

_____ means anything can change the heart rate.

Chronotropy

______ refers to the strength/force of heart contraction.

Inotropy

_____ refers to the velocity of electricity through the heart’s conduction system.

Dromotropy