Heart Muscle Memory Terms

Front 1

syncytium

Back 1

a multinucleate mass of protoplasm produced by the merging of cells.

Front 2

Hematocrit

Back 2

The hematocrit is the fraction of the blood composed of red blood cells.

Front 3

What are normal values of Hematocrit?

Back 3

Hematocrit = 40 to 45 %, RBC's 4 to 6 million per ul.

Front 4

End diastolic volume

Back 4

During diastole, normal filling of the ventricles increases the volume of each ventricle to about 110 to 120 milliliters. This volume is called the end-diastolic volume.

Front 5

End systolic volume

Back 5

The remaining volume in each ventricle, about 40 to 50 milliliters, is called the end-systolic volume.

Front 6

stroke volume output

Back 6

As the ventricles empty during systole, the volume decreases about 70 milliliters.

Front 7

Afterload

Back 7

the load against which the muscle exerts its contractile force.

The afterload of the ventricle is the pressure in the artery leading from the ventricle.

Sometimes the afterload is loosely considered to be the resistance in the circulation rather than the pressure.

Front 8

preload

Back 8

it is important to specify the degree of tension on the muscle when it begins to contract, which is called the preload

Front 9

Stroke work output

Back 9

The stroke work output of the heart is the amount of energy that the heart converts to work during each heartbeat while pumping blood into the arteries.

Front 10

Minute work output

Back 10

Minute work output is the total amount of energy converted to work in 1 minute; this is equal to the stroke work output times the heart rate per minute.

Front 11

Ejection Fraction

Back 11

The fraction of the end-diastolic volume that is ejected is called the ejection fraction—usually equal to about 60 per cent.
(EDV-ESV)/EDV * 100

Front 12

Filling Pressure

Back 12

The greater the volume of blood in the circulation, the greater is the mean circulatory filling pressure because extra blood volume stretches the walls of the vasculature. The red curve in Figure 20–10 shows the approximate normal effect of different levels of blood volume on the mean circulatory filling pressure. Note that at a blood volume of about 4000 milliliters, the mean circulatory filling pressure is close to zero because this is the “unstressed volume” of the circulation, but at a volume of 5000 milliliters, the filling pressure is the normal value of 7 mm Hg. Similarly, at still higher volumes, the mean circulatory filling pressure increases almost linearly.

Front 13

Diastasis

Back 13

The last stage of diastole in the heart, occurring just before contraction and during which little additional blood enters the ventricle.

Front 14

Heart rate

Back 14

Number of heart beats per minute.

Front 15

Cardiac Output (CO)

Back 15

The amount of blood from each ventricle pumped per minute.

CO (volume/minute) = SV (volume/beat) * HR (beats/minute)

Front 16

Cardiac Reserve

Back 16

The maximum percentage that the cardiac output can increase above normal is called the cardiac reserve. Thus, in the healthy young adult, the cardiac reserve is 300 to 400 per cent. In athletically trained persons, it is occasionally 500 to 600 per cent. But in heart failure, there is no cardiac reserve.

Front 17

Cardiac Index

Back 17

cardiac output is frequently stated in terms of the cardiac index, which is the cardiac output per square meter of body surface area. The normal human being weighing 70 kilograms has a body surface area of about 1.7 square meters, which means that the normal average cardiac index for adults is about 3 L/min/m2 of body surface area.

Front 18

Mean arterial pressure

Back 18

The mean arterial pressure (MAP) is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle.

MAP= ( CO * SVR ) + CVP
CO is cardiac output
SVR is systemic vascular resistance
CVP is central venous pressure

Front 19

Pulse Pressure

Back 19

The difference between systolic and diastolic pressure.

In the healthy young adult, the pressure at the top of each pulse, called the systolic pressure, is about 120 mm Hg. At the lowest point of each pulse, called the diastolic pressure, it is about 80 mm Hg. The difference between these two pressures, about 40 mm Hg, is called the pulse pressure.

Front 20

Incisura

Back 20

A so-called incisura occurs in the aortic pressure curve when the aortic valve closes. This is caused by a short period of backward flow of blood immediately before closure of the valve, followed by sudden cessation of the backflow.

Front 21

Dicrotic notch

Back 21

The acute drop in arterial pressure pulse curves following the systolic peak, corresponding to the incisura of the displacement pulse curve.

Front 22

Diastole

Back 22

a period of relaxation called diastole in the cardiac cycle.

Front 23

Systole

Back 23

A period of contraction in the cardiac cycle.

Front 24

Hyperpolarization

Back 24

Furthermore, the potassium channels remain open for another few tenths of a second, temporarily continuing movement of positive charges out of the cell, with resultant excess negativity inside the fiber; this is called hyperpolarization. The hyperpolarization state initially carries the “resting” membrane potential down to about -55 to -60 millivolts at the termination of the action potential.

Front 25

Hyperpolarization

Back 25

Furthermore, the potassium channels remain open for another few tenths of a second, temporarily continuing movement of positive charges out of the cell, with resultant excess negativity inside the fiber; this is called hyperpolarization. The hyperpolarization state initially carries the “resting” membrane potential down to about -55 to -60 millivolts at the termination of the action potential.

Front 26

Depolarization

Back 26

In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations. The rising and falling phases of an action potential are often imprecisely called depolarization and hyperpolarization, respectively.

Front 27

Repolarization

Back 27

In neuroscience, repolarization refers to the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value. Repolarization results from the movement of positively charged potassium ions out of the cell. Typically the repolarization phase of an action potential results in hyperpolarization, attainment of a membrane potential that is more negative than the resting potential.

Front 28

The EKG wave forms

Back 28

P, Q, R, S, T

Front 29

Atrial Pressure waves

Back 29

a, c, & v waves