Fill-in-the-Blank 2024 Pumping action of heart-Cardiac Cycle

atria

I. Function of the __

AV valves; atria; ventricles

A. When __ __ are open, most blood returning to __ pass right through to the __ (60-90% of blood)

atria; ventricles

B. When __ do contract, they push more blood into __ (10-40%)

atria

C. __ function to enhance the amount of blood in __, which enhances ventricular pumping

ventricles

II. Function of the __

A. Pump blood through pulmonary circulation (right) and systemic circulation (left)

valves

III. Function of __

valves

A. __ open and close passively

valves

1. Forward pressure gradient opens __

valves

2. Backward pressure gradient closes __

AV valves; atria; ventricles

B. Papillary muscle and chordae tendinae of __ __ prevent cusps from protruding into __ as __ contract

ventricles

1. Damage to chordae tendineae or papillary muscle can result in backward flow of blood as __ contract

Semilunar valves

2. __ __ DO NOT have chordae tendineae or papillary muscle

cardiac cycle; cardiac cycle

IV. Phases of __ __-the __ __ refers to the sequence of events (electrical and mechanical) occurring in the heart during a single beat.

cardiac cycle

(Be able to describe all events taking place at any given point on the __ __ figure)

(Described for the left side of the heart; although the same events occur on the right side almost simultaneously)

A. Atrial contraction

1. AV valve is open; atrium pumps blood into ventricle

2. Active filling of ventricle

B. Period of isovolumetric contraction-

1. Ventricle begins to contract- once pressure in ventricle exceeds that of atrium, the AV valve will close

2. This period of contraction while the AV valve and semilunar valve are closed is the isovolumetric contraction phase

3. Once the pressure in the ventricle exceeds that of the aorta (arterial pressure) then the semilunar valve will open—leading to the ejection phase

C. Period of ejection

1. As ventricular pressure rises above arterial pressure, semilunar valve opens and blood is ejected out of ventricle

D. Period of isovolumetric relaxation

1. Ventricle begins to relax; pressure begins to drop within ventricle

2. As pressure drops below arterial pressure, semilunar valve closes

valves; semilunar valves

3. This period of relaxation while both __ (AV and __ __) are closed is the isovolumetric relaxation phase

4. Ventricle continues to relax and eventually the pressure drops below that of atrium and therefore the AV valve opens leading to the ventricular filling phase

E. Ventricular filling

1. Passive filling of ventricle

Case Study (Volume-Pressure Loops):

Case Study (Volume-Pressure Loops):

V. Terminology and definitions (values in parenthesis are normal resting values; you do need to know these)

V. Terminology and definitions (values in parenthesis are normal resting values; you do need to know these)

systole; diastole; ventricles

A. __ and __ (unless specified, usually refers to contraction or relaxation of the __)

systole; cardiac cycle

1. __: Contraction phase of __ __

diastole; cardiac cycle

2. __: Relaxation phase of __ __

NOTE: Systolic blood pressure (SBP) = the pressure in the systemic arteries while the left ventricle is contracting and ejecting blood (120 mmHg); Diastolic blood pressure (DBP)= the pressure in the systemic arteries while the left ventricle is relaxing and not ejecting blood (80 mmHg)

NOTE: Pulse pressure is the difference between the systolic and diastolic pressures (SBP-DBP= pulse pressure)

end diastolic volume

B. __ __ __ (EDV)

diastole

1. The volume of blood in the ventricle at the end of __ (110 ml)

2. In other words, the amount of blood in the ventricle once it is filled just before it contracts

venous return

3. __ __ is an important determinant of EDV

end systolic volume

C. __ __ __ (ESV)

systole

1. The volume of blood in the ventricle at the end of __ (40 ml)

2. In other words, the amount of blood remaining in the ventricle after it has contracted and ejected blood.

stroke volume

D. __ __ (SV)

1. The volume of blood pumped out of the ventricle per contraction (70 ml)

preload; afterload; contractility

2. Determined by __, __, and __

ejection fraction

E. __ __

1. The fraction of EDV that was pumped out of the left ventricle per contraction (60%)

2. SV/EDV x 100= EF

cardiac output

F. __ __ (CO, Q)

1. The amount of blood pumped out of the left ventricle per minute

cardiac output; stroke volume

2. __ __ = heart rate x __ __ (5000 ml)

venous return

G. __ __

1. The amount of blood returned to the heart (right atrium) from the systemic circulation

preload

H. __

diastole

1. The ventricular wall stress before it contracts (at the end of __)

2. As the muscle stretches, the stretching induces length-dependent activation of the contractile apparatus leading to greater strength of contraction

preload; preload

3. In other words, __ is the stretched state of the ventricle before it contracts; the greater the stretch, the greater the __… so when it contracts it will contract with greater force

preload

4. __ is determined primarily by EDV

afterload

I. __

1. The pressure that the ventricle has to produce to eject blood

afterload; afterload

2. Aortic pressure is an important determinant of the __ of the left ventricle; pulmonary pressure is an important determinant of the __ of the right ventricle

3. As aortic pressure increases, such as when a patient has systemic hypertension, the left ventricle has to produce higher pressures (produce more tension; work harder) in order to eject blood into the aorta against that higher pressure

afterload

4. Therefore, it can be said that as aortic pressure (arterial pressure) increases, the __ of the left ventricle increases

contractility

J. __ (Inotropy)

1. The intrinsic ability of cardiac muscle to produce tension, independent of fiber (sarcomere) length

contractility; contractility

2. A change in the force of contraction at a constant end-diastolic fiber length reflects a change in __ (anything that affects excitation-contraction, other than sarcomere/fiber length, affects __)

contractility; contractility

3. Intracellular Ca2+ concentration is an important determinant of __; under normal physiological conditions, it is primarily the changing intracellular Ca2+ that will alter __ throughout the day.

contractility

Anything that produces an increase in intracellular Ca2+ concentration in cardiomyocytes, such as norepinephrine (SNS), will increase __

preload; contractility

(NOTE 1: An increase in __ or an increase in __ will each increase the strength of contraction, however, they do it by different mechanisms- one is dependent on stretch and the other is not dependent on stretch)

K. Lusitropy

1. Rate of myocyte relaxation

2. Physiologically, determined by the rate that the Ca++ is sequestered back out of the cytosol

chronotropic

L. __ effect

1. Affecting heart rate

inotropic

M. __ effect

contractility

2. Affecting __

cardiac reserve

N. __ __

1. The work that the heart is able to perform beyond that required of it under basal/resting conditions (the heart can usually increase its work by 300-400%…for example, when you go from resting to exercising)

pressure-rate product

O. __-__ __ or Double Product

1. An indirect index of myocardial O2 consumption (how hard the ventricle is working)

2. HR x SBP (or MAP)

VI. Heart sounds

VI. Heart sounds

S1; S2

A. Lub-dub (__ & __)

S1; AV valves

B. __: closing of __ __

S2; semilunar valves

C. __: closing of __ __

ejection fraction

EF = __ __ = SV/EDV

stroke volume

SV = __ __ = EDV-ESV

end diastolic volume

EDV = __ __ __

end systolic volume

ESV = __ __ __

afterload

Increased __ = decreased SV