Cardiac cycle Flashcards

1
Q

Illustrate the sequence of changes in pressure and volume in the chambers of the heart throughout the cardiac cycle.

A
  1. late diastole- both sets of chambers are relaxed and ventricles fill passively.
  2. atrial systole- atrial contraction forces a small amount of additional blood into ventricles
  3. isovolumetric ventricular contraction- ventricle contraction pushes AV valves closed but doesnt creat enough pressure to open semilunar valves
  4. ventricular ejection- as ventricular pressure rises and exceeds pressure in arteries the semilunar valves open and blood is ejected.
  5. isovolumetric ventricular relaxation- ventricles relax, pressure falls. blood falls back into cusps of semilunar valves and snaps them closed and cycle repeats
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2
Q

Interpret a pressure-volume loop.

A
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3
Q

Explain the generation of the heart sounds (phonocardiogram).

A
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4
Q

what is the diastole phase

A

filling of atrium or ventricles

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5
Q

what is the systole phase

A

ejection phase of atrium or ventricles

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6
Q

what is the a wave

A

atrial contraction

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7
Q

what is the c wave

A

when mistrial valve closes and because its quite flappy it will budge into the left atrium increasing pressure

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8
Q

what is the V wave

A

blood returning from lungs into the left atrium which has a low volume so when blood flows in pressure gradually increases and increases

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9
Q

what is pulse pressure

A

difference between diastolic and systolic of the aorta

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10
Q

what is mean arterial pressure

A

is a third of the way between diastolic and systolic

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11
Q

what is the dicrotic notch

A

It is universally used to demarcate the end of systole and the beginning of diastole in these arteries. Due to the elastic properties of the aorta it decreases slowly

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12
Q

what is it called between the distance of end systolic volume to end of diastolic volume

A

stroke volume however mainly is affected by size of the person

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13
Q

what is the ejection fraction

A

stroke volume divided by the end diastolic volume which is a percentage of the blood in the ventricle pumped out with each contraction. in an unhealthy person this would be below 60%

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14
Q

describe isometric contraction phase

A

mitral and aortic values are closed

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15
Q

describe rapid ejection phase

A

pressure in left ventricle exceeds pressure on the aorta and pushes aortic value open and blood is pumped out of left ventricle quickly so volume is decreased rapidly

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16
Q

isometric relaxation phase

A

mistrial and aortic values closed again

17
Q

rapid filling phase

A

pressure in left atrium exceeds left ventricle causing mitral value to open and blood is pushed from left atrium to left ventricle quickly.

18
Q

what side of the heart has a higher pressure

A

right side is only 1/5 of the left as only pumping into pulmonary circulation

19
Q

describe the phonocardiogram

A
  1. closure of the AV valves
  2. closure of the semi-lunar valves
  3. rapid passive filling phase
  4. active filling phase

heart sounds are caused by turbulence of blood flow. All heart valves are passive and open and close due to changes of pressure in the heart

20
Q

describe a systolic murmur

A

stenosis or narrowing of the aortic or pulmonary valves causing turbulence or regurgitation of blood through mitral or tricuspid valves (LUB SHHH DUB)

21
Q

describe a diastolic murmur

A

stenos of mitral and tricuspid valves or regurgitation from the aortic or pulmonary valves (LUB DUB SHH)

22
Q

normla phonocardiogram

A

lub systole dub diastole

23
Q

continuous murmur

A

Begins in the systole and is continuous. Could be patent ductus arteriosus.