Cardiac Cycle

Front 1

What happens when Atrial Systole begins (A)??

Back 1

Atrial contraction forces a small amount of

additional blood into relaxed ventricles

Front 2

What happens when atrial systole ends (B)?

Back 2

Atrial Diastole begins

Front 3

What happens during Ventricular Systole

(C, 1st phase)?

Back 3

- 1ST PHASE

- Ventricular

contraction pushes AV valves closed but does not create enough pressure to open the semilunar valves

Front 4

What happens during Ventricular Systole (D, 2nd phase) ?

Back 4

As ventricular pressure rises and exceeds the pressure in the arteries , the semilunar valves open and blood is ejected

Front 5

What happens during Ventricular Diastole

(early ,E) ?

Back 5

As the ventricles relax :

- the pressure in the ventricles drops

- blood flows back against the cusps of

semilunar valves and forces them closed.

- Blood flows into the relaxed atria

Front 6

What happens during Ventricular Diastole (late, F)?

Back 6

All chambers are

relaxed , ventricles fill passively

Front 7

One cardiac cycle lasts roughly how long?

Back 7

roughly 800 seconds for entire cycle

Front 8

Timing is everything , because we need to have what?

Back 8

need to have pressure differences, for blood to flow from high pressure to low pressure

Front 9

What is a cardiac cycle?

Back 9

beginning of one heart beat to the next.

Includes a cycle of contraction and relaxation

Front 10

When will blood only move?

Back 10

Blood will only move from one chamber to the next

- if the pressure in the 1st chamber exceeds the pressure in the second

Front 11

What is boyle's law?

Back 11

Inverse relationship

between pressure and

volume

Front 12

Change in pressure gradient creates

a change in?

Back 12

Creates a change in volume and drives

blood flow

Front 13

What are the opposing pressures , in the heart?

Back 13

- Atria

- Ventricles

- Large arteries

Front 14

As volume increases ,

what happens to pressure?

Back 14

Pressure decreases

Front 15

As volume decreases what happens to

pressure?

Back 15

Pressure Increases

Front 16

How is cardiac output determined?

Back 16

HR x stroke volume = cardiac output

Front 17

If someone had a resting heart rate of 70 BPM and the average stroke volume is 70 mL per beat.

What is the cardiac output?

Back 17

70 X 70 = 4,900 mL / min

Front 18

If we say this is the demand for the cells for the tissues of the body. You have a stroke volume of 100 , but still need 5,000 ml/ min

distributed.

What can happen to the HR?

Back 18

- we know stroke volume is 100

divide cardiac output 5,000 by 100

= 50 for HR

Front 19

What happens during Diastasis?

Back 19

- All four chambers are relaxed

- AV (mitral and tricuspid) valves open and blood flows into ventricles

- Heart sound 3 occurs from blood "pouring" into ventricles

- 80 percent of ventricular filling occurs

passively ( occurs in TP segment)

Front 20

The cardiac cycle is 800 msec total ,

has how many msec during diastasis?

Back 20

430 sec of diastasis

Front 21

During Diastasis all chambers are relaxed and blood is coming back to?

Back 21

Blood is coming back to the Atria through the veins.

Blood accumulates in the Atria and eventually that volume gets so large that it opens b/c of pressure. And blood continues to fill.

Front 22

When heart is healthy it could eject a good?

Back 22

Stroke volume , because they could afford more time in between beats and perfuse

Front 23

80 % of ventricular filling occurs passively.

During what segment does this occur?

Back 23

TP segment

Front 24

During diastasis , as blood comes back from the Atria to the veins:

- Blood accumulates where?

Back 24

- Blood accumulates in the Atria ,

eventually volume gets so large that it opens av valves b/c

of pressure

Front 25

During Diastasis, when AV valves are pushed open , it continues to pour into the?

- What occurs during this time?

Back 25

- Continues to pour into the ventricles

- 80 percent of ventricular filling occurs

during this time "passive filling"

Front 26

What is the most important segment to watch on an EKG for your patient's heart health?

Back 26

T-P segment

Front 27

If we have a long T-P segment , what does this mean?

Back 27

- more time for filling and more time for

perfusion

Front 28

When cardiocytes "remodel" , what does this mean?

Back 28

When cardiocytes "remodel" (hypertrophy) equally bigger in width as they do in height = more contractile proteins

Front 29

What happens during Atrial Systole?

Back 29

- SA node fires , atria depolarizes

- P wave = atria will contract

- Atrial contraction forces final 20 % percent of blood into ventricles

- EDV (end diastolic volume, avg 120 mL)

- heart sound 4 occurs (turbulence caused by inrush of blood into ventricles)

Front 30

A p-wave on the EKG means?

Back 30

Atria will contract

Front 31

20 % of ventricular filling is also going to cause what two things?

Back 31

1. Turbulent flow

2. Causes heart sound 4

Front 32

All four valves can never be?

Back 32

opened!!

Front 33

What happens during isovolemic contraction of the ventricles?

Back 33

- Atria repolarize and relaxes,

ventricles depolarize= QRS complex

- Ventricles initiate contraction

- Rising pressure closes AV valves

- No ejection of blood yet (no change in

volume)

- Heart sound 1 (S1) occurs (turbulence against AV valves)

Front 34

AV valves stands for?

Back 34

atrioventricular valves

- mitral = left valve , bicuspid

- tricuspid = right valve

Front 35

Where do you hear heart sound 1(S1)?

Back 35

- During isovolemic

contraction of the ventricles

- turbulence against AV valves

Front 36

Where is QRS coming from?

Back 36

From two bundle branches spiking AP down the IV septum

Front 37

Where does the Q wave come from?

Back 37

Comes from Right bundle branch, that has a weird turn to it (anatomical bend) , explains downward electrode of Q

Front 38

What does the R wave represent?

Back 38

Overall current going down to the left, towards the Apex of the heart

Front 39

When Purkinje fibers are carrying AP to the Right myocardial wall in the ventricle and

the Left myocardial wall.

What are the differences?

Back 39

Right side of heart ,myocardial wall =

- 1/7 of resistance compared to the left and has the same volume out (70 mL), just doesn't have to work as hard!

Left side of heart =

- Thicker than the right

- Has to generate greater force to push blood to the entire body. A lot of resistance , heart has to work harder

Front 40

What happens during Ventricular Ejection?

Back 40

- Semilunar (aortic and pulmonary artery) valves open

b/c of rising pressure

- Stroke volume (SV , amount ejected) = 70 mL

- Rapid and Reduced ejection phases

- SV / EDV = Ejection Fraction

- End-systolic Volume (ESV) = amount left in heart = 50 mL

Front 41

Stroke Volume divided by

End Diastolic Volume =

Back 41

SV / EDV = ejection fraction

Front 42

What is End- Systolic Volume (ESV) ?

Back 42

- Amount left in the heart

- 50 mL

Front 43

What happens during Isovolemic Relaxation of ventricles?

Back 43

- T wave appears on EKG=

Ventricles repolarize

- Semilunar valves close

- AV valves remained closed

- Ventricles expand but do not fill

- heart sound 2 (S2) =

turbulence against semilunar valves

Front 44

In isovolemic relaxation , what do you see on the EKG?

What heart sound do you hear , during this phase?

Back 44

T wave and Heart sound 2 (S2)

Front 45

During Heart sound 2 (S2) , what happens during this time?

Back 45

Turbulence against semilunar valves

Front 46

What happens during Ventricular Filling?

Back 46

- AV valves open

- 3 phases of filling :

1. Rapid Ventricular Filling

2. Diastasis

3. Filling completed by atrial systole

- Heart sound 3 (S3) may occur (in rushing blood against ventricular walls)

Front 47

Where does heart sound 3 occur?

Back 47

During ventricular filling

Front 48

What is cardiac output?

Back 48

The amount of blood

ejected by ventricles per minute

Front 49

Normal resting value of Cardiac output is?

Back 49

4 to 6 L/min

Front 50

Vigorous exercise increases Cardiac output to?

Back 50

21 L /min

*for a fit person

Front 51

If someone was a world class athlete, their

Cardiac output would be?

Back 51

35 L/ min

Front 52

A couch potato gets 50 mL out instead of 70 mL. Whats their HR to reach 5,000?

Back 52

100 BPM for HR

Front 53

The heart has to compensate to?

Back 53

To meet the demands of the body

Front 54

When a heart has less time to fill ,

What happens?

Back 54

The heart works harder and it has less time to be perfused

Front 55

After you workout , your heart has what two things?

Back 55

- muscle mass that can generate a great force of contraction

- eject a greater stroke volume

Front 56

If you don't workout , what happens to your heart?

Back 56

- The heart has to compensate , it has less time to fill , heart is working harder

- has less time to perfuse (

T-P segment shortened)

Front 57

A person has a stroke volume of 100 mL and still needs 5,000 mL/min distributed. What can happen to their HR?

Back 57

HR would decrease

- 100 times ____ = 5,000 mL

- 100 (SV) x HR = CO

100 x 50 = 5,000

HR is 50 BPM

Front 58

End diastolic volume (EDV) mL?

Back 58

120 mL

Front 59

End Systolic Volume (ESV) mL?

Back 59

50 mL

Front 60

Ejection Volume also known as?

how many mL?

Back 60

also known as stroke volume

70 mL

Front 61

How can you find ejection volume?

Back 61

120 - 50 = SV or ejection volume

(EDV) (ESV)

Front 62

What is ejection fraction?

Back 62

Ejection volume (SV) / EDV

70 mL / 120 mL = 58 % normally 60 %

Front 63

If HR is 70 BPM , What is the cardiac output?

Back 63

70 beats/min * 70mL/min = 4900 mL/min

(HR) (SV)

Front 64

Stroke volume is affected by?

Back 64

EDV and ESV

Front 65

What does End Diastolic Volume depend on?

Back 65

- VENOUS RETURN

- Filling time (diastole)

- Skeletal pumping (muscular pressure exerted on veins)

- Respiratory pumping ( lower intrathoracic pressure during inspiration takes blood into atria)

Front 66

What is Venous return?

Back 66

the rate of blood flow into the heart from veins

Front 67

What is part of the intrinsic regulation ( aka regulation of heart pumping)?

Back 67

1. EDV

2. ESV

3. Frank sterling mechanism

Front 68

End Systolic Volume (ESV) depends on?

Back 68

- Preload (frank-sterling principe)

- Contractility of the Ventricle

- Afterload

Front 69

What is Preload?

Back 69

- degree of muscle tension ,

when it begins to contract

- frank-sterling mechanism

(more in , more out)

Front 70

What is Contractility of the Ventricle?

Back 70

- Availability of calcium

- positive or negative inotropy(rare)

Front 71

What is Afterload?

Back 71

- Contractile force needed for ejection

- affected by peripheral vasculature

Front 72

A high stroke volume results in?

Back 72

LOW ESV (end systolic volume)

Front 73

What is the Frank-sterling mechanism?

Back 73

- More in , more out

- Within physiological limits, the heart pumps all the blood that comes to it without excessive damning in the veins

Front 74

In frank-sterling mechanism, length-tension

relationship of cardiocytes is?

Back 74

- Extra stretch on cardiac myocytes makes actin and myosin filaments interdigitate to a

more optimal degree for force of generation

Front 75

What happens to cardiac cycle when HR

increases?

Back 75

- all phases are shortened

- Diastole is shortened the most ( TP segment on EKG)

- reduced by almost 75 % at 200 BPM

- Reduced Diastole = less time to fill

Front 76

What drugs affect the Cardiac Output , HR and Stroke volume?

Back 76

1. Atropine

2. Pilocarpine

3. Propanalol

4. Digoxin

Front 77

Atropine

Back 77

- Parasympathetic blocking

-blocks muscarinic AchR agent

(+,+)

Front 78

Pilocarpine

Back 78

- drug that causes cholinergic neurons to release Ach

- since Ach decreases HR , it causes (-,) effect on heart

Front 79

Propranalol

Back 79

- Reversible competitive blocker of

Beta 1 receptor

- Blocks sympathetic effect of heart (-,-)

- decrease HR and force of contraction and lowers BP

Front 80

Where does Digoxin (shorter half life) come from?

Where is it derived from?

Back 80

- come from a group of drugs derived

from digitalis

- derived in turn from foxglove plants

Front 81

What effect does Digoxin have on the heart?

Back 81

Has a (-,+) effect

- Negative chronotropy

- Positive Inotropy

- slows heart rate but increases force

of contraction

(the only drugs with this effect)

Front 82

What is another name for Digoxin?

Back 82

Cardiotonic Glycosides or Cardiac Glycosides

Front 83

How do Cardiac Glycosides (Digoxin)

increase cardiac

contractility?

Back 83

- Glycosides inhibit the

Na / K (sodium potassium) ATPase

- increases intracellular NA+

- decreases NA+ gradient

- decrease NA+ / CA+ counter transport

- increase intracellular CA+

Front 84

Digoxin is used to treat?

Back 84

Heart failure

* has been used for decades and is the only oral inotropic support agent in clinical practice

Front 85

Digitalis is extremely toxic and optimal dose is close to?

Back 85

optimal dose is close to a lethal dose (stops the heart)

Front 86

What are the side effects of

Digoxin (Digitalis toxicity) ?

Back 86

- disturbance in yellow-blue vision , similar to viewing the world through yellow filter

(xanthopsia)

- Glare and colored Haloes ,

(may be experienced as visual side effects)