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Physiology > More heart stuff yayy :( > Flashcards

More heart stuff yayy :( Flashcards

1
Q

What EXACTLY is the cardiac cycle

A

It is the coordinated and consistent contraction (systole) and relaxation (diastole) of the atrial and ventricular functional synctia

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2
Q

What is the total duration of the cardiac cycle

A

0.8 seconds

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3
Q

What are the different phases of cardiac cycle

A
  1. Phase of ventricular filling.
  2. Phase of atrial systole.
  3. Phase of isovolumetric contraction (ventricles contract)
  4. Phase of ventricular ejection.
  5. Phase of isovolumetric relaxation.
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4
Q

What happens in ventricular filling

A
  1. All 4 chambers diastole
  2. AV valves open
  3. Semilunar valves closed
  • Blood enters via large veins into atria, into ventricles
  • First 1/3 of phase= RAPID FILLING PHASE then filling speed decreases, DIASTASIS
    Pressure in the ventricles is 0 mmHg
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5
Q

What happens in the phase of atrial systole

A
  1. SAN fires AP and causes atria to contract then to AVN
    2, More blood enters ventricles
  • pressure right= 4-6mmHg Left=7-8mmHg
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6
Q

The phase of atrial systole is reflected as what wave on the ECG

A

P wave
And PQ interval

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7
Q

What is the volume of blood that is contained in the ventricles at the end of diastole

A

End Diastolic Volume (EDV)

it is abt 130 ml

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8
Q

If theres no valves at the start of the atria, how does the blood not flow back into the venous vessels

A

Bc of circular muscle fibers that contract at the beginning of the Atrial systole

Directs blood to the AV valves

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9
Q

What is the pre ejection period divided into
Use left ventricle as example

A

Asynchronous= when tension starts to develop, not all the left ventricular cardiomyocytes are excited and the whole ventricle hasnt contracted yet Lasts until closure of mitral valve

Isovolumetric contraction= when mitral and aortic valve closed. The intraventricular volume DOES NOT change now

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10
Q

What happens in Phase of isovolumetric contraction

A
  1. ventricular pressure> atrial pressure so valves close
  2. Hear the first heart sound (S1) (closure of AV valves)
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11
Q

Phase of isovolumetric contraction (start of ventricular depolarization) is refelcted as what wav eon the ECG

A

Q wave

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12
Q

What triggers the ejection phase

A

When ventricular pressure reaches diastolic pressure of the large arterial vessels, causes the semilunar valves to open

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13
Q

What happens in the phase of ventricular ejection

A
  1. Stroken volum is ejected out of Aorta/ Pulmonary artery
  2. Pressure in arteries rech max systolic value
    Aorta =125mmHg Pulmonary=25mmHg
  3. Myocardial relaxation begins at the end of ventrcular repolarization
  4. Hear the 2nd heart sound (S2) when semilunar valves close due to drop in intraventricular pressure
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14
Q

Isovolumetric ejection (ventricular repolarization) is reflected as what wave on ECG

A

T wave

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15
Q

After ejection of stroke volume, what is left in ventricles

A

End systolic volume (ESV)

60 ml

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16
Q

What happens in the phase of isovolumetric relaxation

A
  1. Closure of semilunar valves (S2)
  2. Bc of semilunar valve closure, some blood returns to the heart then back to periphery
    Ths causes small peak (on aortic oressure curve) called DICHROITIC WAVE
    Detected by caraotid SPG
17
Q

When does cardiac cycle begin again

A

When AV valves open due to interventricuao pressure being less than atrial pressure

18
Q

ECG AND PCG

A

Records the ELECTRICAL activity of heart during cardiac cycle

Records the SOUNDS of the heart during cardiac cycle

19
Q

How is pulse wave generated

A

By deformation of aortic wall during ventricykar systole

It is transmitted along arterial system

20
Q

What does a carotid sphygmogram register

A

MECHANICAL OSCILLATIONS of arterial wall

21
Q

WHat kind of sensor and where is the carotid sphygmogram placed

A

A piezelectric crystal is used placed on the RIGHT carotid artery

22
Q

Elements of sphygmogram

A

Ao: reflects the opening of aortic valve.

(i) incisure: reflects aortic valve closure.

The P-wave on the anachoretic limb reflects
the maximum pressure in the aorta (systolic
presser).

T-wave (tidal wave), reflects the “summation”
of the pulse wave with reflected pulse waves
from the peripheral part of the vascular
system.

D-wave (dichroitic wave): reflects the blood
that returns to the heart and goes back again
to the periphery, after closer of semilunar
valves during diastole.

23
Q

Where is the peripheral pulse curve (PPC) registered

A

These peripheral pulse oscillations from peripheral blood vessels are registered on one of the fingers or toes

24
Q

What detects the oscillations in the peripheral blood vessels

A

pressure transducer indirectly senses volume change in the area

25
Q

Why do we place the sensors for both sphygmogram and peripheral pulse curve on right side of body

A

Bc of BRACHIOCEPHALIC TRUNK

as thats where the rigt common carotid artery and right subclavian comes from

26
Q

What is the main difference btw carotid SPG and PPC

A

In PPC, opening of aortic valve delayed bc it takes time for pulse wave to propagate to site of registration

Due to this phenomenon, the simultaneous
registration of SPG and PPC allows to determine
the velocity of pulse wave (PWV).

27
Q

What determines the velocity of the Pulse wave

A

It increases w decreasing radius and increasig vessel wall thickness

PWV^2=Eh/2rρ

28
Q

Where is pulse wave velocity lowest and highest

A

low= AORTA

high= ARTERIOLES

29
Q

How to register linear blood velocity using Doppler flowmetry

A

Send ultrasonic waves
Relflected back by cells of blood
Leads to changing of frequency to hearing spectrum

30
Q

3 main things that determine pre ejection period

A

preload (end diastolic volume)

yocardial contractility

Afterload (arterial pressure)

31
Q

Duing isovolumetric period, how does the ventricle change

A

since some cardiomyocytes do change length (isotonic), ventricle:

Becomes more sphercal, circumference increases, base to apex distance decreases

32
Q

When do the aortic valves open in isovolumetric contraction

A

when it reaches diastolic value of arterial presssure

33
Q

Why do we have to work out central time for phase analysis of left ventricle

A

Delay of SPHYGMOGRAM compared to electrocardiogram and phonocardiogram

DELAY DUE TO time required for pulse ave to reach site of sphygmography recording

34
Q
A

Physiology (20 decks)

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