Physiology Flashcards

1
Q

Cardiac output equation

A

CO=SV x HR

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2
Q

Fick principle

A

CO=rate of O2 consumption/ arterial O2 content - venous O2 content

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3
Q

Mean Arterial Pressure (MAP) equation

A

MAP = CO x TPR (total peripheral resistance)

MAP= 2/3 diastolic pressure + 1/3 systolic pressure

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4
Q

pulse pressure equation

A

PP=systolic pressure -diastolic pressure

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5
Q

pulse pressure is proportion to

A

Stroke Volume

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6
Q

pulse pressure is inversely proportional to

A

arterial compliance

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7
Q

what are examples of pulse pressure being proportional to SV

A

increase PP in hyperthyroidism, aortic regard, aortic stiffening (isolated systolic hypertension in elderly), obstructive sleep apnea (increase sympathetic tone), exercise (transient)

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8
Q

what are examples of pulse pressure being inversely proportional to aortic compliance

A

decrease PP in aortic stenosis,, cardiogenic shock, cardiac tamponade, advanced heart failure

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9
Q

Stroke volume equation

A

SV = EDV - ESV

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10
Q

how is CO maintained in the early stages of exercise?

A

by increase in HR and increase in SV

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11
Q

how is CO maintained in the late stage of exercise?

A

increase in HR ONLY (SV plateaus)

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12
Q

Diastole is preferentially shortened with

A

increase HR; less filling time –> decrease CO (ex: V tach)

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13
Q

stroke volume is affected by what variables

A

Contractility, after load and preload

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14
Q

an increase in SV is seen with:

A

an increase in contractility and preload, but a decrease in afterload

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15
Q

what are examples of increased contractility

A

exercise pregnancy anxiety

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16
Q

a failing heart has an increase or decreased SV

A

decreased

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17
Q

Contractility (and SV) increases with:

A

Catecholamines, increase intracellular Ca2+, decrease extracellular Na+, digitalis

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18
Q

contractility (and SV) decrease with:

A

B1 blockade, HF with systolic dysfunction, acidosis, hypoxia/hypercapnia, Non-dihydropyridine Ca2+ channel blockers

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19
Q

and increase in myocardial oxygen demand is increased by:

A

increase in contractility, increase in after load, increase in hr, increase in diameter of ventricle (increase in wall tension)

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20
Q

what law does wall tension follow?

A

Laplaces law

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21
Q

What is laplace’s law

A

wall tension: Pressure x Radius / 2 x thickness

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22
Q

preload is approximated by what variable?

A

ventricular EDV

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23
Q

after load is approximated by what variable?

A

MAP

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24
Q

preload depends on:

A

venous tone and circulating blood volume

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25
Q

what drugs will decrease preload?

A

Venodilators (ex: nitroglycerin)

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26
Q

what drugs will decrease after load?

A

Vasodilators (ex: hydralazine)

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27
Q

if you have an increase in after load you will see and increase in what else?

A

increase after load–> increase pressure –> increase wall tension

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28
Q

how does the LV compensate for an increase after load

A

lv compensates for an increase afterlaod by thickening (hypertrophy) in order to decrease wall tension

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29
Q

what drugs will decrease both after load and preload?

A

ACEi and ARBs

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30
Q

if you have chronic hypertension (increase MAP)

A

increase LV hypertrophy

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31
Q

Ejection Fraction

A

EF= SV/EDV= EDV-ESV/EDV

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32
Q

what is a normal ejection fraction?

A

> 55%

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33
Q

Left ventricular EF is an index of

A

ventricular contractility

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34
Q

does ejection fraction increase or decrease in systolic HF?

A

decreases

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35
Q

does ejection fraction increase or decrease in diastolic HF?

A

normal

36
Q

Force of contraction is proportional to end diastolic length of cardiac muscle fiber (preload)

A

True

37
Q

how can you increase contractility?

A

digoxin, catecholamines

38
Q

how can you decrease contractility?

A

mi, b blockers, nondihydropyrdinine Ca channel blockers, dilate cardiomyopathy

39
Q

resistance presssure flow equation

A

change in P = Q x R

40
Q

Ohm’s law

A

change in V = IR

41
Q

volumteric flow rate equation

A

change in Q= V (flow velocity) x A (cross-sectional area)

42
Q

resistance equation

A

change in P / Q = 8n x Length / (pi)r^4

43
Q

Total resistance of vessels in series

A

TR= R1 +R2 +R3…

44
Q

Total resistance of vessels in parallel

A

1/TR=1/R1+1/R2+1/R3….

45
Q

viscosity depends on

A

hematocrit

46
Q

when do you see an increase in viscosity

A

hyperproteinemic states (multiple myeloma) or polycythemia

47
Q

when do you see a decrease in viscosity?

A

anemia

48
Q

Capillaries have the highest total cross-sectional area and lowest flow velocity

A

TRUE

49
Q

what changes will you see in TPR and CO when removing an organ, for example in nephrectomy

A

increase in TPR, decrease in CO

50
Q

who accounts for most of TPR

A

arterioles

51
Q

who provides most of blood storage capacity?

A

veins

52
Q

who provides most of blood storage capacity?

A

veins

53
Q

isometric contraction

A

period between mitral valve closing and aortic valve opening

period of highest O2 consumption

54
Q

systolic ejection

A

period between aortic valve opening and closing

55
Q

isovolumetric relaxation

A

period between aortic valve closing and mitral valve opening

56
Q

rapid filling

A

period just after mitral valve opening

57
Q

reduced filling

A

period just before mitral valve closing

58
Q

S1

A

mitral and tricuspid valve closure

loudest at mitral area

59
Q

S2

A

aortic and pulmonary valve closure

loudest at left upper sternal border

60
Q

S3

A

in early diastole during rapid ventricular filling phase

61
Q

Which S sound is associated with increase filling pressured more common in dilated ventricles?

A

S3

62
Q

S4

A

in late diastole (“atrial kick”

63
Q

which S sound is best heard at apex with patient in left lateral decubitus position?

A

S4

64
Q

Which S sound is associated with a high atrial pressure, ventricular hypertrophy ( left atrium must push against LV wall)?

A

S4

65
Q

a wave

A

atrial contraction

66
Q

when do you see an absent a wave?

A

afib

67
Q

c wave

A

RV contraction (closed tricuspid valve bulging into atrium)

68
Q

x descent

A

atrial relaxation and downward displacement of closed tricuspid valve during ventricular contraction

69
Q

when is X descent absent

A

in tricuspid regurg

70
Q

v wave

A

increase right atrial pressure due to filling against closed tricuspid valve

71
Q

y descent

A

RA emptying in RV

72
Q

R to L shunt description

A

early cyanosis; “blue babies”, diagnosed prenatally or immediately after birth

usually require surgery/correction and/or maintenance of a PDA

73
Q

examples of a R to L shunt

A

THE 5 T’s:

  1. Truncus Arteriosus
  2. Transposition
  3. Tricupsid Atresia
  4. Tetralogy of Fallot
  5. TAPVR
74
Q

Persistent Truncus Arteriosus

A

failure of the Truncus Arterioles to divide into Ascending aorta and pulmonary trunk due to failure of Aorticopulmonary septum to form

most puts have accompanying VSD

75
Q

D-Transposition of great vessels

A

Due to failure of the aorticopulmonary septum to spiral, causing the Aorta to leave from the Right ventricle and the Pulmonary trunk to leave from the left ventricle, in turn this causes a separationg of the pulmonary and systemic circulations

this is not compatible with life unless a shunt is created to allow the mixing of blood (ex: VSD, patent foramen ovale or PDA)

without surgical intervention most infants die within a few months of life!

76
Q

Tricuspid atresia

A

absence of a tricuspid valve and hypoplastic RV

requires both ASD and VSD for survival!

77
Q

Tetralogy of fallot

A

caused by anterosuperior displacement of the infundibular septum

78
Q

which congenital heart disease is the most common cause of early childhood cyanosis?

A

TOF

79
Q

what are the 4 defects seen in TOF?

A

PROV

  1. Pulmonary infundibular stenosis (most important determinant factor for diagnosis)
  2. Right ventircualr hypertrophy- boot shaped heart on CXR
  3. Overriding aorta
  4. VSD
80
Q

what causes the early cyanotic get spells and RVH in TOF?

A

pulmonary stenosis forces R to L flow across VSD

81
Q

What improves cyanosis in TOF?

A

squatting

82
Q

how does squatting improve cyanosis in TOF?

A

increase in SVR , decrease in R to L shunt†

83
Q

how does squatting improve cyanosis in TOF?

A

increase in SVR , decrease in R to L shunt

84
Q

how does squatting improve cyanosis in TOF?

A

increase in SVR , decrease in R to L shunt

85
Q

TAPVR

A

Pulmonary veins drain into right heart circulation (SVC, coronary sinus, etc)

associated with ASD and sometimes PDA to allow for R to L shunting to maintain CO