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Physio II > cardiac muscle VOP > Flashcards

cardiac muscle VOP Flashcards

1
Q

vasodilator theory

A

According to the vasodilator theory, the greater the rate of metabolism or the less the availability of oxygen or some other nutrients to a tissue, the greater the rate of formation of vasodilator substances in the tissue cells. The vasodilator substances then are believed to diffuse through the tissues to the precapillary sphincters, metarterioles, and arterioles to cause dilation. Some of the different vasodilator substances that have been suggested are adenosine, carbon dioxide, adenosine phosphate compounds, histamine, potassium ions, and hydrogen ions.

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2
Q

oxygen demand theory

A

oxygen is needed for muscle contraction and in its absence vessels dilate

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3
Q

layers of the heart from out to in (serous pericardium and in )

A

Fibrous pericardium (connective tissue and holds the heart in place)

Parietal layer

then the Epicardium
which is made up of the visceral layer and
the surface of the heart

Myocardium

endocardium

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4
Q

coronary vessels are found in what layer of the heart

A

myocardium

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5
Q

veins bring blood

A

towards the heart

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6
Q

coronary sinus is found where and brings blood from

A

right atrium

collects blood from coronary vessels returning to the myocaridum

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7
Q

right ventricle and right atrium are separated by the

A

tricuspid valve

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8
Q

pulmonary valve is similar to the tricuspid in what way

A

3 cusps but no chordae tendinae

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9
Q

arteries carry blood

A

Away from the heart

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10
Q

atrioventricular valve found on the left side fof the heart is also known as the

A

mitral valve( two cusps)

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11
Q

S1 is what sound

A

the sound of the left and right ventricles contracting and making the LUB sound

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12
Q

S2

A

the sound of the aortic and pulmonic valves closing after blood leaves the ventricle

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13
Q

systole

A

between S1 and S2

occurs when ventricles are squeezing which means higher pressure

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14
Q

diastole

A

when the heart is filling
lower pressure
occurs after S2

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15
Q

amount pumped out of the heart

A

cardiac output

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16
Q

the time it takes for blood to return

A

venous return

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17
Q

vessels that are high volume and low pressure

A

veins

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18
Q

Muscle fibers not linear they are _____

and are lined up ___

A

muscle fibers are interwoven

they are lined up end to end

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19
Q

d. Gap junctions b/w the cells help with what function

A

sharing cytoplasm b/w cells

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20
Q

e. Intercalated discs connect ends when you pull on them,

A

they trigger action potential
ii. When one muscle fiber contracts, it pulls on the adjoining muscle fibers through those intercalated discs and stimulates action potential in the adjoining muscles (this causes the chamber wall to contract as a single unit)

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21
Q

connective skeleton separates chambers in what two ways

A

Connective tissue skeleton separates chambers physically and electrically

Electrical signals in these chambers don’t and should not move to other chambers

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22
Q

When there are electrical problems or problem with electrical isolation then we have

A

When there are electrical problems or problem with electrical isolation then we have pacing abnormalities (arrhythmias)

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23
Q

When R ventricle contracts its going to leave through the _______ at the origin of the _____ which bifurcates into ______

A

When ventricle contracts its going to leave through the semilunar valve at the origin of the pulmonary trunk which bifurcates into pulmonary arteries

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24
Q

L ventricle >R d/t …

A

” L>R d/t needed for system output/pressure to overcome systemic resistance

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25
Q

Most of ventricle filling is _____ contraction of atrium pushes some in but not completely responsible/tops it off

A

Most of ventricle filling is passive; contraction of atrium pushes some in but not completely responsible/tops it off

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26
Q
  • RV is thick; LV thin and changes after birth why?
A
  • Pulmonary circuit is high resistance circuit forcing blood into systemic and away from the pulmonary circuit since not exchanging with the lungs thus lots of resistance in that circulation
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27
Q

what is responsible for the closing of the valves

A

flow of blood NOT contraction

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28
Q

what is the name of the m that the chordae tendinae attach to?

A

papillary

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29
Q

Cardiac muscle cells at rest have what membrane potential

A

-(85-95)mV

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30
Q

conducting cells have what resting membrane potential

A

b. -(90-100) mV in conducting cells

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31
Q

AP of cardiac muscle cells are typically

A

high magnitude

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32
Q

Extended AP of cardiac muscle cells due to calcium channel which create what is called

A

the plateau phase

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33
Q

why do cardiac muscle cells have a refractory period

A

The membrane voltage does not just spike and drop immediately down to rest. It plateaus; it levels off in the positive range. This is the result of calcium channels in the cardiac muscle cell membrane that don’t exist in the nerve cell membrane

this is seen as a slow AP

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34
Q

At rest at -90 mV (that is polarized). When the membrane potential reaches some_____ and action potential is triggered, it is ________ This is the result of _______into the cell, driving the membrane potential into a positive range.

A

a. At rest at -90 mV (that is polarized). When the membrane potential reaches some threshold and action potential is triggered, it is depolarized.

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35
Q

describe phase 0 of the cardiac cell

A

Na+ enters the cell at this phase and depolarizes it

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36
Q

Phase 2 of cardiac cell . AP

A

Ca++ enters the cell through slower channels causing plateau and initiation of contraction

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37
Q

phase 3 of the cardiac cell AP

A

K+ exits the cell and it polarizes

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38
Q

EC Coupling refers to

A

excitation contraction coupling

how do we go from excitation to contraction

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39
Q

reptilian features of cardiac muscle cells

A

single T tubule

Invagination - a point where the muscle cell membrane dives down into the length of the muscle and creates a tube and contents of the tube are external to the cytoplasm of the muscle separated by the membrane of the T tubule

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40
Q

In skeletal muscle there are______. In cardiac muscle, only 1 T tubule per sarcomere

A

In skeletal muscle there are 2 tubules. In cardiac muscle, only 1 T tubule per sarcomere

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41
Q

describe calcium gated ion channels in cardiac muscle

A

When Ca gated ion channels open in the T tubules in response to threshold ,

ions flow directly into where the contractile elements are

Ca from sarcoplasmic reticulum floods the cytoplasm of the cardiac muscle

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42
Q

what causes sarcomeres to move together in striated muscle cells

A

Ca–> contraction!

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43
Q

wiggers diagram refers to

A

reflects the changes in a cardiac cycle

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44
Q

____of the cardiac cycle will be in contraction,_____rest

A

40% of the cardiac cycle will be in contraction, 60% rest

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45
Q

tachycardia will result in the loss of what phase in the wigger’s diagram

A

relaxation phase

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46
Q

LVEDV

A

left ventricular end diastolic volume

47
Q

LVESV

A

left ventricular end systolic volume

48
Q

top curve in wigger’s diagram measures what?

what numbers do we normally see here

A

pressure in the aorta

between 120 and 80 mm

49
Q

red dotted line represents

A

left ventricular pressure

50
Q

LVEDV - LVESE (difference)

A

blood that is ejected during ventricular systole

51
Q

what is the cardiac cycle and how long is it usually

A

from the beginning of one beat to the beginning of the next beat (beginning of one phase of contraction to the beginning of the next)

normally this is about .8 seconds (about 75 bpm)

52
Q

Ejection fraction, what is it

A

the proportion of EDV that leaves ventricle with each contraction

53
Q

built in delay of the cardiac cycle is at the

A

AV node (wall between atrium and ventricles)

54
Q

periods of excitation are known as

A

systole

55
Q

periods of relaxation in the cardiac cycle are known as

A

Diastole

56
Q

usually the reference point for systole and diastole is the

A

ventricle

if you are referring to the atrium you need to say so

57
Q

what is happening at atrial contration

A

topping of the ventricle

remember it is not fililing the ventricle because this happens passively

58
Q

the slight spike in pressure we see in the atrium following atrial contraction is due to

A

the tricuspid valve closes so they don’t swing open and this creates this indirect spike in pressure in the atrium seen as the “c” wave in an atrial pressure

59
Q

why do we see a spike in right atrial pressure before the semilunar valve closes

A

little bit of backflow intro the ventricles

60
Q

what is isovolumetric contraction refer to?

A

Pressure is rising within the ventricle but volume is not changing. All 4 valves are closed and ventricle is just generating pressure to try to get over the systemic pressure in the aorta in order to eject blood.

61
Q

what is the name for the cardia phase in which right ventricle pressure rises without volume rise?

what does this pressure rise to?

A

needs to rise above aortic pressure in order to be ejected

this is referred to as isovolumetric contraction

62
Q

phase 3 of the cardiac cycle is known as the

A

ejection phase

63
Q

phase 5 of the cardiac cycle where pressure is falling but we see no volume change

A

diastole

64
Q

what is aortic pressure at normally

A

iv. Aortic pressure í b/w 120-80 mmHg

65
Q

why do you see the aorta never drop below 80 mmHg when the left ventricle approaches 0

A

because of the compliance

66
Q

LVEDV under normal conditions

A
  1. LVEDV ~ 120 ml of blood- normal conditions holds
67
Q

what is LVESV (also known as residual volume of the left ventricle)

A

50ml

68
Q

how can you calculate CO

A

difference between residual volume and LVEDV

120-50= 70

70ml X 70 bpm=4900ml or around 5L of blood (same as total blood volume)

69
Q

ejection fraction equation

A

SV/EDV X 100

70
Q

When is ejection fraction indicative of HF

A

<40%

71
Q

amount of energy spent per stroke

A

stroke work output

72
Q

amount of energy spent per minute based on HR

A

minute work output

73
Q

energy that the heart has to spend to overcome external pressure/afterload

A

external work output

74
Q

do diuretics effect systolic or diastolic pressure more and why?

A

diuretic reduce blood volume have a bigger effect on systolic volume because diastolic volume doesn’t respond to filling unless it is over 150ml

75
Q

phase II

A

isovolumemetrioc contraction where volume does not change but pressure goes up

76
Q

phase III

A

ejection and volume change

77
Q

a. Preload

A

is end diastolic pressure

78
Q

is opposition to ejection

A

b. Afterload

comes from systemic circuit

79
Q

Chemical energy from pumping is dereived from

A

c. Chemical energy from pumping from oxidative metabolism of fatty acids

80
Q

intrinsic and extrinsic regulation CO

A

intrinsic is the response of cardiac muscle (frank)

Extrinsic
1. ANS
Sympathetic and parasympathetic responses that affect the SA node and control rate and contractility of the cardiac muscle

81
Q

CO calculation

A

stokre volume x HR

82
Q

increase or decrease of either values will change CO

Ex. Increase 3x HR and 2x SV for an athlete will increase from 5L

A

Increase 3x HR and 2x SV for an athlete will increase from 5L to 30L/min; but as HR is increase → takes away from passive ventricular filling and can become counter-productive (wont be getting enough oxygenated blood back into system)

83
Q

when does the increase in heart rate stop increasing CO

A

reduction of the resting phase starts to reduce the filling of the ventricle output

84
Q

______resets membrane potential so heart can beat again

A

Potassium resets membrane potential so heart can beat again

85
Q

Excess potassium ion results in what CO change

A

Excess potassium ion results in a flaccid, dilated heart, slowing its rate or blocking conduction

86
Q

Calcium effect on CO

A

Calcium has the opposite effect of potassium in excess: spastic contraction

directly related to the contraction of the sarcomeres

87
Q

term for when the heart does not close properly

A

incompetent

88
Q

term that signifies inappropriate backflow

A

regurgitant

89
Q

term meaning stiff or scarred

A

Stenotic: stiff or scarred

90
Q

valvular d/o that imparts pressure overload.

what is the term and describe the pathophys

A

b. Valvular stenosis

You have to push with a higher pressure/force to get fluid through a stenotic valve which creates a pressure overload

91
Q

valvular d/o that imparts volume overload

A

c. Valvular regurgitation

i. As blood is leaving the ventricle, it is backflowing and creates volume overload

92
Q

MCC of mitral stenosis

A

rheumatic heart disease (almost all cases)

93
Q

safety factor in the mitral valve

A

has to be a ~60% reduction in opening area required for symptoms

valves don’t open or close fully with the opening and closing

94
Q

MC population for mitral valve stenosis

A

women greater than men in 4th or 5th decade of life

95
Q

opening snap followed by a lowe pitched rumbling woosh at the axilla is the description of what heart disorder

A

mitral stenosis

heard in diastole

96
Q

increased LA pressure (dilated left atrium) causes what pulmonic and cardiac complications

A

ncreased LA pressure (dilated left atrium) causes pulmonary vasoconstriction and restricted inflow to LV –> limiting cardiac output

as it get worse you begin to see failure of the right ventircle

97
Q

____apical impulse and____ lift

are physical exam findings with regard to mitral stenosis

A

Quiet apical impulse and parasternal lift

98
Q

what kind of S1 sound would you here with mitral stenosis ?

what kind of S2?

S3?
S4?

A

b. Loud S1, split S2 and no S3 or S4

i. Differential closing of valves on the left and right causes split S2

99
Q

what kind of murmur would you

A

c. Low pitched early diastolic rumble murmur of mitral stenosis

100
Q

isometric hand-grips increase intensity
Elevated JVP with edema and ascites
Accompanied by Pulmonic Insufficiency

are all descriptors of what type of valve d/o

A

mitral stenosis

Accompanied by Pulmonic Insufficiency (Graham Steele) diastolic blowing murmur

101
Q

what can lead to mitral regurgitation

A

prolapse, rupture CT, endocarditis, drug effects - phenfen)

102
Q

what are we usually looking for with

A

Look for enlarged ventricle and hyperdynamic impulse

103
Q

Pansystolic murmur to neck is associated with what valve d/o

A

mitral regurgitation i.

Blood is moving from ventricle to atrium toward the neck

104
Q

describe pathophys of mitral regurg

A

bloood that is supposed to go into the aorta is getting pushed into the atrium so cardia output drops

we see an overload of the ventricle–> leading to enlargment

105
Q

c. Decompensated MR

A

regurgitant volume increases LA pressure so get CHF with a low cardiac output and pulmonary congestion despite normal LV contractility

106
Q

sxs of MR

A

PND fatigue
due to excess pressure in the pulmonary circuit

also seen with dyspnea and orthopnea,

107
Q

Valsalva maneuver or standing make what difference with MVP and why

A

e. Valsalva maneuver or standing make click earlier, murmur holosystolic and louder

108
Q

MVP sxs

A

most asx

syncope
chest pain from reduced output

109
Q

MVP dx

A

ekg normal
CXR normal

test of choice is always echocardiogram
need to be able to see the back flow this is the gold standard

110
Q

MVP chance of sequale

A

10% of patients can go onto have sequalae

Sequalae includes endocarditis, stroke, MR, or sudden death

111
Q

Describe the differences in cardiac muscle versus skeletal

A

1] More calcium influx from t-tubules which allow for stronger contraction
2] SR in cardiac muscle has more mitrochondria allow for more oxidation-phosphylations which decrease fatiguability of cardiac muscle

112
Q

What are the two forms of work output

A

1] External work (overcoming pressure, the afterload), 2] Kinetic energy of blood flow (accelerating blood)

113
Q

Describe where the energy that supplies the heart muscles

A

Approximately 70 to 90 percent of this energy is normally derived from oxidative metabolism of fatty acids, with about 10 to 30 percent coming from other nutrients, especially lactate and glucose.

114
Q

Describe the evaluation of tricuspid regurgitation

A

1] EKG shows right ventricular hypertrophy,
2] CXR reads cardiomegly,
3] ECHO reveals tricuspid regurgitation, pulmonary hypertension, and right ventricular dialation

Physio II (18 decks)

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