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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
Most of ventricle filling is _____ contraction of atrium pushes some in but not completely responsible/tops it off
Most of ventricle filling is passive; contraction of atrium pushes some in but not completely responsible/tops it off
26
- RV is thick; LV thin and changes after birth why?
- 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
27
what is responsible for the closing of the valves
flow of blood NOT contraction
28
what is the name of the m that the chordae tendinae attach to?
papillary
29
Cardiac muscle cells at rest have what membrane potential
-(85-95)mV
30
conducting cells have what resting membrane potential
b. -(90-100) mV in conducting cells
31
AP of cardiac muscle cells are typically
high magnitude
32
Extended AP of cardiac muscle cells due to calcium channel which create what is called
the plateau phase
33
why do cardiac muscle cells have a refractory period
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
34
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. At rest at -90 mV (that is polarized). When the membrane potential reaches some threshold and action potential is triggered, it is depolarized.
35
describe phase 0 of the cardiac cell
Na+ enters the cell at this phase and depolarizes it
36
Phase 2 of cardiac cell . AP
Ca++ enters the cell through slower channels causing plateau and initiation of contraction
37
phase 3 of the cardiac cell AP
K+ exits the cell and it polarizes
38
EC Coupling refers to
excitation contraction coupling how do we go from excitation to contraction
39
reptilian features of cardiac muscle cells
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
40
In skeletal muscle there are______. In cardiac muscle, only 1 T tubule per sarcomere
In skeletal muscle there are 2 tubules. In cardiac muscle, only 1 T tubule per sarcomere
41
describe calcium gated ion channels in cardiac muscle
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
42
what causes sarcomeres to move together in striated muscle cells
Ca--> contraction!
43
wiggers diagram refers to
reflects the changes in a cardiac cycle
44
____of the cardiac cycle will be in contraction,_____rest
40% of the cardiac cycle will be in contraction, 60% rest
45
tachycardia will result in the loss of what phase in the wigger's diagram
relaxation phase
46
LVEDV
left ventricular end diastolic volume
47
LVESV
left ventricular end systolic volume
48
top curve in wigger's diagram measures what? what numbers do we normally see here
pressure in the aorta between 120 and 80 mm
49
red dotted line represents
left ventricular pressure
50
LVEDV - LVESE (difference)
blood that is ejected during ventricular systole
51
what is the cardiac cycle and how long is it usually
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
Ejection fraction, what is it
the proportion of EDV that leaves ventricle with each contraction
53
built in delay of the cardiac cycle is at the
AV node (wall between atrium and ventricles)
54
periods of excitation are known as
systole
55
periods of relaxation in the cardiac cycle are known as
Diastole
56
usually the reference point for systole and diastole is the
ventricle if you are referring to the atrium you need to say so
57
what is happening at atrial contration
topping of the ventricle remember it is not fililing the ventricle because this happens passively
58
the slight spike in pressure we see in the atrium following atrial contraction is due to
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
why do we see a spike in right atrial pressure before the semilunar valve closes
little bit of backflow intro the ventricles
60
what is isovolumetric contraction refer to?
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
what is the name for the cardia phase in which right ventricle pressure rises without volume rise? what does this pressure rise to?
needs to rise above aortic pressure in order to be ejected | this is referred to as isovolumetric contraction
62
phase 3 of the cardiac cycle is known as the
ejection phase
63
phase 5 of the cardiac cycle where pressure is falling but we see no volume change
diastole
64
what is aortic pressure at normally
iv. Aortic pressure í b/w 120-80 mmHg
65
why do you see the aorta never drop below 80 mmHg when the left ventricle approaches 0
because of the compliance
66
LVEDV under normal conditions
1. LVEDV ~ 120 ml of blood- normal conditions holds
67
what is LVESV (also known as residual volume of the left ventricle)
50ml
68
how can you calculate CO
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
ejection fraction equation
SV/EDV X 100
70
When is ejection fraction indicative of HF
<40%
71
amount of energy spent per stroke
stroke work output
72
amount of energy spent per minute based on HR
minute work output
73
energy that the heart has to spend to overcome external pressure/afterload
external work output
74
do diuretics effect systolic or diastolic pressure more and why?
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
phase II
isovolumemetrioc contraction where volume does not change but pressure goes up
76
phase III
ejection and volume change
77
a. Preload
is end diastolic pressure
78
is opposition to ejection
b. Afterload comes from systemic circuit
79
Chemical energy from pumping is dereived from
c. Chemical energy from pumping from oxidative metabolism of fatty acids
80
intrinsic and extrinsic regulation CO
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
CO calculation
stokre volume x HR
82
increase or decrease of either values will change CO Ex. Increase 3x HR and 2x SV for an athlete will increase from 5L
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
when does the increase in heart rate stop increasing CO
reduction of the resting phase starts to reduce the filling of the ventricle output
84
______resets membrane potential so heart can beat again
Potassium resets membrane potential so heart can beat again
85
Excess potassium ion results in what CO change
Excess potassium ion results in a flaccid, dilated heart, slowing its rate or blocking conduction
86
Calcium effect on CO
Calcium has the opposite effect of potassium in excess: spastic contraction directly related to the contraction of the sarcomeres
87
term for when the heart does not close properly
incompetent
88
term that signifies inappropriate backflow
regurgitant
89
term meaning stiff or scarred
Stenotic: stiff or scarred
90
valvular d/o that imparts pressure overload. what is the term and describe the pathophys
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
valvular d/o that imparts volume overload
c. Valvular regurgitation | i. As blood is leaving the ventricle, it is backflowing and creates volume overload
92
MCC of mitral stenosis
rheumatic heart disease (almost all cases)
93
safety factor in the mitral valve
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
MC population for mitral valve stenosis
women greater than men in 4th or 5th decade of life
95
opening snap followed by a lowe pitched rumbling woosh at the axilla is the description of what heart disorder
mitral stenosis heard in diastole
96
increased LA pressure (dilated left atrium) causes what pulmonic and cardiac complications
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
____apical impulse and____ lift are physical exam findings with regard to mitral stenosis
Quiet apical impulse and parasternal lift
98
what kind of S1 sound would you here with mitral stenosis ? what kind of S2? S3? S4?
b. Loud S1, split S2 and no S3 or S4 | i. Differential closing of valves on the left and right causes split S2
99
what kind of murmur would you
c. Low pitched early diastolic rumble murmur of mitral stenosis
100
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
mitral stenosis Accompanied by Pulmonic Insufficiency (Graham Steele) diastolic blowing murmur
101
what can lead to mitral regurgitation
prolapse, rupture CT, endocarditis, drug effects - phenfen)
102
what are we usually looking for with
Look for enlarged ventricle and hyperdynamic impulse
103
Pansystolic murmur to neck is associated with what valve d/o
mitral regurgitation i. | Blood is moving from ventricle to atrium toward the neck
104
describe pathophys of mitral regurg
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
c. Decompensated MR
regurgitant volume increases LA pressure so get CHF with a low cardiac output and pulmonary congestion despite normal LV contractility
106
sxs of MR
PND fatigue due to excess pressure in the pulmonary circuit also seen with dyspnea and orthopnea,
107
Valsalva maneuver or standing make what difference with MVP and why
e. Valsalva maneuver or standing make click earlier, murmur holosystolic and louder
108
MVP sxs
most asx syncope chest pain from reduced output
109
MVP dx
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
MVP chance of sequale
10% of patients can go onto have sequalae Sequalae includes endocarditis, stroke, MR, or sudden death
111
Describe the differences in cardiac muscle versus skeletal
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
What are the two forms of work output
1] External work (overcoming pressure, the afterload), 2] Kinetic energy of blood flow (accelerating blood)
113
Describe where the energy that supplies the heart muscles
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
Describe the evaluation of tricuspid regurgitation
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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