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Kin 426 > 9.1 > Flashcards

9.1 Flashcards

1
Q

where do the right and left coronary arteries arise from

A

at the root of the aorta behind the right and left cusps of the aortic valve

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2
Q

what do the right and left coronary arteries provide

A

the entire blood supply to the myocardium

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3
Q

heart needs

A

own vascular supply

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4
Q

the right coronary artery supplies

A

principally the right atrium and ventricle

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5
Q

the left coronary artery divides near

A

its origin into the anterior descending and the circumflex branches

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6
Q

the branches of the left coronary artery supplies

A

principally the left ventricle and atrium, but there, but there is some overlap

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7
Q

what artery wraps around and supplies the back of heart

A

circumflex artery

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8
Q

in humans the right coronary artery is

A

dominant in 50% of individuals

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9
Q

in humans the left coronary artery is

A

dominant in another 20%

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10
Q

how many people have about equal flow in two main arteries

A

remaining 30%

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11
Q

the microcirculatory unit of coronary vessels consists of

A

terminal arterioles, precapillary sinuses, capillaries, and venules

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12
Q

cardiac myocytes are surrounded by

A

capillaries that are aligned with them

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13
Q

the average length of the microcirculatory unit is

A

about 350 um

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14
Q

during diastole, precapillary sinuses may serve as

A

a blood reservoir (helps with constant perfusion of heart)

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15
Q

during systole, precapillary sinuses

A

disgorge the blood so as to sustain myocyte perfusion (because most happens during diastole)

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16
Q

after the blood passes through the capillary beds, most of venous blood

A

returns to the right atrium through the coronary sinus

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17
Q

after blood passes through the capillary beds, some of the venous blood

A

reaches the right atrium by way of the anterior coronary veins

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18
Q

where are there also vascular communications

A

between the vessels of myocardium and the cardiac chambers (not all transport is directly through L+R arteries)

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19
Q

what do the vascular communications between myocardium and cardiac chambers constitute

A

arteriosinusoidal, arterioluminal, and thesbesian vessels

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20
Q

arteriosinusoidal channels consist of

A

small arteries or arterioles

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21
Q

the vessels of the arteriosinusoidal channels lose their

A

arterial structure as they penetrate the chamber walls and divide into irregular, endothelium-lined sinuses

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22
Q

what do the divided sinuses of the arteriosinusoidal channels do

A

anastomose (shunt) with other sinuses and with capillaries, and they communicate with the cardiac chambers

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23
Q

the arterioluminal vessels are

A

small arteries or arterioles that open directly into the atria and ventricles

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24
Q

the thebesian vessels are

A

small veins that connect capillary beds directly with the cardiac chambers

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25
thebesian vessels also communicate with
cardiac veins and other thebesian veins
26
extensive plexus of subendocardial vessels
intercommunication appears to exist among all the minute vessels of the myocardium in the form of this plexus
27
the myocardium does not receive
significant nutritional blood flow directly from the cardiac chambers
28
back of right atrium is where
majority of venous side of coronary blood dumps
29
what is the principle factor responsible for perfusion of the myocardium
aortic pressure which is generated by heart itself
30
changes in aortic pressure generally evoke
parallel changes in coronary flow
31
if infarction occuring, blockages of coronary artery, what happens with pressure and flow
squeeze function impaired so low pressure, perfusion pressure to coronary arteries decreased so decreased flow
32
if cannulated coronary artery is perfused by blood from a pressure controlled reservoir
perfusion pressure can be altered without changing aortic pressure and cardiac work
33
under pressure controlled condition what do abrupt variations in perfusion pressure produce
equally abrupt changes in coronary blood flow in the same direction
34
how much blood making it somewhere is highly determined by
pressure
35
maintenance of the perfusion pressure at the new level is associated with
a return of blood flow toward the level observed before the induced change in perfusion pressure (reflexive)
36
phenomenon of blood flow being reflexive is example of
autoregulation blood flow
37
autoregulation in coronary arteries is mediated by a
myogenic mechanism, by the metabolic activity of cardiac muscle, and by the endothelium
38
thus autoregulation depends on
the interplay of activities of vascular smooth muscle and cardiac muscle
39
under normal conditions what is blood pressure kept at
within relatively narrow limits by the baroreceptor reflex mechanisms
40
Controller of heart (autoregulation) is independent of
Rest of body
41
With autoregulation, a decrease in flow will cause
Something to increase flow Will dilate to increase
42
Decreases pressure causes
Reflexive increase in flow Drop is temporary and dilation to increase flow
43
If pressure gets to high
Coronary arteries reduce flow
44
What are the white dots
The new reflexive pressure and flow
45
What does autoregulation cause for flow
Very little fluctuation in flow
46
Autoregulation
Flow will adapt to give heart what it needs Coronary arteries constrict (decrease flow) and dilate (increase flow)
47
In autoregulation what is the tendency
For flow to return toward the control level, most prominent over intermediate pressure range (60-180mmHg)
48
What can produce alterations of cardiac work
Increase or decrease in aortic pressure
49
Alterations of cardiac work have a
Considerable effect on coronary resistance
50
Increased metabolic activity of the heart
Decreases the coronary vascular resistance (flow increases)
51
A reduction in cardiac metabolism
Increases the coronary resistance (maintain perfusion pressure)
52
The position of the auto regulatory region is affected by
The metabolic state of cardiac muscle
53
Because position of auto regulatory region is affected by metabolic state of cardiac muscle, changes in coronary blood flow are caused mainly by
Caliber changes (charges in area) of the coronary resistance vessels in response to metabolic demands of the heart
54
Coronary flow reserve is
The difference between max flow as caused by a vasodilator drug and the flow in the physiological range (what is biggest vessel can be)
55
metabolic activity can have an effect on what
autoregulatory region
56
when cardiac metabolism increases, as during exercise
autoregulation persists as the pressure-flow relation shifts upward
57
metabolic activity increase determines a
increase requirement of flow
58
what is autoregulatory region
within perfusion pressure 60-180 mmHg
59
the head of pressure drives
blood through the coronary vessels
60
in addition to providing head of pressure to drive blood through coronary vessels, the heart also influences its
blood supply by the squeezing effect of the contracting myocardium in the blood vessels that course through it
61
extravascular compression or extracoronary resistance
squeezing effects (systole) of the contracting myocardium on the blood vessels that course through (restricts flow)
62
max left coronary inflow occurs in
early diastole when the ventricles have relaxed and extravascular compression of coronary vessels is virtually absent (flow overshoots)
63
what happens to phasic left coronary flow during systole
drops
64
what happens to right coronary flow during systole
still biphasic but doesnt increase as much as left
65
what happens to coronary flow during squeeze
decreases
66
why is left coronary artery blood flow overshoot during diastole
LV thicker muscle compressing more LV predominantly fed during diastole
67
where is the flow pattern seen
in the phasic coronary flow curve for the left coronary artery
68
after the initial reversal in early systole, left coronary blood flow follows
the aortic pressure until early diastole, when it rises abruptly and then declines slowly as aortic pressure falls during the remainder of diastole
69
flow in the right coronary artery shows
a similar pattern
70
because of the lower pressure developed during systole by thin right ventricle
reversal blood flow does not occur in early systole, and systolic blood flow constitutes a much greater proportion of total coronary inflow than it does in the left coronary artery
71
what does angioplasty do
balloons vessel where plaque was pinching
72
angina pectoris
chest pain associated with myocardial ischemia
73
what drugs are available for use in patients with coronary artery disease to relieve angina pectoris
many of compounds are organic nitrates and nitrites
74
what do organic nitrates and nitrites not do
dilate the coronary vessels selectively
75
the vasodilation from organic nitrates and nitrites occurs from what
the production of NO, which has effects on the arterial and venous circulations
76
organic nitrates and nitrites have little effect on
autoregulation in the coronary circulation
77
the arterioles in the ischemic heart that would dilate in response to the drugs are
undoubtedly already maximally dilated by the ischemia responsible for the symptoms
78
in a patient with marked narrowing of a coronary artery, administration of certain vasodilators can
fully dilate normal vessel branches parallel to the narrowed segment and reduce the head of pressure to the partially occluded vessel
79
the effect of the vasodilators can further
compromise blood flow to the ischemic myocardium and elicit pain and electrocardiographic changes indicative of tissue injury
80
coronary steal
Coronary steal is a phenomenon where blood flow is diverted away from diseased coronary arteries due to vasodilation in healthier vessels, leading to worsened ischemia in affected areas
81
coronary steal is observed with
vasodilator drugs such as dipyridamole
82
what does dipyridamole act by
blocking cellular uptake and metabolism of endogenous adenosine
83
what does dipyridamole reduce or eliminate
coronary autoregulation because it dilates small resistance vessels
84
how do nitrites and nitrates alleviate angina pectoris, or partly, by
reducing cardiac work and myocardial O2 requirements by relaxing the great veins (decreased preload) and decreasing BP (decreased afterload)
85
the reduction in pressure work and o2 requirements must be greater than
the reduction in coronary blood flow and o2 supply consequent to the lowered coronary perfusion pressure
86
nitrites and endogenous NO also
dilate large coronary arteries and coronary collateral vessels
87
what does dilation of large coronary arteries and coronary collateral vessels do
increases blood flow to ischemic myocardium and alleviating precordial pain
88
when will chest pain be relieved
lower 02 need by lowering BP
89
under abnormal conditions when diastolic pressure in coronary arteries is low, the ratio of
endocardial to epicardial blood flow falls below a value of 1
90
what are abnormal conditions when diastolic pressure in coronary arteries is low
severe hypotension, partial coronary artery occlusion, and severe aortic stenosis
91
the ratio change indicates that blood flow to endocardial regions is
more severely impaired than that to the epicardial regions of the left ventricle
92
reduced blood flow to the endocardium is also reflected in
an increase in the gradient of myocardial lactic acid and adenosine concentrations from epicardium to endocardium
93
the myocardial damage observed in the left ventricle after occlusion if a major coronary artery is
greater in the inner wall than in the outer wall of the ventricle
94
extent to which extravascular compression restricts coronary inflow can be detected when
heart is suddenly arrested in diastole, or with induction of ventricular fibrillation
95
ventricular fibrillation figure illustrates the
changes in mean left coronary flow when vessel was perfused with blood at a constant pressure from a reservoir
96
ventricular fibrillation figure at the arrow (in A) shows
ventricular fibrillation was electrically induced, and blood flow increased immediately and substantially
97
left coronary blood flow is restricted during
ventricular systole as a result of extravascular compression
98
left coronary blood flow is greatest during
diastole when the intramyocardial vessels are not compressed
99
myocardial ischemia impairs
LV function

Kin 426 (12 decks)

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