Cardiology Physiology Flashcards
1
Q
what is cardiac output
A
the amount of blood leaving the left ventricle to the body
2
Q
what is venous return
A
the amount of blood that comes back through the veins to the right atrium
3
Q
how is blood flow measured
A
changes in pressure over resistance
4
Q
what impacts resistance
A
blood viscosity
total blood vessel length
blood vessel radius
5
Q
what is blood viscosity
A
thickness of the blood from plasma and formed elements
whatever else is in the blood (glucose, plaques, etc) also increase viscosity
6
Q
what is blood vessel radius
A
how big (dilated) or how small the blood vessel is(constricted)
7
Q
what is the most important factor affecting resistance
A
blood vessel radius
8
Q
what are the three layers of the heart
A
epicardium
myocardium
endocardium
9
Q
what are the two types of cells in the myocardium
A
conducting and contractile cells
10
Q
what are the conducting cells of the heart
A
SA node and AV node
11
Q
what are the contractile cells of the heart
A
myocytes
12
Q
what are gap junctions
A
allows for the flow of ions (calcium) through the heart muscle
13
Q
what is the goal of the conducting system
A
to initiate a depolarization to send to the contractile system
14
Q
what is the order of the conduction in the heart
A
SA node
AV node
bundle of His
R/L bundle branch
purkinje fibers
15
Q
how does the conducting system receive neural innervation
A
cardiac plexus –> sympathetic trunk and vagus nerve
16
Q
what part of the heart is innervated by the sympathetic trunk
A
atria and ventricles
17
Q
what are the NT that are released by the sympathetic nervous system (trunk)
A
norepinephrine and epinephrine
18
Q
what receptors are the target of the sympathetic trunk
A
beta-1 receptors
19
Q
what part of the heart is innervated by the parasympathetic nervous system (vagus nerve)
A
atria
20
Q
what do the vagus nerve fibers release to slow heart rate down
A
Ach
21
Q
what receptors are the target of the the parasympathetic nervous system
A
muscarinic receptors
22
Q
what is represented by the p wave
A
SA node initiating depolarization, causing the atria to contract
23
Q
what is the PR interval
A
when the atria are depolarized, the impulse is delayed at the AV node
24
Q
what is represented by the QRS interval
A
ventricle depolarization that begins at the apex, also atria are repolarizing during this time
25
what does the t wave represent
ventricular repolarization beginning at the apex
26
what are the steps of the depolarization of the conducting system
1. pacemaker potential
2. depolarization
3. repolarization
27
what occurs during the pacemaker potential in conducting system depolarization
it is a slow depolarization due to Na+ channels opening and K+ channels closing
there is a constant flow of ions which is why there is never a flat line
28
what is happening during depolarization in the conduction system
the pacemaker potential reaches a threshold which trigger Ca2+ channels to open and an influx of calcium occurs
29
what is happening during repolarization of the conducting system
due to Ca2+ channels inactivating and K+ channels opening
K+ flows out of the cell to become more negative
30
how does the contractile system get started
when the action potential occurs, calcium flows in
31
what is important about calcium in the contractile system
allows for actin and myosin to begin to crosslink
magnitude of contraction is directly proportional to the amount of calcium released
32
what is the target of inotropic medications
contractile system of the heart
33
how does the contractile system become depolarized
begins due to an influx of Na+
because of the Na+, Ca2+ is released through slow channels
potassium then flows out, repolarizing the cel
34
what is the absolute refractory period in the cardiac muscle cell depolarization
no matter how strong the stimulus, there is no additional contraction
35
what is the relative refractory period in the cardiac muscle cell depolarization
if there is a strong enough stimulus, another contraction will occur
happens during repolarization
36
what are the four determinants of cardiac output
preload
afterload
heart rate
contractility
37
what is preload
volume of blood filling the heart before contraction
38
what is preload related to
venous return
39
what is afterload
pressure the heart must pump against to eject blood
40
what is afterload related to
vascular resistance
41
how is cardiac output determined
heart rate x stroke volume
42
what are the ways to influence stroke volume (positive)
increase preload
increase contractility
decrease afterload
43
what are the ways to influence stroke volume (negative)
decrease preload
decrease contractility
increase afterload
44
what is stroke volume
the volume of blood ejected during contraction
45
how is stroke volume determined
end diastolic volume - end systolic volume
46
what is end diastolic volume
the amount of blood in the ventricles at the end of relaxation
47
what is end systolic volume
the amount of blood remaining in the ventricles are the end of contraction (should be reduced)
48
chronotropic effects
increase or decrease heart rate
49
what do sympathetic effects have on chronotropes
increase the heart rate through binding NE/Epi on a beta-1 receptor
50
what meds increase heart rate (chronotropic)
atropine
51
what do parasympathetic effects have on chronotropes
decrease the heart rate through binding ACh on muscarinic receptors
52
what medications decrease heart rate (chronotropic)
digoxin
beta blockers
53
inotropic effects
increase or decrease contractility
54
sympathetic nervous system effects on inotropes
increases contractibility through working on beta-1 receptors
55
what meds are positive inotropes
digoxtin
dobutamine
epi
56
what impact does heart rate have on end diastolic volume
at extremely high heart rates there is a decrease in end diastolic volume because ventricles cannot fill properly
example is SVT
57
what impact does heart rate have on cardiac output have at moderate increases
increases cardiac output
58
what impact does an increase in contractility have on cardiac output
increases cardiac output
59
why does an increase in contractility increase cardiac output
decreases end systolic volume because the heart is pumping harder/more intensive
60
what part of the nervous system causes vasoconstriction
sympathetic
61
what impact does vasoconstriction have on afterload
increases afterload, because there is an increase in systemic resistance
62
what impact does vasoconstriction have on cardiac output
there is a variable impact on CO
could cause an decrease in stroke volume but often increases CO due to sympathetic input on HR and contractility
63
what would happen to cardiac output in extreme hypertensive crisis
decreases
64
what are the overall parasympathetic impacts on cardiac output/stroke volume
decreases heart rate
decreases contractility
vasodilation
65
what impact does a decrease heart rate have on end diastolic volume
increases end diastolic volume because heart has time to fill completely
66
what impact does a decrease heart rate have on cardiac output
decreases cardiac output because heart rate is so slow
67
what impact does a decrease in contractility have on stroke volume
minimal effect on stroke volume, which could indirectly increase end stroke volume in cases of heart failure
68
what impact does a decrease in contractility have on cardiac output
decreases cardiac output
69
what impacts does vasodilation have
decreases afterload
increases stroke volume by decreasing end stroke volume
increases cardiac output
70
what happens in cases of severe vasodilation
there may be a decrease in preload because not enough blood is circulating in the body which could decrease cardiac output
71
what is ejection fraction
a way to quantify contractility and written in a percentage form
72
how is EF measured
SV/EDV
73
what is a normal ejection fraction
50-75%
74
how is blood pressure measured
BP is taken through arteries
75
what do arteries use to move blood
use elasticity recoil and pressure of the heart pumping to move blood
76
how do veins move blood through the body
skeletal muscle and valves to move blood back to the heart
77
what is systolic pressure measuring
systemic circulation
78
what is diastolic pressure measuring
pulmonary circulation
79
how is compliance measured
change in volume over change in pressure
80
what does compliance correlate with
an increase in compliance means that there is an increase in stretch
81
what is systolic pressure
maximum arterial pressure reached during te peak of ventricular contraction/ejection
82
what is diastolic pressure
minimum arterial pressure reached just prior to ventricular ejection
83
what is pulse pressure
the difference between SBP and DBP
84
what can influence the pulse pressure
stroke volume
speed of ejection
arterial compliance
85
what does a pulse pressure greater than 60mmHg indicate
considered that arteries are widened may indicate arterial-sclerosis or atherosclerosis, HTN, or aortic regurgitation
86
what is arterial-sclerosis
basically whenever we get older, everything thickens
87
what is atherosclerosis
a build up of plaques
88
what does a pulse pressure lower than 25mmHg indicate
considered that arteries are narrow and may indicate low cardiac output or blood loss
89
what is the mean arterial pressure
average pressure driving blood to the tissues over a cardiac cycle
90
how is MAP measured
MAP = DBP + 1/3PP
91
what impacts MAP
vasodilation and vasoconstriction
92
what does vasodilation do to MAP
decreases MAP
93
what does vasoconstriction do to MAP
increases MAP
94
how does our body regulate MAP
through baroreceptors
95
what happens if there is a decrease in MAP
decrease stretch on baroreceptors
decrease firing of carotid sinus nerve
the medullary cardiovascular response increases sympathetic activity, increases HR, increases contractility, vasoconstriction
96
what happens if there is a increase in MAP
increase firing of baroreceptor
medullary cardiovascular response causes a decrease in sympathetic outflow of heart rate, contractility, also causes vasodilation
increases in parasympathetic outflow
97
what happens when there is a hemorrhage initially
decrease in stroke volume
cardiac output decreases
MAP decreases
98
what happens when there is a hemorrhage reflex mechanisms
heart rate will try to increase to increase cardiac output
stroke volume decreases
total peripheral resistance increases to increase MAP
99
what happens to prevent blood pressure from skyrocketing
negative feedback loop
100
how does the RAAS system work when there is a drop in blood pressure
renin stimulates the conversion of angiotensin to angiotensin I
ACE converts angiotensin I to angiotensin II
angiotensin II works on aldosterone to reabsorb sodium and water
stimulates vasoconstriction to increase total peripheral resistance
101
what does aldosterone do to blood pressure
reabsorbs sodium and water to increase blood pressure
102
what is ANP
atrial natruritic peptide
103
when is ANP released
by atria when there is a time of stretch or overwork
104
what are the four types of shock
hypovolemic
low resistance
cardiogenic
obstructive
105
what is hypovolemic shock
due to a decrease in blood volume
106
what is low-resistance shock
due to a decrease in total peripheral resistance
secondary to vasodilators from allergy and immune response
107
what is cardiogenic shock
due to an extreme decrease in cardiac output
108
what are examples of why cardiogenic shock occurs
heart attack
extreme bradycardia
109
what is obstructive shock
due to an obstruction in blood flow from a blood clot, tumor, collapsed lung
110
what are reasons for primary hypertension
genetics, smoking, obesity, increased salt, increased alcohol usage, stress
111
what is the most common cause of secondary hypertension
renal arterial stenosis
112
what are other reasons for secondary hypertension
hyper secretion of cortisol, aldosterone, and thyroid hormone
sleep apnea
113
what is diastolic heart failure
difficulty with filling when the heart is relaxed
there is a decrease in compliance, reduced SV, reduced ejection diastolic volume
114
what is systolic heart failure
ventricular ejection is reduced, and there is a decrease in conractility
115
what are symptoms of left sided heart failure
pulmonary congestion
sleep apnea
cyanosis
116
what are the symptoms of right sided heart failur
fatigue
ascites
extended jugular venous distention
enlarged liver/spleen
