Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

APEX-CV & Respiratory > CV Anatomy modules 1-9 > Flashcards

CV Anatomy modules 1-9 Flashcards

1
Q

What is resting membrane potential of cardiac myocytes

A

-90 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does potassium level affect resting membrane potential of the myocyte

A

hypokalemia = DECREASES RMP (more negative)
-Resistant to depolarization

HYPERkalemia = INCREASES RMP (less negative)
-Depolarizes easier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How much mitochondria do myocytes contain compared to skeletal myocytes

A

MORE mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What ion regulates resting membrane potential of myocyte

A

Potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the normal threshold potential of the myocyte

A

-70 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What ion regulates threshold potential

A

Calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does calcium level affect threshold potential

A

HYPOcalcemia = DECREASE TP (more negative)
-Easier depolarization

HYPERcalcemia = INCREASES TP (less negative)
-Resistant to depolarization
-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is depolarization transmitted in the heart

A

Via gap junctions (NOT t-tubules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define automaticity

A

The ability to generate an action potential spontaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define excitability in relation to myocardial cells

A

The ability to respond to an electrical stimulus by depolarizing and firing an AP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define resting membrane potential

A

The difference in electrical potential between the inside and outside of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define threshold potential

A

It’s the voltage change that must occur to initiate depolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define depolarization

A

It’s the movement of a cell’s membrane potential to a more positive value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define repolarization

A

It’s the return of a cell’s membrane potential towards a more negative value after depolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the role of the Na/K ATPase in excitable tissue

A

To restore the ionic balance towards resting membrane potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What properties make cardiac myocytes unique

A

They have properties of both skeletal and neural tissue
NEURAL properties:
-generate a TMP
-propagate an AP

SKELETAL m properties:
-Contain contractile elements arranged in sarcomeres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What properties are unique to cardiac muscle

A

Myocytes are joined end-to-end by specialized junctional complexes called INTERCALATED DISC to form a functional syncytium

INtercalated discs transfer mechanical force and contain low resistance pathways (gap junctions)that spread the AP

Myocytes contain more mitochondria than skeletal muscle and consume more O2 at rest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How much O2 do cardiac myocytes consume at rest

A

8-10 mL O2/100 g/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q 
Is the equilibrium potential for each ion positive or negative in the ECF
K
Ca
Na
Cl
A 
K = negative (-94)
Ca = positive (+132)
Na =  positive (+60)
Cl = negative (-97)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Inotropy definition

A

The force of myocardial contraction during systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Chronotropy definition

A

heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Dromotropy definition

A

conduction velocity through heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Lusitropy

A

rate of myocardial relaxation during diastole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What 3 things determine the resting membrane potential

A
  1. Chemical force (concentration gradient)
  2. Electrostatic counterforce
  3. Na/K ATPase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The difference in these 2 values determine the ability of a cell to depolarize

A

Difference in RMP and TP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When is depolarization easier to achieve

A

When RMP is closer to TP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

When is depolarization harder to achieve

A

When RMP is further from TP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What purpose does the Na/K ATPase serve in excitable tissue

A

Restoring ionic balance toward resting membrane potential

  • By removing Na+ that enters the cell during depolarization
  • Returns K+ that has left the cell during repolarization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What type of channel is the Na/K ATPase

A

An active transport channel requiring ATP for energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does severely elevated potassium affect the heart

A

It inactivates the Na+ channels and they arrest in their closed-inactive state
Cells are unable to repolarize

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Describe the 5 phases of the myocyte action potential

A

Phase 0 = depolarization; Na+ in
Phase 1 = initial repolarization; Cl- in, K+ out
Phase 2 = plateau; Ca++ in, K+ out
Phase 3 = repolarization; K+ out
Phase 4 = maintenance of TMP; K+ out, Na/K-ATPase function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How does the cardiac myocyte AP differ from the neuron AP

A

The myocyte AP has a plateau phase where depolarization is prolonged
This allows for contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Which ions move across the cell membrane during phase 1 (initial repolarization) and how

A

Na+ channels inactivated
K+ out via Ito channels
Cl- in via Icl channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which ions move across the cell membrane during phase 2 (plateau) and how

A

Ca++ in, via slow voltage-gated Ca++ channels (Ica)
Na+ channels inactive state
K+ out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Which ions move across the cell membrane during phase 3 (final repolarization) and how

A

K+ out via delayed rectifiers (Ik)

Ca+ in briefly but slow Ca++ channels become deactivated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Which ions move across the cell membrane during phase 4 (resting phase) and how

A

K+ out via leak channels

Na+ removed, K+ replaced via Na/K-ATPase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Which ions move across the cell membrane during phase 0 (depolarization) and how

A

Na+ in via fast voltage-gated Na+ channels (Ina)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What makes up the cardiac conduction system, in order from start to finish

A

SA node -> internodal tracts -> AV node -> bundle of His -> left/right bundle branches -> Purkinje fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What determines the HR

A

The intrinsic firing of the SA node, the rate of phase 4 spontaneous depolarization, and autonomic tone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How does volatile anesthetics affect SA node automaticity

A

They depress automaticity explaining why junctional rhythms occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Describe the SA/AV node AP (3 phases)

A

Phase 4 = spontaneous depolarization; Na+ in (I-f) Ca++ in (T-type)
Phase 0 = depolarization; Ca++ (L-type)
Phase 3 = repolarization; K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How can we increase HR via the AP phases

A

Increase the rate of phase 4 spontaneous depolarization

Bring resting membrane potential and threshold potential closer together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Which ions move across the cell membrane during SA node phase 4 (spontaneous depolarization) and how

A

Na+ in, via I-f activated by hyperpolarization

Ca++ in, via T-type channels at -50 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Which ions move across the cell membrane during SA node phase 0 (depolarization) and how

A

Ca++ in, via voltage-gated L-type channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Which ions move across the cell membrane during SA node phase 3 (repolarization) and how

A

K+ out, via open K+ channels and closing Ca++ L-type channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the intrinsic firing rate (bpm) for each node
SA
AV
Purkinje fibers

A 
SA = 70-80
AV = 40-60
Purkinje = 15-40
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What CN provides PNS tone to the heart nodes

A

Vagus nerve (CN 10)- right innervates the SA node, left innervates the AV node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What spinal levels provide SNS tone to the heart

A

T1-T4 via cardiac accelerator fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What factors can increase heart rate via the AP

A
  1. The slope of phase 4 depolarization increases
  2. The TP becomes more negative and shortens the distance between RMP and TP
  3. The RMP becomes less negative and shortens the distance between RMP and TP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

How is phase 4 slope of the SA node AP affected by SNS

A

The slope is INCREASED because norepinephrine stimulates beta-1 receptors thus increasing Na+ and Ca++ conductance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How is phase 4 slope of the SA node AP affected by PNS

A

The slope is DECREASED because ACh stimulates M2 receptors and slows the HR by increasing K+ conductance
Leads to hyperpolarization of SA node

52
Q 
Normal values for the following
CaO2 \_\_
DO2 \_\_ 
VO2 \_\_
CvO2 \_\_
A 
CaO2 = 20 mL/O2/dL
DO2 = 1,000 mL/min
VO2 = 250 mL/min
CvO2 = 15 mL/dL
53
Q

What does DO2 tell us

A

How much O2 is carried in arterial blood and how fast it’s being delivered to tissues

54
Q

What is the DO2 equation

A

CO x [(Hgb x SaO2 x 1.34) + (PaO2 x 0.003)] x10

or CO x CaO2 x 10

55
Q

What is CaO2

A

How many grams of O2 are contained in a deciliter of arterial blood

56
Q

What is the CaO2 equation

A

(Hgb x SaO2 x 1.34) + (PaO2 x 0.003)

57
Q

How much O2 is extracted by the tissues

A

25%

58
Q

What is VO2

A

How much O2 is consumed by the tissues

59
Q

What is normal VO2

A

250 mL/min or 3.5 mL/kg/min

60
Q

What is CvO2

A

How much O2 is carried in venous blood (15 mL/dL)

61
Q

What portion of the CaO2 equation depicts the amount of O2 carried by hgb

A

Hgb x SaO2 x 1.34

62
Q

What portion of the CaO2 equation depicts the amount of O2 dissolved in blood

A

PaO2 x 0.003

63
Q

The amount of O2 dissolved in blood (PaO2) follows what law?

A

Henry’s law
At a constant temperature, the amount of gas that dissolves in solution is directly proportional to the partial pressure of that gas

64
Q

What is Henry’s law and how does it relate to PaO2

A

At a constant temperature, the amount of gas that dissolves in solution is directly proportional to the partial pressure of that gas

Dissolved O2 in blood follows henry’s law

65
Q

How is blood flow related to hematocrit

A

Inversely proportional. Hct indicates viscosity
Increased Hct = decreased BF
Decreased Hct = increased BF

66
Q

How is Ohm’s law applied to the circulatory system

A

It describes flow related to pressure and resistance

  • flow directly proportional to pressure
  • flow inversely proportional to resistance
67
Q

What is Poiseuille’s law

A

An adaptation of Ohm’s law that incorporates vessel diameter, viscosity, and tube length

68
Q

What is best method to impact blood flow described by Poiseuille’s law

A

Increase radius

Flow is directly proportional to radius to the 4th power

radius increase then flow increase 4 fold

69
Q

What is the primary determinant of vascular resistance

A

The radius of the arterioles

70
Q

When turbulent flow is present, what may be assessed

A

Bruit (carotid stenosis) or murmur (valvular heart disease)

71
Q

How is blood viscosity related to Hct and body temperature

A

Hct - directly proportional

Body temp - inversely proportional

72
Q

What is Ohm’s law

A

Flow = (pressure gradient)/resistance

73
Q

How do the variables of ohm’s law correlate with CV hemodynamics

A

Flow = CO
Pressure gradient = MAP-CVP
Resistance = SVR

74
Q

What are the components of Poiseuille’s equation

A

Q = flow
Top:
R = radius
dP = AV pressure gradient

Bottom:
n = viscosity
L = length of tube

75
Q

According to Poiseuille’s equation, when radius is tripled how much does flow increase

A

81-time increase of flow

76
Q

What are 3 types of blood flow

A

Laminar flow
Turbulent flow
Transitional flow

77
Q

What is laminar flow

A

Molecules travel in a parallel path through the tube

78
Q

What is turbulent flow

A

Molecules travel in a non-linear path and will create eddies

79
Q

What is transitional flow

A

laminar flow along the vessel walls with turbulent flow in the center

80
Q

What are consequences of turbulent blood flow

A
  1. A lot of energy is lost to heat and vibration

2. Viscosity increases from intermolecular friction

81
Q

How does adding warm saline to PRBCs during transfusion affect flow

A

Dilution by NS decreases Hct and the increased temperature decreases viscosity

82
Q

Equation for stroke volume when CO and HR are known

A

CO x (1,000/HR)

83
Q

Equation for EF

A

[(EDV-ESV)/EDV] x 100

84
Q

Equation for systemic vascular resistance

A

[(MAP - CVP)/CO] x 80

85
Q

MAP equation when CO, SVR, and CVP are known

A

[(CO x SVR)/80] + CVP

86
Q 
Normal hemodynamic values for 
CO \_\_
SV \_\_
EF \_\_
MAP \_\_
SVR \_\_ 
PVR \_\_
A 
CO 5-6 L/min
SV 50-100 mL/beat
EF 60-70%
MAP 70-105 mmHg
SVR 800-1,500 dynes*sec*cm^-5
PVR 150-250 dynes*sec*cm^-5
87
Q

How do cardiac index and stroke volume index compensate for CO and SV respectively

A

They are divided by BSA

88
Q

How is the Frank-Starling mechanism applied to the heart

A

It relates ventricular volume to ventricular output

89
Q

Which variables are related by the Frank-Starling mechanism

A 
PAOP (ventricular volume)
Stroke volume (ventricular output)
90
Q

What is the Frank-Starling law

A

The heart will eject a larger stroke volume if it’s filled to a higher volume at the end of diastole

91
Q

What is another word for end-diastolic volume

A

Preload

92
Q

What are clinical indices of ventricular preload

A

CVP, PAD, PAOP, LAP, LVEDP, PVEDV, RVEDV

93
Q

What are clinical indices of ventricular output

A

CO, SV, LV stroke work, RV stroke work

94
Q

How much does atrial contraction contribute to cardiac output

A

20-30%

95
Q

What are 4 conditions associated with reduced myocardial compliance?
What are consequences if A-Fib is present

A
  • Myocardial hypertrophy
  • Heart failure with preserved EF (diastolic HF)
  • Fibrosis
  • Aging

HYPOTENSION, because they are dependent on preload

96
Q

How is the tension a sarcomere generates related to contraction

A

The amount of tension each sarcomere can generate is directly r/t the number of cross-bridges that can form before contraction
increased tension = increased contraction (to a point)

97
Q

What is the definition of preload

A

the ventricular wall tension (stretch) at the end of diastole
Or the volume that returns to the heart during diastole which causes end-diastolic tension

98
Q

What are 7 factors that influence preload

A 
Blood volume
Atrial kick
Venous tone
Intrapericardial pressure
Intrathoracic pressure
Body position
Valvular regurgitation
99
Q

What measures of ventricular filling pressures

A

CVP, PAD, PAOP, LAP, LVEDP

100
Q

What are measures of end-diastolic volume

A

RVEDV

LVEDV

101
Q

What can alter ventricular compliance

A

myocardial ischemia

hypertrophy

102
Q

What are the two measures of ventricular compliance

A

volume and pressure

103
Q

How does contractility (inotropy) affect ventricular output

A

At a given preload:
increased contractility increases ventricular output
decreased contractility reduces ventricular output

104
Q

Which metabolic conditions alter inotropy

A

Hypoxia (acidosis)
Hyperkalemia
Hypercapnia

105
Q

What is inotropy

A

Contractility

The ability of the myocardial sarcomeres to perform work and produce force

106
Q

What are factors that increase inotropy

A

SNS stimulation
Catecholamines
Digitalis
PDE inhibitors

107
Q

What are factors that decrease contractility

A 
Myocardial depression:
Myocardial ischemia
Severe hypoxia
Acidosis
Hypercapnia
Hyperkalemia
Hypocalcemia
Volatile anesthetics
Propofol
Beta-blockers
CCBs
108
Q

How does hyperkalemia impair contractility

A

Locks voltage-gated Na channels in their closed-inactive state
This prevents cells from depolarizing

109
Q

What role does Ca++ play in the myocardium

A

Ca++ is a second messenger that plays a role in excitation-contraction coupling

110
Q

How does Ca++ affect contractility

A

It increases contractility by binding to troponin C, stimulating cross-bridge formation and contractility

111
Q

Where is Ca++ stored inside the myocyte

A

Inside the sarcoplasmic reticulum bound to calsequestrin

112
Q

How does beta-1 stimulation affect contractility? How?

A

Stimulation increases contractility

  • Activation of adenylate cyclase converting ATP to cAMP activating PKA.
    1. Activates more L-type Ca++ channels
    2. Stimulates ryanodine 2 receptors to release Ca+
    3. Stimulate SERCA2 pump to increase Ca++ uptake
113
Q

What cardiac effects does beta-1 receptor stimulation have

A

Positive inotropy = more forceful contraction over shorter time
Positive lusitropy = enhanced relaxation between beats

114
Q

Define afterload

A

The force that the ventricle must overcome to eject its stroke volume

115
Q

Describe the difference in afterload between the left and right ventricles

A

Left ventricle must overcome a much higher afterload than the right ventricle

116
Q

What measure is used as a surrogate for afterload? Normal value

A

SVR 800-1500 dynesseccm^-5

117
Q

What determines a portion of afterload

A

Arteriolar tone aka SVR

118
Q

Aside from arterioles, what conditions can alter afterload

A

Aortic stenosis
hypertrophic cardiomyopathy
coarctation of the aorta

119
Q

What other factors, besides SVR, determine afterload (3)

A

Blood viscosity
Blood density
Ventricular wall tension

120
Q

What are the variable to measure SVR

A

[(MAP-CVP)/CO] x 80

121
Q

What are the variable to measure PulmVR

A

[(MPAP-PAOP)/CO] x 80

122
Q

How is the Law of Laplace applied to the mechanics of afterload

A

Wall stress = (intraventricular pressure * radius)/ventricular thickness

123
Q

What variables are used when apply the Law of Laplace to afterload effects on myocardial wall stress

A

Intraventricular pressure = force that pushes the heart apart
Wall stress = force that holds the heart together
Wall thickness/radius

124
Q

How does wall stress relate to intraventricular press, radius, and myocardial wall thickness

A

Directly proportional to intraventricular pressure and radius:
if IVP and radius decrease, so does wall stress

Inversely proportional to wall thickness:
If wall thickness increase, wall stress decreases

125
Q

How is oxygen consumption affected by myocardial wall stress

A

Increased stress = increased myocardial O2 consumption

Decreased wall stress improves O2 supply and demand

126
Q

MAP equation

A

(1/3 x SBP) + (2/3 x DBP)

[(CO x SVR)/80] + CVP

127
Q

What effect would be seen on a pressure-volume loop when phenylephrine is given

A

ESV shifts right

Loop width reduced

APEX-CV & Respiratory (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions