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Physiology III - Freedman > Unit 1: Pt 3 Physiology III > Flashcards

Unit 1: Pt 3 Physiology III Flashcards

1
Q

What are some extrinsic influences on the heart?

A
  • Autonomic NS
  • Hormonal influences
  • Ionic influences
  • Temperature influences
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2
Q

What will sympathetic innervation have on the heart?

A
  • Increase HR
  • Increase strength of contraction
  • Increase conduction velocity
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3
Q

What will parasympathetic innervation have on the heart?

A
  • Decrease heart rate
  • Decrease strength of contraction
  • Decrease conduction velocity
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4
Q

How are SNS effects on the heart blocked?

A

Using propranolol (beta blocker), Which blocks beta receptors (which bind NE and Epi)

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5
Q

How are parasympathetic effects on the heart blocked?

A

Using atropine, which block muscarinic receptors (which bind Ach)

  • HR will increase
  • Strength of contraction decreases
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6
Q

Describe the interaction of the ANA under resting conditions. (What is dominant at rest?)

A

Parasympathetic NS exerts a dominant inhibitory influence on HR (rate of contraction)

Sympathetic NS exerts a dominate stimulatory influence on strength of contraction

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7
Q

If we were to block BOTH sympathetic and parasympathetic autonomic systems, what would occur?

A

HR will go up and strength of contraction will go down

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8
Q

What neurotransmitter does the postganglionic neurons of the SNS and the Parasympathetic neurons release?

A

SNS— NE

Parasymp— ACh

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9
Q

How does the interaction of the SNS and paraysmp. Systems work?

A

They inhibit each other (think about brake and gas pedal, do not want to push on both at same time)

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10
Q

What is the intrinsic rate of the SA when there is no neural influence?

A

100-110 bpm

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11
Q

T/F. Indirect effect of cardiac cells accounts for most of the SNS effect.

A

False. Direct innervation of cardiac cells accounts for most of the SNS effect

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12
Q

Which system is NE acting on beta-1 receptors an example of?

A

Sympathetic nervous system

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13
Q

What would indirect effects of SNS on the heart be?

A

Due to circulating catecholamines (Epi and NE) released primarily from the adrenal medulla (blood borne), which would find their way to cardiac beta-1 receptors

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14
Q

SNS influence on the heart comes from ______ percent Direct innervation, and _____ percent Indirect effects.

A

85% direct

15% indirect

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15
Q

If a heart is de-innervated, can there still be SNS effect on the heart?

A

YES, due to the circulating catecholamines (80% epi and 20% NE)

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16
Q

What percent of the circulating catecholamines released primarily from the adrenal medulla is Epinephrine and NE?

A 
Epi = 80%
NE = 20%
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17
Q

When the SNS stimulates the left stellate ganglion, what occurs?

A
  • Decreased ventricular fibrillation threshold
  • Prolongation of QT interval
    (worry about LV in D-Fib)
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18
Q

When the SNS stimulates the right stellate ganglion, what occurs?

A
  • Increased ventricular fibrillation threshold

puts you in more protective position

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19
Q

Is it better to have SNS stimulation of the left or right stellate ganglion?

A

The right stellate ganglion b/c that will increase ventricular fibrillation threshold, and therefore put you in more protective position

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20
Q

Recall: What nerve controls about 75% of the parasympathetic nervous system?

A

Vagus Nerve

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21
Q

Left cardiac sympathetic denervation can increase what activity?

A

Vagus nerve activity —incrase vagal activity has a lot of benefits, like preventing life threatening arrhythmias like D-Fib
(chiro adjustments are shown to help Vagal activity)

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22
Q

What is the Cardioaccelerator reflex?

A

AKA Brainbridge reflex; stretch on the right atrial wall will stimulate stretch receptors which send signals to medulla oblongata and stimulate SNS outflow of heart

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23
Q

What does the Brainbridge/ Cardioaccelerator reflex prevent?

A

It prevents damning of blood in the heart and central veins

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24
Q

What is the Benzold-Jarisch reflex? What nerve(s) are involved?

A

Are baroreceptors in ventricles (stretch receptors detecting pressure)
- Reflex via CN X, to CNS

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25
Q

Where is the site of the majority of the baroreceptors involved in the Benzold-Jarisch reflex?

A

Inferoposterior wall of LV (supplied by circumflex artery)

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26
Q

*What two things does the Benzold-Jarisch reflex result in? (as in when the baroreceptors are detecting too much pressure)

A

Reflex effects result in:

  1. Hypotension
  2. Bradycardia
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27
Q

What is the Benzold-Jarisch reflex stimulated by?

A
  • occlusion of circumflex artery (inf. wall infarct

- increase in LVP and LV volume (i.e. aortic stenosis)

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28
Q

How do Thyroid hormones influence the heart?

A
  • positive inotropic (increase strength of contraction)
  • positive chronotropic (increase HR)
  • increase in CO by increase in BMR (basal metabolic rate)
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29
Q

How is the heart affected in hypothyroidism?

A

BMR decreases; and therefore heart pumps less blood

also get cold, and decrease weight loss

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30
Q

How is the heart affected in hyperthyroidism?

A

BMR increase; and therefore heart pumps more blood (also get hot, and increases weight loss)

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31
Q

What is the effect on cardiac cells of elevated concn. of K+ in extracellular fluid (ECF)?

A
  • dilation of flaccidity of cardiac muscle at concs. 2-3x normal
  • decreases resting membrane potential
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32
Q

The effect that elevated conc. of K+ is associated with what way of death?

A

ass. with drowning in fresh water

- b/c increase RBC lysis and the RBC’s release K+

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33
Q

What is the effect on cardiac cells of elevated conc. of Ca++ ECF?

A

spastic contraction

Ca++ binds troponin

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34
Q

What does the effect of an elevated body temp have on our Heart Rate?

A

HR increases about 10 beats for every degree F elevation in body temp.

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35
Q

What does the effect of elevated body temp have on the heart’s contractile strength?

A

Contractile strength will increase TEMPORARILY, but prolonged fever can decrease contractile strength due to exhaustion of metabolic systems

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36
Q

What effect does decreased body temp have on the heart?

A

will decreased HR and strength

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37
Q

What is the preferred energy substrate for the heart?

A

fatty acids – 70% preferred

can also use: Glucose, glycerol, lactate, pyruvate, amino acids

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38
Q

Most of the energy the heart utilizes is converted into what? What is the remaining percentage utilized as?

A

heat; 75%

remaining 25% used for Work

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39
Q

How is the 25% of energy utilized for work by the heart broken down?

A

Pressurization of blood >99%

Acceleration of blood <1%

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40
Q

What is most of the Work of the heart used as?

A

Pressurization >99%

potential energy

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41
Q

Pressurization of the blood = _________, where as Acceleration of blood to its ejection velocity = ________.

A

= potential energy

= kinetic energy

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42
Q

What does pressurization of the blood involve?

A

moving blood from low pressure to high pressure
(volume pressure work or external work)
–is the majority of the work component, at >99%

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43
Q

What does the acceleration of blood to its ejection velocity involve?

A

out the aortic and pulmonary valves; accounts fro less than 1% of work component

can increase to 50% with valvular stenosis

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44
Q

What does an EKG measure?

A

measures potential difference across the surface of the myocardium with respect to time

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45
Q

For an EKG, what is the definition of a lead?

A

= pair of electrodes (one + and one -)

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46
Q

For an EKG, what is the line connecting the electrodes called??

A

axis of lead

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47
Q

For an EKG, what is the line perpendicular to axis of lead called?

A

transition line (this is the weak spot for bipolar limb leads–therefore need the unipolar limb leads)

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48
Q

What is the normal rate of the heart?

A

60-80 bpm

49
Q

What is it called when the HR is greater than 100 bmp?

A

tachycardia

50
Q

What is it called when the HR is less than 50bpm?

A

bradycardia

51
Q

What does the PR interval include?

A

includes the AV node delay

should be ~ .16 sec

52
Q

If the PR interval is greater than .20 seconds what does it equal?*

A

= 1st degree AV block (longer than normal)

53
Q

If the PR interval is less than .10 seconds, what does this mean?

A

inadequate delay–> possible accessory conduction pathway from atria to ventricle

54
Q

What does the P wave represent?

A

atrial depolarization

55
Q

What does the QRS complex represent?

A

ventricular depolarization

56
Q

What does the T wave represent?

A

ventricular repolarizaiton

57
Q

What is normally buried in the QRS complex and doesn’t show up on an EKG?

A

Atrial repolarization

58
Q

What does the U wave represent?

A

repolarization of purkinje system (not always seen)

59
Q

What is the difference between intervals and segments on an EKG?

A

intervals = include wave form

segments = on baseline; have no wave form

60
Q

What it comes to the Leads for an EKG, what does the pair of recording electrodes consist of?

A

+ electrode = active

- electrode = a reference

61
Q

What is the direction of the deflection based on for an EKG?

A

it can be + or -; and it is based on what the active electrode (+) sees relative to the reference electrode (-)

62
Q

How many leads does a routine EKG consists of?

A

12 leads:

  • 6 frontal plane leads
  • 6 chest leads (horizontal/transverse plane)
63
Q

What type of deflection is it when a wave of depolarization is moving toward the + electrode?

A

a positive deflection (R wave)

64
Q

What type of deflection is it when a wave of repolarization is moving toward the + electrode?

A

negative deflection

65
Q

What type of deflection is it when a wave of depolarization is moving toward the - electrode?

A

negative deflection (S wave)

66
Q

What type of deflection is it when a wave of repolarization is moving toward the - electrode?

A

positive deflection (T wave)

67
Q

What plane are the limb leads in for an EKG?

A

frontal plane

68
Q

What lane are the chest (V) leads in for an EKG?

A

view heart in horizontal/transverse plane

69
Q

What are all the bipolar limb leads and where do they go? (may want to draw the triangle)

A

Lead I (+LA -RA)

Lead II (+LL -RA)

Lead III (+LL -LA)

70
Q

What are all the unipolar limb leads (Augmented)?–may want to draw triangle

A

(assist with/helps/adds to)

AvR (+RA -LA and LL)

AvL (+LA -RA and LL)

AvF (+LL -RA and LA)

71
Q

Which Unipolar limb lead is perpendicular to Lead I?
Lead II?
Lead III?

A

Lead I –> AvF (F for foot)
Lead II –> AvL
Lead III –> AvR

72
Q

If the wave is perpendicular to the axis of the bipolar limb lead, will there be a deflection?

A

no

73
Q

Where are the positive electrodes for the Chest leads? Where are the negative electrodes?

A

Positive electrodes– all on chest wall

Negative electrodes– all limb electrodes hooked together

74
Q

What does and EKG NOT give us information about?

A

about the mechanical activity of the heart

- could take a valve out and the EKG would be normal

75
Q

The analysis of an EKG can tell us what 5 things?

A
  • rate
  • rhythm and intervals
  • axis
  • hypertrophy
  • infarction/ischemia
76
Q

What are the sequence of numbers one can use to count the big boxes b/w R waves to get the estimated HR?

A

300-150-100-75-60-50

1 1/2 1/3 1/4 1/5 1/6

77
Q

What on the EKG is the time from SA node to entering the ventricle?

A

PR interval

78
Q

What on the EKG includes the AV nodal delay?

A

PR interval

79
Q

If a PR interval is greater than .2 seconds, what is that called?

A

1st degree AV block

80
Q

If someone has a prolonged QT interval, what are two increased risks they may experience?

A
  • increased incidence of sudden cardiac death

- high propensity to develop ventricular fibrillation

81
Q

What is a sinus arrhythmia?

A

an irregular heartbeat that is either too slow or too fast

- longest and shortest RR vary by greater than .16 seconds

82
Q

Do we want a heart rate that has increased variability or no?

A
  • less the heart is varying = more at risk you are to die

- increase heart rate variability = the better off you are

83
Q

What is AV block?

A

Atrioventricular block is a type of heart block where conduction b/w the atria and ventricles of heart is impaired

84
Q

What is 1st degree AV block?

A

depolarization wave from atria to ventricle is delayed excessively
- PR interval is greater than .2 seconds

85
Q

An occasional P wave with no associated QRS complex (a dropped heart beat) describes what?

A

2nd Degree AV block

- some depolarization wave pass, others blocked

86
Q

What is a 3rd degree AV block?

A

ALL depolarization waves from atria to ventricles are blocked
- no relationship b/w P waves and QRS complexes

87
Q

What is the normal duration of QRS complex?

A

duration .06-.08 seconds

88
Q

A QRS complex that is prolonged, greater than .12 seconds is associated with what?

A

with ventricular hypertrophy or conduction block in purkinje system

89
Q

What is the Mean Electrical Axis (MEA)?

A

average direction of ventricular depolarization

90
Q

How does the ventricle depolarize?

A

A.D.I.O

  • from base (above) to apex (down)
  • from endocardium (inside) to epicardium (out)
91
Q

What is the axis range for a normal heart beat?

A

between -30 and +105 degrees

92
Q

What must the QRS of lead I and the AvF must be to be a MEA that is normal?

A

both are positive

93
Q

What way will the axis shift if there is a problem such as conduction block or hypertrophy?

A

axis will shift to the side of the problem

94
Q

If there is left bundle branch block, how will the axis shift/ what will the deviation be?

A

a left axis deviation

95
Q

Hypertrophy may results if the QRS complex is shortened or prolonged?

A

if it is prolonged to greater than .12 seconds

96
Q

What can be associated with anything that creates an abnormally high work load on the ventricle chamber?

A

hypertrophy

97
Q

What is an example of something that may increase work load on the left ventricle? What can it cause?

A

Systemic hypertension; will cause hypertrophy of that left ventricle

98
Q

What supplies the myocardium?

A
  • the coronary arteries and their branches
99
Q

Cells near the endocardium may be able to receive some oxygen from where?

A

some oxygen from chamber blood

100
Q

When is myocardial blood flow limited? Esp. where in the heart?

A

during cardiac muscle contraction; esp. limits the LV

101
Q

When does left coronary artery flow peak? When does right coronary artery flow peak?

A

Left– at onset of diastole
Right– as mid systole

– due to more compression of small blood vessels in wall of LV during systole

102
Q

At resting HR the myocardium will take maximum oxygen out of the perfusing coronary flow, which is what percentage?

A

70% extraction rate

103
Q

How is any increase demand on the heart met?

A

by increase coronary flow

104
Q

Normally the ____ cells to depolarize are the ____ cells to repolarize.

A

first; last

105
Q

T/F. Depolarization and repolarization waves are in the same directions.

A

False; they are in opposite directions

106
Q

The ___ and the ___ wave point in the same direction.

A

QRS and T wave

107
Q

What does ischemia prolong? Therefore, what is it delaying?

A

prolongs depolarization, therefore delays repolarizaiton

108
Q

What does ischemia cause the depolarization and repolarization waves to do?
What will this cause on an EKG?

A

go in same direction

will cause an inversion in T wave

109
Q

If there is an inversion in T wave (opposite deflection compared to QRS), what do we think is occurring to the heart?

A

ischemia

110
Q

When an infarction occurs, what do damaged cells lose the ability to do?

A

repolarize

111
Q

When does most of the frank damage occur when an infarction occurs?

A

upon reperfusion and is associated with free radical damage

112
Q

The damaged area from an infarction is in an abnormal what?

A

in an abnormal state of depolarizaiton

113
Q

What occurs when normal myocardium is in a resting polarized state, but there is damage from an infarction on part of the heart?

A

there is a “current of injury” b/w damaged and normal myocardium

114
Q

What is created on an EKG when there is a “Current of injury” b/w damaged and normal myocardium?

A

creates a depressed baseline which appears as an elevated ST segment

115
Q

When we see a depressed baseline, which is appearing as an elevated ST segment on an EKG, what do we think occurred?

A

an infarciton, and therefore why there is a “current of injury” b/w damaged and normal myocardium when normal myocardium is in a resting polarized state

116
Q

What are preferred blood markers to tell if there has been an infarction?

A

cardiac troponins T and I are preferred markers for myocardial injury

117
Q

What have the highest sensitivities and specificities for the diagnosis of acute myocardial infarction?

A

cardiac troponins T and I

118
Q

Why is troponin used as an elevated marker in a myocardial infarction?

A

b/c troponin is a contractile protein NOT normally found in serum
- is released ONLY when myocardial necrosis occurs

Physiology III - Freedman (18 decks)

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