Part 12 Flashcards
1
Q
A
2
Q
Depolarization changes a cardiac myocyte’s membrane potential to make it less ___, allowing for…
A
negative, …the mechanical contraction of the myocyte
3
Q
Cardiac myocyte primary function
A
-contraction initiated with electrical depolarization (removal of negative resting potential) coordinated from myocyte to myocyte
4
Q
The heart can conduct signals ___ to ___, or via the ____ system which is much faster
A
cell to cell, conduction system
5
Q
AV delay allows for…
A
…contraction of the atria before the ventricle
6
Q
P wave represents…
A
Atrial depolarization from the SA node for about .08-.1 sec
7
Q
PR SEGMENT represents…
A
The time in which the impulse is traveling within the AV node where conduction velocity is greatly slowed
8
Q
QRS complex represents…
A
Ventricular depolariztiation normally about .06-.1 seconds
9
Q
ST segment represents…
A
The period of time from which the entire ventirlce has depolarized and corresponds to the plateau phase of the ventricular action potential before ventricular repolarization occurs
10
Q
T wave represents…
A
ventricular repolarization which typically tkes longer than the wave of depolarization
11
Q
12 lead EKG
A
Use of 10 electrodes placed in standard locations on the body in that each show a different perspective of the heart’s electrical activity
12
Q
Electrode placement of a 12 lead ekg
A
- V1 right 4th intercostal space sternal border
- V2 left 4th intercostal space sternal border
- V3 between V2 and V4
- V4 at the left 5th intercostal space mid clavicular line
- V5 5th intercostal space anterior axillary line
- V6 5th intercostal space mid axillary line
- 1 on left arm
- 1 on right arm
- 1 on left leg
- 1 on right leg
13
Q
A wave of ___ traveling ___ a positive electrode results in a ____ deflection of an EKG trace, while traveling ___ a positive electrode resuls in a ___ deflection.
A
depolarization (positive charge) toward, positive, away, negative
14
Q
PEA
A
Pulseless electrical activity, occurs when the patient has normal electrical conduction but a lack of a pulse often seen in cardiac arrest where the heart either does not contract or there is insufficient cardiac output to supply the organs
15
Q
Automaticity of the heart
A
Refers to ability of cardiac muscles to depolarize spontaneously without outside stimulation from nervous system at the SA node (normal pacemaker of heart), despite also receiving innervation from sympathetic and parasympathetic fibers
16
Q
Conduction system pathway of the normal heart
A
- SA node in right atrium
- bachmann’s bundle goes to left atrium
- AV node receives the signal from the SA node and delays ventricular contraction
- AV goes thru bundle of His
- Bundle of His goes to bundle branches and then to purkinje fibers
- At the apex we see the signal then finally move to the ventricular myocardium where it contracts
17
Q
PR Segment vs PR Interval
A
Segment is from the end of the P wave to the start of the QRS complex, interval is from the start of the P wave to the start of the QRS complex
18
Q
A prolonged PR interval >___sec indicates ____
A
.2, first degree heart block (conduction defect in AV node)
19
Q
A prolonged QRS complex >___sec indicates ___
A
.1 sec, bundle branch block
20
Q
QT interval represents…
A
Timeline of both ventricular depolarization and repolarization, ranges from .2-.4 seconds depending on heart rate (have to measure corrected QT (QTc)
21
Q
The right atrium and ventricle are ___ compared to the left
A
more anterior
22
Q
Y axis of an EKG is measured in ___ but is almost always commonly described in ____
A
mv, mm
23
Q
Tall P wave indicates….
A
…right atrial enlargement
24
Q
Delta wave
A
A sign of early excitation of ventricles, indicative of re-entry such as global (wolff-parkinson-white syndrome causing tachycardia in children) characterized by a slurred upstroke of the QRS complex
25
U wave
Follows T wave, not always present, same direction of deflection of the T but much smaller amplitude (often not picked up), unknown what it represents
26
Hyperkalemia causes ___ on an ekg finding, what does hypokalmeia cause?.
Increased amplitude and peaking of T wave, flat or inverted T wave
27
1 square represents what values in mm, sec, and mv horizontal and vertically?
1mm or .04 sec horizontally, and 1mm or .1mv vertically
28
R wave gets progressively ___ from V1 to V4-5, loss of this can indicate what?
Bigger, loss of ventricular myocardial conduction (often MI)
29
ST segment elevation indicates...
| ST segment depression indicates...
elevation indicates acute infarction and pericardidits, and depression in ischemia
30
T wave abnormalities
, may become inverted, peaked, or flattened due to ischemia, infarction, or medications
31
Chest pain (most of the time, sometimes other areas) upon exertion that is relieved upon rest, always assume....
....cardiac in nature until proven otherwise
32
Dependent edema definition
Gravity dependent, refers to edema that shifts in observation depending on how the patient is positioned (if bed ridden in flanks and back, if upright then feet) often seen in congestive heart failure
33
Classic angina pain presentation
Sharp pain that radiates to the shoulders and sometimes the jaw
34
Left sided heart failure results in blood pooling in the ___, right side results in blood pooling in the ___
lungs, extremities
35
Paroxysmal nocturnal dyspnea definitoin
A form of orthopnea where a patient awakes suddenly with feeling of suffocation and has to quickly sit upright for relief, a sign of cardiovascular condition
36
Orthopnea (cardiac history)
Dyspnea that occurs in the recumbent position caused by redistribution of blood from abdominal and lower body venous vasculature to chest increasing workload of heart, develops within minutes of laying flat, often a sign of cardiac disease
37
claudication (cardiac history)
Sharp pain caused by absence of blood flow often experienced in the extremities and during exercise, often a sign of cardiac disease
38
Coarctation of aorta
Aortic arch narrowing, often congenital condition that results in a smaller aorta past the 3 great vessels that therefore requires left ventricle to work much harder to pump blood to perfuse the lower extremity, often a sign of cardiac disease
39
Fatty streak development
Intracellular lipid accumulation in the early stage progression of atherosclerosis, often seen in ages 4-5 in about 50% of patients and indicative of slight increasing endothelial dysfunction (but does not manifest with any clinical symptoms and is clinically "silent")
40
Stable plaque vs vulnurable plaque
Stable - a buildup of cholesterol that has fibrous scar tissue forming around it as well as migrating smooth muscle tissues that narrow the lumen of the artery (fibrous plaque)
Vulnurable - occurs in more advanced stages of atherosclerosis, where scar tissue has calcified over and if endothelium is damaged collagen is exposed causing platelets to aggregate and clot forming a thrombus at risk for embolism
41
Metabolic syndrome
A condition characterized by 3 of the following
- abdominal obesity (>40 inch males and 35 inch in females)
- HDL below 40mg/dL male and 50mg/dL female
- hypertension >130/85mmHg
- elevated fasting glucose to either pre-diabetic (>110mg/dL) or diabetic stage (>125mg/dL)
42
Apolipoprotein B100 serum lab study and healthy values
Measurement test of secondary marker for LDL measuring a substrate of LDL indicating risk of developing cardiovascular disease, with normal values below 100mg/dL
43
Ultra sensitive CRP and homocystine serum lab studies
Measurement test that detects non specific marker of inflammation that could be indicating increased inflammation of vessels and heart putting patient at risk for heart attack, but could also be due to any number of inflammatory conditions or infection
44
Statin therapy and pregnancy
Contraindicated!!! can be replaced with less effective bile acid sequestrant
45
Patients with triglycerides greater than ___mg/dL are at risk for developing ___ and therefore require ____ therapy if triglycerides exceed ___mg/dL
1000mg/dL, Spontanous pancreatitis, fibrate, 500
46
Hyperlipidemia secondary prevention guidelines
-begin statin therapy independent of baseline LDL levels, if patients do not acheive <70 mg/dL LDL (monitored every six weeks) then maximize statin therapy and consider adding a second agent (Ezetimibe)
47
How does the wave of electrical current generated in the heart spread to adjoining cells?
gap junctions allow ions to pass freely from cell to cell
48
In cell, for depolarization of resting membrane potential must become less ____ (negative or positive?)
negative
49
At resting state, what ion is found in higher conc inside the cardiac muscle cell?
K+
50
Where are the 3 normal areas of the heart to have automaticity?
- SA node
- AV nde
- Bundle of His/purkinje fibers
51
At rest in a cardiac myocyte, Na+ conc. is higher ___ the cell. K+ conc. is higher ___ cell, Ca2+ is at higher conc. ___ cell
outside, inside, outside
52
Action potential generation in autorhythmic cell mech of action
- autorhythmic cells begin depolarizing (becomes less negative) due to slow continuous inward movement of Na+ and reduced outward movement of K+ from -60mV approx resting potential
- upon reaching threshold -40mV, Ca2+ channels open and Ca2+ rushes into cell making cell much less negative, depolarization occurs
- K+ channels are triggered at -10mV and opened and Ca2+ channels close resulting in K+ flow out of the cell (repolarization)
- Ion pumps use ATP to move Ca2+ back to extracellular space and Na/K ATPase pumps Na+ out of cell and K+ back into cell
53
Action potential generation in cardiac myocyte mech of action
- -90mv is resting potential for the cardiac myocyte
- Positive ions moving thru gap junctions create small voltage change initiating depolarization
- this stimulates opening of fast Na+ cells at -70mV, begins depolarization
- myocyte contraction begins here
- Depolarization to +20mV triggers opening of slow Ca2+ channels, allowing Ca2+ entry from extracellular space
- At same time, depolarization to +20mV triggers K+ channels to allow K+ to begin leaving the cell
- This generates the plateau phase
- Ca2+ channels close and more K+ channels open causing cell to become less positive (repolarization)
- myocyte relaxation begins here
- simultaneously, ions pump Ca2+ out to extracellular space and Na+/K+ATPase pumps Na+ out and K+ back in
54
Primary pacemaker of heart normally and where is it located anatomically?
SA node, posterior wall of right atrium
55
Intrinsic rate of the heart of the SA node
100-110 BPM
56
Vagal tone
parasympathetic nervous influence from cranial nerve X that slows the heart rate from its intrinsic beat at rest (100-110 bpm) to 60-80bpm in healthy patient
57
AV node function and intrinsic rate
Slows signal from SA node down by 120 msec allowing ventricles to fill allowing for complete atrial depolarization, contraction, and emptying of blood into ventricle prior to ventricular contraction, intrinsic rate is 40-60bpm
58
4 big classes of drugs that we can use to alter AP in the heart
- Na+ channel blockers
- B blockers
- K+ channel blockers
- Ca2+ channel blockers
59
How does a PVC/extra systole appear on the EKG?
As an extra, often widened and inverted QRS complex with an absence of a P wave preceding the contraction
60
Bundle of His
High speed conduction network that forms the narrow QRS complex allowing for ventricular contraction, receives signal (delayed by) the AV node and transmits signal to rest of heart
61
How does a drug that partially inactivates fast Na+channels impact AP in ventricular myocyte and thus conduction veolcity in the ventricle?
It decreases conduction velocity
62
Ectopic foci
Sites that spontaneously depolarize and produce AP independent of SA node (normally overridden by SA node), occurs anytime the pacemaker of the heart is not the SA node, acts as a protective mechanism to ensure the heart still beats even in the absence of the SA node
63
Purkinje fibers
Network of conducting cells that receive a signal from the bundle of His and spread the AP fastest to the rest of the heart activating the ventricles from the apex upwards
64
Sometimes nonpacemaker cells after becoming hypoxic will...
...change into pacemaker cells that then depolarize spontanously and demonstrate automaticity resulting in irregular beats and arrhythmia
65
2 components of autonomic NS, what is the primary neurotransmitter associated with it, and what are the receptors associated with it?
- Sympathetic/thoracolumbar (norepi, adrenergic)
- Parasympathetic/craniosacral (acetycholine, cholinergic)-
66
Somatic vs autonomic pathways of efferent innervation
ANS has 2 neurons opposed to one that span distance form CNS to effectors with presynaptic neuron cell body in CNS followed by a myelinated preganglionic fiber (same as somatic) that then transfers to a postsynaptic neuron cell body which carries the rest of the signal thru an unmyelinated postganglionic fiber to the target organ
67
In sympathetic division, pregangionic fibers tend to be very ___ and postganglionic tend to be very ___. In parasympathetic division, preganglionic are very ___ and post are very ___
short, long, long, short
68
Adrenal medulla function (include what percentage of released catecholamines are epi vs norepi)
Very large modified sympathetic ganglion that receives pregangionic innervation and is stimulated to release epi (80%) and norepi (20%) into the body, causes prolonged activity of the substances, helps the body deal with stress, takes longer to metabolize from body leading to prolonged "keyed up" feeling
69
Cranial nerves are classified as ____ _____ nerves, which is the most important one?
- Autonomic parasympathetic
| - Vagus nerve (X), responsible for majority of parasympathetic stimulation to different viceral systems of the body
70
Dual innervation
Refers to tendency of most viscera of the body to receive nerve fibers from both parasympathetic and sympathetic divisions that often have antagonistic effects or occasionally cooperative effects desppite not normally innervating the organ equally
71
Dual innervation of the iris (don't forget the names of the muscles that perform the actions!)
The radial muscle is controlled by the sympathetic NS, stimulation sees contraction causing pupilary dilation (mydriasis) while parasympathetic stimulates the circular muscles, stimulation causes constriction of pupil (myosis)
72
Control without dual innervation and 4 examples
Certain areas of the body that only receive predominantly one type of innervation (adrenal medulla, sweat glands, erector pilli, vasomotor tone)
73
2 major neurotransmitters of ANS, what releases them, and where are they found
- acetylcholine: released by cholinergic neurons to all pre ganglionic neurons and postganglionic parasympathetic neurons)
- norepi: released by adrenergic neurons from postganglionic sympathetic neurons
74
3 types of cholinergic receptors
Nicotinic type I and type II and muscarinic
75
4 types of adrenergic receptors
alpha 1 and alpha 2 and B1 and B2 receptors
76
a1 vs a2 vs B receptor functional 2ndary messenger systems
- a1 receptors utilize Ca2+ as a secondary messenger
- a2 receptors suppress cyclic AMP as a 2ndary messenger
- B receptors activate cyclic AMP as a 2ndary messenger
77
a1 adrenergic receptors
Bound by catecholamines (epi or norepi), found on virtually all sympathetic target organs, sees vasoconstriction of vascular smooth muscle, ejaculation, contraction of bladder neck and prostate, and pupillary dilation
78
a2 adrenergic receptors
Bound by catecholamines (epi or norepi), located in synaptic cleft between target organ and post synaptic neuron where upon being bound it inhibits its further release of catecholamines
79
B1 adrenergic receptors
Bound by catecholamines (epi or norepi), located at the heart causes increased heart rate, force of contraction, and increased velocity of conduction to AV node, as well as stimulates renin release at the JG cells of the kidney
(think about B blockers Tav)
80
B2 adrenergic receptors
Bound only by epi, seen in the lungs to cause bronchial dilation, uterine muscle relaxation (premature labor prevention with drugs), coronary and skeletal muscle blood vessels vasodilation, stimulate glycogenolysis
81
catechol-o-methyl-transferase (COMT) and monoamine oxidase (MAO)
- COMT functions to breakdown circulating NE and Epi in tissues thruout the body
- MAO functions to desrtroy NE released from adrenergic nerve fibers reabsorbed into the presynaptic nerve ending
82
Nicotinic type I receptors
Bound by acetycholine, found in the autonomic ganglia in both divisions of the ANS between pre and post ganglionic fibers as well as in the adrenal medulla
83
Nicotinic type II receptors
Bound by acetycholine, found in the somatic nervous system on motor end plates of skeletal muscle acting excitatory
84
Muscarinic receptors
Bound by acetylcholine, found on all target tissues of parasympathetic NS, either excitatory or inhibitory when ACh binds depending on subclass of muscarinic receptors
85
Acetylcholinesterase
Enzyme responsible for Ach degradation in the synaptic cleft causing parasympathetic stimulation to have a short duration of effect
86
Sympathomimetic definition
An Adrenergic agonist drug that simulates sympathetic stimulation of the ANS
87
Sympatholytic definition
An adrenergic antagonist drug that inhibits sympathetic stimulation of the ANS
88
Inactivation of catecholamine adrenergic agonists occurs by ___ and ___ and as a result these drugs must be administered by ____
MAO, COMT, by continuous infusion
89
Catecholamines vs noncatecholamine drugs
Catecholamines are quickly inactivated by MAO and COMT and cannot cross BBB and therefore have minimal CNS effects, noncatecholamines are metabolized slowly and thus have longer half lives and can be delivered PO and can penetrate BBB, therefore have effect on CNS
90
Indirect acting adrenergic agonists and 2 examples
Tend to be noncatecholamines, cause release of NE from presynaptic terminals, inhibit its reuptake, and inhibit deactivation of it
- amphetamines
- ephedrine (which can do both)
91
Direct acting adrenergic agonists and 2 examples
Tend to be catecholamines, work by directly binding to and activating adrenergic receptors
- epi
- isoproterenol
92
Epi cardiovascular effects
- hr increase
- BP increase
- bronchodilation
93
Isoproterenol cardiovascular effects
- HR increase
- bronchodilation
| - bronchodilation
94
Norepi cardiovascular effects
- HR increase
- BP increase
- no bronchodilation
95
Therapeutic applications of a1 stimulation (4)
- hemostasis to prevent bleeding via vasoconstriction
- nasal decongestants
- mydriasis
- elevation of BP in shock
96
cocaine overdose resulting in MI cause of death mechanism of action
- Cocaine acts as an adrenergic agonist and has activity on a1 receptors
- such potent activity results in coronary artery constriction (vasospasm) and lack of perfusion to the heart
97
Example of a1 agonists in nasal sprays and oral decongestants
- phenylephrine
- pseudoephedrine
| - pseudoephedrine
98
a2 stimulation has minimal effect on ____ but larger effect on ____
PNS, CNS
99
Examples of a2 therapeutic agents (2)
- clondine (directly binds a2 receptors)
- a methyldopa (converted in adrenergic nerve terminals to a-methylnorepi released by adrenergic neuron and binds a2 receptors
100
B1 stimulation clinically relevant responses act on the...
...heart
101
Therapeutic applications of B1 stimulation (4)
- cardiac arrest
- heart failure
- shock
- AV heart block
102
B1 agonist ADR's (2)
- altered heart rate or rhythm (tachycardia or arrhythmia)
- angina pectoris
103
B2 stimulation therapeutic uses (2)
- asthma
- delay of preterm labor
104
examples of B2 selective agents (3)
- albuterol
- levabuterol
- terbutaline (po for asthma or subQ for preterm labor)
105
B2 agonists ADR's (3)
- hyperglycemia (not normally an issue unless diabetic)
- tremor
- at high doses may stimulate b1 receptors resulting in overstimulation of heart
106
Dopamine receptor stimulation function
-activates peripheral dopamine receptors causing dilation of mesenteric and renal vasculature to treat shock and improve renal perfusion
107
Anaphylaxis treatment DOC and mech of action to treat hypotension, laryngeal edema, and bronchoconstriction
- Epinephrine subQ
- B1 stimulation increases cardiac output raising BP, a1 promotes vasoconstriction that can elevate BP and suppress laryngeal edema, B2 counteracts bronchoconstriction
108
Epi dosing ratio for oral/inhalation, subq/im, and IV/intracardiac
1: 100 oral or inhalation
1: 1000 subq, im
1: 10,000 IV or intracardiac
109
Norepinephrine (levophed) mech of action and therapuetic uses (2)
-only activates a1 and B1 receptors, equivalent on B1 receptors but less potent on a1 receptors
- used in hypotensive states
- cardiac arrest
110
Dopamine (intropin) administration and therapeutic uses (3)
-IV
- Low doses to increase renal flow
- moderate doses to increase CO
- high doses to produce vasoconstriction (heart failure and shock)
111
Dobutamine (dobutrex) therapeutic use (1) and ADR's (1)
- only indicated for heart failure or stress testing
- - Increase AV conduction putting caution in using with afib
112
Albuterol (ventolin) mech of action and therapuetic use (1)
- selectively stimulates B2 receptors with much less stimulation of heart than isoproternol
- asthma for relaxation of bronchial smooth muscle
113
Heart primarily has ___ adrenergic receptors
B1
114
Blood vessels primarily have ____ adrenergic receptors
a1
115
Vascular beds in skeletal muscle have both a1 and B2 receptors. What will NE cause as a net response and why?
Vasodilation due to a greater number of B2 receptors and greater sensitivity
116
Drugs that stimulate a1 receptors (5)
- epi
- NE
- phenylephrine
- ephedrine
- dopamine
117
Drugs that stimulate a2 receptors (3)
- epi
- NE
- ephedrine
118
Drugs that stimulate B1 receptors (5)
- epi
- norepi
- isoproterenol
- dopamine
- ephedrine
119
Drugs that stimulate B2 receptors (4)
- epi
- isoproterenol
- terbutaline
- ephedrine
