Ch 17 - Part B Flashcards

1
Q

defects in intrinsic conduction system may cause:

A

arrhythmias, fibrillation

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2
Q

Arrhythmias

A

irregular heart rhythms; uncoordinated atrial and ventricular contractions

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3
Q

Fibrillation

A

rapid, irregular contractions; heart becomes useless for pumping blood, causing circulation to cease

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4
Q

ectopic focus

A

an abnormal pacemaker that takes over pacing; caused by defective SA node

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5
Q

Extrasystole (premature contraction)

A

ectopic focus of small region of heart that triggers impulse before SA node can, causing delay in next impulse; can be from excessive caffeine or nicotine

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6
Q

heart block

A

caused y defective AV node; few impulses or no impulses reach ventricles which is too slow to maintain adequate circulation

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7
Q

heart block treatment

A

artificial pacemaker, which recouples atria and ventricles

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8
Q

Heartbeat is modified via…

A

cardiac centers in medulla oblongata

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9
Q

cardioacceleratory center

A

sends signals thorugh sympathetic trunk to increase both rate and force

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10
Q

cardioinhibitory center

A

parasympathetic signals via vagus nerve to decrese rate

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11
Q

contractile muscle fibers

A

make up bulk of heart muscle are are responsible for pumping action

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12
Q

How are contractile muscle fibers different from skeletal muscle?

A

in skeletal muscle contraction, cardiac muscle action potentials have plateau

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13
Q

electrocardiograph

A

can detect electrical current generated by heart

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14
Q

electrocardiogarm (ECG or EKG)

A

a graphic reccording of electrical activity; composite of all action potential at a given time, not a tracing of a single one

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15
Q

P wave

A

depolarization of SA node and atria

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16
Q

QRS complex

A

ventricular depolarization and atrial repolarization

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17
Q

T wave

A

ventricular repolarization

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18
Q

P-R interval

A

beginning of atrial excitation to beginning of ventricular excitation

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19
Q

S-T segment

A

entire ventricular myocardium depolarized

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20
Q

Q-T interval

A

beginning of ventricular depolarization through ventricular repolarization

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21
Q

systole

A

period of heart contraction

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22
Q

diastole

A

period of heart relaxation

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23
Q

cardiac cycle

A

blood flow through heart during one complete heartbeat

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24
Q

One Cardiac cycle

A

atrial systole and diastole are followed by ventricular systole and diastole

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25
Q

Isovolumetric contraction

A

split-second period when ventricles are completely closed, volume remains constant, ventricles continure to contract

26
Q

Isovolumetric relaxation: early diastole

A

following ventricular repolarization (T wave), ventricles relax

27
Q

End systolic volume (ESV)

A

volume of blood remaining in each ventricle after systole

28
Q

dicrotic notch

A

closure of aortic valve raises aortic pressure as backflow rebounds off closed valve cusps

29
Q

Quiescent period

A

total heart relaxation that lasts about 0.4 seconds

30
Q

First heart sound

A

closing of AV valves at the beginning of ventricular systole

31
Q

second heart sound

A

closing of SL valves at the beginning of ventricular diastole

32
Q

heart murmurs

A

abnormal heart sounds heard when blood hits obstructions

33
Q

incompetent valve

A

fails to close completely, allowing backflow of blood; causes swishing sound as blood regurgitates backward from ventricle into atria

34
Q

stenotic valve

A

fails to open completely, restricting blood flow through valve; causes high-pitched sound or clocking as blood is forced through narrow valve

35
Q

cardiac output

A

amount of blood pumped out by each ventricle in 1 minute; equals heart rate times stroke volume

36
Q

stroke volume

A

volume of blood pumped out by one ventricle with each beat

37
Q

cardiac reserve

A

difference between resting and maximal CO

38
Q

Three main factors that affect SV

A

preload, contractility, afterload

39
Q

preload

A

degree to which cardiac muscle cells are stretched just before they contract

40
Q

venous return

A

amount of blood returning to heart; most important factor in preload

41
Q

Contractility

A

contractile strength at given muscle length

42
Q

negative intropic agens

A

decrease contractility; acidosis, increased extracellular K+, calcium channel blockers

42
Q

positive inotropic agents

A

increase contractility; thyroxine, glucagon, epinoephrine

43
Q

afterload

A

pressure that ventricles must overcome to eject blood

43
Q

Atrial (Bainbridge) reflex

A

sympathetic reflex initiated by increased venous return, hence increased atrial filling

44
Q

Hormones heart regulation

A

epinephrine from adrenal medulla increases heart rate and contractility; thyroxine increases heart rate which enhances effects of norepinephrine and epinephrine

45
Q

Ions heart regulation

A

intra and extracellular ion concentrations (CA2+ & K+) must be maintained for normal heart function

46
Q

Hypocalcemia

A

depresses heart

47
Q

Hypercalcemia

A

increases HR and contractility

48
Q

Hyperkalemia

A

alters electrical activity, which can lead to heart block and cardiac arrest

49
Q

Hypokalemia

A

results in feeble heartbeat; arrhythmias

50
Q

Tachycardia

A

abnormally fast heart rate (>100 bpm)

51
Q

Bradycardia

A

heart rate slower than 60 bpm

52
Q

Congestive heart failure (CHF)

A

progressive condition; CO is so low that blood circulation is inadequate to meet tissue needs

53
Q

Coronary atherosclerosis

A

clogged arteries caused by fat buildup; impairs oxygen delivery to cardiac cells

54
Q

multiple myocardial infarcts

A

heart becomes weak as contractile cells are replaced with scar tissue

55
Q

Dilated cardimyopathy (DCM)

A

ventricles stretch and become flabby, and myocardium deteriorates

56
Q

pulmonary congestion

A

left-sided failure; blood backs up in lungs

57
Q

peripheral congestion

A

right-sided failture; blood pools in body organs, causing edema

58
Q
A