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DMD 5247 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

(73 cards)

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1
Q

heartbeat

A

a single contraction of the heart

the entire heart contracts in series

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2
Q

order of contraction within the heart

A

first atria, then ventricles

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3
Q

2 types of cardiac muscle cells

A

conducting system

contractile cells

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4
Q

conducting system

A

controls and coordinates the heartbeat

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5
Q

contractile cells

A

produce contractions that propel blood

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6
Q

what begins the cardiac cycle

A

an action potential at the SA node

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7
Q

what happens after the production of an action potential at the SA node

A

transmitted through conducting system

produces action potentials in cardiac muscle cells(contractile cells)

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8
Q

electrocardiogram

A

electrical events in the cardiac cycle can be recorded on an electrocardiogram

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9
Q

the conducting system

A

a system of specialized cardiac muscle cells

  • initiates and distributes electrical impulses that stimulate contraction
  • automaticity: cardiac muscle tissue contracts automatically
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10
Q

contractile cells

A
  • purkinje fibers distribute the stimulus to the contractile cells, which make up most of the muscle cells in the heart
  • resting potential: of a ventricular cell: -90 mV
  • of an atrial cell about -80 mV
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11
Q

conduction system ion channels

A

potassium, sodium, calcium

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12
Q

myocardium ion channels

A

potassium, sodium, calcium

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13
Q

blood vessels ion channels

A

calcium, potassium, chlorine

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14
Q

action potential in cardiac muscle

A
  • rapid depolarization
  • plateau
  • repolarization
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15
Q

rapid depolarization

A

caused by sodium entry and ends with closure of voltage-gated fast sodium channes

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16
Q

the plateau

A

caused by calcium entry and ends with closure of the slow calcium channels

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17
Q

repolarization

A

caused by potassium loss and ends with closure of slow potassium channels

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18
Q

absolute refractory period

A

long

cardiac muscle cells cannot respond

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19
Q

relative refractory period

A

short and response depends on degree of stimulus

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20
Q

purpose of the long refractory period in cardiac cells

A

prevent summation and tetany

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21
Q

contraction of a cardiac muscle cell is caused by

A

an increase in calcium ion concentration around myofibrils

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22
Q

the role of calcium ions in cardiac contractions

A

calcium ions enter plasma membrane during the plateau phase

this triggers release of calcium ion reserves from sarcoplasmic reticulum

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23
Q

as slow calcium channels close

A

intracellular calcium is absorbed by the SR
or pumped out of the cell

cardiac muscle tissue is very sensitive to extracellular Ca concentrations

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24
Q

structures of the conducting system

A

sinoatrial node
atrioventricular node
conducting cells: throughout myocardium

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25
conducting cells in the atrium
present in internodal pathways
26
conducting cells in the ventricles
present in the AV bundle and bundle branches
27
Prepotential
pacemaker potential resting potential of conducting cells -gradually depolarizes toward threshold SA node depolarizes first, establishing the heart rate
28
the sinoatrial node
- in posterior wall of right atrium - caontains pacemaker cells - connected to AV node by internodal pathways - begins atrial activation
29
AV bundle
- in the septum - carries the impulse to the left and the right bundle branches - which conduct to purkinje fibers - and to the moderator band - which conducts to papillary muscles
30
purkinje fibers
distribute the impulse through the ventricles atrial contraction is completed ventricular contraction begins
31
abnormal pacemaker function
bradycardia thachycardia ectopic pacemaker
32
ectopic pacemaker
abnormal cells generate high rate of action potentials bypass conducting system disrupt ventricular contractions
33
P wave
atria depolarize
34
QRS complex
ventricles depolarize
35
T wave
ventricles repolarize
36
P-R interval
from the start of atrial depolarization to the start of a QRS complex
37
Q-T interval
from ventricular depolarization | to ventricular repolarization
38
the cardiac cycle
is the period between the start of one heartbeat and the beginning of the next includes both contraction and relaxation
39
2 phases of the cardiac cycle
systole: contraction diastole: relaxation * each is within any one chamber
40
atrial systole
atrial contraction begins right and left AV valves are open atria eject blood into ventricles
41
atrial systole ends
AV valves close ventricles contain maximum blood volume known as end-diastolic volume
42
ventricular systole
ventricles contract and build pressure: AV valves close and cause isovolumetric contraction
43
ventricular ejection
ventricular pressure exceeds vessel pressure opening the semilunar valves and allowing blood to leave the ventricle amount of blood ejected is called the stroke volume
44
ventricular pressure falls
semilunar valves close | ventricles contains end-systolic volume: about 40% of end diastolic volume
45
ventricular diastole
ventricular pressure is higher than atrial pressure all heart valves are closed ventricles relax: isovolumetric relaxation
46
atrial pressure is higher than ventricular pressure
AV valves open passive atrial filling???? passive ventricular filling
47
blood pressure in any chamber
rises during systole | falls during diastole
48
blood flows from high to low pressure
controlled by the timing of the contractions | directed by one-way valves
49
when heart rate increases
all phases of the cardiac cycle shorten, particularly diastole
50
S1: heart sound
loud sounds | produced by AV valves
51
S2: heart sound
loud sounds | produced by semilunar valves
52
S3 and S4 sounds
soft sounds | blood flow into ventricles and atrial contraction
53
heart murmur
sounds produced by regurgitation through valves
54
cardiodynamics
the movement and force generated by cardiac contractions
55
stroke volume
EDV-ESV = -SV
56
ejection fraction
the percentage of EDV represented by SV
57
cardiac output
the volume pumped by left ventricle in 1 minute | CO = HR * SV
58
factors affecting cardiac output
- changes in heart rate or stroke volume - heart rate is adjusted by the autonomic nervous system or hormones - stroke volume can be adjusted by changing the EDV or ESV
59
autonomic innervation
- cardiac plexuses innervate heart - vagus nerves carry parasympathetic preganglionic fibers to small ganglia in cardiac plexus - cardiac centers of the medulla oblongata
60
cardiac centers of medulla oblongata
- cardioaccelatory center: controls sympathetic neurons: increases heart rate - cardioinhibitory center: controls parasympathetic neurons: slows hart rate
61
cholinergic receptors
activated by parasympathetic M2 muscarinic receptors are mainly in the SA node M2 activation: reduces heart rate: negative chronotropic
62
adrenergic receptors
activated by sympathetic B1 adrenergic receptors int he myocardium, SA node B1 activation: increases contractility(positive inotropic) : increased heart rate(positive chronotropic)
63
angiotensin
AT1 Myocardium: positive inotropy
64
membrane potential of the pacemaker cells
lower than other cardiac cells
65
rate of spontaneous depolarization depends on:
resting membrane potential | rate of depolarization
66
sympathetic and parasympathetic stimulation
greatest at the SA node
67
Acetylcholine
parasympathetic | slows heart
68
norepinephrine
sympathetic | speeds the heart
69
atrial reflex
adjusts rate rate in response to venous return stretch receptors in the right atrium -trigger an increase in heart rate -through increased sympathetic activity
70
the frank-starling principle
as EDV increases, stroke volume increases
71
afterload
caused by any factor that resists arterial blood flow
72
afterload increases
stroke volume decreases
73
preload
degree of ventricular stretching during ventricular diastole

DMD 5247 (13 decks)

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