the heart Flashcards
1
Q
What carries blood to the lungs for gas exchange and back to heart, and is on the right side of the heart?
A
The pulmonary circuit
2
Q
What supplies oxygenated blood to all tissues of the body and returns it to the heart, and is on the left side of the heart?
A
Systemic circuit
3
Q
Fully oxygenated blood arrives from lungs via?
A
pulmonary veins
4
Q
blood is sent to all organs via?
A
the aorta
5
Q
oxygen-poor blood arrives from what?
A
inferior and superior venae cavae
6
Q
blood is sent to the lungs via?
A
pulmonary trunk
7
Q
a double-walled sac that encloses the heart
A
the pericardium
8
Q
what allows the heart to beat without friction?
A
the pericardium
9
Q
the outer wall, not attached to the heart
A
fibrous pericardium
10
Q
serous pericardium has 2 layers
A
parietal layer and visceral layer
11
Q
what lines the fibrous pericardium?
A
parietal layer
12
Q
what is covering the hearts surface?
A
visceral layer (epicardium)
13
Q
the space between parietal and visceral layers of the serous pericardium
A
pericardial cavity
14
Q
painful inflammation of the pericardium
A
pericarditis
15
Q
coronary blood vessels travel thru?
A
epicardium
16
Q
the smooth inner lining of the heart and blood vessels
A
endocardium
17
Q
layer of cardiac muscle that is proportional to the workload
A
myocardium
18
Q
what does the myocardium do?
A
it spirals around the heart which produces a wringing motion(vortex of the heart)
19
Q
framework of collagenous and elastic fibers
A
fibrous skeleton of the heart
20
Q
provides structural support and attachment for cardiac muscle and is an anchor for valve tissue
A
fibrous skeleton of the heart
21
Q
what are the 4 chambers of the heart
A
right and left atria
right and left ventricle
22
Q
two superior chambers that receive blood returning from the heart
A
right and left atria
23
Q
two inferior chambers that pump blood into arteries
A
right and left ventricles
24
Q
separates atria and ventricles
A
coronary sulcus
25
overlies the interventricular septum
interventricular sulcus
26
sulci contain?
coronary arteries
27
what divides the right ventricle from the left?
interventricular septum
28
what doe valves do?
ensure one way flow of blood through the heart
29
what do atrioventricular(AV) valves do?
control blood flow between atria and ventricles
30
right av valve has how many cusps
three (tricuspid valve)
31
left av valve has how many cusps?
two (mitral valve)
32
what does the chordae tendineae do?
connect av valves to papillary muscles on the floor of ventricles
prevent av valves from flipping or bulging into atria
33
what do semilunar valves do?
control flow into great arteries
open and close of blood flow and pressure
34
pulmonary semilunar valve is?
in an opening between right ventricle and pulmonary trunk
35
aortic semilunar valve is?
in an opening between left ventricle and aorta
36
how many mL of blood is pumped to the heart through coronary circulation per minute?
250 mL
37
coronary circulation requires what?
abundant amounts of O2 and nutrients
38
anterior interventricular branch does what?
supplies blood to both ventricles and anterior two-thirds of interventricular septum
39
circumflex branch does what?
supplies left atrium and posterior wall of left ventricle
40
right coronary artery does what?
supplies right atrium and sinuatrial node (pacemaker)
41
right marginal branch does what?
supplies lateral aspect of right atrium and ventricle
42
posterior interventricular branch does what?
supplies posterior walls of ventricles
43
flow through coronary arteries is greatest when heart relaxes because?
contraction of myocardium compresses the coronary arteries and obstructs blood flow
44
angina pectoris pain is caused by what?
ischemia of cardiac muscle
44
angina pectoris is what?
chest pains from partial obstruction of coronary flow
44
what often obstructs coronary arteries?
atheroma (fatty tissue and clot)
44
5% to 10% of coronary blood drains directly into chambers by way of?
small cardiac veins
44
great cardiac vein does what?
collect blood from anterior portion of heart and empties into coronary sinus
44
myocardial infarction(MI) is what?
the sudden death of a patch of myocardium resulting from long-term obstruction of coronary circulation
44
what percentage of death in the US is caused by MI
27%
45
coronary sinus is ?
a large transverse vein that collects blood and empties it into right atrium
45
most coronary blood returns to right atrium by coronary sinus which has three main inputs:
great cardiac vein
middle cardiac vein
left marginal vein
45
middle cardiac vein does what?
collects blood from posterior portion of heart and drains into coronary sinus
45
left marginal vein does what?
empties into coronary sinus
46
cardiomyocytes are ?
short thick cells with one central nucleus
47
intercalated discs join cardiomyocytes to end with three features:
interdigitating folds
mechanical junctions
electrical junctions
48
interdigitating folds do what?
interlock with each other and increase surface area
49
mechanical junctions do what?
tightly join cardiomyocytes
50
fascia adherens are?
broad bands where the actin of myofilaments is anchored to plasma membrane
51
desmosomes are what
mechanical linkages that prevent contracting cardiomyocytes from being pulled apart from each other
52
electrical(gap) junctions allow ions to do what
flow between cells
53
electrical(gap) junctions can also do what?
stimulate neighbors
54
Cardiac muscle depends almost exclusively on what? to make?
aerobic respiration to make ATP
55
ATP is rich in
myoglobin and glycogen
56
systole is what?
contraction
57
diastole is what?
relaxation
58
the conduction system does what?
coordinates heartbeat
59
the conduction system is composed of what?
internal pacemaker and conduction pathways of myocardium
60
the conduction system generates and conducts rhythmic electrical signals in what order?
sinuatrial node- initiates each heartbeat and determines heart rate
61
second step in conduction system
signals spread throughout the atria
62
third step in conduction system
atrioventricular (AV) node- electrical gateway to the ventricles
63
fourth step in conduction system
atrioventricular (AV) bundle (Bundle of His)
64
fifth step in conduction system
subendothelial conducting networks- cardiomyocytes pass signal from cell to cell through gap junctions
65
what is sinus rhythm?
normal heartbeat triggered by SA node
66
what is a normal sinus rhythm?
70 to 80 bpm
67
what is ectopic focus?
region of spontaneous firing other than SA node
68
what is nodal rhythm
if SA node is damaged, heart rate is set by AV node usually 40 to 50 bpm
69
SA node membrane potential starts at
-60 mv and drifts upward due to slow sodium inflow
70
SA node threshold is what?
-40 mv?
71
what happens at threshold?
calcium and sodium channels open
72
after threshold what happens?
potassium channels open and then sodium leaves the cell (causing repolorization)
73
How long does it take for the SA node to reach the AV node
50 ms
74
cardiomyocytes has a stable resting potential of?
-90 mV and depolarize when stimulated
75
three phases to cardiomyocyte action potential are?
depolarization, plateau, repolarization
76
depolarization phase does what?
stimulation opens Sodium gates where sodium rushes in, and gates closes quickly
77
depolarization phase peaks at ?
+30 mV
78
Plateau phase lasts how long?
200-250 ms
79
plateau phase does what?
slow calcium channels open, calcium comes in, which triggers the sarcoplasmic reticulum calcium channels to open
80
calcium in the plateau phase binds to what? triggering what?
binds to troponin triggering contraction
81
what does the repolarization phase do?
calcium channels close, potassium channels open causing rapid diffusion of potassium out of the cell
82
how long is the refractory period in repolarization phase?
250 ms
83
what is an electrocardiogram (ECG or EKG)
composite of all action potentials of nodal and myocardial cells detected
84
What is a P wave in an EKG
SA node fires, atria depolarize and contract, atrial systole begins 100 ms after SA signal
85
what is a PR interval in an EKG
signal conduction through AV node, before activating ventricles
86
what is QRS complex in an EKG
ventricular depolarization, complex shape of spike due to different thickness and shape of the 2 ventricles
87
what is QT interval in an EKG
duration of ventricular depolarization
88
what is ST segment in an EKG
ventricular systole- corresponds to plateau
89
what is a T wave in an EKG
ventricular repolarization and relaxation
90
deviations of ECG from normal can indicate what
myocardial infarction
abnormalities in conduction pathways
heart enlargement
electrolyte and hormone imbalances
91
ventricular fibrillation is what
serious arrhythmia caused by electrical signals traveling randomly. Heart cannot pump blood
92
ventricular fibrillation is the hallmark of what
heart attack
93
defibrillation is what
strong shock with intent to depolarize entire myocardium and reset heart to sinus rhythm
94
atrial fibrillation is what
chaotic depolarizations that do not stimulate ventricles
95
heart block is what
failure of any part of cardiac conduction system to conduct signals
96
premature ventricular contraction is what
ventricular ectopic focus with extra beat
