Chapter 19: Heart Flashcards
(137 cards)
1
Q
myocardium is composed of __________________ tissue
A
cardiac muscle tissue
2
Q
cardiac muscle cells are ________, _____________, and ____________
A
short, branched and striated
3
Q
cardiac muscle cells house how many nuclei?
A
one or two
4
Q
cardiac muscle cells are supported by _____________________ tissue called _______________
A
areolar connective tissue called endomysium
5
Q
sarcolemma
A
- plasma membrane
- invaginates to form t-tubules extending into the sarcoplasmic reticulum
6
Q
sarcoplasmic reticulum
A
- contains calcium
- surrounds bundles of myofilaments
7
Q
the sarcolemma folded at connections between cells do what?
A
- increase structural stability
- facilitates communication between cells
8
Q
cells are connected with __________________
A
intercalated discs
9
Q
desmosomes
A
- join cells with protein filaments
- transfer of electrolytes b/w of the cells
- for structural integrity
10
Q
gap junctions
A
electrically join cells and allow ion flow to make each heart chamber a functional unit
11
Q
action potential is the rapid release of _____ and rapid absorption of _____
A
K+/Na+
12
Q
ATP in cardiac muscle is used to/for:
A
- activate myosin
- calcium pumps require ATP
13
Q
metabolism of cardiac muscle has a
A
high demand for energy
14
Q
cardiac muscle has a high demand for energy because
A
- extensive blood supply
- numerous mitocondria
- myoglobin and creatine kinase
i know this doesn’t make sense but i hqd to fit it into a card somehow
15
Q
cardiac muscle is able to use different types of which fuel molecules
A
- fatty acids
- glucose
- lactic acid
- amino acids
- ketone bodies
16
Q
cardiac muscle mostly relies on ______________ metabolism
A
aerobic
17
Q
because cardiac muscle relies mostly on aerobic metabolism,
A
it makes it susceptible to failure when ischemic
18
Q
ischemic
A
oxygen is low
19
Q
the heart rest between how many beats
A
2
20
Q
how much of the PNS is made up of the vagus nerve
A
75%
21
Q
perfusion
A
the delivery of blood per unit time of gram per tissue
22
Q
venae cavae
A
drain deoxygenated blood into the right atrium
23
Q
pulmonary trunk
A
receives deoxygenated blood pumped from the right ventricle
24
Q
pulmonary veins
A
drain oxygenated blood into left atrium
25
right atrioventricular (AV) valve
between the right atrium and right ventricle, also known as the tricuspid valve
26
pulmonary semilunar valve
between right ventricle and pulmonary trunk
27
left atrioventricular (AV) valve
between the left atrium and left ventricle; also known as bicuspid valve or mitral valve
28
aortic semilunar valve
between left ventricle and aorta
29
pulmonary circulation
includes the movement of blood to and from the lungs for gas exchange
30
systematic circulation
includes the movement of blood to and from the systematic cells/the body
31
epicardium
outermost heart layer and is also called the visceral pericardium; composed of simple squamous epithelium
32
myocardium
middle layer of the heart wall and composed of cardiac muscle
33
endocardium
innermost layer of the heart wall; composed of simple squamous epithelium and underlying areolar connective tissue
34
conduction system
initiates and propagates an action potential
35
the conduction system contains specialized
cardiac muscle cells that have action potentials but do not contract
36
conduction systems activity is influenced by
the autonomic nervous system
37
sinoatrial (SA) node
located high in the posterior wall of the right atrium
38
the sinoatrial node is the ______________ of the heart
pacemaker
39
atrioventricular (AV) node
located on the floor of the right atrium
40
the atrioventricular node is the __________________ of the heart
backup pacemaker
41
atrioventricular (AV) bundle
- extends from AV node through interventricular septum
- divides into left and right bundles
- also known as bundle of His
42
Purkinje fibers
- extend from left and right bundles at heart's apex
- course through walls of ventricles
43
white meat/muscles
fast twitch
44
red meat/muscles
slow twitch
45
the nerves of the heart are made of
modified muscle cells
46
the nerves of the heart are ___________________
self-polarizing
47
cardiac center of the medulla oblongata contains __________________ and ____________________ centers
cardioacceleratory and cardioinhibitory centers
48
the cardiac center receives signals from ________________ and _________________ in the cardiovascular system
baroreceptors and chemoreceptors
49
the cardiovascular system sends signals via the __________________ and ____________________ pathways
sympathetic and parasympathetic
50
parasympathetic innervation
decreases heart rate; "rest and digest"
51
the parasympathetic innervation starts
at medulla's cardioinhibitory center; vagal tone
52
sympathetic innervation
increases heart rate and force of contraction; "fight or flight"
53
the sympathetic innervation starts
at the medulla's cardioacceleratory center
54
cardiac muscle cells
initiate action potentials and contract
55
SA nodal cells
initiate heartbeat
56
RMP for the SA nodal cells
-60mV
57
pacemaker potential
ability to reach the threshold without stimulation
58
vagal tone
parasympathetic activity relayed by the vagus nerve
- keeps heart rate slower
59
the process of the conduction system of the heart
1- SA node conducts AP
2- AP is distributed through atria, reaches AV node, both atria contract
3- AP is delayed at the AV node, delay allows ventricles to fill
4- AP travels through AV bundle to bundle branches to purkinje fibers
5- AP spreads through ventricles, cells of two ventricles contract almost simultaneously
60
wave summation
twitches that overlap
61
tetany
sustained contraction
62
cardiac muscle cells have a RMP of
-90mV (very polarized)
63
cardiac muscle cells contain 3 specific voltage-gated channels
1- voltage-gated Na+ channels
2- voltage-gated Ca2+ channels
3- voltage-gated K+ channels
64
depolarization
the change from a relatively negative membrane potential to a relatively positive membrane potential
65
what happens during depolarization
- impulse opens voltage-gated Na+ channels
- Na+ enters the cell, changing membrane potential from -90mV to 30+ mV
- voltage-gated Na+ channels start to inactivate
66
plateau
leveling off
67
what happens during the plateau
- depolarization opens voltage-gated K+ and voltage-gated Ca2+ channels
- K+ leaves cardiac muscle cell as Ca2+ enters
- stimulates sarcoplasmic reticulum to release more Ca2+
- membrane remains depolarized
68
repolarization
allows a cardiac muscle to propagate a new action potential when the cardiac muscle is simulated again
69
what happens during repolarization
- voltage-gated Ca2+ channels close while K+ channels remain open
- membrane potential goes back to -90mV
70
Ca+ makes ATP ___________
last longer
71
cardiac ATP is longer because of
the plateau phase
72
can cardiac muscle exhibit tetany?
no
73
unlike skeletal muscle, cardiac cells have a long _______________
refractory period
74
cardiac muscle cells plateau phase leads to a refractory period of about ________
250 ms
75
cell cannot fire a new impulse during
the refractory period
76
electrocardiogram (ECG/EKG)
skin electrodes detect electrical signals of cardiac muscle cells
77
P wave
reflects electrical charges associated with atrial depolarization originating in SA node; atria are starting their AP
78
QRS complex
- electrical changes associated with ventricular depolarization
- atria also simultaneously repolarizing
79
T wave
electrical change associated with ventricular repolarization; end of activity in ventricles
80
P-Q segment
associated with atrial cells' plateau
- ATRIA ARE CONTRACTING
81
S-T segment
associated with ventricular plateau
- VENTRICLES ARE CONTRACTING
82
plateau phases
P-Q segment and S-T segment
83
atrial depolarization
- recorded as the P wave
- muscle cells of atria stimulated to contract
84
atrial plateau
- recorded as PQ segment
- muscle cells of atria contract and relax
85
atrial repolarization
not visible on ECG
86
ventricular depolarization
- recorded as the QRS wave
- muscle cells of ventricles stimulated to contract
87
ventricular plateau
- recorded as ST segment
- muscle cells of ventricles contract and relax
88
ventricular repolarization
recorded as T wave
89
arrhythmia
any abnormality in the heart's electrical activity
90
heart blocks
impaired conduction
91
AP conduction
problem in the conducting system
92
cardiac cycle
all events in heart from the start of one heart beat to the start of the next
93
systole
contraction
94
diastole
relaxation
95
blood moves ________ its pressure gradient
down (high to low)
96
EDV (end-diastolic volume)
- volume of blood left in the ventricle at the end of diastole
- blood volume to be "squeezed"
97
SV (stroke volume)
the amount of blood pushed out during ventricular contraction
98
ESV (end-systolic volume)
volume of blood in ventricle at the end of systole
99
atrial contraction and active ventricular filling
1 - SA node starts atrial contraction
2 - atria contract, pushing remaining blood into ventricles
3 - semilunar valves are closed
4 - ventricles filled to EDV
100
isovolumetric ventricular contraction
1- early systole
2- ventricles contract
3- pressure rises
4- AV valves are pushed closed
5- semilunar valves still closed
101
ventricular ejection
1- late systole
2- semilunar valves forced open as blood moves from ventricles to arterial trunks
102
how to find stroke volume
SV(mL)=EDV-ESV
103
isovolumetric ventricular relaxation
1- early diastole
2- ventricles relax and start to expand, lowering pressure
3- blood closes semilunar valves
4- AV valves remain closed
104
the diastolic pressure in a BP reading is the pressure the
left ventricle has to overcome to open semilunar valves
105
atrial relaxation and passive ventricular filling
1- late diastole
2- all heart chambers are relaxed
3- AV valves open and blood flows into ventricles passively
4- semilunar valves remain closed
106
ventricular balance
1- equal amounts of blood are pumped by left and right sides of the heart
107
edema
swelling of fluid around the heart
108
cardiac output (CO)
amount of blood pumped by a single ventricle in one minute
109
cardiac output is measured in
liters per minute
110
cardiac output is determined by ________________ and _______________
heart rate and stroke volume
111
equation for CO
HR x SV= CO
112
CO must
meet tissue needs
113
cardiac reserve
the potential of what your heart can do
114
chronotropic agents
change heart rate by altering the activity of nodal cells
115
positive chronotropic agents
increase heart rate
116
sympathetic innervation of SA nodal cells (positive chronotropic agents)
- causes adrenal to release NE and epinephrine
- NE and EPI bind to nodal cells and increase their firing rate
- G-protein is activated and forms a second messenger
- activates kinase and Ca2+ channels to open
117
what factors can increase heart rate at different steps within the sympathetic innervation of SA nodal cells
- TH
- nicotine
- cocaine
- caffeine
118
negative chronotropic agents
decrease heart rate
119
parasympathetic innervation of SA nodal cells (negative chronotropic agents)
- PS axons release acetylcholine
- ACh opens K+ channels and K+ exits the cell making it more negative
120
beta-blocker drugs
used to treat high BP
121
autonomic reflexes
- baroreceptors and chemoreceptors send signals to the cardiac center
- cardiac center influences SNS and PNS to alter output as needed
122
atrial reflex
protects the heart from overfilling
123
venous return
volume of blood returned to the heart
124
inotropic agents
change stroke volume and alter contractility
125
positive inotropic agents
increases contractility by increasing available Ca2+
126
negative inotropic agents
decreases contractility by decreasing available Ca2+
127
afterload
resistance in arteries to ejection of blood by ventricles
128
atherosclerosis
plaque in vessel linings
129
heart rate depends on
chronotropic agents
130
stroke volume generally depends on
state of myocardium
131
increased afterload _____________ stroke volume
decreases
132
does the size of the heart affect SV?
yes
133
bradycardia
slow heart rate
134
tachycardia
fast heart rate
135
ectopic pacemaker
group of cardiac muscle cells that have the ability to spontaneously depolarize and act as the pacemaker
136
atrial fibrillation
chaotic timing of atrial action potentials
137
ventricular fibrillation
chaotic electrical activity in ventricles
