Heart Flashcards
(264 cards)
1
Q
in cardiac muscle the action potential is caused by the opening of _ channels
A
2 types
2
Q
the presence of the plateau in the action potential causes ventricular contraction to last as much as 15x longer in cardiac muscle as in
A
skeletal muscle
3
Q
the cardiac muscle have __ action potentials and __
A
prolonged action potentials and plateau in cardiac muscles
4
Q
the AP of skeletal muscles caused almost entirely by sudden opening of large numbers of __ channels
A
fast sodium
5
Q
in cardiac muscle the AP is caused by the opening of 2 types of channels:
A
the same fast sodium channels as skeletal and the SLOW CALCIUM CHANNELS aka calcium-sodium channels
6
Q
the slow calcium channels
A
remain open longer and are slower to open than the sodium channels
7
Q
another difference in cardiac muscle membrane is that after the onset of the AP, the permeability of the cardiac muscle membrane for ___ decreases about 5 fold= which does not happen in skeletal muscle
A
potassium (K+)
8
Q
the strength of the cardiac muscle contraction is directly proportional to
A
intracellular Ca concentration
9
Q
the refractory period of atrial muscle is much __ than that of the ventricles
A
shorter = therefore the rhythmic rate of contraction of the atria can be much faster than that of the ventricles
10
Q
skeletal muscle cells have a _ refractory period that allows them to be stimulated to contract a second time before they have relaxed from an initial concentration
A
short
11
Q
the bicuspid is aka
A
mitral valve
12
Q
the bicuspid is on the left/right
A
left
13
Q
which valve is unique in having a different number of cusps than the others
A
mitral valve/bicuspid!
14
Q
the valves bw the atria and ventricles prevent
A
blood from backflowing
15
Q
- Atrioventricular valves are anchored to the wall of the ventricle by ___, which prevent the valve from inverting.
A
- chordae tendineae
16
Q
- The chordae tendineae are attached to __ that cause tension to better hold the valve.
A
papillary muscles
Together, the papillary muscles and the chordae tendineae are known as the subvalvular apparatus
17
Q
the pulmonary semilunar valve is located
A
at the entrance to the pulmonary trunk
18
Q
the pulmonary semilunar valve has how many cusps
A
3
19
Q
the pulmonary semilunar valve prevents
A
backflow of blood from the artery into the right ventricle during ventricular relaxation
20
Q
the aortic semilunar valve Is located at the entrance to the aorta and is composed of how many cusps
A
3
21
Q
aortic semilunar valve prevents backflow during
A
left ventricular relaxation
22
Q
the semilunar valves are open during
A
systole
23
Q
when are all the valves in the heart open at the same time in the cardiac cycle
A
never
24
Q
the first heart sound, S1 is the _
A
AV valves closing
25
the second heart sounds S2 is the
closure of the semilunar valves
26
the electrocardiogram is a graphic illustration of the
cardiac conduction system
27
the natural pacemaker of the heart is the
sinoatrial node
28
the signals that make the heart muscle fibers contract come from the
sinoatrial node = pacemaker of the heart
29
the _ wave is the electrical recording from the body surface of atrial depolarization and precedes atrial contraction
P wave= so right after the p wave the atria should contract.
30
the _ wave represents repolarization of the ventricles
T wave (relaxing of the ventricles)
31
the QRS complex represents
ventricular depolarization
32
the first heart sounds represent the closure of the _ valves on the onset of systole
AV
33
the second heart sound represents the closure of the _ valves on the onset of diastole
semilunar
34
both heart sounds are of _ of the valves
closing
35
why is there no distinct wave visible on ECG of the atrial repolarization?
bc it occurs during ventricular depolarization and so it is obscured
36
an ECG with extra P waves before each QRS indicates
partial heart block (second degree block)
37
if P wave and QRS complex are dissociated -
complete heart block
38
Cardiac output =
SV x HR
39
CO is expressed in
L/min
40
SV is the
stroke volume per beat
41
HR is
the number of beats per minute
42
average resting cardiac output is
5.6 L per minute for men and 10-20% less for women
43
stroke volume is determined by
preload, afterload and contractility
44
__ is the arterial pressure against which the muscle will contract
afterload
45
SV =
```
end diastolic volume - end systolic volume
SV = EDV - ESV
stroke volume (SV) is the volume of blood pumped from one ventricle of the heart with each beat
```
46
SV is average
70-80mL
47
is the cardiac output of the left and right side of the heart the same or different
same (equal)
48
total peripheral resistance =
BP = CO x TPR
49
The _ reflex is a positive feedback mechanism in which there is a compensatory increase in heart rate due to a rise in right atrial pressure
Bainbridge reflex
50
Bainbridge Reflex is commonly referred to as an
Atrial reflex
51
Bainbridge Reflex is a _ feedback mechanism (Positive or negative)
positive
52
in Bainbridge Reflex what increases due to what
increase in heart rate due to rise in the right atrial pressure
53
the stretch receptors in the atria transmit their __ signal thru the __ nerves to the medulla of the brain
afferent
| vagus nerves
54
then efferent signals are transmitted back thru vagal and sympathetic nerves to increase heart rate and strength of contraction. this helps prevent?
damming of the blood in the veins atria and pulmonary circulation
55
each cardiac cycle lasts how long
0.8 seconds = from the end of one heart contraction to the end of the subsequent heart contraction
56
two phases of the cardiac cycle
```
diastole = ventricles are relaxed and heart fills with blood.
systole = ventricles contract and pump blood into the arteries
```
57
during the _ phase the atria and the ventricle are both relaxed (the whole heart)
diastole
58
blood flow to the coronary arteries would be greatest during ___ in a resting individual
ventricular relaxation
59
ventricular volume is greatest when
following atrial systole
60
ventricular pressure is greatest during ___
ventricular ejection
61
increased ventricular volume ___ end diastolic fiber length
increases
62
how many beats per minute?
75 bpm
63
each beat takes __ sec
0.8sec
64
when we say the heart is in diastole, relaxed and filling what does that mean
it is not consuming a lot of oxygen or ATP
65
the heart spends 2/3 of its time in
diastole
| 1/3 of the time the heart is in systole
66
stroke volume is the amount of blood pumped out from
ventricles
67
at rest stroke volume is about
70mL per beat
68
you have a greater capacity to change your heartbeat or stroke volume?
heartbeat. can go up into 200s
69
cardiac output is
the amount of blood pumped out per min
70
your average blood volume is
5L
71
CO is about
5L/min = so our body pumps all of our blood
72
venous return is?
if heart is pumping at 5L/min then the venous return should be the same. venous return should equal the cardiac output
73
EDV
the amount of blood in the ventricle at the end of diastole
74
do we pump all the EDV out?
no. some remains. ESV. the amount of blood left after systole is the ESV
75
Ejection volume is =
SV/EDV x100
76
ejection volume in a healthy person should be
at least 50%
77
3 phases of diastole:
1st rapid inflow = rapid passive filling, volume changing the most
2nd phase: diastasis: slow passive filling passive, less volume change because getting full
3rd phase: atrial systole
78
ECG shows atrial depolarization as
P wave. = right before it will contract
79
most of the filling occurs in which phase?
in PASSIVE FILLING: Rapid inflow is the most and second is diastasis. 80-90% of filling occurs passively: which is good bc we need our energy to pump blood. also ok because if you don't have a P wave it is ok because your heart is still filling, you just don't have the little bit from atrial systole
80
if you hear a 3rd heart sound what is it?
it is at the end of rapid passive phase of diastole = you hear the blood rushing into the ventricle
81
P wave occurs just before
atrial systole
82
when does the heart use the most energy and oxygen?
isovolumic/isoventricular contraction
83
T wave
is ventricular repolarization = relaxing ventricles
84
which is longer and louder = the lub or the dub
the lub (1st heart sound) is the louder and longer one
85
___ starts with the first heart sound (LUB)
ventricular systole
86
___ ends with the first heart sound
ventricular diastole
87
___ begins with the second heart sound
diastole
88
which valve closes before the other semilunar valve?
the aortic valve closes before the pulmonary valve = causes splitting of the second heart sound
89
the ventricles are COMPLETELY DEPOLARIZED DURING which isoelectric portion of the ECG
S-T segment
90
This portion of the ECG represents the segment bw depolarization of the atria and depolarization of the ventricle
PR
91
2 isoelectric segments of ECG
ST segment
| and bw T and P waves
92
__ interval represents the period bw ventricular depolarization and ventricular repolarization
QT
93
isoelectric means
ventricle is at resting membrane potential
94
cardiac muscle is very similar to __
skeletal muscle
| bc actin, myosin, etc
95
the heart lies behind the
sternum
96
the heart lies between the
lungs
97
2/3 of the heart mass is on the
left side. it is in the middle of your chest but most mass is on the left
98
the apex of the heart is at the top or bottom?
bottom = formed by the tip of the left ventricle
99
the top of the heart is called the
base
100
the base of the heart (top of the heart) is near which rib?
the 2nd costal cartilages = to remember think your hear is split bw two people
101
the vessels of the heart emenate from the base/apex
base
102
the anterior surface consists primarily of
the right ventricle
103
___ is the arterial pressure against which the ventricle ejects the blood
afterload
104
what nerve stimulates the diaphragm
phrenic
105
___ is stretch of the fibers by blood during ventricular filling.
preload
106
preload is related to __ atrial pressure
right
107
the most important determining factor for preload is
venous return
108
the heart is a ___ pump.
dual
109
afterload for the left ventricle is determined by __
aortic pressure
110
afterload for the right ventricle is determined by
pulmonary artery pressure
111
increase in heart rate will also increase cardiac output EXCEPT at
very high heart rates where there will be less time for filling
112
the atria/ventricles are thinner
atria bc less muscle tissue there. therefore they are not as powerful as pumping as the ventricles
113
the atria are separated by the ___in adults
interatrial septum
114
as a fetus the atria are connected by a hole called the
foramen ovale
115
before birth the foramen ovale will fuse to form
foramen ovalis = depression in interatrial septum = remnants of foramen ovale. it should fuse after birth but if it doesn't surgery needed
116
failure of the foramen ovale to close over time in infants results in
patent foramen ovale
117
the __ activation of the heart will increase heart rate, conduction velocity and contractility
sympathetic
118
atrial septal defect is the term used to describe
an interatrial septum that fails to develop properly = anytime a defect in this wall = usually means there is a hole there
119
what is the problem with patent foramen ovale
less oxygenated blood will mix with the oxygenated blood (venous blood mixes)
120
why is it ok that the two bloods mix in the baby?
bc they are not using their lungs, mom is breathing for the baby
121
the myocardium functions only __ aerobically/anaerobically
aerobically
122
intraventricular septum
separates the ventricles
123
___ septal defects are the most common congenital abnormalities
ventricular septal defects = they are found in 30-60% of all newborns with a congenital heart defect
124
ventricular septal defects can also be acquired by forming within a few days after a
myocardial infarction due to macrophage remodeling of dead heart tissue before scar tissue forms
125
the larger the vessel, the _ the resistance
less
126
resistance =
resistance = ((viscosity (of blood) x length (vessel)) /(radius)^4
127
each ventricle holds about _ mL of blood = called
150mL = end diastolic volume
128
if the radius is double the resistance will decrease by a factor of
16
129
the major physiological regulation of blood flow is via the activation of
vascular smooth muscle (vasoconstriction)
| resistance = ((viscosity (of blood) x length (vessel)) /(radius)^4
130
do you pump out the entire 150mL of the end diastolic volume?
no, you pump out a little more than half = called the stroke volume. you don't pump out all because you need pressure in the ventricles from the blood to keep the chambers from collapsing
131
ejection fraction is
SV/EDV ie. 75mL/150mL x 100% = 50%
132
the circulating pressure is about
100mmHg
133
if ejection fraction is lower than the 50% you get
congestive heart failure because the heart is overfilling and not pumping it out
134
endocardium is the inner layer of the heart. it is serous and thin. the myocardium is the _ layer
middle and thickest = all muscle = responsible for pumping.
135
can the myocardium regenerate?
no. therefore no hyperplasia (= cell division)
136
can the myocardium undergo hypertrophy or hyperplasia?
hypertrophy = means no extra cells but instead they get bigger. heart can do that.
137
why is pathological hypertrophy bad?
muscle gets too thick = so the ventricles can't fill up with enough blood so you cant pump a lot of wall. Also the walls become too rigid.
138
what metabolites cause local vasodilation?
CO2, NO2, H+, K+, lactate, and adenosine
139
cardiac muscles have:
1. shape
2. # nucleus
3. branched/unbranched
1. cylindrical branching cells
| with a single nucleus
140
intercalated disks are ONLY found in what muscle
cardiac muscle only!
141
the visceral pericardium is aka
epicardium = external layer of the heart with nerve fibers, lymph vessels, bv's, and fat, thin layer
142
bradykinin and histamine causes arteriolar __- and venous__
arteriolar dilation and venous constriction
143
serotonin causes
arteriolar constriction
144
the parietal pericardium is the
heart sac
145
the space bw the heart and the sac is the
pericardial space = pericardial fluid = 10mL of fluid = lubricant to prevent friction as heart beats
146
valves of heart have ONE JOB what is it
to ensure blood is flowing in one direction only
147
the contraction of _ increases venous return to the heart:
skeletal/cardiac/smooth muscle
skeletal
148
increase/decrease in intrathoracic pressure will increase venous return to the heart:
decrease
149
which valve is thicker the mitral/bicuspid or the tricuspid
mitral bicuspid
150
the presence of venous valves/peristalsis increases venous return to the heart:
valves
151
the heart strands are called
chordae tendinae
152
chordae tendinae attach to
bottom of AV valve and endocardium's papillary muscle
153
do the chordae tendinae cause opening or closing of the AV valves?
NO. they help continue to keep it open or closed once they have done so. keeps them from inverting into the atria like an inverted umbrella. help keep valves open or valves closed
154
an increase/decrease in venous compliance increases venous return to the heart:
decrease
155
venous return is influenced by several factors: muscle contraction of the limbs muscle as in moving, walking swimming promotes
venous return by the muscle pump mechanism
156
__ activation of veins decreases venous compliance, increases central venous pressure and promotes venous return indirectly by augmenting cardiac output
sympathetic
157
during respiratory inspiration the venous return will increase/decrease
increase because of a decrease in right atrial pressure
158
First heart sound is called
S1 = lub
| Second sound is called S2 = dub
159
the right atrium receives blood from the
superior vena cava, inferior vena cava, and carotid sinus
160
trace flow of blood into the heart
superior vena cava, inferior vena cava, and carotid sinus ==> right atrium ==> tricuspid ==> r ventricle ==> pulmonic valve ==> PULMONARY TRUNK ==> splits into the two pulmonary arteries ==> lungs ==> pulmonary vein ==> left atrium ==> mitral valve ==> left ventricle ==> aortic valve ==> aorta ==> systemic circulation
161
the carotid SINUS received _ blood from
deoxygenated blood from the cardiac wall muscles
162
vena cava compression = an increase in the resistance of the vena cava will _ venous return
decrease
163
Starling's law of the heart states that the rate of ___ is the major factor that determines cardiac output
venous return
164
the veins have a great degree of compliance that can be regulated by the
sympathetic nervous system
165
an increase in sympathetic nervous system activation will __ compliance and __ venous return
decrease compliance and increase venous return
166
an increase in intrathoracic pressure will decrease/increase venous return
decrease
167
during exercise the total peripheral resistance decreases due to
the accumulation of vasodilator metabolites (lactate, K+, adenosine). these accumulate bc increase metabolic rate. the arterial vasodilation = decrease in TPR
168
3 major effects essential for circulatory system supplying body with blood flow during exercise
mass discharge of SNS throughout the body
increase CO
increase arterial pressure
169
during exercise:
1. BV in active skeletal muscle __
2. elsewhere in the body sympathetic __ occurs to compensate for this
3. there is an increase in the activity of the sympathetic nerves to the heart and a __ of PNS nerves activity
1. dilate = increase blood to muscles
2. vasoconstriction
3. decrease
170
during exercise venous return
is enhanced bc pumping effects of the contracting skeletal muscles and sympathetic vasoconstrictor effects
171
during exercise the increase in CO is greater than the decrease in TPR so the _ rises
mean arterial pressure
172
an anxious dental patient may have a higher systolic blood pressure than normal due to a _ arterial compliance
decreased
173
Parasympathetic fibers innervate the heart by way of the _ nerves
vagus
174
HR is controlled primarily by the ANS. Sympathetic (norepinephrine) stimulation causes an increase in
heart rate
175
parasympathetic (AcH) stimulation of the heart causes _ HR
decrease in heart rate
176
the main centers for autonomic cardiac control are located in the
medulla oblongata of the brain stem
177
Sympathetic cardiac effects:
1. increase in rate of discharge of the _
2. increase in rate at which _ spreads through the heart.
3. increase in ICF __ which increases the _
1. sinoatrial node (SA)
2. depolarization spreading = heart contracts more uniformly = which increases its pumping effectiveness
3. calcium which increases the FORCE of the ventricular contractions
178
the right vagus nerve goes to the
SA node
179
left vagus nerve goes to the
AV node
180
Parasympathetic innervation will decrease what two things
heart rate and spread of depolarization from the atria to the ventricles
181
SA node initiates impulse which is propagated from the
SA node to the atria and ultimately reaches the AV node. after a delay in the AV node, the cardiac impulse is propagated thru the ventricles
182
velocity of conduction is highest in
Purkinje system
183
velocity of conduction is lowest in the
AV node
184
automaticity
heart can generate its own beat
185
rhythmicity
regularity of pacemaker activity
186
rhythmicity and automaticity allow for the heart to __
beat even when removed from body
187
automaticity is greater in the SA or AV node or Purkinje
SA > AV > Purkinje
188
skeletal muscle: a muscle fiber is aka
muscle cell.
189
a myofibril is within a
muscle fiber
190
anytime you see "sarco" or "myo" it means
muscle
191
the sarcolemma is the
membrane of the muscle fiber (cells) since they are cells they have membranes
192
t tubules penetrate deep into muscle cell. function
carry the electrical signal (action potential) deep into muscle where the myofibrils are since the myosin etc are on the myofibrils
193
ER of muscle
Sarcoplasmic reticulum
194
the terminal cisternae are the ends of the __ where we store
ends of SR store calcium
195
cylinders within the muscle fiber/cell is
muscle myofibril
196
a unit of myofibril is called a
sarcomere
197
the thin/thick filament has three proteins
thin
198
the __ filament has one protein
thick
199
Myosin bound to ADP and Pi will release ___ and bind the actin
Pi
200
upon __ being released power stroke is done
ADP
201
cardiac muscle have thick and thin filaments? sarcomeres
yes
202
in skeletal muscle, AP comes down T-tubules, and releases calcium only from
terminal cisternae in Sarcoplasmic reticulum
203
cardiac muscle cells have lots of _ channels along the surface of the sarcolemma
calcium
204
when the AP spreads along the sarcolemma and t tubules in cardiac muscle, calcium will
enter into the cardiac muscle cells when the calcium channels open they go down their gradient
205
cardiac cells have dependency of __ calcium
extracellular (vs skeletal muscle cells that get it from SR)
206
cardiac are different from skeletal muscles bc they get their calcium from
2 sources (not 1): SR and ECF
207
once calcium enters the cardiac cell from ECF, that triggers
the release of calcium from the SR
208
in both cardiac and skeletal muscle Ca2+ binds to
troponin
209
troponin has 3 subunits called
I, C, T
210
Troponin C binds
calcium
211
when calcium binds to troponin, __ moves
tropomyosin moves and reveals binding sites of actin for myosin
212
the force of contraction and extent of contraction heavily depends on
how much calcium there is in the cell.
213
cardiac muscle MUST have a period of relaxation so that
the heart can fill
214
if you shorten the relaxation phase of the cardiac muscle
will effect how much blood you pump
215
big difference of skeletal and cardiac muscle is that cardiac muscle is ALWAYS
involuntary
216
1. skeletal muscle is for the most part __
| 2. when can skeletal muscle be involuntary?
1. voluntary
| 2. deep tendon reflexes and diaphragm
217
skeletal muscle/cardiac has more mitochondria
cardiac has wayyyy more bc it is always beating! skeletal is not always moving. so cardiac muscle makes way more ATP
218
skeletal muscle/cardiac has more sarcoplasmic reticulum
skeletal has more. but that is ok because bc cardiac has 2 sources of calcium
219
intercalated discs = wavy lines under microscope that stains darker under microscope. there are 2 parts to the disc. what are they
2 parts = desmosome and gap junctions
220
desmosomes purpose in cardiac muscle
glue cells together so the muscle cells don't separate during contraction
221
gap junctions in cardiac muscle allow
ions to pass freely from cell to cell directly transmitting the stimulus
222
angina vs myocardial infarction
1. both due to
2.
1. both are due to ischemia, usually bc of lack of blood flow to the tissue
2.
223
the coronary vessels
feed the heart with oxygenated blood
224
both angina and myocardial ischemia is due to myocardial ischemia which is commonly the result of
atherosclerosis
225
both MI and angina result in
chest pain
226
in general, __ pain is often related to exertion emotion eating, cold, it is usually short lived and relieved by NG
angina
227
the pain associated with MI often occurs ___ and is more long lasting compared to angina pain and not relieved by NG
spontaneously
228
the key difference bw angina and MI is that there is no __ in angina
cell death in angina. in angina cells don't die.
229
Creatine kinase is an enzyme in all muscle cells. T/F
True
230
Tropinin I (cTnI) is good for MI detection bc
only cardiac cells have Troponin I
231
which can stay elevated longer the troponin I or troponin T
T
| cTnT
232
in the plateau phase of cardiac actin potential what is happening
calcium channels open and calcium enters the cell from the ECF
233
the sinoatrial node (SA) = pacemaker is located
in the right atrium. right next to where the superior vena cava drains into the atria
234
SA node spreads electrical impulse to the right side via the __ tracts and to the left side of the heart via the_ tracts
right = internodal tracts
left - interatrial tracts
(simultaneously)
235
on the left side the electrical activity dies (dissipates out). on the right side the internodal tract leads to the
AV node ==> AV bundle (bundle of His) which enter the interventricular septum, then splits into the Rand L bundle branches that runp parallel to the apes. the bundle branches spread to the outer wall. little pieces of tissue from bundle brances are the purkinje fibers
236
purkinje fibers stimulate the _
ventricles to contract
237
you first stimulate the apex of the ventricles and then it spreads
up
238
two types of cardiac action potentials:
1. non pacemaker AP aka fast response AP
happen in what cells.
2. pacemaker aka slow response AP occur in __
1. atria, ventricles and purkinje = undergo fast depolarization
2. occur in SA and AV node - undergo slow depolarization
239
phases of fast response AP?
phase 0 ==> 1 --> 2 ==> 3 ==> 4
| 0 is influx of Na, 1 Na close, 2 calcium channels open (long lasting channels) = plateau phase = 3 and 4 K+
240
CICR calcium induced calcium release is
when calcium influx from AP triggers release of ca from SR. via ryanodine receptors RyR2
241
NT that alter calcium conductance. NE will
increase calcium conductance
242
NT AcH
will decrease calcium conductance
243
in slow response (pacemaker AP) the phases are
4 ==> 0 ==> 3
244
in which phase in slow response (pacemaker AP) does calcium rush in
phase 0
245
in slow response (pacemaker AP) phase 4
slowly depolarizes. sodium channels open and sodium flows in. called If
246
steps in in slow response (pacemaker AP) vs fast?
0 ==> 1 ==> 2==> 3 ==> 4 (fast)
| 4 ==> 0 ==> 3
247
conduction velocities: spreads fastest in the
purkinje
248
conduction velocities slowest in
AV node - which allows ventricles to fill before the atria contract
249
chronotropic effect
means a change in the heart rate
250
if someone is enduring a negative chronotropic effect means
decrease heart rate = decreasing rate of SA node firing
251
if someone is enduring a positive chronotropic effect means
increase heart rate = decreasing rate of SA node firing
252
SA node cannot change its rate of firing. something has to force it to change. T/F
true
| ANS tells it. SNS cranks it up, PNS cranks it down
253
dromotropic effect means
when you change the conductance velocity. how fast it goes from SA node to purkinje. usually we change the conduction velocity in the AV nodes
254
the SA node, atria, and AV node have __ innervation but the ventricles do not.
parasympathetic innervation
255
negative dromotropic effect means
decreased velocity of conductance
256
the NT for PNS is __ which acts at
ACh = muscarinic receptors
257
The SA node, AV node, atria AND VENTRICLES have __ innervation
sympathetic.
258
The NT for SNS is _ acts on _ receptors
NE Beta 1
259
the ventricles are only innervated by
sympathetic
260
sympathetic fibers will cause _ dromotropic and chromotropic effects
positive = increase heart rate and increase conduction
261
PNS slows down which part of slow acting AP to make negative chronotropic effect
phase 4 the slow depolarization
262
1. negative dromotropic effect decreases conduction velocity thru the
2. increase the __interval
1. AV node
| 2. PR interval
263
mechanism of negative dromotropic effect is
decreased inward calcium current and increased outward K+ current
264
the _ lung is shorter, wider and heavier.
right lung. it is shorter, heavier, and wider and has three lobes. to remember think of him as the fat one, and thRee is the Right lung
