Heart Physiology- Winden Flashcards
1
Q
what is the valve between the right atrium and the right ventricle?
A
tricuspid
2
Q
A red blood cell leaving the right lung would pass which structures (in order):
A
LA –> LV –>aorta/body–> RA
3
Q
what is the prupose of the chordae tendineae?
A
helps keep the bi and tricuspid vavle from inverting
keeps blood flowing in one direction
4
Q
Which chamber of the heart has the greatest volume?
A
The wall of the LV is larger bc pumps blood out to the body
the volume of the ventricles are the same
5
Q
which is the bicuspid valve
A
between the LA and LV
(mitral, left AV valve)
6
Q
When do I do CPR?
A
When someone’s heart has stopped
7
Q
which of the following lines the chambers of the heart?
A
endocardium
(also line endothlium)
8
Q
The right coronary artery arises from the anterior aortic sinus of the ascending aorta and runs forward between the pulmonary trunk and the right auricle.
The left coronary artery, which is usually longer than the right coronary artery, arises from the left posterior aortic sinus of the ascending aorta and passes forward between the pulmonary trunk and the left auricle.
A
both are true
9
Q
All of the following carry deoxygenated blood from the systemic circuit and empty directly into the right atrium EXCEPT one. Which one is the EXCEPTION?
inferior vena cav
azygos vein
superior vena cava
coronary sinus
A
azygos vein
10
Q
Which of the following valves guards the opening between the left atrium and left ventricle?
A
mitral valve
(bicuspid)
11
Q
Which of the following structures prevents the AV valves from everting (or being blown out) back into the atria during ventricular contraction?
A
chordae tendineae and papillary muscle
12
Q
The base of the heart is formed mainly by the
A
left atrium
13
Q
Thrombosis in the coronary sinus might cause dilation of all of the following veins EXCEPT one.
great cardiac vein
middle cadiac vien
anterior cardiac vein
small cardiac vein
oblique cardiac vein
A
anterior cardiac vein
14
Q
Which of the following describes the function of the ductus arteriosus in the fetus?
A
shunts blood from the pulmonary artery to the aorta
15
Q
Inotropy
A
Force of contraction
positive inotropic
negative inotropic
16
Q
chronotropy
A
rate of contractions
positive chronotropic
negative chronotropic
17
Q
Dromotrophy
A
conduction velocity
postive dromotropic
negative dromotropic
18
Q
Brady
A
slow
19
Q
Tachy
A
fast
20
Q
Tachycardia
A
fast beating heart
21
Q
Bradycardia
A
slow beating heart
(below 70-100)
22
Q
Arrhythmia
A
no rhythm
23
Q
Dysrhythmia
A
irregular rhythm
atypical
24
Q
Heartbeat
(series…)
A
- A single contraction of the heart
- entire heart contracts in series
- First the atria
- then the ventricles
25
two types of cardiac muscle cells
conducting system
contractile cells
26
conducting system
controls and coordinated heartbeat
myocytes
27
contractile cells
produce contractions that propel blood
myocyte
28
cardiac cycle starts with
action potential at SA node
* transmitted through conducting system
* produces action potentials in cardiac muscle cells (contractile cells)
29
Electrocardiogram (ECG or EKG)
electrical events in the cardiac cycle can be recorded on an electrocardiogram
measured AP
30
The conducting system
a system of specialized cardiac muscle cells
(initiates/distributes electrical impulses that stimulate contraction)
31
Automaticity
cardiac muscle tissue contracts automatically
(can go to thershold without additional stimulus)
32
Contractile Cells
Purkinje fibers distribute the stimulus to the contractile cells, which makes up most of the muscle cells in the heart
33
Resting potential
ventricular cell about 90 mV
Atrial cell about 80 mV
34
Conduction system ions
K+
Na +
Ca ++
35
Myocardium ions
K+
Na+
Ca++
36
Blood Vessels ions
Ca++
K+
Cl-
37
Action Potential in cariac muscle steps
1. Rapid Depolarization
2. Peak because of the K
3. The plateau ( caused by Ca)
4. Repolarization
38
absolute refractory period
the heart/ skeletal muscle cannot contract until the cycle is complete
39
Rapid Depolarization
**cause:** Na+ entry
**duration**: 3-5m sec
**ends with**: closure of voltage-gated fast sodium channels
40
The plateau
**cause:** Ca++
**Duration**: about 175 msec
**Ends:** closure of slow calcium channels
41
repolarization
cause: K+ loss
Duration: 75msec
ends with: closure of slow potassium channels
42
which only have an endothelial layer
capillaries
43
ventricles fill at about
70% before they contract
44
what take control of the heart,
SA node
45
Refractory Period
absolute refractory period
relative refractory period
46
absolute refractory period
long
cardiac muscle cells cannot respond
47
relative refractory period
short
response depends on degree of stimulus
48
timing of refractory periods
* length of cardiac action potential in ventricular cell
* 250-300 msec
* 30 times longer than skeletal muscle fiber
49
Role of ca in skeletal muscle contraction
1. Somatic motor neuron releases ACh at neuromuscular junction
2. Net entry of Na+ through ACh receptor channel initiates a muscle action potiental
3. AP in t tubule alters conformation of DHP receptor
4. DHP receptor opens Ca2+ release channels in SR and Ca2+ enters cytoplasm
5. Ca2+ binds to troponin allowing strong actin mysosin binding
6. myosin heads execute power stroke
7. actin filaments slides towards center of sarcomere
50
Smooth muscle
myocardium
skeletal muscle
**_Ca dependence_**
Smooth muscle: extraceullular ca
Myocardium: extracellular ca
skeletal muscle: intracellular ca
51
Ion channel drugs
Na+
Ca++
K+
52
Aerobic energy of heart
* from mito breakdown of fatty acids and glucose
* oxygen from circulating hemoglobin
* cardiac muscle store oxygen in myoglobin
53
structures of conducting system
* Sinoatrial (SA) node - wall of right atrium
* Atrioventricular (AV) node - junction between atria and ventricles
* Conducting cells - throughout myocardium
54
conducting cells
interconnect SA and AV nodes
distribute stimulates through myocardium
55
conducting in the atrium
internodal pathways
56
conducting cells in the ventricles
AV bundle and the bundle branches
57
Prepotential conducting cells
* also called pacemker potential
* resting potential (depolarizes toward threshold)
* SA node depolarizes first, establishing heart rate
***reaches potential thershold w/o any help.***
***Na leaks into cell via funny channels***
58
SA node generates ______ action potentials per minute
80-100
parasympathetic stimulation slows heart rate
59
AV node generates _______ AP per minute
40-60
60
SA node
Sinoatrial Node
posterior wall of right atrium
contains pacemaker cells
connected to AV node by internodal pathways
61
the AV node is located in
floor of right atrium
62
what is the main parasympthaetic nerve ?
vegas
63
Ectopic pacemaker
* Abnormal cells
* Generate high rate of action potentials
* Bypass conducting system
* Disrupt ventricular contractions
64
The AV node is the pacemaker of the heart
the conducting system of the heart is all modiufies cardiac muscle fiber and not nerves
false (SA node), true
65
heart Impulse path
SA node--\> atrial muscle--\> av node--\> bundle of his--\> bundle branches--\> purkinje fibers--\> ventricular muscle
66
the presence fo the plateau in the AP causes causes ventricular contraction to lst as much as 15 times as long in cardiac muscle as in skeletal muscle
the strength of the cardiac muscle contraction is directly proportional to intracellular Na concentration
first is true
Second is false
67
craig has a tachycardia
sa node
68
if patient SA and AV nodes fail what happens?
both the atria and ventricles will contine to contract of set the pace of the buncle of His (30-40 impulses per minute)
69
ECG or EKG
Electrocardiogram
* a recording of electrical events in the heart
* obtained by electrodes at specific body locatoins
* abnormal patterens diagnose damage
70
do we have electrical impulses in the heart?
yes, due to ion channels
71
P wave
atria depolarize
72
QRS complex
ventricles depolarize
ventricles contractions
(larger than p wave beacuse ventrical has more muscle than the atrium)
73
T wave
ventricles repolarize
ventrial relaxation
74
P-R interval
from start of atrial depolarization
to start of QRS complex
75
Q-T interval
from ventricular depolarization
to ventricular repolarization
76
which poriton of the ECG is the only isoelctrical period when the entire ventricle is depolarized
S-T segment
77
this portion of the ecg reps ventricular repolarization
T wave
78
this portion of the ECG \_\_\_
S-T segment
79
electrocardiograph is a rep. of what?
cardiac conductuion sytstem
80
long refreactory period prevents
summations and tetany
81
contraction of a cardiac muscle cell produced by an increase in
Ca ion concentrations
82
role of calcium ions in cardiac contractions
* 20% of Ca ions required for a contraction of extraceullar
83
calcium ions enter plasma membrane during
plateau phase
84
arrival of extraceullar Ca 2+ triggers release of
calcium ion reserves from sacroplasmic reticulum
85
As slow calcium channels close
INtracellular Ca is absobed by the SR or pump out of the cell
86
cardiac muscle tissue is very sensitive to extracellular
ca concentrations
87
AV bundle
in septum
carris impulse to left and right bundle branches (--\> Purkinje fibers)
then to moderator band (--\>papillary muscles)
88
Purkinje fibers
distribute impulse through ventricles
atrial contraction is completed
ventricular contraction starts
89
what are the differnt portions of the ECG
90
Premature atrial contractions
another P wave (premature atrial contractions)
91
Proxysmal Atrial tachycardia
PAT
atria are happening to quickly, ventricles are following
92
Atrial FIbrillation (AF)
no p wave, atria are not defined (no coordinated top down contraciton)
ventricles are working bc av nodes allows ventricles to contract
93
Premature ventricular contractions (PVCs)
extra beat, ventricle kicked in early
94
Ventricle tachycardia
only QRS wave
ventricular
95
Ventricular Fibrillation (VF)
no corrdinated contraction
no blood circulating
96
the cardiac cycle
period between the start of one heartbeat and the beginning of the next
includes both contraction and relaxation
97
the two phases of the cardiac cycle
systole (contraction)
diastole (relaxation)
98
The four phases of the cardiac cycle
Atrial systole
Atrial diastole
Ventricular systole
Ventricular diastole
99
atrial systole
Atrial contraction begins
Right and left AV valves are open
100
Atria eject blood into ventricles
filling ventricles
101
Atrial systole ends
AV valves close
Ventricles contain maximum blood volume
Known as end-diastolic volume (EDV)
102
ventricles contract and build pressure
AV valves close cause isovolumetric contraction
103
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 (SV)
104
Ventricular pressure falls
semilunar valves close
Ventricles contain end-systolic volume (ESV), about 40% of end-diastolic volume
105
End- systolic volume (ESV)
about 40% of end diastolic volume
106
Ventricles contract and build pressure
AV valves close cause isovolumetric contraction
107
Ventricular ejection
## Footnote
* 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 (SV)
108
amount of blood ejected is called
Ventricular ejection
stroke volume (SV)
109
Ventricular diastole
Ventricular pressure is higher than atrial pressure
All heart valves are closed
Ventricles relax (isovolumetric relaxation)
110
another name for ventricular diastole/ relaxation
isovolumetric relaxation
111
Atrail pressure is higher than ventricular pressure
AV valves open
passive atrial filling
passive ventricular filling
112
blood pressure in any chamber
rise during systole
falls during diastole
113
blood flows from _______ to \_\_\_\_\_\_.
controlled by
high to low pressure
controlled By:
* timing of contractions
* one-way valves
114
At 75 beats per minute the cardiac cycle lasts about
800 msec
115
when heart rate increases what hapen to the cardiac cycle?
all phases of cardiac cycle shorten
**\*\*mainly diastole**
116
Heart sound 1
Lound souns
produced by AV valves
117
Heart sound 2
loud sounds
produced by semilunar valves
118
Heart sounds 3 and 4
soft sounds
blood flow into ventricles and atrial contraction
119
heart murmur
sounds produced by reguritation thorugh valves
120
Cardiodynamics
the movements and force generatd by cardiac contractions
121
How to calulate SV
SV= EDV-ESV
EDV- end-diastolic volume
ESV-End-systolic volume
122
ejection fraction
the percentage of EDV represented by Stroke Volume
123
what is cardiac output
Co
the volume pumped by left ventricle in 1 minute
124
how to calculate cardiac output
CO= HR x SV
```
CO = cardiac output (mL/min)
HR = heart rate (beats/min)
SV = stroke volume (mL/beat)
```
125
cardiac output adjusted by
changes in the heart rate or stroke volume
126
heart rate is adujusted by
autonomic nervous system or hormones
127
stroke volum adjusted by
changing EDV or ESV
128
factors that affect heart rate (HR)
autonomic innervation
hormones
129
factors affecting stroke volume
end diastolic volume
end systolic volume
130
what affects cardiac output?
heart rate
and stroke volume
131
Autonomic innercation of heart (3)
cardiac plexuses
vagus nerves (N X)
cardiac centers in medulla oblongata
132
what innervate the heart
cardiac plexuses
133
vagus nerves carry
parasympathetic preganglionic fibers to small ganglia in cardiac plexus
134
cardiac centers of medulla oblongata
cardioacceleratory center
cardioinhibitory center
135
cardioacceleratory center
controls sympathetic neurons
(increases heart rate)
136
cardioinhibitory center of medulla oblongata
controls parasmpathetic neurons (slows heart rate)
137
cardiac cholinergic receptors
*activated by parasympathetic*
**_M2 muscarinic receptors_:** mainly in SA Node
**_M2 activation:_** Reduces heart rate (negative chronotropic)
138
Adrenergic heart receptors
*activated by sympathetic*
β1 Angioadrenergic receptors in myocardium, SA Node
β1 activation: Increases contractility (positive inotropic)
:Increases heart rate (positive chronotropic)
139
Angiotensin
AT1 Myocardium: positive inotropy
140
cardiac centers monitor
```
Blood pressure (baroreceptors)
Arterial oxygen and carbon dioxide levels (chemoreceptors
```
141
cardiac centers adjust
cardiac activity
142
Autonomic tone:
* Dual innervation maintains resting tone by releasing ACh and NE
143
effects of the SA node
* membrane potential of pacemaker cells
* Rate of spontaneous depolarization depends on
144
membrane potential of pacemaker cells
lower thatn other cardiac cells
145
rate of spontaneous depolarization depends on
resting membrane potential
rate of depolarization
146
pacemaker cells have membrane potentials closer to
threshold than those of other rcardiac muscle cells
(-60 mV vs -90mV)
147
effects on the SA node
sympathetic and parasympathetic stimulation
greatest at SA node (heart rate)
148
effects of SA node
ACh
parasympathetic stimulation
slows the heart
149
effects on the SA node NE
sympathetic stimulation
speeds the heart
150
parasympathetic stimulation releases
Ach
which extends repolarization and dcreases the rate of spontaneous depolarization
(heart rate slows)
151
Brainbridge reflex
atrial reflex
adjusts heart rate in response to venous return
152
strech receptors in right atrium
trigger increase in heart rate through increased sympathetic activity
153
hormonal effects on heart rate
increase heart rate (by sympathetic stimulation of SA node)
154
which hormones effect the heart rate
Epinephrine E
Norepinephrine (NE)
thyroid hormone
155
Depolarization of the ventricles is represented on an electrocardiogram by the
QRS complex
156
the normal pacemaker of the heart is
Sinoatrial node
157
Factors affecting the stroke volume
filling time: duration of ventrical diastole
Venous return: rate of blood flow during ventrical diastole
158
three factors that affect ESV
preload
contractility
afterload
159
preload
ventricular stretching during diastole
proportional to EDV
affects ability of muscle cells to produce tension)
160
contractility
force produced diring contraction at a given preload
161
afterload
tension the ventricle produces to open the semilunar valve and eject blood
162
The EDV and stroke volume at rest
EDV is low
Myocardium stretches less
stroke volume is low
163
EDV and stroke volume with exercise
EDV increases
myocardium streches more
stroke volume increases
164
frank-starling principle
as EDV increases, stroke colume increases
165
Ventricular expansion limited by
Myocardial connective tissue
the cardiac(fibrous) skeleton
the pericardial sac
166
more blood in ventricle means
\> more forceful contraction
167
frank-starling law of contraction
**The force of contraction of myocardium is directly proportional to the stretch of the muscle (preload)**
*helps to pump out the blood received by the heart without excessive accumulation*
168
End- systolic volume (ESV)
amount of blood that remains in the ventricle at the end of ventricular systole
169
contractility is affected by
autonomic activity
hormones
170
Effects of Autonomic Activity on Contractility
Sympathetic stimulation
* NE released by postganglionic fibers of cardiac nerves
* Epinephrine and NE released by adrenal medullae
* Causes ventricles to contract with more force
171
Effects of Autonomic Activity on Contractility
Parasympathetic activity
Acetylcholine released by vagus nerves
Reduces force of cardiac contractions
172
as afterload increases stroke volume
decreases
173
heart rate control factors
* autonomic nervous system (sympathetic and parasympathetic)
* Circulating hormones
* Venous return and stretch receptors
174
EDV
stroke volume control
filling time and rate of venous return
175
ESV
stroke volume control factors
preload, contractility, afterload
176
on the surface of the chest, the apex of the heart is located:
in the left fifth intercostal space
177
the dub is the sound of which valve
aortic and pulmonary
178
tricuspid valve is located between which two chambers of the heart?
which valve has a unquie
right A and V
mitral
179
where should you put the stethoscope to listen to the sound of the tricuspid valve
right half of the lower end of the body of the sternum
180
A) Semilunar valve opens
181
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes
182
The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the
systolic ejection phase
183
what is the parasympathetic nerve for the heart?
vegas nerve
184
Resistance=
_viscosity(of blood) x length of vessel_
radius^4
185
flow=
flow=( intial pressure-final pressure)/resistance
