Chapter 18 - The Cardiovascular System - Heart Flashcards
1
Q
The right side pump of the heart receives:
A
oxygen-poor blood from tissues
2
Q
The right side pump of the heart pumps to:
A
lungs to get rid of CO2
3
Q
The right side pump of the heart picks up O2 via ___.
A
the pulmonary circuit
4
Q
The left side pump of the heart receives:
A
oxygenated blood from lungs
5
Q
The left side pump of the heart pumps to ___ via ___.
A
body tissues; systemic circuit
6
Q
The receiving chambers of the heart are:
A
- right atrium
2. left atrium
7
Q
What is the function of the right atrium?
A
Receives blood returning from systemic circuit
8
Q
What is the function of the left atrium?
A
Receives blood returning from pulmonary circuit
9
Q
The pumping chambers of the heart are:
A
- Right ventricle
2. Left ventricle
10
Q
What is the function of the right ventricle?
A
Pumps blood through pulmonary circuit
11
Q
What is the function of the left ventricle?
A
Pumps blood through systemic circuit
12
Q
The heart is approximately the size of ___.
A
the fist
13
Q
The location of the heart:
A
- in mediastinum between second rib and fifth intercostal space
- on superior surface of diaphragm
- two-thirds of heart to left of midsternal line
- anterior to vertebral column, posterior to sternum
14
Q
The base (posterior surface) of the heart leans toward ___.
A
the right shoulder
15
Q
The apex of the heart points toward ___.
A
the left hip
16
Q
The apical impulse of the heart is located:
A
palpated between fifth and sixth ribs, just below left nipple
17
Q
What covers the heart?
A
pericardium
18
Q
What are the characteristics of pericardium?
A
- it’s a double-walled sac
2. it has superficial fibrous pericardium
19
Q
What is the function of fibrous pericardium?
A
- protects the heart
- anchors to surrounding structures
- prevents overfilling
20
Q
What are the two layers of the serous pericardium?
A
- Parietal layer
2. Visceral layer
21
Q
Where is the parietal layer located within the serous pericardium?
A
It lines the internal surface of fibrous pericardium.
22
Q
Where is the visceral layer of serous pericardium located in the heart?
A
On the external surface of the heart.
23
Q
The visceral layer of serous pericardium is also known as:
A
epicardium
24
Q
The two layers of the serous pericardium are separated by:
A
the fluid-filled pericardial cavity
25
What is the purpose of the pericardial cavity?
decreases friction
26
Homeostatic imbalance of pericardium can lead to:
1. pericarditis
| 2. cardiac tamponade
27
What is pericarditis?
inflammation of pericardium
28
What happens to the membrane surfaces of the pericardium when someone has pericarditis?
the surfaces are roughened; the heart has pericardial friction rub (creaking sound) that can be heard with a stethoscope
29
What is cardiac tamponade?
Excess fluid sometimes compresses the heart, which leads to limited pumping ability.
30
The three layers of the heart wall are:
1. epicardium
2. myocardium
3. endocardium
31
The visceral layer of serous pericardium is:
epicardium
32
Characteristics of the myocardium:
1. spiral bundles of contractile cardiac muscle cells
| 2. cardiac skeleton; crisscrossing, interlacing layer of connective tissue
33
What is the function of the cardiac skeleton of myocardium?
1. anchors cardiac muscle fibers
2. supports great vessels and valves
3. limits spread of action potentials to specific paths
34
The endocardium is continuous with:
endothelial lining of blood vessels
35
Where is the endocardium located?
1. lines heart chambers
| 2. covers cardiac skeleton of valves
36
The four chambers of the heart:
1. Two superior atria
| 2. Two inferior ventricles
37
separates atria
interatrial septum
38
remnant of foramen ovale of fetal heart
fossa ovalis
39
separates ventricles
interventricular septum
40
The chambers and associated great vessels:
1. coronary sulcus
2. anterior interventricular sulcus
3. posterior interventricular sulcus
41
The coronary sulcus is also known as:
atrioventricular groove
42
This encircles the junction of atria and ventricles.
coronary sulcus
43
This is located in the anterior position of the interventricular septum.
Anterior interventricular sulcus
44
This is a landmark on the posteroinferior surface.
posterior interventricular sulcus
45
appendages that increase atrial volume
auricles
46
The atria are the ___ chambers.
receiving
47
The ventricles are the ____ chambers.
discharging
48
The right atrium has ____.
pectinate muscles
49
The posterior and anterior regions of the right atrium are separated by ____.
crista terminalis
50
The left atrium has pectinate muscles only in ____.
auricles
51
What are the characteristics of atria?
1. small, thin-walled
2. Contribute little to propulsion of blood
3. Three veins empty into right atrium
4. Four pulmonary veins empty into left atrium
52
What are the three veins that empty into the right atrium?
1. superior vena cava
2. inferior vena cava
3. coronary sinus
53
Most of the volume of the heart is:
the ventricles
54
Where is the right ventricle of the heart located?
most of the anterior surface
55
Where is the left ventricle of the heart located?
posteroinferior surface
56
irregular ridges of muscle on walls
trabeculae carneae
57
The papillary muscles of the ventricles anchor ____.
chordae tendineae
58
What are the characteristics of ventricles?
1. thicker walls than atria
| 2. they are the actual pumps of the heart
59
The right ventricle pumps blood into the _____.
pulmonary trunk
60
The left ventricle pumps blood into the ____.
aorta
61
largest artery in the body
aorta
62
What are the characteristics of heart valves?
1. Ensure unidirectional blood flow through the heart
2. Open and close in response to pressure changes
3. Two atrioventricular (AV) valves
4. Two semilunar (SL) valves
63
What is the purpose of the atrioventricular valves?
To prevent backflow into atria when ventricles contract.
64
What is the purpose of semilunar valves?
1. Prevent backflow into ventricles when ventricles relax.
| 2. Open and close in response to pressure changes.
65
Atrioventricular valves are composed of:
1. tricuspid valve (right AV valve)
2. mitral valve (left AV valve, bicuspid valve)
3. Chordae tendineae
66
Chordae tedineae of the atrioventricular valves anchor cusps to _____. What is the purpose of this?
papillary muscles; to hold valve flaps in closed position
67
Semilunar valves are composed of:
1. Aortic semilunar valve
| 2. Pulmonary semilunar valve
68
Homeostatic imbalance involving heart valves can lead to:
1. Incompetent valve
| 2. Valvular stenosis
69
What happens during incompetent valve?
Blood backflows so the heart repumps the same blood over and over.
70
What happens during valvular stenosis?
Stiff flaps; they constrict opening - the heart must exert more force to pump blood
71
How can heart valve disease be treated?
By replacing the valve with a mechanical, animal, or cadaver valve.
72
Pathway of blood through the heart: Pulmonary Circuit: Right atrium:
---> tricuspid valve ---> right ventricle
73
Pathway of blood through the heart: Pulmonary Circuit: Right ventricle:
---> pulmonary semilunar valve ---> pulmonary trunk ---> pulmonary arteries ---> lungs
74
Pathway of blood through the heart: Pulmonary Circuit: Lungs:
---> pulmonary veins ---> left atrium
75
Pathway of blood through the heart: Systemic Circuit: left atrium:
---> mitral valve ---> left ventricle
76
Pathway of blood through the heart: Systemic Circuit: left ventricle:
---> aortic semilunar valve ---> aorta
77
Pathway of blood through the heart: Systemic Circuit: aorta:
---> systemic circulation
78
What is the amount of blood pumped to the pulmonary and systemic circuits?
equal amount
79
Characteristic of the pulmonary circuit:
short, low-pressure circulation
80
Characteristic of the systemic circuit:
long, high-friction circulation
81
What is the size of the left ventricle in comparison to the right?
3x thicker; pumps with greater pressure
82
functional blood supply to heart muscle itself
coronary circulation
83
Blood is delivered via coronary circulation when:
the heart is relaxed
84
Most of the blood supply from the coronary circulation is received in:
left ventricle
85
The coronary circulation contains many of these.
anastomoses (junctions)
86
What are the characteristics of anastomoses?
1. Provide additional routes for blood delivery
| 2. Can not compensate for coronary artery occlusion
87
Arteries arise from the base of ____.
the aorta
88
The left coronary artery branches into:
1. anterior interventricular artery
| 2. circumflex artery
89
The right coronary artery branches into:
1. right marginal artery
| 2. posterior interventricular artery
90
What does the left coronary artery supply to?
1. interventricular septum
2. anterior ventricular walls
3. left atrium
4. posterior wall of left ventricle
91
What does the right coronary artery supply to?
1. right atrium
| 2. most of right ventricle
92
These collect blood from capillary beds.
cardiac veins
93
This empties into the right atrium.
coronary sinus
94
The coronary sinus is formed by merging cardiac veins. Which are they?
1. Great cardiac vein
2. Middle cardiac vein
3. Small cardiac vein
95
Where is the great cardiac vein located?
anterior interventricular sulcus
96
Where is the middle cardiac vein located?
posterior interventricular sulcus
97
Where is the small cardiac vein located?
inferior margin
98
Several _____ empty directly into right atrium anteriorly.
anterior cardiac veins
99
Diseases involving coronary circulation:
1. Angina pectoris
| 2. Myocardial infarction
100
Characteristics of angina pectoris:
1. Thoracic pain caused by fleeting deficiency in blood delivery to myocardium
2. cells are weakened
101
Characteristics of myocardial infarction:
1. Prolonged coronary blockage
| 2. Areas of cell death repaired with noncontractile scar tissue
102
myocardial infarction is also known as
heart attack
103
Physical characteristics of cardiac muscle cells:
1. short
2. branched
3. fat
4. interconnected
5. 1 (perhaps 2) central nuclei
6. T tubules are wide, less numerous
7. SR is simpler than in skeletal muscle
8. numerous large mitochondria
104
The connective tissue matrix of cardiac muscle connects to ____.
cardiac skeleton
105
Another name for connective tissue matrix of cardiac muscle:
endomysium
106
This contains numerous capillaries.
endomysium
107
Mitochondria of cardiac muscle cells are what percentage of cell volume?
25-35%
108
Cardiac muscle also contains:
1. intercalated discs
2. desmosomes
3. gap junctions
109
junctions between cells that anchor cardiac cells
intercalated discs
110
These prevent cardiac muscle cells from separating during contraction.
desmosomes
111
These allow ions to pass from cell to cell; they also electrically couple adjacent cells.
gap junctions
112
Gap junctions allow the heart to be:
functional syncytium
113
What is functional syncytium?
Behaves as a single coordinated unit.
114
What are the three differences between cardiac muscle and skeletal muscle?
1. ~1% of cardiac muscle cells have automaticity (autorhythmicity)
2. All cardiomyocytes contract as a unit, or none do
3. Long absolute refractory period
115
Automaticity (authorhythmicity) in cardiac muscle cells allow for:
1. not needing nervous system stimulation
| 2. can depolarise the entire heart
116
What is the time length of the absolute refractory period in cardiac muscle cells?
250 ms
117
Why do cardiac muscle cells have a long absolute refractory period?
To prevent tetanic contractions.
118
What are the three similarities between cardiac muscle and skeletal muscle?
1. Depolarisation opens few voltage-gated fast Na+ channels in sarcolemma
2. Depolarisation wave down T tubules
3. Excitation-contraction coupling occurs
119
When depolarisation opens voltage-gated fast Na+ channels in sarcolemma of cardiac muscle cells, what happens?
1. The membrane potential is reversed from -90mV to +30 mV
| 2. It is brief; Na channels close rapidly
120
After depolarisation wave goes down T tubules in cardiac muscle cells, what happens?
SR releases Ca2+
121
When excitation-contraction coupling occurs in cardiac muscle cells, what happens?
Ca2+ binds troponin ---> filaments slide
122
More differences between cardiac muscle cells and skeletal muscle cells:
1. Depolarisation wave also opens slow Ca2+ channels in sarcolemma ---> SR to release its Ca2+
2. Ca2+ surge prolongs the depolarisation phase
3. Action potential and contractile phase last much longer
4. Repolarisation is a result of inactivation of Ca2+ channels and opening of voltage-gated K+ channels
123
When Ca2+ surge prolongs the depolarisation phase of cardiac muscle cells, what is it known as?
plateau
124
The action potential and contractile phase of cardiac muscle cells lasts much longer. What does this allow for?
Blood ejection from heart
125
After Ca2+ channels are inactivated and repolarisation results of cardiac muscle cells, what happens?
Ca2+ is pumped back to SR and extracellularly
126
Cardiac muscle has many ____.
mitochondria
127
Cardiac muscle energy requirements:
1. Mitochondria have great dependence on aerobic respiration
2. Mitochondria have little anaerobic respiration ability
3. Cardiac muscle readily switches fuel source for respiration
4. Cardiac muscle even uses lactic acid from skeletal muscles
128
Homeostatic imbalance of cardiac muscle:
1. Ischemic cells
2. --->anaerobic respiration
3. --->lactic acid
4. ---> High H+ concentration
5. ---> high Ca2+ concentration
6. ---> mitochondrial damage
7. --->decreased ATP production
8. --->gap junctions close
9. ---> fatal arrhythmias
129
The heart depolarises and contracts without:
nervous system stimulation
130
Heart rhythm can be altered by:
the autonomic nervous system
131
Coordinated heartbeat is a function of:
1. presence of gap junctions
| 2. intrinsic cardiac conduction system
132
What are the characteristics of the intrinsic cardiac conduction system?
1. network of noncontractile (autorhythmic) cells
| 2. initiates and distributes impulses ---> coordinated depolarisation and contraction of heart
133
Characteristics of autorhythmic cells:
1. Have unstable resting membrane potentials (pacemaker potentials or prepotentials) due to opening of slow Na+ channels
2. At threshold, Ca2+ channels open
134
Because autorhythmic cells have unstable resting membrane potentials due to opening of slow Na+ channels, what happens?
They continuously depolarise.
135
After autorhythmic cells reach threshold and Ca2+ channels open, what happens?
Explosive Ca2+ influx produces the rising phase of the action potential.
136
Repolarisation of autorhythmic cells results from what?
Inactivation of Ca2+ channels and opening of voltage-gated K+ channels.
137
What are the three parts of action potential by pacemaker cells?
1. pacemaker potential
2. depolarisation
3. repolarisation
138
When the pacemaker potential of pacemaker cells initiates, what happens?
Repolarisation closes K+ channels and opens slow Na+ channels ---> ion imbalance
139
After ion imbalance due to pacemaker potential of pacemaker cells, depolarisation occurs; what happens?
Ca2+ channels open ---> huge influx ---> rising phase of action potential
140
After rising phase of action potential of pacemaker cells, repolarisation occurs. What happens?
K+ channels open ---> efflux of K+
141
Cardiac pacemaker cells pass impulses across heart in what speed?
~220 ms
142
What is the sequence of cardiac pacemaker cell impulses?
1. Sinoatrial node
2. ---> Atrioventricular node
3. ---> Atrioventricular bundle
4. ---> Right and left bundle branches
5. ---> Subendocardial conducting network (Purkinje fibres)
143
Heart Physiology: Sequence of Excitation:
1. Sinoatrial node
2. Impulse spreads across atria, and to AV node
3. Atrioventricular Node
4. Atrioventricular Bundle
5. Right and left bundle branches
6. Subendocardial conducting network
7. Ventricular contraction immediately follows from apex toward atria
144
Pacemaker of heart in right atrial wall
Sinoatrial (SA) node
145
Characteristics of SA node:
1. Depolarises faster than the rest of myocardium
2. Generates impulses about 75X/minute
3. Inherent rate of 100X/minute tempered by extrinsic factors
146
The Sinoatrial node generates impulses at about 75X/minute. What is this known as?
sinus rhythm
147
Where is the AV node located?
In inferior interatrial septum
148
Characteristics of AV node:
1. delays impulses approximately 0.1 second
| 2. Inherent rate of 50X/minute in absence of SA node input
149
Why does the AV node delay impulses by approximately 0.1 second?
1. Because fibres are smaller diameter, and have fewer gap junctions
2. It allows atrial contraction prior to ventricular contraction
150
Where is the AV bundle located?
In superior interventricular septum
151
AV bundle has only electrical connection between:
atria and ventricles
152
Why does AV bundle only have electrical connection between atria and ventricles?
Because atria and ventricles are not connected via gap junctions
153
Characteristics of right and left bundle branches:
1. Two pathways in interventricular septum
| 2. Carry impulses toward apex of heart
154
Characteristics of subendocardial conducting network:
1. Complete pathway through interventricular septum into apex and ventricular walls
2. More elaborate on left side of heart
155
The AV bundle and subendocardial conducting network depolarise at:
30X/minute in absence of AV node input
156
Defects in intrinsic conduction system may cause:
1. Arrhythmias
| 2. Fibrillation
157
irregular heart rhythms
arrythmias
158
What happens with arrythmias?
Uncoordinated atrial and ventricular contractions.
159
rapid, irregular contractions
fibrillation
160
When fibrillation leads to rapid, irregular contractions, what happens?
1. It's useless for pumping blood
2. --->circulation ceases
3. ---> brain death
161
How is fibrillation treated?
defibrillation
162
Defective SA node may cause:
1. Ectopic focus
2. AV node may take over
3. Extrasystole
4. To reach ventricles, impulse must pass through AV node
163
abnormal pacemaker
ectopic focus
164
Because of a defective SA node, AV node may take over. What happens then?
AV node sets junctional rhythm (40-60 beats/min)
165
premature contraction
extrasystole
166
What are the characteristics of extrasystole?
1. Ectopic focus sets high rate
| 2. Can be from excessive caffeine or nicotine
167
Defective AV node may cause:
heart block
168
Charactieristics of heart block:
1. Few (partial) or no (total) impulses reach ventricles
| 2. Ventricles beat at intrinsic rate--too slow for life
169
How does one treat heart block?
artificial pacemaker
170
Heartbeat is modified by:
autonomic nervous system via cardiac centres in medulla oblongata
171
When the sympathetic nervous system is activated:
heartbeat is increased in rate and force
172
When the parasympathetic nervous system is activated:
heartbeat is decreased in rate
173
The cardioacceleratory centre is ____.
sympathetic
174
The cardioinhibitory centre is ____.
parasympathetic
175
What does the cardioacceleratory centre affect?
1. SA
2. AV nodes
3. heart muscle
4. coronary arteries
176
What does the cardioinhibitory centre inhibit?
SA and AV nodes via vagus nerves
177
Composite of all action potentials generated by nodal and contractile cells at a given time
electrocardiogram (ECG or EKG)
178
The 3 waves of an electrocardiogram are:
1. P wave
2. QRS complex
3. T wave
179
A P wave is characteristic of:
depolarisation of SA node ---> atria
180
A QRS complex is characteristic of:
ventricular depolarisation and atrial depolarisation
181
A T wave is characteristic of:
ventricular repolarisation
182
A P-R interval of ECG lasts from:
beginning of atrial excitation to beginning of ventricular excitation
183
What happens during an S-T segment of ECG?
Entire ventricular myocardium is depolarised
184
A Q-T interval of ECG lasts from:
Beginning of ventricular depolarisation through ventricular repolarisation
185
Two sounds are associated with the closing of heart valves (lub-dup). What happens during these?
1. First happens as AV valves close
2. Second happens as SL valves close
3. Pause indicates heart relaxation
186
When AV valves close, what happens?
Systole begins
187
When SL valves close, what happens?
Ventricular diastole begins
188
abnormal heart sounds; usually indicate incompetent or stenotic valves
heart murmurs
189
Characteristics of the cardiac cycle:
1. Blood flows through heart during one complete heartbeat: atrial systole and diastole followed by ventricular systole and diastole
2. systole
3. diastole
4. Series of pressure and blood volume changes
190
contraction
systole
191
relaxation
diastole
192
The phases of the cardiac cycle:
1. ventricular filling
2. ventricular systole
3. isovolumetric relaxation
193
When does ventricular filling of the cardiac cycle take place?
in mid-to-late diastole
194
When does isovolumetric relaxation of the cardiac cycle take place?
early diastole
195
Characteristics of ventricular filling in the cardiac cycle:
1. AV valves are open; pressure is low
2. 80% of blood passively flows into ventricles
3. Atrial systole occurs, delivering remaining 20%
4. End diastolic volume (EDV)
196
What is the end diastolic volume (EDV)?
volume of blood in each ventricle at the end of ventricular diastole
197
Characteristics of ventricular systole in the cardiac cycle:
1. Atria relax; ventricles begin to contract
2. Rising ventricular pressure ---> closing of AV valves
3. Isovolumetric contraction phase
4. In ejection phase, ventricular pressure exceeds pressure in large arteries, forcing SL valves open
5. End systolic volume (ESV)
198
What happens during the isovolumetric contraction phase of ventricular systole in the cardiac cycle?
all valves are closed
199
What is the end systolic volume (ESV)?
volume of blood remaining in each ventricle after systole
200
Characteristics of isovolumetric relaxation of the cardiac cycle:
1. Ventricles relax; atria are relaxed and filling
2. Backflow of blood in aorta and pulmonary trunk closes SL valves
3. When atrial pressure exceeds that in ventricles --> AV valves open; cycle begins again at step 1
201
The backflow of blood in aorta and pulmonary trunk closes SL valves during isovolumetric relaxation of the cardiac cycle. This causes what?
dicrotic notch; ventricles totally closed chambers
202
What is the dicrotic notch?
brief rise in aortic pressure as blood rebounds off closed valve
203
the volume of blood pumped by each ventricle in one minute
cardiac output
204
What is the formula for cardiac output?
CO = heart rate (HR) x stroke volume (SV)
205
number of beats per minute
heart rate (HR)
206
volume of blood pumped out by one ventricle with each beat
stroke volume (SV)
207
What is the normal cardiac output?
5.25 L/min
208
At rest, the CO is:
CO (ml/min) = HR (75 beats/min) x SV (70 ml/beat) = 5.25 L/min
209
Cardiac output increases if:
either or both SV or HR is increased
210
Characteristics of maximal cardiac output:
1. it is 4-5 times resting cardiac output in nonathletic people
2. it may reach 35 L/min in trained athletes
211
the difference (-) between resting and maximal CO
cardiac reserve
212
Equation for SV:
SV = EDV - ESV
213
EDV is affected by:
length of ventricular diastole and venous pressure
214
ESV is affected by:
arterial BP and force of ventricular contraction
215
What are the three main factors that affect SV?
1. Preload
2. Contractility
3. Afterload
216
What is preload?
The degree of stretch of cardiac muscle cells before they contract.
217
The degree of stretch of cardiac muscle cells before they contract follows which principle?
Frank-Starling law of heart
218
Characteristics of preload:
1. Cardiac muscle exhibits a length-tension relationship
2. At rest, cardiac muscle cells are shorter than optimal length
3. Most important factor stretching cardiac muscle is venous return
219
What is venous return?
the amount of blood returning to the heart
220
How is venous return increased?
slow heartbeat and exercise increase
221
When venous return is increased, what happens?
it distends (stretches) ventricles and increases contraction force
222
What is contractility?
contractile strength at given muscle length, independent of muscle stretch and EDV
223
Contractility is increased by:
1. Sympathetic stimulation ---> increased Ca2+ influx ---> more cross bridges
2. Positive inotropic agents
224
What are the positive inotropic agents that increase contractility?
1. Thyroxine
2. glucagon
3. epinephrine
4. digitalis
5. high extracellular Ca2+
225
Contractility is decreased by:
negative ionotropic agents
226
What are the negative ionotropic agents that decrease contractility?
1. acidosis
2. increased extracellular K+
3. calcium channel blockers
227
What is afterload?
the pressure ventricles must overcome to eject blood
228
Afterload is increased by:
hypertension, resulting in increased ESV and reduced SV
229
Positive chronotropic factors ___ heart rate.
increase
230
Negative chronotropic factors ___ heart rate.
decrease
231
The sympathetic nervous system is activated by:
emotional or physical stressors
232
What happens when the sympathetic nervous system is activated?
1. Norepinephrine causes pacemaker to fire more rapidly (and increases contractility)
2. Norepinephrine binds to Beta1-adrenergic receptors ---> increased HR
3. increased contractility; faster relaxation
4. increased contractility offsets lower EDV due to decreased fill time
233
What happens when the parasympathetic nervous system is activated?
1. Acetylcholine hyperpolarises pacemaker cells by opening K+ channels ---> slower HR
2. Little to no effect on contractility
234
Heart at rest exhibits ____.
vagal tone
235
What is vagal tone?
Parasympathetic nervous system is dominant the influence.
236
How is heart rate chemically regulated?
1. hormones
| 2. intra and extracellular ion concentrations must be maintained for normal heart function
237
Hormones that regulate heart rate:
1. epinephrine
| 2. thyroxine
238
Epinephrine is released from the ___.
adrenal medulla
239
What does epinephrine do for the heart?
increases heart rate and contractility
240
What does thyroxine do for the heart?
1. increases heart rate
| 2. enhances effects of norepinephrine and epinephrine
241
Homeostatic imbalance of heart rate can lead to:
1. hypocalcemia
2. hypercalcemia
3. hyperkalemia
4. hypokalemia
5. tachycardia
6. bradycardia
7. congestive heart failure (CHF)
242
What does hypocalcemia do?
depresses heart
243
What happens in hypercalcemia?
increased HR and contractility
244
What happens in hyperkalemia?
electrical activity is altered ---> heart block and cardiac arrest
245
What happens in hypokalemia?
feeble heartbeat; arrhythmias
246
Characteristics of tachycardia:
1. abnormally fast heart rate (>100 beats/min)
| 2. if persistent, may lead to fibrillation
247
Characteristics of bradycardia:
1. heart rate is slower than 60 beats/min
2. may result in grossly inadequate blood circulation in nonathletes
3. may be desirable result of endurance training
248
Characteristics of congestive heart failure:
1. progressive condition
2. cardiac output is so low that blood circulation is inadequate to meet tissue needs
3. weakened myocardium
249
Weakened myocardium in congestive heart failure can be caused by:
1. coronary atherosclerosis--clogged arteries
2. persistent high blood pressure
3. multiple myocardial infarcts
4. dilated cardiomyopathy (DCM)
250
The embryonic heart chambers are:
1. sinus venosus
2. atrium
3. ventricle
4. bulbus cordis
251
The fetal heart structures that bypass pulmonary circulation:
1. foramen ovale
| 2. ductus arteriosus
252
The foramen ovale connects:
two atria
253
The remnant of foramen ovale in adults is:
fossa ovalis
254
The ductus arteriosus connects:
pulmonary trunk to aorta
255
The remnant of ductus arteriosus in adults is:
ligamentum arteriosum
256
The foramen ovale and ductus arteriosus close:
at or shortly after birth
257
Most congenital heart defects are one of two types:
1. due to mixing of oxygen-poor and oxygen-rich blood, e.g. septal defects, patent ductus arteriosus
2. narrowed valves or vessels --> increased workload on the heart, e.g. coarctation of aorta
258
In Tetralogy of Fallot:
both congenital heart defects are present
