Cardio Flashcards
(291 cards)
1
Q
Give Approximate Dimensions of the Heart.
A
5 inches by 3.5 inches in an adult
2
Q
How much of the heart lies left of midline?
A
2/3
3
Q
What heart surface is Anterior (Sternocostal)- deep to sternum and ribs?
A
2/3 Right Ventricle and 1/3 Left Ventricle
4
Q
What heart surface is Inferior (Diaphragmatic)- Rests on central tendon of diaphragm?
A
2/3 Left Ventricle and 1/3 Right Ventricle
5
Q
What heart surface is Right- faces right lung?
A
Mainly Right Atrium
6
Q
What heart surface is Left- Pulmonary boarder, faces left lung?
A
Mainly Left Ventricle
7
Q
What heart surface forms the Base- faces posterior chest?
A
Mainly Left Atrium. Small portion of Right Atrium. Consists of 4 Pulmonary Veins & 2 Pulmonary Arteries
8
Q
What heart surface forms the Apex- faces anterior chest?
A
Inferolateral part of Left Ventricle. Usually lies posterior to left 5th intercostal space (adults)
9
Q
What is Situs Inversus Totalis?
A
Complete transposition (right to left reversal) of the thoracic and abdominal organs.
10
Q
Define: Cardiology
A
The Scientific study of the normal heart and the diseases associated with it.
11
Q
Give the location of the heart
A
Mediastinum: Anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs
12
Q
Describe the Pericardium
A
Membrane that surrounds and protects the heart and the beginning of the great vessels (Aorta, pulmonary arteries/veins, venae cavae
13
Q
What are the two main parts of the Pericardium?
A
Fibrous pericardium
Serous pericardium
14
Q
The Fibrous Pericardium is composed of?
A
tough, inelastic, dense irregular connective tissue
15
Q
Purpose of the Fibrous Pericardium?
A
Prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum
16
Q
The Fibrous Pericardium is partially fused to what?
A
“Open End” fused to connective tissue of great vessels.
Central tendon of the diaphragm. Movement of the diaphragm facilitates movement of blood by the heart
17
Q
The Serous Pericardium is further broken down into what two layers?
A
Parietal Layer Visceral Layer (Also called Epicardium)
18
Q
The Parietal Layer (Outer Layer) of the Serous Pericardium is fused to what?
A
The Fibrous Pericardium
19
Q
The Visceral Layer (Inner Layer) of the Serous Pericardium is also know as?
A
The Epicardium
20
Q
The outer most layer of the heart is called?
A
The Epicardium (Visceral Layer of the Serous Pericardium)
21
Q
The Epicardium adheres tightly to?
A
The surface of the heart
22
Q
Cavity between the Parietal Layer and Visceral Layer (Epicardium) of the Serous Pericardium is known as?
A
The Pericardial Cavity
23
Q
The Pericardial Cavity contains what fluid?
A
Pericardial Fluid (few milliliters)
24
Q
What is the purpose of the Pericardial Fluid?
A
Thin film of lubricating serous fluid
25
What is the purpose of Pericardial Fluid?
reduce friction between the layers of the Serous Pericardium as the heart moves.
26
What are the three layers of the Heart? (External to Internal)
Epicardium (Visceral Layer of Serous Pericardium)
Myocardium- Muscle Layer
Endocardium- Inner Layer
27
Which layer is both a part of the pericardium and a part of the heart wall?
Epicardium (Visceral Layer of Serous Pericardium)
28
What layer of the heart contains blood vessels & lymphatics to supply the myocardium?
Epicardium
29
What is the purpose of the Adipose tissue on the Epicardium (Visceral Layer of Serous Pericardium)
Protect major coronary/cardiac vessels
30
What layer makes up 95% of the heart wall?
Myocardium
31
This layer is responsible for the pumping action and organized in bundles that swirl diagonally around the heart?
Myocardium
32
What gives the "torque appearance of the heart when beating?
Myocardium
33
What layer makes up the smooth lining of the chambers of the heart and also covers the valves of the heart?
Endocardium
34
What layer is continuous with the endothelial lining of the great vessels?
Endocardium
35
What chambers are considered to be the receiving chambers of the heart?
Atria
36
These chambers receive blood from veins?
Atria
37
What chambers are considered to be the pumping chambers of the heart?
Ventricles
38
These chambers pump blood away from the heart?
Ventricles
39
What is the name of the pouch like structures on the anterior surface of each atria that allow for a slight increase in holding capacity?
Auricles
40
These structures are considered to be an extension of the atria and may be different sizes in different people and has a variable amount of muscle allowing for some contraction?
Auricles
41
Describe the Auricles
Pouch like structure on the anterior surface of each atria, allowing for a slight increase in holding capacity and has some muscle allowing for contraction.
42
What is the name of the special feature on the heart that makes up a series of grooves on the surface of the heart?
Sulci (Sulcus: Singular)
43
This sulcus externally separates the atria from the ventricles
Coronary Sulcus
44
Give the other name of the Coronary Sulcus
Atrioventricular Sulcus
45
This sulcus externally separates the right and left ventricles.
Interventricular Sulcus
46
These sulci can be seen on the anterior and posterior surface of the heart.
Coronary Sulcus (Atrioventricular Sulcus) & Interventricular Sulcus
47
Describe what Pectinate Muscles are.
Muscular ridges found in the right atrium on the anterior aspect. The posterior wall is smooth.
48
Pectinate Muscles are also found where in the heart?
In the Left and Right Auricles
49
What provides the dividing line in the right atrium from smooth surface transition to pectinate muscles?
Crista Terminalis
50
What is the C-shaped ridge in the right atrium?
Crista Terminalis
51
The Right Atrium receives blood from what veins?
Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus.
52
What is the thickness of the right atrium?
2-3mm (0.08-0.12in)
53
What separates the left and right atria?
Interatrial Septum
54
What is the name of the prominent feature, located on the Interatrial Septum that is an oval depression?
Fossa Ovalis
55
The Fossa Ovalis is the remnant of what?
Foramen Ovale
56
What is the purpose of the Foramen Ovale?
Opening in the Interatrial septum allowing blood to pass from right atrium to left atrium during fetal development.
57
What valve does blood pass through to go from Right atrium to Right Ventricle?
Tricuspid Valve (Right Atrioventricular (AV) Valve)
58
What are the Raised bundles of cardiac muscle fibers called?
Trabeculae Carneae
59
Some of these convey part of the conduction system of the heart?
Trabeculae Carneae
60
What is the name of the cone shaped Trabeculae Carneae?
Papillary Muscles
61
What are the tendon like cords that connect to the papillary muscles and cusps of the Tricuspid and Bicuspid value?
Chordae Tendineae
62
What is the thickness of the right ventricle?
4-5mm (0.16-0.20in)
63
Where are the special Features, Trabeculae Carneae, Chordae Tendineae, and Papillary Muscles located?
Right and Left Ventricle
64
What valve does blood pass through to go from right ventricle to the pulmonary trunk?
Pulmonic Valve (It is a semilunar valve with three cusps)
65
The Pulmonary trunk divides into what?
Left and Right Pulmonary Arteries
66
Blood returns to the heart from the lungs through?
Pulmonary Veins
67
What heart chamber forms most of the base of the heart?
Left Atrium
68
This chamber receives blood from the four pulmonary veins?
Left Atrium
69
What is the thickness of the Left Atrium?
2-3mm (0.08-0.12in)
70
The left atriums anterior and posterior walls are smooth due to what?
Pectinate muscles are confined to the auricle
71
What valve does blood pass through to get from the left atrium to the left ventricle?
Bicuspid (Mitral Valve or Left Atrioventricular (AV) Valve)
72
This chamber forms the apex of the heart.
Left Ventricle
73
What is the thickness of the Left Ventricle?
10-15mm (0.4-0.6in)
74
From the left ventricle blood passes through what valve to enter the ascending aorta?
Aortic Valve (Aortic Semilunar Valve)
75
Some blood from the proximal ascending aorta will pass into what?
Coronary arteries
76
Purpose of the coronary arteries
Supply the heart walls with blood
77
During fetal life this temporary blood vessel shunts blood from the pulmonary trunk into the aorta.
Ductus Arteriosus
78
The Ductus Arteriosus normally closes after birth to become?
Ligamentum Arteriosum
79
The Ligamentum Arteriosum connect what?
Arch of the aorta to the pulmonary Trunk
80
What is considered to be the medial boarders of the atria and ventricles?
Septum
81
The Interatrial septum is the split between?
Right and Left Atria
82
What contains the electrical tract that sends electrical message to the Left Atria to contract at the same time as the Right Atria?
Interatrial Septum
83
This septum is thought to be mostly left ventricle due to the wall size.
Interventricular Septum
84
This septum houses a large portion of the heart conduction system and is the only normal pathway for electricity to conduct from the atria to the ventricles.
Interventricular Septum
85
Describe the Fibrous Skeleton.
Dense connective tissue found throughout the heart muscle.
| Ring surrounds each heart valve and fuse together and merge to connect them to the interventricular septum.
86
What importance does the Fibrous Skeleton serve in electrical conduction in the heart?
Acts as an electrical insulator allowing for organized rhythm of the heart beat.
87
This structure prevents overstretching of the heart valves.
Fibrous Skeleton
88
Describe the pathway of blood through the heart.
1. Blood enters the heart through the Superior and Inferior Vena Cava and Coronary Sinus into the Right Atrium.
2. Right atrium through the Tricuspid Valve into Right Ventricle.
3. Right Ventricle through pulmonary valve into pulmonary trunk through the Pulmonary Arteries and into Lungs
4. From lungs into pulmonary veins
5. Pulmonary veins into left atrium
6. Left atrium through the bicuspid (mitral) valve into left ventricle
7. Left Ventricle through the aortic valve into the ascending aorta.
8. Blood enters the aortic arch goes to the body and into the coronary arteries for the heart.
89
What does the Foramen Ovale allow?
Fetal Circulation; Bypasses the right ventricle and lungs and blood passes from Right atrium to left atrium. Some blood will enter right ventricle and pulmonary trunk.
90
What is the purpose of the Ductus Arteriosus in Fetal circulation?
Shunts blood from the pulmonary arteries to the descending aorta. Small amount of blood enters the lungs.
91
Give the names of the valve that separates the Right Atrium from the Right Ventricle.
Tricuspid Valve (Right Atrioventricular Valve)
92
Give the names of the valve that separates the Left Atrium from the Left Ventricle.
Bicuspid Valve (Mitral Valve, Left Atrioventricular Valve)
93
Give the name of the valve blood flows through when leaving the right ventricle to enter into the pulmonary trunk.
Pulmonic/Pulmonary Valve
94
Give the name of the valve blood flows through when leaving the left ventricle to enter into the ascending aorta.
Aortic Valve
95
What other name/classification is given to the Pulmonary and Aortic Valves?
Semilunar Valves
96
What causes the valves to open and close?
The opening and closing is in response to a change in pressure within the chambers caused by contraction of the heart.
97
What purpose do the heart valves serve?
Prevent backflow of blood
98
What is Valve eversion?
Process of the valve cusps flipping the opposite direction
99
What valves close during Systole (Contraction) of ventricles?
Atrioventricular Valves (Tricuspid and Bicuspid/Mitral Valves)
100
What valves open during Systole (Contraction) of ventricles?
Semilunar Valves (Pulmonary and Aortic Valves)
101
What valves close during Diastole (Relaxation) of ventricles?
Semilunar Valves (Pulmonary and Aortic Valves)
102
What valves open during Diastole (Relaxation) of ventricles?
Atrioventricular Valves (Tricuspid and Bicuspid/Mitral Valves)
103
The AV valves project into what when open?
Ventricles
104
Atria contraction provides higher pressure in the atria and the ventricles are relaxed which allows for what to occur with the valves? What occurs with the supporting structures?
AV Valves open and blood moves from higher pressure to lower pressure. The papillary muscles are relaxed when the ventricles are relaxed and this causes the Chordae Tendineae to become slack.
105
Ventricular contraction causes what to happen to the valves? What occurs with the supporting structures?
AV Valves close due to blood pushing on the cusps, preventing blood from back flowing into the atria. The papillary muscles tense causing the Chordae Tendineae to tighten and prevent the valve cusps from everting into the atria.
106
Semilunar valves (Aortic and Pulmonic) when open project where?
Into the lumen of the vessels they supply
107
The back flow of blood in the Aorta and pulmonary trunk cause the Semilunar valves to close. Why is there no eversion?
The Semilunar Valves are comprised of three flaps that close tightly against each other and form a deep cusp.
108
There are no valves between what structures?
Right Atrium and Superior and Inferior Vena Cava and the Coronary Sinus.
Left Atrium and the Pulmonary Veins
109
What occurs in the area that there are no valves?
Small amount of back flow however the atria contraction causes mechanical closure and compresses the venous entry points.
110
What two closed circuits does the heart pump blood?
Systemic Circulation
| Pulmonary Circulation
111
What side of the heart provides blood to the Systemic Circulation?
Left Side
112
What side of the heart provides blood to the Pulmonary Circulation?
Right Side
113
Describe the movement of blood to deliver Oxygen and nutrients and picking up Carbon Dioxide and waste.
Blood flows from Aorta through arteries to arterioles to capillaries when exchange of nutrients and gases occur. Blood then flows from capillaries into venules then into veins back to the right atrium.
114
What vessels make up the Coronary Circulation for the Myocardium of the heart?
Coronary Arteries
Coronary Veins
Coronary Sinus
115
These vessels branch from the proximal ascending aorta and encircle the heart.
Coronary Arteries
116
What occurs to the Coronary Arteries during systole of the ventricles?
Coronary Arteries are squeezed shut mechanically and there is little blood flow.
117
What causes blood to fill into the coronary arteries, capillaries and then coronary veins?
High back pressure from the aorta when the heart relaxes
118
During which phase of contraction does the highest blood flow occur to the coronary circulation?
Diastolic phase of the ventricles
119
What is the name of the Coronary arteries that branch from the ascending aorta?
Left Coronary Artery
| Right Coronary Artery
120
The left coronary artery passes inferiorly to this structure and divides into what branches?
Inferior to the left auricle and branches into the Anterior Interventricular Branch (Left Anterior Descending artery (LAD)) and the Circumflex Branch
121
The Anterior Interventricular Branch (Left Anterior Descending artery) lies in which sulcus and supplies blood to what aspects of the heart?
Anterior Interventricular Sulcus and supplies both ventricles with the bulk being the left ventricle (Middle to lower portion) and a large portion of interventricular septum
122
The Circumflex Branch lies in which sulcus and supplies blood to what aspects of the heart?
Coronary Sulcus and supplies the high lateral wall of left ventricle and left atrium.
123
The Right Coronary Artery supplies small atrial branches that provide blood to what aspect of the heart?
Right Atrium
124
The Right Coronary Artery passes inferiorly to this structure of the heart and then divides into what branches?
Right Auricle and divides into the Posterior Interventricular Branch and the Marginal Branch
125
The Posterior Interventricular Branch lies in which sulcus and supplies blood to what aspects of the heart?
Posterior Interventricular Sulcus and supplies the inferior wall of the left ventricle and part of the interventricular septum
126
The Marginal Branch runs along what aspect of the heart and supplies blood to what aspect of the heart?
Runs along the right margin of the heart and supplies the right ventricle
127
Define: Anastomoses
The connection of two or more vessels that supply the same region.
128
What importance do anastomoses have?
Provide a possible alternate route called COLLATERAL CIRCULATION
129
Most deoxygenated blood from the myocardium drain into what large vascular sinus?
Coronary Sinus
130
The Coronary Sinus is found where on the heart and empties into what aspect of the heart?
Coronary Sulcus on the posterior surface and empties into the right atrium
131
What tributaries carry venous blood to the coronary sinus?
Great Cardiac Vein
Middle Cardiac Vein
Small Cardiac Vein
Anterior Cardiac Vein
132
The Great Cardiac Vein lies in which sulcus and drains the blood provided by which artery?
```
Lies in the Anterior Interventricular Sulcus.
Coronary Artery (Provides blood to Left and right ventricles and left atrium)
```
133
The Middle Cardiac Vein lies in which sulcus and drains the blood provided by which artery?
Lies in the Posterior Interventricular Sulcus.
| Posterior Interventricular Branch of the right coronary artery (Provides blood to left and right ventricles)
134
The Small Cardiac Vein lies in which sulcus and drains the blood from what aspect of the heart?
Lies in the Coronary Sulcus.
| Drains right atrium and right ventricle
135
The Anterior Cardiac Vein drains what aspect of the heart and opens directly into what aspect of the heart?
Drains the right ventricle and opens directly into the right atrium.
136
This great vessel ascends from the left ventricle and contains these two arteries branch from it.
Ascending Aorta and the Left and Right Coronary Arteries branch from it.
137
The Aortic Arch gives rise to what Arteries?
Brachiocephalic Artery
Left Common Carotid Artery
Left Subclavian Artery
138
The Brachiocephalic Artery Branches into what arteries?
Right Common Carotid Artery
| Right Subclavian Artery
139
What artery leads to the rest of the Systemic Circulation?
Descending Aorta
140
This Great Vessel returns blood from the head, arms, and upper body to the heart.
Superior Vena Cava
141
This Great Vessel returns blood from the lower body and pierces the diaphragm.
Inferior Vena Cava
142
The Pulmonary Trunk divides into what and carriers what kind of blood?
Left and Right Pulmonary Arteries carries deoxygenated blood from right ventricle to the lungs
143
What veins (Give number) carry oxygenated blood from the lungs to what chamber of the heart?
2 Left Pulmonary Veins and 2 Right Pulmonary Veins from the lungs to the Left Atrium
144
Typical Cardiac muscle fiber has a length of and diameter of?
50-100 micrometer length
| 14 micrometer diameter
145
The end of Cardiac fibers are connected by thickenings of the sarcolemma (plasma membrane) called?
Intercalated Discs
146
Intercalated disc contain?
Desmosomes
| Gap Junctions
147
What is the purpose of Desmosomes?
Hold Fibers together physically
148
What is the purpose of Gap Junctions?
Allow action potentials (electrical signals) to conduct from one muscle fiber to the next
149
Gap Junction allow what to occur in reference to contraction?
The entire myocardium of the atria or ventricles to contact as a single, coordinated unit.
150
What difference is there in the mitochondria of Cardiac tissue vs skeletal tissue?
Mitochondria are much larger and more numerous in cardiac tissue. (25% of cytosolic space vs 2% in skeletal tissue)
151
What difference is there in the Sarcoplasmic Reticulum (SR) of Cardiac tissue vs skeletal tissue?
Sarcoplasmic Reticulum is smaller and there is a smaller intracellular reserve of Ca++
152
What are the two types of Cardiac Fibers?
Autorhythmic/Excitatory/Conductive Fibers
| Atrial/Ventricular Muscle Fibers
153
What are the characteristics of Autorhythmic/Excitatory/Conductive Cardiac Fibers?
Relatively non-contractile
| Initiates & conducts Action Potentials (APs) that help control rhythmical beating
154
What are the characteristics of Atrial/Ventricular Cardiac Muscle Fibers?
Contracts like skeletal muscle but for much longer duration
155
What General concept regarding the heart conductive system is important to understand?
Conductive system of the heart is NOT a nerve tract. 1% of cardiac muscle fibers differentiate into specialized fibers that conduct electricity.
156
The electrical signal is sent through what fibers and the task of contraction is carried out by what fibers?
Autorhythmic/Excitatory/Conductive Cardiac fiber system and carried out by the Cardiac Muscle Fibers
157
What are the two main forces that drive ion movement across the cell membrane?
Chemical Potential
| Electrical Potential
158
Describe: Chemical Potential
Movement down a concentration gradient
159
Describe: Electrical Potential
An Ion will move away from ions of like charge
160
Give the pathway of electrical activity in the heart from origin to completion of a single contraction.
Sinoatrial (SA) Node normally originates electrical impulse and acts as the pacemaker. The signal travels through right atria via the ANTERIOR INTERNODAL TRACT (Branch into BACHMANN'S BUNDLE for left Atrial contraction), MIDDLE INTERNODAL TRACT, POSTERIOR INTERNODAL TRACT. From the right atria to the ATRIOVENTRICULAR (AV) NODE into ATRIOVENTRICULAR (AV) BUNDLE (Bundle of His) to the Right and Left Bundle Branches and then into the Purkinje Fibers.
161
Where is the SA (Sinoatrial) Node located?
Right atrial wall (Endocardium) just inferior and lateral to the opening of the Superior Vena Cava.
162
Where is the AV (Atrioventricular) Node located?
Interatrial Septum just anterior to the opening of the coronary sinus.
163
What purpose does the AV Node serve?
Slows the conduction cycle to allow for complete filling of the ventricles prior to contraction of the ventricles.
164
What is the only site within the heart in which action potential can conduct from the atria to the ventricles?
Atrioventricular (AV) Bundle
165
What is the other name of the Atrioventricular Bundle?
Bundle of His
166
The atrioventricular bundle branches into what two bundles and these bundles are located where?
Right Bundle Branch
Left Bundle Branch
Located in the interventricular septum leading towards the apex of the heart
167
The action potential continues from the right and left bundle branches into what fibers?
Purkinje Fibers
168
Purkinje Fibers rapidly conduct the action potential beginning where and continue what direction?
Apex of the heart upward pushing the blood from the bottom of the ventricles up toward the semilunar valves.
169
What are the two function of Autorhythmic fibers?
Pacemaker- set the rhythm of electrical excitation
| Cardiac conduction system- ensure chambers become stimulated and contract in a coordinated manner
170
SA nodes initiates an action potential at what rate and is also known as what?
Action potential rate of 0.6 seconds (100 times per min)
| Also known as the natural pacemaker of the heart
171
What is the SA nodes resting potential?
Does NOT have a stable resting potential. Repeatedly depolarize to threshold spontaneously
172
The spontaneous depolarization of the SA node becomes what?
Pacemaker Potential
173
What occurs when the Pacemaker Potential of the SA node reaches threshold?
Triggers an action potential
174
How is threshold reached within the SA node turning the pacemaker potential into action potential?
Slow influx of Na+ (sodium) bringing the node to a more positive state
175
What occurs once the potential crosses over to a more positive state?
Rapid Efflux (flowing out) of K+ (Potassium) occurs bringing the node back to a more negative state
176
At threshold of pacemaker potential what influx occurs?
Fast Ca++ (Calcium) channels open causing influx of CA++ and rapid depolarization
177
The Action potential of the SA node propagates through what internodal pathways of the right atrium?
Anterior Internodal- Tract of Bachmann
Middle internodal- Tract of Wenkeback
Posterior Internodal- Tract of Thorel
178
Give the reasons the Action Potential slows at the AV node.
Various differences in cell structure at the node
| Provides time for the atria to empty blood into the ventricles
179
The Bundle of His (Atrioventricular Bundle) is embedded in what?
Fibrous Skeleton
180
What is the inherent Rate of the SA Node?
60-100 bpm
181
What is the inherent rate of the AV Junction? (Not the node, area as it exits the node and begin to enter the Bundle of His)
40-60 bpm
182
What is the inherent Rate of the Ventricles?
20-40 bpm
183
What is the Fiber velocity (Speed of the Action Potential through the fibers) of the SA and AV nodes?
0.01-0.02 m/s (Slowest
184
What is the Fiber velocity (speed of the Action Potential through the fibers) of the Atria and Ventricles?
1 m/s (Intermediate)
185
What is the Fiber velocity (speed of the Action Potential through the fibers) of the Purkinje Fibers?
2 m/s (Fastest)
186
What are the 5 phases the contractile cardiac muscles fibers go through for contraction?
```
0- Depolarization
1- Brief Repolarization
2- Plateau
3- Repolarization
4- Resting Membrane Potential
```
187
Describe the propagation of Action Potential through the contractile fibers during Phase 0.
Phase 0 (Depolarization)-
- Rapid influx of Na+ (Multiple voltage gated channels open at the same time)
- Cell becomes positive (+10mV)
- Cell considered depolarized
188
Describe the propagation of Action Potential through the contractile fibers during Phase 1.
Phase 1 (Brief Repolarization)
- Peak Positive Charge
- Rapid Na+ influx slows and shuts off (K+ is leaking out)
- Slow-voltage gated Na+ and Ca++ channel open
- This allows influx into cell and transition to plateau phase
189
Describe the propagation of Action Potential through the contractile fibers during Phase 2.
Phase 2 (Plateau Phase)
- Slow influx of Ca++ and Na+
- Simultaneous efflux of K+ (Cell in a depolarized state)
- Ca++ allows activation of troponin and myosin causing the cell to begin contraction
190
Describe the propagation of Action Potential through the contractile fibers during Phase 3.
Phase 3 (Repolarization)
- Voltage gated K+ channels open allowing rapid efflux from the cell
- Causes rapid repolarization
191
Describe the propagation of Action Potential through the contractile fibers during Phase 4.
Phase 4 (Resting Membrane Potential)
- Resting Membrane Potential Reached once Rapid efflux of K+ is complete (K+ equal intra/extra cellular)
- The cell is ready to accept another Action Potential
192
What is Absolute Refractory Period?
Another action potential cannot occur during the Phases. Cardiac muscle must complete one AP prior to another or dysrhythmias occur. Skeletal muscles can build AP on AP for stronger contraction.
193
What are the three clearly recognizable waves on an ECG (EKG)?
P Wave- Atrial Depolarization
QRS Complex- Rapid Ventricular Depolarization
T Wave- Ventricular Repolarization
194
What does the P-Q Interval of an ECG represent?
Conduction time from beginning of atrial excitation to the beginning of ventricular excitation
195
What does the S-T Segment of an ECG represent?
Ventricular depolarization during the plateau phase (Phase 2) (End of Contraction)
196
What does the Q-T Interval of an ECG represent?
Beginning of ventricular depolarization to end of ventricular repolarization
197
A Lengthened Q-T interval may be an indication of what?
Myocardial damage or conduction abnormalities
198
Systole shows what in regards to the ventricles?
Ventricular Contraction
199
Diastole shows what in regards to the ventricles?
Ventricular relaxation
200
What appears on the ECG when the Action Potential from the SA to end of AV node, as atrial fibers depolarize?
P Wave
201
What represents the completion of Ventricular repolarization on the ECG?
Flat line prior to the next P wave
202
What are the ventricles doing at the beginning of the T wave?
Ventricles begin to relax
203
Which side of the heart has the highest pressure?
Left side of the heart. However the same volume of blood is expelled from each side per beat.
204
Atrial Systole: What causes it?
Symbolized as what on ECG?
What phase are the ventricles in?
Depolarization of Atria (0.1sec)
P Wave on ECG
Ventricles are in Diastole
205
What forces the AV valves open?
The force of blood on the AV valves due to the contraction of the Atria.
206
The first heart sound is created by what?
The AV valves closing during systole of the ventricles
207
Approximately how much blood enters the ventricles during atrial systole?
105mL
208
The final 25mL of blood is pushed into the ventricles by what?
Atrial Kick (Which is atrial systole)
209
The end of atrial systole also means the end of what for the ventricles?
Ventricular Diastole
210
The 130mL in the ventricles at the completion of atrial systole is called what?
End-Diastolic Volume (EDV)
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On average ventricular Systole lasts?
0.3sec
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What causes ventricular Systole?
Depolarization of the ventricles
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What causes the SL valves to open and the AV valves to close?
Ventricular Systole, pressure increase in ventricles forces AV valves Closed (Blood turbulence on valves causes S1 (1st Heart Sound)) and SL Valves open.
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For 0.05 Seconds what valves are open?
All AV and SL valves.
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When the AV and SL valves are all open what is this known as?
Isovolumetric contraction
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At what pressure will the Aortic Valve open allowing the blood from the left ventricle to be ejected into the systemic blood flow?
80mm Hg
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At what pressure will the pulmonic (pulmonary) valve open allowing blood to flow from the right ventricle to the lungs?
20mm Hg
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How many mmHg are required to open the Aortic Valve?
80mm Hg
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How many mmHg are required to open the Pulmonary (Pulmonic) Valve?
20mm Hg
220
When does ventricular ejection occur?
When both SL valves open.
Pressure in the left ventricle rises to about 120 mmHg. Approximately 70mL is ejected into the Aorta.
Pressure in the right ventricle rises to about 25-30mmHG.
221
Approximately how much blood is ejected from the right ventricle into the pulmonary trunk?
70 mL
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What is the volume remaining in each ventricle know as?
End-Systolic Volume (ESV)
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What is the formula to calculate Stroke Volume (SV)?
Stroke Volume= End-Diastolic Volume - End-Systolic Volume (Ex: SV= 130mL (EDV) - 60mL (ESV) SV=70mL)
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What is Ejection Fraction?
Relative measurement of the fraction of blood ejected by the ventricles relative to its end-diastolic volume
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What is the formula to calculate Ejection Fraction?
EF= SV/EDV
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Relaxation Period lasts what length of time and what is relaxed?
0.4 sec and both the ventricles and atria are relaxed
227
The relaxation period will short due to what?
Faster heart beat
228
During Ventricular repolarization what is caused?
Ventricular Diastole
229
When the pressure from the ventricles falls what occurs to the blood it was pushing?
Blood begins to backflow in the aorta and pulmonary trunk causing the SL valves to close (This blood turbulence creates S2 (Heart Sound 2)).
230
The aortic valve will close at what pressure?
100mm Hg
231
The rebound of blood off of the aortic valve is shown as what on an aortic pressure curve?
Dicrotic Wave
232
The period of time when all AV and SL valves are closed is known as?
Isovolumetric Relaxation
233
What is the primary cause of heart sounds?
Blood turbulence caused by the closing of the valves
234
What heart sound are typically able to be auscultated?
S1 and S2
235
Each cardiac cycle produces how many heart sounds?
4, however only the first two are typically able to be auscultated
236
Give the Characteristics of S1.
Blood turbulence on the AV valves (Ventricular Systole)
- Slightly louder and longer than S2
- Described as "LUBB"
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Give Characteristics of S2.
Blood turbulence on the SL valves (Ventricular Diastole)
- Quieter and Shorter than S1
- Described as "DUPP"
238
Give Characteristics of S3.
Not normally loud enough for auscultation
| Caused by blood turbulence of rapid filling of ventricles
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Give Characteristics of S4.
Not normally loud enough for auscultation
| Caused by blood turbulence during atrial systole
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Define: Cardiac Output
Volume of blood ejected from left ventricle (or right ventricle) into the aorta (or pulmonary trunk) each minute
241
Define: Stroke Volume
Volume of blood ejected by the ventricle during each contraction
242
Define: Heart Rate
Number of beats per minute
243
Give the formula used to calculate Cardiac Output (CO)
CO (mL/min) = SV (Stoke Volume) x HR (beats/min)
244
Typical blood volume in adult male and female is?
Male- 5 Liters
| Female- less than 5 liters
245
Factors that increase SV or HR will normally increase what?
CO- Cardiac Output
246
Name a factor that will contribute to an increase in stroke volume, HR, and ultimately Cardiac Output.
Strenuous Exercise
247
What is Cardiac Reserve?
The difference between a person's maximum CO (Cardiac Output) and resting CO
248
The average person has a cardiac reserve of what value?
4-5 time's the resting value
249
A top endurance athlete may have a cardiac reserve of what value?
7-8 time's the resting value
250
What effect will severe heart disease have on Cardiac reserve?
The individual will have little to no cardiac reserve. Difficult to complete simple tasks
251
At rest Stroke Volume (SV) is what percentage of End-diastolic volume (EDV)?
50-60%
252
What three factors regulate SV and ensure left and right ventricles pump the same amount of blood?
Preload
Contractility
Afterload
253
Define: Preload
Degree of stretch of the heart before contraction
254
Define: Contractility
Forcefulness of Contraction
255
Define: Afterload
Pressure that must be exceeded before ejection of blood from ventricles occurs (Opening of SL valves)
256
During Preload, what effect does the stretching of cardiac muscle fibers have?
Greater preload (stretch) prior to contraction increases the force of the contraction
257
What is Frank-Starling Law of the heart?
- Equalizes the output of Right and left ventricles
- Within limits, the more the heart fills with blood during diastole the great the force of contraction
- Preload is proportional to the EDV (Greater EDV->Greater Preload-> More Forceful contraction)
258
What two factors determine EDV?
- Duration of ventricular diastole (shorter, less blood in ventricles)
- Venous return (volume in right ventricle less blood to push to systemic causing less return to right side of heart.
259
Define: Inotrope
Something that alters the force of contraction
260
Define: Positive Inotrope
Increases contractility by increasing stroke volume
261
What are some causes of a positive inotrope?
- Increased influx of Ca++ during action potentials, strengthening the contraction
- Stimulation of the autonomic nervous system, hormones (epinephrine, norepinephrine, digitalis)
262
Define: Negative Inotrope
Decreased Contractility
263
What are some causes of a negative inotrope?
- Calcium channel blockers (reduce Ca++ influx, reducing contraction strength)
- Inhibition of autonomic nervous system, anoxia, acidosis, anesthetics
264
What pressure must be reached by the right ventricle in order for the Pulmonic Valve to open and allow blood to flow into the pulmonary trunk?
20mm Hg
265
What pressure must be reached by the left ventricle in order for the Aortic Valve to open and allow blood to flow into the Aorta?
80mm Hg
266
What occurs to stroke volume if there is an increase in afterload?
decreased stroke volume and more blood remains in the ventricles
267
What are some conditions that cause an increase in afterload?
Hypertension, Atherosclerosis
268
Autonomic Regulation of Heat Rate originates where?
Originates in the cardiovascular center of medulla oblongata
269
Medulla Oblongata receives input from...
Sensory receptors, limbic system, cerebral cortex
270
Cardiovascular center directs...
increase or decrease of nerve impulses in both parasympathetic and sympathetic branches of the ANS
271
Proprioceptors monitor and effect....
- Monitor position of limbs and muscles
- Send nerve impulses at an increased frequency to cardiovascular center
- Major stimulus for quick rise in HR
272
Chemoreceptors monitor....
Chemical changes in the blood
273
Baroreceptors monitor...
- Stretching of major arteries and veins (blood pressure)
| - Important baroreceptors located in arch or aorta and carotid arteries
274
How do parasympathetic impulses reach the heart?
Via the left and right Vagus Nerves
275
Where do Vagal Axons terminate?
SA node
AV node
Atrial Myocardium
276
The parasympathetic impulses have little control of what?
Contractility of ventricles due to few fibers terminating in the ventricular muscle
277
At rest what predominates the resting HR?
parasympathetic stimulation (rate of 75bpm) which is lower than the Autorhythmic rate of SA node (100bpm)
278
Name some hormones that provide Chemical Regulation of HR.
Epinephrine/norepinephrine
| Thyroid Hormones
279
What Cations provide Chemical regulation of HR?
Sodium, Potassium, Calcium
280
What effect do increased Na+ levels have on the heart?
Decrease HR and contractility (Blocks Ca++ inflow during Action Potential)
281
What effect does elevated K+ levels have on the heart?
Decrease HR and contractility (blocks generation of AP)
282
What effect does elevated Ca++ levels have on the heart?
Increased HR and contractility
283
What other factors have an effect on HR regulation?
Age, Gender, Physical Fitness Level, Body Temperature
284
What is an infants resting HR?
120bpm
285
What difference is there in female resting HR compared to Males?
Slightly Higher resting HR
286
What effect may a fever have on HR?
Increase in HR
287
What is Therapeutic Hypothermia?
Deliberate cooling of the body to slow metabolism and reduce oxygen demand
288
At what age can cardiovascular fitness be improved?
Any age
289
What must occur for sustained exercise which increases oxygen demand?
Adequacy of Cardiac output and proper functioning respiratory system
290
What is physiological cardiomegaly?
Enlargement of the heart due to exercise
291
What is Pathological cardiomegaly?
Enlargement of the heart due to disease
