Cardiovascular System Flashcards
1
Q
The secondary functions of the CVS (3)
A
- Thermoregulation
- Distribution of hormones to target cells
- Immunity (distribution of body’s defense mechanisms)
2
Q
Intercalated discs are something unique to ___ muscle
A
Cardiac
3
Q
Cardiac muscle has these things in common with skeletal muscle (3)
A
- Striated appearance
- Troponin and tropomyosin present
- T-tubule system and associated Ca2+-loaded sarcoplasmic reticulum
4
Q
Cardiac muscle has these 2 things in common with smooth muscle
A
- Gap junctions
2. Single nucleus
5
Q
A structure in cardiac muscle by which two adjacent cells are attached (Hint: Cell type thing)
A
Desmosomes
6
Q
The connection of cardiac muscle cells by intercalated discs, gap junctions, and desmosomes forms a ____
A
Functional syncytium
7
Q
The cardiac cycle consists of these two elements
A
Diastole (Ventricles relax, atria fill w/blood)
Systole (Ventricles contract - pump blood to aorta/pulmonary arteries)
8
Q
The conduction system of the heart consists of these 5 elements:
A
- Sinoatrial node (SA)
- Atrioventricular node (AV)
- Bundle of His (AV bundle)
- Right and Left bundle branches
- Purkinje fibers
9
Q
The resting membrane potential of cardiac muscle cells is approximately ___
A
-85 mV (millivolts)
10
Q
Something unique to ___ muscle cells is that their action potential is of long duration
A
Cardiac
11
Q
Action potential duration varies from 150 msec in ___, to 250 msec in ____, to 300 msec in ____
A
Atria, ventricles, purkinje fibers
12
Q
What is mainly responsible for the “plateau” phase of the cardiac action potential?
A
The prolonged opening of slow calcium-sodium channels
13
Q
The threshold potential in cardiomyocytes is approximately ___
A
-70 mV
14
Q
Phase 4 (the return to resting membrane potential) is completed by these 3 things:
A
- Ca2+-ATPase
- Na+/Ca2+ exchanger
- Na+/K+-ATPase (pump)
15
Q
The velocity of conduction of the excitatory action potential along cardiac muscle cells is very ___ (Fast or slow)
A
FAST
16
Q
Inside the muscle cell, calcium binds to ___ exposing myosin-binding sites to prepare for crossbridge cycle
A
Troponin
17
Q
The calcium release channels in cardiac muscle fibers are known as ____ receptors
A
Ryanodine
18
Q
The T tubules of cardiac muscle have a diameter __ times that of the T tubules in skeletal muscle
A
5x
19
Q
The strength of a cardiac muscle contraction depends greatly on the concentration of ____ ions in the extracellular fluid
A
Calcium
20
Q
In cardiac muscle, the conductance to K+ at rest is ___ and the conductance to Na+ is ____
A
High, low
21
Q
The 3 subtypes of voltage-gated potassium channels we discussed are:
A
- Transient outward (lto)
- Delayed rectifier (lKr)
- Inward rectifier (lir or lKI)
22
Q
What subtype of voltage-gated potassium channels contributes to phase 1 (initial repolarization) in cardiac muscle cells?
A
Transient outward (lto)
23
Q
What subtype of voltage-gated potassium channels contributes to phase 3 (fast repolarization) in cardiac muscle cells?
A
Delayed rectifier (lKr)
24
Q
What subtype of voltage-gated potassium channels contributes to phase 4 (maintaining of RMP) in cardiac muscle cells?
A
Inward rectifier (lir or lKI)
25
In skeletal muscle, the action potential signals a ____ receptor on the plasma membrane, which then opens the Ryanodine receptor of the sarcoplasmic reticulum for release of Ca2+
Dihydropyridine
26
In cardiac muscle, the action potential reaches a ______, which allows extracellular Ca2+ to flow into the cell to bind the Ryanodine receptor on the sarcoplasmic reticulum to then release more Ca2+ from the SR
Voltage-gated Ca2+ channel (L-type)
27
In cardiac muscle cells, there is a cleft of roughly ___nm for the Ca2+ to cross before it can bind to the Ryanodine receptor on the SR
12
28
The 2 types of cardiac muscle cells
Contractile, conducting
29
____ cells constitute the majority of atrial and ventricular tissues, and are the WORKING cells of the heart
Contractile
30
____ cells function to rapidly spread action potentials over the entire myocardium
Conducting
31
This is known as the "pacemaker" of the heart
Sinoatrial node (SA)
32
Slow conduction through the ____ ensures that the ventricles have enough time to fill with blood before being activated to contract
AV node
33
Conduction through the _____ system is extremely fast to allow for efficient contraction and ejection of blood
Bundle of His-Purkinje
34
In an electrocardiogram (ECG, EKG), the P wave is reflecting what?
Atrial depolarization
35
In an ECG, the QRS complex is reflecting what?
Ventricular depolarization
36
In an ECG, the T wave is reflecting what?
Ventricular repolarization
37
In an ECG, S-T segment depression may suggest what?
Myocardial ischemia (coronary artery disease - fat/plaque buildup in coronary arteries)
38
This specialized part of the conducting system can generate action potentials spontaneously without neural input. It also has an unstable resting membrane potential
SA node
39
In SA nodal cells, the upstroke (phase 0) is a result of _____, rather than the fast influx of Na+ in most muscle and neural cells
Fast inward Ca2+ currents
40
The slow Na+ influx in SA nodal cells that "drifts" the cell to threshold potential is known as ____
Pacemaker potential
41
Pacemaker potential, or phase 4, of the SA nodal cells is also known as ____
Spontaneous depolarization
42
Threshold potential in an SA nodal cell is approx. ____
-30 to -40 mV
43
The slow Na+ inflow current (spontaneous depolarization) is also known as ____
"Funny current" or lf
44
In SA nodal cells, when the membrane potential reaches approx. -50mV ______ open, allowing the fast depolarization (upstroke) of the action potential
T-type Ca2+ channels (transient)
45
The rate of phase 4 depolarization (in SA nodal cells) sets the ___
Heart rate
46
At the end of phase 3 (in SA nodal cells), the membrane potential reaches it's most negative value (approx. -60 to -65 mV). This is known as ____
Maximum diastolic potential
47
The AV node, Bundle of His and Purkinje fibers also have the availability for automaticity, but it is not usually expressed. These are known as _____
Latent pacemakers
48
Override suppression
When the SA node sets the heart rate, the latent pacemakers are suppressed
49
If a latent pacemaker becomes the pacemaker of the heart it is called ____
Ectopic pacemaker
50
____ is the capacity of myocardial cells to generate an action potential in response to inward, depolarizing current
Excitability
51
During _____ it is impossible to evoke another action potential
Absolute Refractory Period
52
During the _____ a stronger than usual stimulus is required to generate and action potential
Relative refractory period
53
____ muscle cannot undergo tetanic contractions (sustained muscle contraction)
Cardiac
54
____ in the aortic arch and carotid arteries monitor blood pressure
Baroreceptors
55
Cardioregulatory and vasomotor centers are in the ______
Medulla oblongata
56
The cranial nerve innervating the heart tissue is ____
Vagus (X) - Parasympathetic
57
A ____ effect changes the heart rate and rhythm by affecting the electrical conduction system of the heart
Chronotropic
58
A ____ chronotropic effect increases the heart rate, while a ____ decreases it
Positive, negative
59
Activation of B1 receptors for a positive chronotropic effect is reliant on what hormone?
Norepinephrine
60
Activation of B1 receptors promotes an increase in ____, causing faster phase 4 depolarization
lf, "funny current" (Na+ flow - in SA nodal cells)
61
Positive Inotropic effect
Increased strength of muscular contraction
62
An increase in cardiac contractility (positive inotropic effect) would cause a ______ in cardiac relaxation (negative lusitropic effect)
Decrease
63
_____ chronotropic effects involve acetylcholine and muscarinic (M2) receptors in the SA node
Negative
64
Activation of the M2 receptors in the SA node will lead to:
A decreased lf (funny current), which is a decreased rate of phase 4 depolarization...slower heart rate
65
M2 receptors a coupled to a type of G-protein (Gk). Gk increases the conductance for _____
Potassium (K+)
66
Increased K+ outflow would lead to ______, a more negative membrane potential and larger threshold potential
Hyperpolarization
67
Describe the RIGHT cardiac circuit
1. Deoxygenated blood is carried to the right atrium via the superior and inferior vena cava
2. This blood is pushed into the right ventricle through the TRICUSPID valve
3. Blood is pushed through the pulmonary semilunar valve
4. Blood travels to the lungs through the pulmonary arteries
68
Describe the LEFT cardiac circuit
1. Oxygenated blood is brought from the lungs to the left atrium via the pulmonary veins
2. Blood is pushed into left ventricle via the MITRAL (Bicuspid) valve
3. Blood is pumped through the aortic semilunar valve
4. Blood is carried to branches/tissues via the aorta
69
The volume of blood pumped from the left ventricle per beat
Stroke volume
70
Stroke volume is determined by three factors:
1. Preload
2. Afterload
3. Contractility
71
____ is the end-diastolic volume created by venous return
Ventricular preload
72
____ is the sum of factors that oppose ejection of blood during systole
Ventricular afterload
73
______ is the intrinsic vigor of muscle contraction related to the biochemical state of the cell
Contractility
74
The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end-diastolic volume) when all other factors remain the same. What's this called?
Frank-Starling mechanism
75
The major component of afterload is the resistance to _____ created by the circulation
Blood flow
76
The sympathetic nervous system _____ the heart rate and ____ the threshold potential
Increases, decreases (norepinephrine, B1 receptors)
77
The parasympathetic nervous system ____ the heart rate and ____ the threshold potential
Decreases, increases (acetylcholine, M2 receptors)
78
When the heart rate increases the tension of each beat increases in a stepwise fashion until it reaches a maximum value
Positive staircase effect
79
Cardiac glycosides are ____ inotropic agents
Positive
80
What effect do cardiac glycosides have on the Na+/K+ pump?
Inhibition - leads to less sodium exiting the cell, so less sodium entering the cell for the Ca2+/Na+ exchanger, more intracellular Ca2+ remains
81
Describe the length-tension relationship
Basically, if there is an increase in end-diastolic volume (more blood) there will be an increase in tension and length on the muscle cells
82
An increased preload would cause the stroke volume to _____
Increase
83
An increased afterload would cause the stroke volume to _____ and the end-systolic volume to ______
Decrease, increase
84
Increased contractility would cause the stroke volume to _____ and the end-systolic volume to _____
Increase, decrease
85
The two types of cardiac minute work are:
1. Volume work (cardiac output)
| 2. Pressure work (aortic pressure)
86
Which type of cardiac minute work is more costly in terms of O2 consumption?
Pressure work (aortic pressure)
87
Aortic stenosis would cause the left ventricle to have to generate _____ (higher/lower) pressures
Higher
88
The point at which you can hear the 1st heart sound ("Lubb") is _____
Isovolumetric ventricular contraction (ventricles contract, but valves are closed so no blood is released yet)
89
The point at which you hear the 2nd heart sound ("Dubb") is _____
Isovolumetric ventricular relaxation (ventricles relax, pressure falls, aortic semilunar valve closes)
90
The principles that govern blood flow in the cardiovascular system
Hemodynamics
91
The highest velocity of blood flow should be in the ____, and the lowest in the ____
Aorta, arterioles/capillaries
92
The resistance of the entire systemic vasculature is called ____
Total peripheral resistance
93
_____ is accomplished by vasodilation and vasoconstriction in the arterioles
Flow regulation
94
The factors that determine the resistance of a blood vessel to blood flow are expressed by the _____ equation
Poiseuille
95
The two types of blood flow in vessels:
1. Laminar
| 2. Turbulent
96
In laminar blood flow, the flow in the middle of the vessel is _____, while the flow next to the vessel wall is ____
Highest, lowest (zero)
97
Turbulence increases the ____ required to drive blood flow
Energy
98
Capacitance, or compliance, of ____ are highest, while ____ are lowest
Veins, arteries (aging, specifically)
