Cardiovascular Flashcards
(180 cards)
1
Q
The pulmonary circuit goes from the ______________ ventricle to the _____________ atrium.
A
Right
Left
2
Q
The systemic circuit can be described as going from the ___________ ventricle to the __________
atrium
A
Left
Right
3
Q
2 functions of the fibrous connective tissue valves between the chambers and major arteries
A
- Preventing backward flow
2. Acts as electrical insulator
4
Q
What is the significance of the heart valves blocking most of the electrical signals between the atria and ventricles
A
This ensures the electrical signals can be directed through a specialized conduction system to the apex of heart for bottom to top contraction.
5
Q
The special connections between cardiomyocytes are called
A
Intercalated disks
6
Q
What 2 functional features does the intercalated disks contain
A
- Gap Junctions
2. Desmosomes
7
Q
What are 2 functions provided by gap junctions and desmosomes
A
- Gap junctions allow electrical signals to pass rapidly from cell to cell
- Desmosomes transfer force from cell to cell
8
Q
How are 1% of myocardiocytes specialized
A
They generate action potential spontaneously
9
Q
Define myogenic
A
This means it or originates within the heart muscle itself. This allows the heart to contract without connections to other parts of the body.
10
Q
Where does the action potential originate in the heart
A
Pacemakers cells
11
Q
How does the action potential spread into the contractile cells
A
Gap junctions
12
Q
The rapidly rising phase of the contractile cell action potential is based on what 2 ions
A
Ca++
Na+
13
Q
L type calcium channels on the membrane of the cardiac contractile cells are what type
A
Voltage gated
14
Q
The influx of calcium releases the calcium from the SR by activating what channels
A
Ryanodine receptor calcium release channels (RyR)
15
Q
What percentage of calcium is released from the SR that is needed for muscle contraction
A
90%
16
Q
The strength of cardiac contraction depends on what 2 things
A
- Sarcomere length at the beginning of contraction
2. The amount if calcium released into the cell
17
Q
How do calcium and the amount of active crossbridges play a role in the force a muscle generates
A
The force generated by cardiac muscle is proportional to the number of cross bridges that are active. The more calcium that goes into the cell, the more calcium that is released from the SR, and the more calcium that binds to troponin, enhancing the ability of myosin to form crossbridges with actin and creating additional force.
18
Q
In cardiac muscle, what happens when cytoplasmic calcium concentrations decrease
A
Calcium unbinds from troponin which leads to myosin to release actin, this causes contractile filaments to slide back and muscles to relax
19
Q
What are 2 ways that calcium is removed from the cytoplasm of cardiac muscle cells
A
- Calcium is transported back into SR with help of calcium ATPase
- Calcium is removed from cell via Na+ -Ca++ exchange (NCX)
20
Q
How does the NCX antiport work
A
1 Ca++ moves out of the cell for every 3 Na++ moving into the cell
21
Q
The number of active cross bridges is determined by what
A
How much calcium is bound to troponin
22
Q
What role does the length tension relationship play in the contractile strength of cardiac muscle
A
- Longer sarcomere length can lead to stronger contraction
- Greater sarcomere length means larger internal volume
- Greater volume needs a stronger contraction to push it out
23
Q
The Frank Starlin’s law of the heart states that
A
When cardiac muscle is stretched more, It contracts more forcefully
24
Q
In the contractile myocardiocytes the resting membrane potential is about
A
-90mV
25
During the contractile cells action potential, the plateau phase is caused by what 2 ions
K+ and Ca++ ions
26
What ion is effluxing and influxing during the plateau phase of the contractile cells AP
K++ effluxing, Ca++ influxing
27
What causes the repolarization phase of the contractile cells
Potassium ion efflux
28
For the autorhythmic cells, the membrane potential is not stable, but fluctuates from what to what
-60mV to -40mV
29
What is the threshold for If channels
-40mV
30
When the If channel opens what comes out of the cell and what goes into the cell
Na+ influx
| K+ efflux
31
What is another name for the unstable membrane potential or type of graded potential of the myocardio autorrhythmic cells
Pacemaker potential
32
What causes the are autorrhythmic cells rapid rising phase of depolarization
Ca++ion influx
33
What causes the autorhythmic cells repolarization phase
Ca channels close, slow K channels open, resulting in the efflux of K+ ions
34
What to type of myocardial muscle does the heart have
Autorhythmic cells and myocardial contractile cells
35
The autorhythmic cells are also called
pacemakers
36
The term intrinsic myogenic indicates that the heart muscle is the source of
The electrical signal that stimulates heart contraction
37
The Na+ influx during the action potential in a cardiac contractile cell causes
The opening of L type calcium channels
38
What is a key property of cardiac muscle cells
The ability of a single muscle fiber to execute graded contractions
39
What does it mean to execute a graded contraction
The fiber varies the amount of force it generates
40
The flattening of the action potentials of myocardial contractile cells, called the plateau phase, is due to a combination of
K+ efflux and Ca++ influx at the same time
41
The end of the plateau phase of cardiac contractile cell action potentials is due to the
Closing of Ca++ channels and opening of K+ channels
42
1. A typical action potential of a myocardial contractile cell lasts?
2. What does this prevent ?
1. At least 200 msec
| 2. Wave summation and tetany
43
Autorhythmic cells can generate action potentials spontaneously because they have
An unstable membrane potentials at -60mV which slowly drifts up towards threshold
44
Autorhythmic cells are also called
Pacemakers because they set the rate of the heartbeat
45
List the order of events of electrical conduction in the heart
SA node-->Internodal pathways-->AV node-->AV bundle if His-->Bundle branches--> Purkinje fibers
46
How does electrical conduction in the myocardial cells transfer or spread
Autorhythmic cells spontaneously fire action potentials. Depolarizations of the autorhythmic cells then spread rapidly to adjacent contractile cells through gap junctions
47
What is the pacemaker of the heart
Sinoatrial node
48
What is pacemaker potential
When the potential for autorhythmic cells drifts up slowly to threshhold, causing an action potential
49
What is the threshold for autorhythmic cell
-40mV
50
Once autorhythmic cells reaches its threshold, which channels open and which channels close, and what ion influx occurs
Voltage gated calcium channels open, I f channels close, Ca++ influx occurs
51
Diastole is
The time during which cardiac muscle relaxes
52
Systole is
The time during which the cardiac muscle contracts
53
When both atria and ventricles are relaxing, which valves are open
AV valves
54
Is the heart in atrial and ventricular systole at the same time
No
55
When both aria and ventricles are relaxing, where is blood flowing
Into the ventricles
56
What percentage of ventricular filling depends on atrial contraction
20%
57
What wave or wave segment on the ECG is associated with ventricular filling
P wave
58
What electrical event precedes ventricular systole
Ventricular Depolarization
59
As the ventricles contract, why do the AV valves close
Because ventricular pressure is higher than atrial pressure
60
What creates the heart sounds
Vibrations following AV closure and semilunar closure
61
Explain what is happening during isovolumetric ventricular contraction
Force without movement or change in volume. The 1st phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves. The volume in the ventricles has not changed. It maintains the end diastolic volume or maximal volume from the end of atrial systole.
62
What happens to pressure in the ventricles during isovolumetric then ventricular contraction
It is increasing rapidly
63
What causes the semilunar valves to open, allowing blood to be ejected into the arteries
As then ventricles contract, enough pressure is generated to open the semilunar valves and push blood into the arteries. This is the driving force for blood flow
64
How is ventricular pressure in comparison to arterial pressure when blood flows out of the ventricles
Then vetricular pressure is higher than arterial pressure
65
What happens to ventricular pressure as the ventricles relax
Then ventricular pressure decreases
66
What causes the semi lunar about to close
Once then ventricular pressure falls below the pressure in the arteries, blood starts to flow backward in the heart. This back flow of blood fills the cup-like cusps of semilunar valves, forcing them together into the closed position
67
When do AV valves open
When ventricular relaxation causes ventricular pressure to become less than arterial pressure
68
What is stroke volume
That amount of blood pumped by one ventricle during a contraction
69
What is the calculation equation for stroke volume
Volume of blood before contraction - volume of blood after contraction
EDV-ESV=SV (mL [per beat])
70
If the EDV increases and the ESV decreases, has the heart pumped more or less blood
More
71
What is the calculation equation for cardiac output
CO (mL / min) =HR × SV
72
What is an average value for (70kg male) stroke volume
70 mL
73
What is an average (70kg male) for cardiac output
5040 ml/min or 5 L/min
74
During the isovolumetric phase of ventricular systole which valves are closed
The atrioventricular valves and semilunar valves are closed
75
What is end systolic volume
The amount of blood in the ventricle available to be pumped out of the heart during the next contraction
76
The term that describes the volume of blood circulated by the heart in one minute
Cardiac output
77
Explain the antagonistic control of heart rate by the sympathetic neurons
NE-->B1 receptor of autorhythmic cells--> Increased Na and Ca influx--> Increased rate of depolarization--> Increased heart rate
78
Explain antagonistic control of heart rate by parasympathetic neurons
ACh--> muscarinic receptors of autorrhythmic cells--> Increased K efflux, Decreased Ca influx--> Hyperpolarization of cell--> Decreased rate of depolarization--> Decreased heart rate
79
How does acetylcholine affect membrane potential of the pacemaker cell
It causes the cell to take longer to reach threshold, delaying the onset of the action potential in the pacemaker and slowing the heart rate
80
Epinephrine and norepinephrine increase ion flow through what channel(s)
I f and Ca++ channels
81
Stimulation of the beta receptors on heart muscle results in what type of signaling
cAMP signaling
82
How does NE and epi effect Pacemaker cells
When cAMP binds to open I f channels, they remain open longer more rapid Cation (Ca++, Na+) entry speeds up the rate of the pacemaker depolarization causing the cell to reach threshold faster and increasing the rate of action potential firing, resulting in increased heart rate
83
Stretching a myocardial cell allows more __________________ and increases ________________
Ca++ to enter, the force of a contraction
84
What factors affect cardiac output
Stroke volume, Heart rate, Contractile force
85
What factors affect force generated
Length of muscle fibers at the beginning of the contraction, number of calcium ions available ( Contractility)
86
How does the cardiovascular system create a region of higher pressure
The heart creates high pressure when it contracts
87
As blood moves away from the heart what happens to the pressure and why
Pressure falls continuously as blood moves farther from the heart. As blood moves through the closed loop of blood vessels, pressure is lost because of friction between fluid and blood vessel walls.
88
Does venous return increase ESV or EDV
End diastolic volume
89
How does sympathetic output increase the force of cardiac muscle contractions
An increase in sympathetic output constricts veins, Decreasing holding capacity and increasing venous return. This increases the stretch of the heart which increases cross bridges and calcium into the heart. This results in an increased contractility of the heart and redistribution of blood to arterial side,increasing MAP.
90
When voltage gated calcium channels are phosphorylated, Their probability of opening is ______________ and more __________________ enters the cell
Increased, calcium
91
A blood flowed through the a order is 5 L/min then what's the blood flow through the pulmonary artery
5 L/min
92
Liquids and gasses flow from areas of ___________
| pressure to areas of __________ pressure
High, low
93
Where is the highest pressure and lowest pressures in the blood vessel is found
Aorta, venae cavae
94
What happens to pressure when the heart relaxes or the blood vessels dilate
Pressure decreases (as container expands)
95
What is a pressure gradient in the cardiovascular system
Change in pressure from regions of higher pressure to regions of lower pressure
96
If fluid is flowing through 2 identical tubes and tube A has a pressure gradient of 50 and tube B has a pressure gradient of 65 which tube will have the greatest flow
Tube B, the one with the greatest pressure gradient
97
What is resistance
The tendency of the cardiovascular system to oppose blood flow
98
What happens to flow as resistance increases
Flow decreases
99
What is the mathematical equation of flows relationship with resistance
Flow 🔀 1/R
100
3 parameters that influence resistance for fluid flowing through a tube
1. The radius of a tube
2. The length of the tube
3. The viscosity of the fluid
101
What factors increase resistance of fluid in a tube
Increased length and increased viscosity
102
What decreases resistance through a tube
An increased radius of a tube
103
In humans which of the 3 factors that influence resistance are not constant and play the most significant role in determining resistance to blood flow
Radius of Tube
104
When the radius of a tube decreases what happens to the resistance of the tube
It increases
105
What happens to flow through a tube where the radius decreases and the resistance increases
Flow decreases
106
Is the radius of a to doubles what happens to the resistance
It decreases and flow increases
107
Define diameter of the vessel and explain the effects on resistance to blood flow
Diameter is the length through the center of a circular object. If there is vasoconstriction or narrowing of the diameter then resistance will increase and flow will decrease. If there is vasodilation or an increase in the diameter then resistance will decrease and flow will increase.
108
Equation that expresses the relationship between flow, the pressure gradient and resistance
Flow🔀 🔺️P/R
109
What is the name of the receptors that detect blood pressure changes
Baroreceptors
110
Where are the baroreceptors for blood pressure located and what is the significance about these locations
They're located in the walls of carotid arteries and aorta. The blood flow to brain and body is monitored here.
111
If you are monitoring the electric activity of the sensory neurons linking baroreceptors to the cardiovascular control center, Would you observe any electrical activity when a person's blood pressure is in normal range? Are these receptors tonic are phasic
These receptors are tonically active and fire action potentials continuously at normal blood pressures. The frequency of action potential changes in response to blood pressure by increasing or decreasing.
112
Describe the Baroreceptor reflex when responding to an increased blood pressure
A increase blood pressure--> Responds by increasing frequency firing rate of baroreceptor--> Sensory neurons send information to--> Cardiovascular control center--> Response is decrease sympathetic output and Increased para sympathetic output--> Less NE and more ACh--> vasodilation, Decreased contractility, heart rate ,blood pressure,
113
A decrease in blood pressure results in what type of sympathetic activity and what type of parasympathetic activity
Increase sympathetic and decreased parasympathetic activity
114
What effect will and increase in sympathetic activity have on heart rate force of contraction and arteriolar diameter
Increase heart, Increase contractility, Decreased arteriolar diameter (vasoconstriction)
115
Pericytes
Contractile cells around capillary endothelium and interstitial fluid. The tightness of capillary permeability means less leaky capillaries This is seen in blood-retina-barrier and BBB. That also help influence capillary growth.
116
Arteries major function and physical characteristics
They are the driving pressure for blood flow during ventricular relaxation known as or "pressure reservoir." Made up of endothelium, thick smooth muscle, Large elastic fibrous tissue. Low volume: 11%
117
Major function of arterioles and physical characteristics
Direct distribution of blood flow to individual tissues by selectively constricting or dilating. Known as "variable resistance." Endothelium, Smooth muscle. It is Divergent has several layers that contract and relax due to chemical changes
118
Major function of the venules and physical characteristics
Flows from capillaries to venules. Endothelium, Fibrous tissue, Larger ones have smooth muscle
119
Veins major functions and physical characteristics
Volume reservoir where blood can be sent to arterial side of circulation if blood pressure falls too low. They have one way valves. Can hold as much as 60% of the body's volume. Made up of endothelium elastic and fibrous tissue and smooth muscle. Also less elastic and expand easier.
120
Capillary major function and characteristics
Leaky epithelium allows exchange of materials between plasma ISF and cell body. Made up of endothelium only
121
What is the difference between flow and the velocity of flow
Flow is measured in liters per minute and is the volume of blood that passes a given point in system per unit time.--> How much
Velocity is measured in centimeters per minute and is the distance a fixed volume of blood travels in a given period of time.--> How fast
122
What is MAP
Mean arterial pressure. The primary driving force for blood flow maintained by arteries during heart relaxation phase
123
Equation that expresses MAP, cardiac output, peripheral resistance in relation to each other
MAP🔀CO X Peripheral resistance
124
What kinds of problems that result when blood pressure's too low or too high
1. If it is too low then the driving force will be unable to oppose gravity and blood flow and oxygen to brain will be impaired resulting in dizziness and fainting.
2. If the blood pressure is too high then pressure on blood vessel walls will weaken areas which could lead to rupture and bleeding into tissues. This can potentially cause a CVA, Aortic distension or dissection, hemorrhage and/or death.
125
How do changes in blood volume affect blood pressure
If blood volume decreases then blood pressure will decrease.
| If blood volume increases then blood pressure will increase
126
Explain myogenic auto regulation
Vascular smooth muscle has the ability to regulate its own state of contraction.
If smooth muscle stretches then mechanically gated channel open allowing Cations to depolarize the cell and open voltage gated calcium channels. Calcium flows into the cell, down its electrochemical gradient. Calcium entering the cell combines with calmodulin and activates MLCK. This increases myosin ATPase activity and crossbridge activity resulting in contraction/constriction.
127
Explain active hyperemia
This is a process in which an increase in blood flow follows an increase in metabolic activity.
If aerobic metabolism increases, then tissue oxygen will decrease and carbon dioxide will increase. This will stimulate vasodilation which is a decrease in resistance and increase of blood flow to tissues. This will meet metabolic demand and remove CO2 and bring more O2 to tissues when more blood comes to area.
128
What type of exchange between the plasma and that interstitial fluid could take place at the capillary
The exchange of gasses such as 02 & CO2, nutrients, fluid, dissolved solutes, proteins, macromolecules; trancytosis
129
For substances that diffuse freely across capillary walls, what factors are the most important for determining the rate of diffusion
1. The concentration gradient between plasma and the interstitial fluid.
2. For O2 and CO2, Plasma concentrations reach equilibrium with ISF and cells by the time blood reaches the venous end of the capillary.
130
Distinguish between filtration and absorption in capillaries
Absorption is bulk flow into capillaries
Filtration is bulk flow out of capillaries
131
What 3 forces determine the direction of capillary bulk flow
1. Hydrostatic pressure (Pcap)
2. colloid osmotic pressure (Posm)
3. Interstitial fluid pressure (Pif)
132
What is hyperemia
Increased blood flow. Vasodilation leads to hyperemia.
133
What is the role of endothelium in a blood vessel
It is the inner lining of a blood vessel. Its functions are secreting Paracrine, helps regulate BP, blood vessel growth, absorption.
134
What creates the osmotic pressure gradient between the plasma and the interstitial fluid
The concentration difference of proteins between plasma and ISF creates osmotic pressure. They are mainly present in the plasma and mostly absent from the ISF.
135
Compare net fluid flow at the arterial end of capillary with net fluid flow at the venous end
The fastest flow is in the relatively small diameter arterial system. The slowest flow is in the capillaries which have the largest cross section. This allows enough time for diffusion to go to equilibrium
136
What are their to typical causes of edema
1. Inadequate drainage of lymph
| 2. Blood capillary filtration that greatly exceeds capillary absorption
137
What are capillaries
Microscopic vessels in which blood exchanges materials with the interstitial fluid
138
Do arteries transport blood towards the heart or away from the heart
Transport blood away from the heart
139
What type of gradient is the driving force for blood flow
Pressure
140
What effect would blocked calcium channels have on the rhythm of the heart
A slower rate due to decreased rate of depolarization
141
What would be the effect on the rhythm of the heart is the ICF became high in potassium (hyperkalemia).
A decreased rhythm due to it taking longer to reach a potential or get to threshold
142
What would be the effect on the heart rhythm if the intracellular concentration of potassium was lowered
A slower rhythm due to it taking longer to repolorize
143
What effect would and increase perm ability to sodium have on the rate of the pacemaker potentia
A steeper depolarization, reaching threshold quicker, more AP, increased heart rate
144
What effect would and increase permeability to calcium have on the effect of the rate of the pacemaker potential
It would have a sympathetic effect, Increasing calcium permeability would cause a steeper depolarization and speed up the rate of depolarization
145
What would be the effect of sympathetic stimulation on the rate of pacemaker potential
NE/Epi bind to B1 adrenergic receptors, cAMP alters If channels and acts as 2nd messenger and activates Ca2+ channels, increasing permeability to Ca2+
146
What effect is parasympathetic output have on the heart rate
Acetylcholine activates muscarinic receptors that activate K+ channels
K+ Permability increases, more K+ efflux, hyperpolarizing cell
Ca2+ permeability decreases-->slower rate of depolarization
AP shallow and takes longer to get to threshold
END RESULT-->Slower heart rate
147
What is CICR
Calcium induced, calcium release.
It is the process of EC coupling in cardiac muscle when calcium entry opens Ryanodine receptor calcium release channels and the SR
148
Is filtration in capillaries exactly = to absorption
No. Filtration is usually greater than absorption resulting and bulk flow of fluid out of capillary and into interstitial space. If it were equal there would be no net movement of fluid.
149
What is one function of the lymphatic system as a relates to the concept of capillary exchange
Restoring fluid lost from capillaries to the circulatory system and proteins (filtered out)
150
What change and a blood vessel radius would increase resistance
Decreased blood vessel radius
151
When a quantitee is expressed as 4 cm a minute then it is describing what
The velocity of flow
152
Smooth muscle is absent in the walls of what type of vessel
Capillaries
153
In active hyperemia blood flow to a tissue will increase if the
level of carbon dioxide at the tissues increase
154
What dehydration cause a decrease in blood pressure
Yes
155
What does myogenic auto regulation mean
Stretched smoothed muscle in a blood vessel constricts reflexively
156
In order to cause vasodilation of most vascular smooth muscle, what type of stimulation output is needed
Decreased sympathetic stimulation
157
Compared to arteries the velocity of flow of the blood through the capillaries is
Much slower
158
Due to the difference in opposing forces, there is net ______________ occurring at the arterial end of most capillaries, coupled with net ______________ at the venous end
Filtration, absorption
159
What is reactive hyperemia
If blood flow to a tissue is occluded and 02 levels fall and metabolic paracrine signals such CO2 and H+ accumulates in ISF, then endothelial cells synthesize NO-->vasodilation. Blood flow to area washes away vasodilator, radius of vessel returns to normal
160
Osmotic pressure resulting from presence of plasma proteins in blood are called
Oncotic and colloid osmotic pressure
161
If a person is in bed for several days the baroreceptor reflex may fail upon standing. Why?
1. Blood pools in the feet and legs
2. There is a decreased blood flow to the brain upon standing.
3. The kidneys have decrease the blood volume
4. Blood pools in the feet and legs and there is decreased blood flow to the brain
162
The inner lining of a blood vessel is called
Endothelium
163
The mean arterial pressure is important because
It represents a driving pressure for blood flow
164
Increased blood volume does what to blood pressure
Increases blood pressure
165
Restoring lost fluid from the capillaries back to the circulatory system is one of the major functions of what system
Lymphatic
166
One purpose of valves in the cardiovascular system is to
Ensure that blood close in one direction
167
Add and intercalated disc, two cardiac muscle cells are connected by what
Gap junctions
168
The term intrinsic myogenic indicates that the heart muscle is the source of
The electrical signal that stimulates heart contraction
169
The sodium influx during the action potential in a cardiac contractile cell causes
Opening of L type calcium channels
170
Stretching a myocardial cell
Allows more calcium to enter and increases the force of contraction
171
The flattening of the action potentials of myocardial contractile cells called the plateau phase is due to a combination of ________ efflux and ________influx occurring at the same time
K+, Ca2+
172
The end of the plateau phase of cardiac contractile cell action potentials is due to the __________ of Ca2+ channels and ___________ of K+ channels
Closing, opening
173
A typical action potential of a myocardial contractile cell last how many seconds? What does this prevent?
At least 200 milliseconds. This prevents wave summation and tetany
174
Auto rhythmic cells can generate action potentials spontaneously because they have
Unstable membrane potentials, -60 mV
175
Autorhythmic cells are also called
Pacemakers because they set the rate of the heart beat
176
During the isovolumic phase of ventricular systole, the atrioventricular valves and semi lunar valves are
Closed
177
The term used to describe the amount of blood in the ventricle available to be pumped out of the heart during the next contraction is
End systolic volume
178
The term that describes a volume of blood circulated by the heart in one minute is
Cardiac output
179
Epinephrine and norepinephrine increase ion flow through what channels
If and Ca2+ channels
180
Stimulation of the beta receptors on heart muscles result in
cAMP SIGNALING
