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Physiology NBCE > Cardiovascular > Flashcards

Cardiovascular Flashcards

1
Q

Liters of blood the heart pumps

A

5-6 per minute

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2
Q

List the two functions of the cardiovascular system.

A
  1. Muscular pump for blood circulation

2. Endocrine functions

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3
Q

What are the two natriuretic peptides?

A
  1. Atrial Natriuretic Peptide

2. B-Type Natriuretic Peptide

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4
Q

What does B-Type natriuretic peptide respond to?

A

Overstretched ventricles

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5
Q

What does atrial natriuretic peptide respond to?

A

Increased atrial pressure

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6
Q

Cardiac muscle is involuntary with ________ striations.

A

cross

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7
Q

What are the individual cardiac cells connected by?

A

intercalated discs

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8
Q

What is the purpose of intercalated discs?

A

cell adhesion and allow the heart to contract in synchrony as one unit (syncytium)

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9
Q

Where are gap junctions located?

A

In the intercalated discs

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10
Q

What is the purpose of gap junctions?

A

Allow passage of ions between the myocytes which ultimately all the action potentials to spread between cardiac myocytes

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11
Q

In a resting state, there is more ____ and ____ outside the cell and more _____ inside the cell.

A

Na +, Ca ++ outside the cell and more K+ inside the cell

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12
Q

Explain Phase 0 of the cardiac muscle contraction.

A

Na + influxes into the cardiac myocyte causing rapid DEPOLARIZATION

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13
Q

Explain Phase 1 of the cardiac muscle contraction.

A

Inactivation of the Na+ influx with K+ efflux= INITIAL REPOLARIZATION

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14
Q

Explain Phase 2 of the cardiac muscle contraction.

A

Ca ++ influx through L-type Ca++ channels= PLATEAU PHASE

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15
Q

Explain Phase 3 of the cardiac muscle contraction.

A

Inactivation of Ca++ influx with continuation of K+ efflux= REST OF REPOLARIZATION

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16
Q

Explain Phase 4 of the cardiac muscle contraction.

A

Removal of excess Na+ and Ca+ with restoration of the membrane potential using the Na+/K+ ATPase pump to push back Na+ out and bring K+ back into the cell

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17
Q

What determines the force of contraction of the myocardial cell?

A

The amount of intracellular calcium

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18
Q

What is the Absolute Refractory Period?

A

No action potential can be initiated regardless of the stimulus strength because the Na channels are closed in Phase 1 though mid Phase 3

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19
Q

What is the Relative Refractory Period?

A

An action potential can be elicited, however a greater stimulus is needed- extends between mid Phase 3 to the start of Phase 4

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20
Q

What is the Effective Refractory Period?

A

From Phase 1 to just beyond mid Phase 3

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21
Q

Why is cardiac muscle incapable of sustained contraction aka tetany in comparison to skeletal muscle?

A

Because of the relatively long refractory period

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22
Q

This law states: cardiac output is directly proportional to the venous return.

A

Frank-Starling Law

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23
Q

What is stroke volume?

A

force of contraction of a myocardial fiber

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24
Q

What is end diastolic volume?

A

length of the myocardial fiber

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25
What is venous return?
amount of blood entering the heart during diastole
26
What is cardiac output?
volume of ejected blood from the heart per minute
27
Explain the premise of Frank-Starling Law.
The force of the contraction of a myocardial fiber (SV) is proportional to the length of the myocardial fiber (equivalent to EDV) The greater the amount of blood entering the heart during diastole (venous return), the greater the stretching of the cardiac myocytes A greater stretch results in a greater force of contraction causing an increase in the cardiac output (volume of ejected blood from the heart per minute)
28
What makes up the 1st heart sound?
The closure of the tricuspid and mitral valves
29
What sound does the 1st heart sound make?
LUB
30
What makes up the 2nd heart sound?
The closure of the pulmonary and the aortic valves
31
What sound does the 2nd heart sound make?
DUB
32
What sound does the 3rd heart sound make?
DUBup
33
When do you hear the 3rd heart sound?
after the 2nd heart sound and is seen in congestive heart failure
34
What sound does the 4th heart sound make?
beLUB
35
When do you hear the 4th heart sound?
before the 1st heart sound and is seen in hypertrophic ventricles
36
When does systole occur?
Between heart sounds 1 and 2
37
When does diastole occur?
Between heart sounds 2 and 1
38
Is systole contraction or relaxation?
Contraction
39
Is diastole contraction or relaxation?
Relaxation
40
What does the electrocardiogram do?
It is a reflection of the electrical activity in the heart as the impulse generated in the SA node is propagated to the rest of the heart
41
What is the initial impulse of the heart generated by?
The SA node
42
What is the intrinsic rhythm of the SA node?
80-100 times per minute (rate of depolarization)
43
How is the impulse that is generated by the SA node spread?
Through the intra-atrial bundles
44
What happens when the impulse goes through the intra-atrial bundles?
It causes both the atria to contract simultaneously
45
Where does the impulse go after going through the intra-atrial bundles?
The impulse is spread to the ventricles from the SA node to the AV node
46
What is the intrinsic rhythm of the AV node?
40-60 times per minute (rate of depolarization)
47
What is the heart rate when the SA nodal rhythm is superimposed on the AV nodal rhythm?
70 beats per minute
48
Where does the impulse go after being passed through the AV node?
Down through the Bundle of His into the right and left bundle branches which are located in the muscular part of the interventricular septum
49
What is the conduction velocity?
The speed at which the action potential is transmitted
50
When is the conduction velocity the slowest?
In the AV node (0.05 m/sec)
51
When is the conduction velocity the fastest?
In the purkinje fibers (4m/sec)
52
When is the rate of depolarization the slowest?
In the purkinje fibers
53
When is the rate of depolarization the fastest?
In the SA node
54
What are the part of the ECG?
P, PR interval, QRS, QT interval, ST segment, T wave, Atrial repolarization
55
What does the P wave represent?
Atrial depolarization and precedes atrial contraction
56
What are the 3 degrees of AV block in the PR interval?
1 st degree AV block: causes a prolonged PR interval (>200 milliseconds) 2 nd degree AV block: causes progressive prolongation of the PR interval with dropped beats 3 rd degree AV block: there is no association between the P and the QRS complex
57
What does the QRS complex represent?
Ventricular depolarization (<120 milliseconds)
58
What does the T wave represent?
Ventricular repolarization
59
Why isn't atrial repolarization seen on the ECG?
Atrial repolarization
60
Explain what happens during vnetricular contraction?
The pressure builds up with the closure of the AV valves and when the aortic and pulmonary valves are open and blood is ejected into the circulation
61
What are the three phases of ventricular contraction?
1. Isovolumic contraction 2. Ejection of blood 3. Isovolumic relaxation
62
Explain isovolumic contraction.
Increase in pressure without change in volume. Occurs between the closure of the AV valves and the opening of the aortic valve
63
Explain ejection of blood.
only 70mL of the 120 mL in the ventricle is expelled= ejection fraction
64
Explain isovolumic relaxation.
Decrease in the ventricular pressure without a change in the volume. Occurs between the closing of the aortic valve and opening of the AV valves
65
What part of the cardiac plexus is the sympathetic nervous system controlled by?
T1-T5 and the middle and inferior cervical ganglia
66
What are the three main functions of the sympathetic nervous system?
1. Increase heart rate (+ chronotropism) by increasing the rate of Phase 4 2. Increases conduction velocity (+ dromotropism) by decreasing the PR interval 3. Increases force of contraction (+ inotropism) by increasing Ca+ influx in Phase 2
67
What part of the cardiac plexus is the parasympathetic nervous system controlled by?
The vagus nerve via its cardiac branches
68
What are the three main functions of the parasympathetic nervous system?
1. Decreases heart rate (- chronotropism) by decreasing the rate of Phase 4 2. Decreases conduction velocity (- dromotropism) by increasing the PR interval 3. Decreases force of contraction (- inotropism) by decreasing Ca+ influx in Phase 2
69
What is the normal systemic arterial blood pressure?
120/80 mmHg
70
What is blood pressure the product of?
Cardiac output multiplied by the peripheral resistance
71
What is cardiac output the product of?
Stroke volume multiplied by the heart rate
72
How much blood is pumped per minute?
70 mL x 70 bpm= approximately 5 liters per minute
73
What three things can affect blood pressure?
Heart rate, peripheral resistance, or stroke volume
74
What are the two main mechanisms that control blood pressure?
1. Baroreceptors | 2. Renin-angiotensin-aldosterone mechanism
75
Which one of the two mechanisms that controls blood pressure is fast?
Baroreceptors
76
Which one of the two mechanisms that controls blood pressure is slow?
Renin-angiotensin-aldosterone mechanism- slow because it is hormonal dependent
77
Where are the two high pressure sensors or baroreceptors located?
1. Carotid sinus | 2. Aortic arch- CN IX and X carries the afferents
78
Where to do the baroreceptors relay information to?
Medulla
79
There is a reflex response to a rise or drop in BP via the __________ nervous system.
Autonomic
80
A ____ in BP will cause the heart rate to ________ and vice versa.
drop, increase
81
Where are the low pressure baroreceptors located and what to they monitor?
SVC, IVC, and right atrium- they monitor volume
82
What does Poiseuille's law state?
Peripheral resistance is directly proportional to the viscosity of blood and to the length of the vessel and inversely proportional to the radius of the vessel to the 4th power.
83
Poiseuille's law says that if the vessel radius decreases by a factor of ____, then the resistance increases by a factor of ____.
2, 16
84
Which structure is responsible for the greatest resistance in the vascular system?
arterioles
85
What law governs blood flow through a tubular structure?
La Place's Law
86
What does La Place's Law state?
That pressure within a blood vessel is related to the tension, size and shape of the vessel
87
Blood flow is _________ proportional to the diameter of the blood vessel.
inversely
88
Blood flow in a normal vessel is smooth and ________.
laminar
89
As the diameter of the vessel becomes smaller, the resistance to flow is ___________.
increased
90
What percentage of total blood volume is contained in the venous system?
60%
91
What percentage of total blood volume is in the arteries and arterioles?
20%
92
What percentage of total blood volume is in the pulmonary system?
15%
93
What percentage of total blood volume is in the capillaries?
5%
94
Which two types of vessels is blood flow the greatest in?
arteries and veins
95
Which type of vessel is blood flow the least in?
capillaries
96
What does intracapillary hydrostatic pressure do?
force fluids into the interstitial space
97
What does intracapillary oncotic (protein related) pressure do?
Pulls fluids into the capillary
98
What does interstitial hydrostatic pressure do?
Forces fluids into the capillary
99
What does interstitial oncotic pressure do?
Pulls fluid out of the capillary
100
What does imbalance of the capillary pressures cause?
Edema; which is due to excess fluid in the interstitial space
101
Stimulation of the sympathetic nervous system results in:
1. increased heart rate, conduction velocity and cardiac contractility 2. vasoconstriction in the skin, gut, and inactive muscles 3. vasodilation of the blood vessels to active skeletal muscle 4. dilation of the coronary arteries
102
What can prolonged exercise result in?
cardiac muscle hypertrophy which leads to athletic heart syndrome

Physiology NBCE (6 decks)

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