Chapter 17- The Cardiovascular System Flashcards

1
Q

What does the cardiovascular system consist of?

A

The heart
Blood vessels
Blood

The heart pumps blood into the blood vessels

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2
Q

What is the apex of the heart?

A

Bottom cone-shape part of the heart that points toward the left hip

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3
Q

What is the base of the heart?

A

The flattened, posterior side of the heart. All of the major vessels of the heart exit from here

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4
Q

What are the four chambers of the heart?

A

Right and left atrium

Right and left ventricle

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5
Q

Veins

A

Vessels which bring blood back to the heart

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6
Q

Arteries

A

Cells which carry blood from the ventricles away from the heart

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7
Q

Why is the right side of the heart sometimes called the pulmonary pump?

A

Because it pumps blood through the pulmonary arteries out to the pulmonary capillaries in the lungs

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8
Q

Where does gas exchange take place in the lungs?

A

Alveoli and pulmonary capillaries

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9
Q

Why is the left side of the heart often called the systemic pump?

A

It pumps oxygenated blood throughout the rest of the trunk and extremities

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10
Q

Which circuit in the heart operates at lower pressure? Why?

A

Pulmonary

Only has to pump to the lungs

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11
Q

Which circuit in the heart operates at higher pressure? Why?

A

Systemic

Has to pump blood to the entire body

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12
Q

What hormone is produced by the heart? How does it lower BP?

A

Atrial natriuretic peptide

Lowers the amount of sodium in the kidneys to less water is retained

Electrolyte homeostasis

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13
Q

What is the pericardium?

A

Membranous structure surrounding the heart composed of the : fibrous (thicker) and serous (thinner) pericardium

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14
Q

Visceral pericardium

A

Aka epicardium

Most superficial layer of the heart wall

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15
Q

Myocardium

A

Deep to the visceral pericardium

2 components: cardiac muscle tissue and the fibrous skeleton made of dense irregular collagen

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16
Q

Functions of fibrous skeleton

A

Gives the cardiac muscle cells something to hold on to

Provide structural support

Acts as an insulator for the hearts electrical activity

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17
Q

Endocardium

A

Deepest layer of the heart wall, lines the lumen of the heart

Composed of endothelium

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18
Q

What are the great vessels?

A

Superior/inferior vena cava

Pulmonary trunk

Aorta

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19
Q

Two veins that drain most of the systemic circuit into the right atrium

A

Superior/inferior vena cava

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20
Q

Pulmonary trunk

A

Receives deoxygenated blood from the right ventricle

Splits into the right/left pulmonary arteries

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21
Q

Pulmonary veins

A

2 from each lung

Drain oxygenated blood into the left atrium

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22
Q

Aorta

A

Supplies the entire systemic circuit with oxygenated blood

Receives blood ejected by the left ventricle

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23
Q

What is the function of the auricles?

A

They expand to give the atria more room to hold blood

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24
Q

What separates the two atria?

A

Interatrial septum

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25
What is the fossa ovalis?
An indentation in the interatrial septum that used to be the foremen ovale
26
What is the foramen ovale?
Hole in the interatrial septum in fetal hearts to allow blood to bypass the lungs
27
What do we call the ridged surface created by irregular cardiac muscle inside the ventricles?
Trebeculae carnea
28
Papillary muscles
Finger-like projections of muscle in the ventricles that attach by the chordae tendineae to the valves between the atria and ventricles
29
What separates the right and left ventricles?
Interventricular septum
30
Atrioventricular valves aka AV valves
Prevent backflow of blood from the ventricles to the atria The two valves consist of cusps. Each valve named for how many cusps it has : bicuspid and tricuspid
31
Valve located between the right atrium and right ventricle
Tricuspid valve
32
Valve located between the left atrium and left ventricle
Bicuspid
33
Semilunar valves
Prevent blood from flowing back into the ventricles They are named for the artery in which they reside: pulmonary valve, aortic valve
34
Coronary circulation
Necessary because the walls of the heart are too thick for oxygen and nutrients to diffuse from inside the chambers. So the heart has its own set of coronary arteries to supply it with the nutrients it needs
35
Two branches that arise from the ascending aorta
Right and left coronary arteries Left coronary splits and becomes the anterior interventricular artery and the circumflex
36
Coronary sinus
Most of the hearts veins empty into the skin which drains to the right atrium Receives blood from 3 major veins: great cardiac, small cardiac, middle cardiac
37
Pacemaker cells
Cardiac muscle cells that rhythmically and spontaneously generate action potentials that trigger contractile cells Reside in the atria
38
Autorhythmicity
When cells set their own rhythm without a need for input from the nervous system
39
Cardiac conduction system
Three populations of cells in the heart capable of spontaneously generating action potentials and setting the pace of the heart SA node AV node Purkinje fibers
40
Phases of a pacemaker action potential
- slow initial depolarization phase - full depolarization phase - repolarization phase - minimum potential phase
41
Pacemaker slow initial depolarization phase
Membrane is hyperpolarized allowing sodium in and potassium out resulting in slow depolarization
42
Pacemaker full depolarization phase
Calcium ion channels open and calcium rushes in resulting in a rapid and complete depolarization
43
Pacemaker repolarization phase
Calcium channels begin to close and potassium channels begin to open causing the cell to repolarize
44
Pacemaker minimum potential phase
Potassium channels stay open until the membrane reaches its minimum potential. The membrane will then be hyperpolarized and the cycle begins again
45
Phases of contractile cell action potentials
- rapid depolarization phase - initial repolarization phase - plateau phase - repolarization phase
46
Contractile cell rapid depolarization phase
Sodium channels open and sodium rushes in rapidly depolarizing the membrane
47
Contractile cell initial repolarization phase
Sodium channels shut down, some potassium channels open and some potassium leaks out causing slight repolarization
48
Contractile cell plateau phase
Calcium channels open and calcium enters as potassium exits simultaneously causing a plateau and prolonging depolarization
49
Contractile cell repolarization phase
Sodium and calcium channels close and potassium continues to exit the cell causing repolarization
50
Where is the Sinoatrial node(SA) and what does it do?
Upper right atrium. Causes the atria to contract
51
Where is the Atrioventricular node (AV) and what does it do?
Located behind the tricuspid valve it is slower than the SA node and causes the ventricles to contract
52
Purkinje fiber system
Slowest group of pacemaker cells Composed of AV bundle, right/left bundle branches, terminal branches
53
Sinus rhythms
Electrical rhythms generated and maintained by the SA node
54
What is AV node delay?
Slow conduction of impulses as a result of a low number of gap junctions between cells and the presence of the non-conducting fibrous skeleton
55
What does an electrocardiogram measure?
Electrical activity occurring in all cardiac muscle cells over a period of time Shown as waves: P wave, QES complex, T wave Periods between waves represent phases of action potentials and denoted as intervals: R-R, P-R, Q-T. One segment to note: S-T
56
P wave
Atrial depolarization
57
QRS complex
Ventricular depolarization
58
T wave
Ventricular repolarization
59
R-R interval
Entire duration of a cardiac action potential
60
Q-T interval
Entire duration of a ventricular action potential
61
S-T segment
Ventricular plateau phase
62
P-R interval
Duration of atrial depolarization and AV node delay
63
Events in cardiac cycle
Ventricular filling phase Isovolumetric contraction phase Ventricular ejection phase Isovolumetric relaxation phase
64
Ventricular filling phase
When blood drains from the atria into the ventricles. Semilunar valves are closed preventing backflow from pulmonary trunk and aorta. AV valves are open due to high atrial pressure pushing blood down its pressure gradient. 80% of blood drains passively from atria to ventricles while in diastole but then the final 20% gets ejected to ventricles during atrial systole
65
End Diastolic Volume (EDV)
Ventricular volume at the end of ventricular diastole (once atria have empties into ventricles) Increases when the ventricles spend more time in diastole
66
Isovolumetric contraction phase
Ventricular systole occurs. High pressure closes the AV valves but pressure not high enough to open semilunar valves yet
67
Ventricular ejection phase
Pressure in the ventricles becomes higher than that in the pulmonary trunk and aorta and pushes semilunar valves open Ejection of blood starts rapidly but then decreases until only 70ml of blood have been pumped, leaving 50ml remaining
68
End systolic volume (ESV)
Blood left in ventricles after ejection, about 50ml
69
Isovolumetric relaxation phase
Occurs as ventricular diastole begins and pressure drops. Semilunar valves shut Pressure is lower but still higher than in the atria so the AV valves remain closed Blood is either entering or exiting the ventricles
70
What causes the heart sounds? What are they called?
Heart sounds are caused by the sound of valves snapping shut S1 is when the AV valves close during the isovolumetric contraction phase S2 is when the SL valves close during the isovolumetric relaxation phase
71
Cardiac output
The amount of blood pumped into the pulmonary and systemic circuits in 1 minute Also determined by the amount of blood pumped in one heartbeat (stroke volume)
72
Preload
The amount that the ventricles can stretch before they contract Largely determined by the EDV (amount of blood in ventricles at end of filling phase)
73
Venous return
Amount of blood returning to the right atrium from the systemic circuit
74
Frank Starling Law
The more the ventricular muscles are stretched, the more forceful the contraction will be Important during exercise when cardiac output must increase to meet the body’s needs
75
Contractility
Pumping ability/ability to generate tension Increasing contractility increases SV and decrease ESV Decreasing contractility decreases SV and increases ESV
76
Afterload
The force the the right and left ventricles must overcome in order to eject blood to their arteries Determined by blood pressure Increase in afterload generally decreases SV, rise in ESV Decrease in afterload increases SV, lower ESV
77
What are chronotropic agents?
Factors that influence the rate at which the SA node depolarizes Positive agents - sympathetic nervous system - hormones - elevated body temp Negative agents - parasympathetic NS - decreases body temp