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BMSC 207 > Cardiovascular System > Flashcards

Cardiovascular System Flashcards

1
Q

What is the cardiovascular system?

A

-The requirement for a circulatory system is a consequence of increasing size and complexity of multicellular organisms
-Provides a concentration gradient from the blood to cells for nutrients and in the opposite direction for waste

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2
Q

What is the primary and secondary roles of the circulatory system?

A
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3
Q

What are the 3 types of transport in the circulatory system?

A
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4
Q

What are the two serial circuits that stem from the heart?

A

Pulmonary circuit:
-Lungs
-Pulmonary capillaries

Systemic circuit:
-Systemic arterioles, capillaries and venules
-In all organs and tissues except the lungs

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5
Q

Explain vasculature in the cardiovascular system

A
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6
Q

Explain the transport of blood through the heart and major blood vessels

A
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7
Q

How does blood flow through the cardiovascular system?

A
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8
Q

What is the source of pressure in the cardiovascular system?

A
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9
Q

Explain how pressure gradients influence fluid flow

A
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10
Q

What opposes flow and how can you predict it?

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11
Q

How does vessel radius influence blood flow?

A
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12
Q

How does vessel length and liquid viscosity influence blood flow?

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13
Q

How does velocity of flow differ from flow rate?

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14
Q

What is the pericardium?

A
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15
Q

Describe Atrioventricular valves (AV)

A
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16
Q

Describe Semilunar valves

A
17
Q

Explain the cardiac conduction system

A
18
Q

What is atrial conduction?

A

Four special conducting bundles:
-Backman’s bundle: conducts action potentials from the SA pacemaker into the left atrium causing contraction
-Anterior, middle and posterior internodal pathways: conduct the action potential from the SA node to the AV node, depolarizing right atrial muscle along the way

19
Q

what is ventricular conduction?

A

-Layer of connective tissue prevents conduction directly from atria to ventricle
-Conduction slows down through the AV node to allow blood from atria to empty into ventricles
-Depolarization proceeds through the septum to the apex (bundle of His followed by bundle branches)
-Then spreads up the walls of the ventricles from apex to base (Purkinje fibres)

Sa node > Internodal pathways > AV node > Bundle of His > Bundle branches > Purkinje fibres

20
Q

How do ventricles contract?

A

-muscles have a spiral arrangement that ensures blood is squeezed upward from the apex of the heart

21
Q

What is a complete conduction block?

A

-Happens if electrical activity cannot be transgerred from the atria to the ventricles
-Caused by a damage in conduction pathway
Eg. Block at the bundle of His results in a complete dissociation between the atria and ventricles
-The SA node continues to be pacemaker for the atria, but electrical activity does not make it to the ventricles so the purkinje fibers take over as the pacemaker for the ventricles
-Requires an artificial pacemaker

22
Q

What is an electrocardiogram (ECG, EKG) and its function?

A

-Represents the summed electrical activity of all cells in the heart recorded from the surface of the body (NaCl-based ECF are good conductors of electricity)
-Provide information on heart rate and rhythm, conduction velocity and even condition of tissues in the heart
-If electrical activity of the heart is moving toward the positive electrode of the lead then an upward deflection is recorded
-If electrical activity is moving away from positive electrode, it is recorded as downward deflection
-Electrical activity moving perpendicular to the axis of the electrodes causes no deflection (baseline)

23
Q

What are arrhythmias?

A

-Electrical problems during the generation or conduction of APs through the heart and can appear as elongated semgments or intervals, altered, missing or additional waves

24
Q

What are premature ventricular contractions?

A

-Purkinje fibres randomly kcik in as pacemaker, can be due to insufficient oxygen to myocardium, excessive Ca2+, hypokalemia, medications, exercise, high levels of adrenaline
-Perceived as skipped beat or palpatation

25
Q

What is long QT syndrome?

A

-Inherited channelopathy (K+, Na+)
-Delayed repolarization of the ventricles
-Palpitations, fainting, and sudden death due to ventricular fibrillation
-can be drug induced

26
Q

What is the cardiac cycle?

A

-One complete contraction and relaxation

Two primary phases:
-diastole: time during which cardiac muscle relaxes
-Systole: Time during which cardiac muscle contracts
-Because the atria and ventricles do not contract and relax at the same time the events are discussed separately

5 Phases:
1: The heart at rest (atrial and ventricular diastole, late diastole)
2: completion of ventricular filling (atrial systole)
3: Early ventricular contraction (isovolumetric ventricular contraction)
4: The heart pumps (ventricular ejection)
5: ventricular relaxation (Isovolumetric ventricular relaxation, early diastole)

27
Q

Explain the 5 phases of the cardiac cycle in detail

A
  1. The heart at rest: atrial and ventricular diastole (late diastole)
    -Cycle starts with atria relaxed and filling with blood from veins
    -Ventricles begin to relax, when the ventricles are sufficiently relaxed and pressure in atria exceeds ventricles, AV valve opens and ventricles passively fill with blood from atria
  2. Completion of ventricular filling (atrial systole)
    -Most blood enters ventricles passively but under normal resting conditions the last 20% enters when the atria contract
  3. Early ventricular contraction (isovolumetric contraction)
    -The ventricles begin to contract, this builds up pressure in the ventricles and causes the AV valves to snap shut (first heart sound s1 “lub”)
    -Both valves are now closed and then the ventricle continues to contract building up pressure
  4. The heart pumps (ventricular ejection)
    -As the ventricles contract pressure in the ventricle exceeds pressure in the outflow arteries (aorta or pulmonary arteries) causing the semi lunar valves to open and blood flow out
  5. Ventricular relaxation (isovolumetric ventricular relaxation)
    -the ventricles then begin to relax, pressure in the outflow arteries begins to exceed the ventricles causing blood to attempt to flow backward into the ventricles causing the semi lunar valves to snap shut (second heart sound s2 “dub”)
28
Q

Describe the pressure volume loop of cardiac cycle

A

A-A’ segment (late diastole):
-Starts at ESV (end systolic volume; not all blood is pumped out during ventricle contraction, the volume of blood left over after contraction is ESV)
-Pressure in ventricle is lower than atria and the AV valve opens causing the ventricle to passively fill with blood (majority is passive)

A’-B segment (atrial systole)
-Atria contracts forcing more blood into the ventricle slightly increasing volume and pressure
-At the end of segment A’-B the maximal amount of blood is in the ventricles, this occurs at the end of ventricular diastole and is termed the end diastolic volume (EDV)

B-C segment (isovolumetric contraction):
-The ventricle begins contracting closing AV valve, continued contraction causes a large increase in pressure within the ventricle

C-D segment (ventricular ejection)
-Once pressure in ventricle rises above 80mmHg, it exceeds the aorta and the aortic valve opens causing a rapid ejection of blood.
-Pressure still rises as the ventricle continues to contract
-Part way through this segment the ventricle begins to relax and pressure begins to drop but blood still flows due to the inertia

DA segment (isovolumetric relaxation)
-Pressure in aorta begins to exceed ventricle causing semi-lunar valve to close, ventricle continues to relax

29
Q

Describe the wiggers diagram

A

D:
-ventricle relaxes, pressure in atria begins to exceed ventricle
-AV valve opens and you get the passive filling of the ventricle (change in volume in ventricle seen from F on)

Atria then contracts increasing the volume and pressure slightly (atria contraction only contributes to 20% of blood)

C:
-Ventricles begin to contract, increasing pressure within ventricle causing the AV valves to snap shut (s1)

E:
-Represents maximal ventricle volume (EDV)

Ventricle continues to contract until it exceeds pressure in aorta at point A
-Aortic valve opens and you get a rapid ejection of blood from point E to F

Ventricle begin to relax, and at point B pressure in aorta starts to exceed ventricle causing the semi lunar valve to snap shut (S2)

Ventricle continues to relax until it is lower than the atrium and passing filling of the ventricle occurs once again

30
Q

What are cardiac volumes and ejection fraction?

A
31
Q

What is cardiac output?

A
32
Q

How can cardiac output be adjusted by modulating stroke volume?

A
33
Q

What controls contractility?

A
34
Q

Explain sympathetic modulation of contraction (stroke volume)

A
35
Q

What is the effect on stroke volume if sarcomere length is increased?

A
36
Q

what is the Frank-starling law of the heart?

A
37
Q

What is determines venous retern and the factors that affect it?

A

-EDV is determined by venous return
-Increased venous return increases venous pressure resulting in increased atrial filling leading to increased ventricle filling

38
Q

What is afterload?

A

BMSC 207 (14 decks)

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