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Medsci > Heart > Flashcards

Heart Flashcards

1
Q

In healthy individuals, the resting heart rate is slower than the intrinsic rate of the pacemaker cells of the sino-atrial node. This is predominantly due to?

A

tonic activity of the parasympathetic nervous system

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2
Q

The viscosity of blood most directly affects?

A

systemic vascular resistance.

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3
Q

What does the word trunk generally refer to?

A

an artery eg. brachiocephalic trunk, pulmonary trunk

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4
Q

The function of the chordae tendineae is to

A

prevent eversion of the AV valves during ventricular systole

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5
Q

An increase in Venous return would result in…

A

An increase in venous return would result in an increase in preload, and so an increase in contractility and therefore stroke volume.

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6
Q

Afterload

A

after pressure
the amount of pressure that the heart needs to exert to eject the blood during ventricular contraction

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7
Q

Pre-load

A

Pre-stretch
The stretch on the heart before it contracts

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8
Q

Cardiac reserve

A

Diff between the cardiac output at rest and max

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9
Q

Venous return

A

The amount of blood returning to the heart each minute from the venous system

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10
Q

Stroke volume

A

The amount of blood ejected out of each ventricle during each contraction

Influenced by pre-load, after-load, contractility

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11
Q

Cardiac output

A

amount of blood ejected into the aorta per minute

CO = HR x SV

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12
Q

Positive inotrope

A

Increases contractility

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13
Q

Positive chronotrope

A

something that increases heart rate

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14
Q

Vein

A

Thin walled low pressure vessels, which drain blood back to the atria. Act as a reservoir which stores blood.

Thinner walled version of muscular artery. Larger ones (eg. legs) have valves to prevent back flow.

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15
Q

Vein

A

Thin walled low pressure vessels, which drain blood back to the atria. Act as a reservoir which stores blood.

Thinner walled version of muscular artery. Larger ones (eg. legs) have valves to prevent back flow.

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16
Q

Venule

A

Low pressure to drain capillary beds (site where WBC leave).

Small: Endothelium plus a little connective tissue. Large: single layer of smooth muscle.

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17
Q

Capillary

A

Single layer of endothelium with external basement membrane to exchange between blood and surrounding tissue fluid

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18
Q

Arteriole

A

Control blood flow into capillary beds . Degree of constriction determines peripheral resistance. Thicker muscular wall relative to their size than any other blood vessel.

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19
Q

Muscular artery

A

Distribute blood around the body at high pressure. Circular smooth muscle wrapped around the middle tunic used to adjust the radius of the vessel and rate of blood flow.

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20
Q

Muscular artery

A

Distribute blood around the body at high pressure. Circular smooth muscle wrapped around the middle tunic used to adjust the radius of the vessel and rate of blood flow.

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21
Q

Elastic artery

A

Very large vessels have many sheets of elastin in the middle tunic

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22
Q

Elastic artery

A

Very large vessels have many sheets of elastin in the middle tunic

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23
Q

Approx max LV and RV volume, how much does LV it empty,

A

120 ml, 60 ml (only 50% empties)

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24
Q

Spread of action potential through heart?

A

SA node- starts in the right atrium → Atrial myocardium → AV node → AV bundle (of His) → L + R bundle branches → Purkinje fibres → Ventricular myocardium

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25
Q

Where is the SA node located?

A

In the right ventricle. The fibrous skeleton is located (horizontally) at the AV node and the termination of the Purkinje fibres.

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26
Q

Isovolumetric ventricular relaxation

A

The volume in the ventricles doesn’t change

27
Q

Ventricular ejection

A

Systole (contraction) continues but ventricular pressure exceeds aortic pressure creating a pressure gradient causing the aortic valve cusps to open quietly and blood to flow out.

28
Q

Isovolumetric ventricular contraction (systole)

A

The ventricle pressure rises to higher than the pressure in the atrium but isn’t higher than the pressure in the aorta so the mitral valve closes but the aortic valve remains closed. Is a brief period

29
Q

What follows Ventricular filling?

A

The atria contracting pushing the remaining blood into the ventricle. The rise in atrial pressure is small.

30
Q

Order of valves

A

Try Pulling My Aorta

31
Q

Mitral valve

A

Is the valve that opens quietly as pressure in the ventricle drops below the atrium. Therefore the ventricle gets filled to about 80%.\

Also known as the (only) bicuspid valve.

32
Q

What effect does the parasympathetic nervous system have on stroke volume, heart rate, contractility and depolarisation of SA and AV nodes?

A

Decreased rate of spontaneous depolarisation of SA and AV nodes, decreased heart rate.

33
Q

What effect does the Sympathetic nervous system have on stroke volume, heart rate, contractility and depolarisation of SA and AV nodes?

A

Increased stroke volume, Increased heart rate, increased contractility of ventricles and atria, and increased spontaneous depolarisation of the SA and AV nodes

34
Q

Where do the hormones come from that increase heart rate?

A

adrenal medulla and thyroid gland

norepinephrine (adrenaline)

35
Q

What is the final wave in ECG?

A

T-Wave, which is ventricular repolarisation. This wave is much slower than the QRS complex as the repolarisation is not as rapid. This leads to relaxation of the ventricles, and the start of diastole

36
Q

The order of waves in the ECG?

A

P romptly depolarises

Q uite R elaxed S pread through AV node then spread back up ventricular walls leading to contraction

Atrial contraction is smaller therefore lost

T oddley repolarisation- slower than QRS results in ventricular relaxation

37
Q

QRS complex shows

A

Quite Rapidly Spreads.
Spread of activation through the ventricles.

Initially, the wave of action potentials spread from the AV node towards the apex of the heart through the interventricular septum. Once it reaches the apex, it spreads back up towards the base through the ventricular walls. This will be followed by ventricular contraction.

Note: atrial contraction also occurs during this phase, but due to the relative amount of myocardium involved, the wave is lost within the much bigger QRS complex. Atrial contraction leads to atrial relaxation.

38
Q

What does the initial wave on the ECG show?

A

Promptly depolarises.
It’s the P-wave which corresponds to atrial depolarization produces atrial contraction

39
Q

What does ECG measure?

A

Electrical events not mechanical

40
Q

0: ion movement influx/efflux? Mem potential change?

1: rise straight vertically up. channels inactivated? Channels activated? influx or efflux?

2: Plateu meaning currents are?

A

0: Rapid depolarisation where Na+ channels open. Influx of Na+. Membrane potential changes from ~-90mV to ~+30mV in 1-2 ms

1: Early repolarisation. Na+ channels inactivated (time dependent). Membrane stops escalating. Some K+ channels are activated. Producing small outward positive current. There is an efflux of positive ions

2: Inward and outward currents are equal

41
Q

3: gradual decline. What channels are dominant?

4: At zero flat. Inward and outward are?

A

3: Repolarization. K+ channels are dominant. Flowing down conc gradient and out of cell. This phase is slower than depolarisation ~20-50ms.

4: Inward and outward currents are balanced.

42
Q

Where is conduction conducted through _____ and out of ___?

A

Through the purkinje fibres then out the ventricular myocardium. This rapid conduction allows for contraction of the ventricular myocytes in synchronicity.

43
Q

Where does the activation spread from the SA node through ____ and to _____?

A

Through the atrial myocardium towards the AV node. The AV node is the only electrical connection between the atria and the ventricles. The wave travels slowly through this node allowing time for mechanical contraction of the atria to fill up the blood in the ventricles.

44
Q

Activation begins with spontaneous firing of myocytes in?

A

the SA node

45
Q

The function of the inlet valves is to

A

Prevent blood from regurgitating back into the atria during ventriuclar contraction

Right ventricle inlet valve is the Tricuspid valve. Left ventricle inlet valve is the mitral valve.

46
Q

Semilunar valves

A

Pulmonary valves located between the right ventricle and the pulmonary trunk

Aortic valve located between the left ventricle and the ascending aorta

47
Q

What does pulmonary mean?

A

It is in relation to the lungs

48
Q

Direction of blood flow?

VA

A

Vena Cava
Atrium
Ventricle (Right)
Artery - pulmonary (to the lungs), pulmonary trunk

Vein - pulmonary (from the lungs)
Atrium
Ventricle (Left)
Aorta

49
Q

Are the levels of oxygen in the vessels different in the pulmonary and systemic circuits?

A

The blood in the arteries of a circuit has the same oxygen level as the blood in the veins of the other circuit

50
Q

What is the difference between the left atrium and the right in an upright person?

A

The left atrium is oriented more horizontally than the right

51
Q

There’s a common disease that can affect the flow of blood through muscular arteries. If this disease were to occur in the small muscular arteries that supply the heart, what is the list of the likely events in the correct order?

A

atherosclerosis-ischemia-angina-infarction

52
Q

What blood vessel contains deoxygenated blood?

A

Pulmonary artery

53
Q

The average volume of whole blood in a 70kg adult is about

A

5 L

54
Q

What ventricle is thick walled?

A

The left ventricle is thick walled needs more muscle to eject blood into the systemic circuit. RV is thinner as needs to eject blood to pulmonary circuit which is very nearby

55
Q

What structure of the heart is made of white fibrous connective tissue?

A

chordae tendineae

56
Q

What are features of the auricles?

A

If you can see the auricles you are in ventral view of the heart. They are made of pectinated muscle.

57
Q

What is the purpose of the moderater band?

A

It is a cardiac muscle as part of the conduction network. It is an extension of the Purkinje network

58
Q

What blood does the LV contain?

A

Contains oxygenated blood. recieves blood from the LA and pulmonary viens returns oxygenated blood from the lungs

59
Q

Where do coronary arteries originate from?

A

the aorta

60
Q

Where are papillary muscles found?

A

Found in the inside wall of the ventricle at the apex of the heart

61
Q

Occasionally after birth the ductus arteriosus fails to close the expected consequence would be:

A

greater blood flow to lungs than systemic circuit. Because after birth the pressure in the pulmonary circuit decreases below that of systemic circuit and there would be the majority of blood in the aorta

62
Q

fill in the blanks
after blood passed through the ______(coronary arteries) it returns to the _____ through _______

A

after blood passed through the coronary arteries it returns to the left anterior vena cava through the cardiac veins

63
Q

Where is the first heart sound best heard?

A

The first heart sound is best heard near the apex of the heart (due to turbulance against the atrioventricular valves contributing to) and the second heart sound is best heard near the base of the heart (semilunar valves are located close to base of heart)

Medsci (5 decks)

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