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CVS > The heart > Flashcards

The heart Flashcards

1
Q

What is preload?

A

is the volume of blood in the heart at the start of systole.

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2
Q

When looking at the cardiac cycle which part of the heart is key?

A

the left ventricle.

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3
Q

What is the first heart sound [M1] ?

A

the closing of the mitral valve.

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4
Q

What is isovolumic contraction?

A

When the pressure of the left ventricle increases but there is no change of volume.

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5
Q

What percentage of the blood is ejected with each contraction?

A

70-75%

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6
Q

Briefly outline what occurs during diastole.

A

left ventricular pressure decreases.
There is a phase of reduced ejection.
The aortic flow is maintained by aortic distensibility.
The left ventricle pressure drops below the aortic pressure so the aortic semi lunar valve closes. A2 of the 2nd heart sound.
The mitral valve will open.

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7
Q

What is the 3rd heart sound?

A

It is caused by a stiffened ventricle when filled with blood.

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8
Q

What is diastasis?

A

it is the time when the rate of filling in the ventricle slows down.

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9
Q

What is meant by elasticity of the heart?

A

the myocardial ability to recover its normal shape after removal of systolic stress.

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10
Q

What is left ventricle filling pressure?

A

the difference between left atrium pressure and left diastolic pressure

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11
Q

What happens when the wave of depolarisation arrives?

A

It opens the L-calcium tubule. Calcium ions arrive at the contractile proteins.

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12
Q

What is the function of the pericardium?

A

To provide a friction free surface for the heart to accommodate its sliding movements.

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13
Q

What innervates the pericardium?

A

The phrenic nerve.

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14
Q

What purpose do the musculi pectinate serve in the right atrium?

A

They allow for a strong contraction with minimal muscle mass.

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15
Q

What was the fossa ovalis’ embryonic relevance?

A

The foramen ovale- A whole between left and right side of heart which allowed the bypass of the pulmonary system.

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16
Q

What do the trabeculae carnae do in the right ventricle?

A

increase contractile strength.

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17
Q

what is the role of the left atrioventricular sulcus?

A

to separate left atrium and left ventricle.

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18
Q

What is the left auricular appendage?

A

a foetal remnant that allows an increase in blood volume.

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19
Q

what is the annulus fibrosis cordis?

A

4 rings of fibrous tissue that provides support to all the heart valves and attachment for muscle fibres. It also plays a role in electrical separation between the atrium and ventricles.

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20
Q

Where is the sinoatrial node located?

A

under the crista terminalis

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21
Q

How does the impulse spread through the myocardium?

A

through gap junctions.

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22
Q

Where is the AV node located?

A

The interatrial septum near the opening of the coronary sinus.

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23
Q

What is innervated first when the heart contracts?

A

The papillary muscles to prevent back flow into the atriums.

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24
Q

how fast do the purkinje fibres conduct impulses compared to normal heart muscle fibres?

A

purkinje - 4 m/s

Normal - 0.3 m/s

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25
Q

what is the resting potential of the sinoatrial node?

A

-55 to -60 mV. this is closer than in skeletal muscle.

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26
Q

Describe the phase of rapid depolarisation.

A

The Na+ channels open and there is a fast inflow of Na+.

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27
Q

describe the plateau phase.

A

Ca2+ slowly inflows

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28
Q

describe partial depolarisation.

A

The K+ ions have an outflow.

the inflow of Na+ stops.

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29
Q

What pushes the polarisation of the membrane to the generator potential?

A

The influx of Ca2+ when the fast Ca2+ channels open.

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30
Q

what are the two main rules of the atrioventricular nod?

A

Transmit cardiac impulses between the atria and the ventricles.
delays impulses so atrias can empty, does this by having less gap junctions and smaller fibres.

31
Q

How do the purkinje fibres conduct electrical impulses at a fast rate?

A

They are very large fibres and contain lots of high permeable gap junctions.

32
Q

which neurotransmitter increases the heart rate, force of contraction?

A

Epinephrine and norepinephrine. They are part of the sympathetic response.

33
Q

How does the release of norepinephrine increase heart rate?

A

It reacts with the receptor B1 which increases adenyl cyclase which intern increases the amount of cyclic AMP.

34
Q

What is the primary energy source for myocardial contraction?

A

Free Fatty acids. They are efficient for energy production.

35
Q

What makes up the A band?

A

Thick, myosin filaments.

36
Q

What is the single signalling process called that activates the contractile proteins?

A

Excitation-contraction coupling.

37
Q

During hypoxia how do cardiomyocytes get energy?

A

Anaerobic respiration supplies just enough energy for contractions to take place.

38
Q

What region defines the sarcomere?

A

the region between a pair of Z-lines.

39
Q

Where are the tropomyosin and troponin located?

A

In the I band.

40
Q

What is the role of the T tubule in the z line?

A

it has a membrane that is continuous with the sarcolemma, so that they carry material in the extracellular space to the centre of the myocardial cell.

41
Q

Where do the Z line lie?

A

They bisect each I-band

42
Q

What is the structure of myosin?

A

2 heavy chains, 4 light chains, and heads on the heavy chains that lie perpendicular to the filament.

43
Q

what is the structure of actin?

A

a globular protein that has a double macromolecular helix.

44
Q

describe the contraction action.

A

The actin slides over the myosin by ATP hydrolysis through the action of ATPase in the head of the myosin molecule. The heads form the cross bridge with the myosin.

45
Q

What is the role of tropomyosin?

A

It Is an elongated molecule of two peptide chain that occupies the longitudinal grooves between the actin strands and acts as a bridge that connects actin to troponin.

46
Q

What is the role of troponin I?

A

it inhibits the actin and myosin interaction.

47
Q

Whats the role of troponin T?

A

binds troponin complex to tropomyosin.

48
Q

Whats the role of Troponin C?

A

It has a high affinity for calcium binding sites. So, when calcium is present it will leave its site on the actin molecule and also myosin to interact with actin.

49
Q

What happens to troponin I when troponin C binds to calcium?

A

it is driven away from the actin to allow myosin to interact with actin.

50
Q

What are the 3 controllers of the contractile system?

A
  • calcium ions
  • troponin phosphorylation
  • Myosin ATPase in the myosin head.
51
Q

What Is the role of the plasma membrane in myocardial cells?

A

It regulates excitation-contraction by regulating the entry and exit of electrolytes.

52
Q

What type of movement is that of the calcium in cardiomyocytes?

A

It is passive downhill movement mediated by channel proteins.

53
Q

What are the 4 main components of myocardial contraction?

A
  • Contractile tissue
  • Connective tissue
  • Fibrous frame
  • Conduction system
54
Q

when in foetal development does the heart appear?

A

appears inn the 3rd weak when diffusion cannot supply nutritional demand.

55
Q

where do the cardiac progenitor cells lie?

A

in the epiblast.

56
Q

where are the blood islands situated?

A

splanchnic mesoderm

57
Q

what two groups of cells are formed from the fusing of the blood islands?

A

haemopoetic cells and angioblasts.

58
Q

when does vasculogenesis and angiogenesis occur?

A

day 17

59
Q

what is formed when all blood islands fuse?

A

they form a horshoe shaped endothelial lined tube called the cariogenic field.

60
Q

what does heart field 1 develop into?

A

develops into the left ventricle the left and right atrium and part of the right ventricle

61
Q

what does heart field 2 develop into?

A

truncus arteriosus

62
Q

when do the 2 endocardial tubes form?

A

by the third week.

63
Q

when does the ‘heart’ first start to pump blood?

A

23 days at the caudal pole

64
Q

how is the cardiac loop formed? [constituents and positions]

A
  • Bulba cordis bends anteriorly, laterally and inferiorly
  • Primitive ventricle moves to embryos left side
  • Primitive atrium and sinus venosum move superiorly
65
Q

where does the right coronary artery arise from?

A

the anterior aortic sinus.

66
Q

which regions are supplied by the right coronary artery?

A

SA node[generally]
Right marginal
AV node
Posterior interventricular groove

67
Q

Where does the left coronary artery travel?

A

It passes behind the pulmonary trunk and the left atrium to the left atrioventricular groove. Divides here into the LAD and the circumflex.

68
Q

where does the left anterior descending coronary artery travel?

A

it runs in the anterior inter ventricular groove and gives off branches to the septum right ventricle and the left ventricle.

69
Q

where does the circumflex travel?

A

It runs in the left atrioventricular groove and gives off septal branches and left ventricle branches.

70
Q

where do the coronary veins drain into?

A

they drain into the coronary sinus then into the coronary sulcus which enters into the right atrium just above the inferior vena cava.

71
Q

Which areas does the great cardiac vein drain?

A

it drains the area supplied bu the left coronary artery- left ventricle and atrium right atrium.

72
Q

Where does the middle cardiac vein drain?

A

drains the area supplied by the posterior inter ventricular branch of right coronary artery.

73
Q

where does the small cardiac vein drain?

A

it drains blood from the right atrium and ventricle.

CVS (6 decks)

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