Heart and Circulation Flashcards

1
Q

What is the main difference between the arterial system and veinous system ?

A

Arterial- arteries here to generate resistance to flow (conductance)

Veinous- Veins here to hold large capacity of blood

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2
Q

What is microcirculation ?

A

Where transfer of nutrients and waste occurs

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3
Q

How much blood is in each system (pulmonary, systemic and heart) at one time ?

A

Systemic- 84%
Pulmonary- 9%
Heart- 7%

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4
Q

Which of ventricles or atria is more of a pumping force ?

A

Ventricles (atria contribute just a little to ventricle filling, mostly a passive process)

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5
Q

Where is the location of the heart ?

A

Centrally in the chest, between lungs and pleura, in middle mediastinum. Surrounded by pericardial sac of fibrous tissue, which is lined by serous membrane which secretes lubricating fluid.

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6
Q

What is the purpose of the lubricating fluid secretes by the membrane lining the pericardiac sac ?

A

Helping heart beat without generating too much effort

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7
Q

What are possible disadvantages of too muscular a heart ?

A

Hypertrophy/cardiomyopathy

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8
Q

What are the main characteristics of the heart ?

A

Muscular, yet able to transmit waves of contraction
Continuously beating
Only allows blood flow in one direction (valves)
Does not allows coagulation (thanks to endothelium)
Remains in a lubricated potential space to allows expansion and contraction

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9
Q

What are the auricles of the heart ?

A

Appendanges to both right and left atrium

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10
Q

Which chamber is not visible in the sternocostal surface ?

A

Left atrium.

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11
Q

What are the different surfaces of the heart ?

A

Sternocostal (anterior) Diaphragmatic (inferior) base (superior)

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12
Q

Which chamber mainly makes up the inferior diaphragmatic surface ?

A

Left ventricle

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13
Q

Which chamber mainly makes up the base of the hear ?

A

The left atrium

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14
Q

What is the entire path of the blood ?

A

Deoxygenated blood into right atrium –> Tricuspid valve –> Right ventricle –> pulmonary trunk –> R and L pulmonary arteries –> lung capillaries –> L, R, superior and inferior pulmonary veins –> L atrium –> Mitral valve –> L ventricle –> Aorta –> Arteries –> Arterioles –> Capillaries –> Venules –> Veins –> Vena Cava –> Back to start

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15
Q

Why doesn’t all blood get ejected (only 50-60% ejected) from left ventricle to the aorta upon contraction ?

A

To keep reservoir (in case of increased tissue demands) and because ejecting all would create surface tension between ventricle walls.

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16
Q

How does the heart get supplied ?

A

Coronary arteries –> coronary veins –> venae cavae –> back to start

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17
Q

How is the fetal heart different to adult heart ?

A

Foramen Ovale connects R atrium to L atrium allowing oxygenated blood coming from mother to bypass non-functioning fetal lungs.

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18
Q

How are the walls of the atria compared to those of the ventricles ?

A

Quite smooth, more fibrous as get to the ventricle. Smooth because we don’t need to produce turbulent blood flow.

19
Q

How does blood get IN the R atrium ?

A

IVC and SVC

CORONARY SINUS

20
Q

Where is the SAN located ?

A

R atrium

21
Q

How does impulse spread from one chamber to the next

A

Because they are all electrically connected (from atria to ventricles through AVN)

22
Q

What is the fossa ovalis ?

A

The site of what was the foramen ovale in embryo

23
Q

How many veins bring in oxygenated blood to the L atrium ?

A

4: Right pulmonary veins (inferior and superior)

and Left pulmonary veins (inferior and superior)

24
Q

What are the components of the cadiac conduction system ?

A

AVN, SAN,

25
Q

How are the walls of the ventricles compared to those of the atria ?

A
Trabeculae carnae (meaty ridges) at the bottom of the ventricle produce turbulent blood flow
Smooth near its outflow to create laminar blood flow into pulmonary trunk and aorta.
26
Q

What conditions must be fulfilled for the aortic valve to open ? To close ?

A

For it to close: blood P in aorta > blood P in ventricles

For it to open: vice versa

27
Q

What structures prevent eversion of valves into atrium during ventricular contraction ?

A

Papillary muscle, since they send tendinous cords to the edges of the valve cusps.

28
Q

At which stage do the mitral and tricuspid valves close ?

A

They remain open until ventricular contraction at which point blood pushes back and the valves close.

29
Q

Which type of cusps do aortic and pulmonary valves have ?

A

Semi-lunar

30
Q

What happens to aortic and pulmonary valves during systole ?

A

They are forced against vessel wall by blood

31
Q

What happens to aortic and pulmonary valves during diastole ?

A

Elastic recoil in pulmonary trunk and aorta forces blood between cusps and vessel wall, which forces the cusps to meet in centre of each vessel.

32
Q

How do pulmonary and aortic valves compare with bicuspid and tricuspid valves in terms of thickness ?

A

Aortic and pulmonary valves much bigger, heavier and thicker.

33
Q

Where do the R and L coronary arteries arise from ?

A

From the aortic sinus just above the valve cusps

34
Q

What is a potential clinical problem arising from the fact that the heart cuts off its own blood supply when it contracts ?

A

That is especially a problem since the heart spends most of its time in contractile system. Angina, whereby Oxygen demands of the heart cannot be met.

35
Q

Where do the different coronary veins drain ?

A

The anterior cardiac veins drain directly into the R atrium.
The remaining cardiac veins converge on coronary sinus which enters the R atrium.

36
Q

List the main coronary arteries and veins.

A

Coronary arteries: L and R coronary arteries
Coronary veins: anterior cardiac veins, great cardiac vein, middle cardiac vein, small cardiac vein, oblique vein of left atrium

37
Q

How is the SAN regulated ?

A

It has “intrinsic automaticity” but it may be sped up or slowed down by Autonomic NS.

38
Q

What are the main components of the elctrical conduction pathways of the heart ?

A

SAN, AVN, Bundle of His, Purkinje fibres, lnterventricular septum, L and R bundle branches, internodal tracts

39
Q

Who is responsible for the built in delay in ecltrical conduction and what is the reason behind it?

A

The AVN, to allow enough time for atrial contraction, otherwise the ventricles would push blood before completely full, leading to low blood pressure

40
Q

What is the path of the electrical impulse ?

A

SAN –> Atrial systole (contract top to bottom) –> AVN receives impulse and delays it slightly –> through Bundle of His –> apex of the heart (bottom of ventricles) –> ventricular systol (from L and R bundle branches, along Purkinje fibers, bottom up)

41
Q

What is the ONLY point of electrical connection between ventricles and atria ?

A

AVN

42
Q

What is the overall function of the electrical conduction pathway ?

A

Ensuring synchronous contraction, in correct sequence, towards outflow of each chamber.

43
Q

Which other systems utilise circulatory system ? How so ?

A
Digestive system (helps circulation of water and nutrients) 
Endocrine system (helps flow of hormones) 
Immune system (helps circulation of immune cells)
Excretory system 
Respiratory system (utilises blood to carry oxygen to tissues and to carry CO2 back to alveoli) 
Urinary system (blood V regulated by adjusting amount of water and sodium lost into urine)

Overall has roles in flow of materials, host defence and homeostasis