HUBS192 Lecture 8 - The Heart as a Pump Flashcards Preview

HUBS192 Lectures 1-38 > HUBS192 Lecture 8 - The Heart as a Pump > Flashcards

Flashcards in HUBS192 Lecture 8 - The Heart as a Pump Deck (45)
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1
Q

what is the design of the mammalian cardiovascular system?

A

a 4 chambered heart where blood flows in one direction

2
Q

what direction does arterial blood flow from?

A

arterial blood flows away from the heart

3
Q

what direction does venous blood flow from?

A

venous blood flows towards the heart from the body

4
Q

what is the left side of the cardiovascular system responsible for?

A

responsible for pumping oxygenated blood through the systemic circuit and then bringing deoxygenated blood to back to the right side

5
Q

what is the function of the right atrium?

A

pumps deoxygenated blood to the lungs for re-oxygenation to be pumped to the left side

6
Q

what are the 4 features that make up the mammalian cardiovascular system?

A

1) four chambered heart
2) blood flows in one direction
3) arterial blood flows away from the heart
4) venous blood flows towards the heart

7
Q

what are the 2 circuits that the heart is pumping blood through to?

A

1) systemic circuit

2) pulmonary circuit

8
Q

what is the function of the pulmonary circuit?

A

sends blood to the lungs for re-oxygenation and then oxygenated blood back to the heart

9
Q

what is meant by saying that the heart is 2 pumps that lie ‘in series’?

A

the heart is effectively composed of a right pump (deoxygenated blood) and a left pump (oxygenated blood) that create an equal flow through the 2 circuits

10
Q

what are in simple terms the 4 phases of a heart beat?

A

1) relaxation
2) atria contract
3) ventricles contract
4) relaxation

11
Q

what is the first chamber of the heart to contract and when do they contract and then what contracts afterwards?

A

the right and left atria contract first simultaneously and then the right and left ventricles contract second simultaneously

12
Q

where is the tricuspid valve in the heart?

A

in the right ventricle

13
Q

where is the mitral/bicuspid valve in the heart?

A

in the left ventricle

14
Q

what is the function of the 2 atrioventricular valves?

A

tricuspid and mitral valves control flow between the atria and ventricles

15
Q

what is the function of the 2 semilunar valves?

A

aortic and pulmonary valves control flow from the ventricles out to the circulatory vessels

16
Q

what happens in atria contraction in terms of the atrioventricular valves and semilunar valves?

A

the atrioventricular valves are open and the semilunar valves are shut

17
Q

how does blood get pumped from the atria during contraction to the ventricles?

A

the atria contract because of the open AV valve build up pressure and this enables all of the blood from the atria to move into the ventricles
- this pathway allows for the maximum amount of volume and pressure to be packed within the atria

18
Q

what happens in ventricular contraction in terms of atrioventricular valves and semilunar valves?

A

the atrioventricular valves close and the semilunar valves open

19
Q

why is it important that the AV valves are closed during ventricular contraction?

A

this is important because as the ventricles contract they create a lot of pressure on the blood within them and we don’t want the pressure to force the blood back into the atria but that can not happen because the AV valves are closed

20
Q

why is it important that the SV valves are open during ventricular contraction?

A

to allow blood to be ejected from the ventricles and into the circulatory system

21
Q

what are the 4 steps of the cellular mechanism of cardiac contraction?

A

1) Ca2+ levels go up, and more Ca2+ is released from the sarcoplasmic reticulum
2) myosin binds to actin to form cross bridges
3) myosin pulls on actin to shorten the sarcomere and generate force
4) every myocyte is activated during each heart beat

22
Q

what 2 things increase the force of a cardiac contraction?

A

1) increased Ca2+

2) increased number of cross bridges

23
Q

what are the 4 steps of the cellular mechanism of cardiac relaxation?

A

1) decrease in Ca2+ levels by being pumped back into the SR
2) cross bridges release when ATP binds to myosin
3) reduction in force means the heart relaxes
4) all cardiac myocytes relax each beat

24
Q

what are 2 things to always associated with diastole?

A

1) relaxation

2) falling pressure

25
Q

what are 2 things always associated with systole?

A

1) contraction

2) rising pressure

26
Q

what is the first phase of the cardiac cycle?

A

cardiac cycle begins where the heart has been relaxed for a period time and is filled up with blood and is ready for a contraction

27
Q

what is the second phase of the cardiac cycle?

A

-atrial systole
where the left and right atrium contract simultaneously with the AV valves open and the SV valves shut, squeezing blood and increasing pressure to move blood from the atria to the ventricles

28
Q

what is the third phase of the cardiac cycle?

A

-atrial diastole
where the left and right atrium relax and the pressure within the atria is falling. Now that the AV valves have closed the ventricles are contracting inducing the fourth phase

29
Q

what is the fourth phase of the cardiac cycle?

A

-ventricular systole (isovolumetric contraction)
where the left and right ventricles are contracting but because the AV valves are closed so blood can’t go back up to the atria and because the SV valves are closed blood can not be ejected into the aorta or pulmonary artery. Therefore there is a build up of pressure to create maximum pressure to be ejected to the entire body. The huge spike in pressure causes the SV valves to burst open

30
Q

what does isovolumetric mean?

A

there is no way to change the volume of blood because both the AV and the SV valves are closed where there is a build up in pressure

31
Q

what does the huge spike in pressure result in during isovolumetric contraction?

A

the huge spike in pressure causes the pressure to overcome the back pressure within the aorta and the pulmonary artery. This causes the SV valves to burst open

32
Q

what is the fifth phase of the cardiac cycle?

A

-ventricular systole (ventricular ejection)
where the built up pressure has opened the path to the aorta and the pulmonary artery for blood to be ejected. The ventricles will keep squeezing until a large volume (but not all) of the blood is ejected

33
Q

what is the sixth phase of the cardiac cycle?

A

-ventricular diastole (early)
where there is low pressure within the ventricles and the back pressure of the aorta and the pulmonary artery starts to catch up and eventually surpass the ventricular pressure. This causes the SV valves to snap shut and the AV valves to remain shut causing the ventricles to relax

34
Q

what is the seventh phase of the cardiac cycle?

A

-isovolumetric relaxation
where the volume of blood remains the same but the relaxation of the ventricles has caused a drop in pressure. The pressure eventually reaches the same initial pressure from the start of the cycle and this opens the AV valves initiating the last phase

35
Q

what is the eight phase of the cardiac cycle?

A

-ventricular diastole (late)
the passive filling phase where the veins fill the atria and the ventricles with blood that has circled all the way around the body - starting the cycle all over again

36
Q

what are the 2 cyclical pressure changes in the arterial network?

A

1) systole (highest pressure your arteries are under during the cardiac cycle)
2) diastole
(lowest pressure your arteries are under during the cardiac cycle)

37
Q

what has a higher arterial pressure, systemic or pulmonary circuit?

A

pulmonary circuit

38
Q

what is pulse pressure?

A

the difference between systolic pressure and diastolic pressure
- subtract the diastole from the systole

39
Q

what is the mean pressure?

A

the average pressure across the cardiac cycle that is always a bit lower than the mid way point

40
Q

why is the mean pressure not in the middle of systole and diastole?

A

because the heart spends more time in diastole, more time relaxing than it does contracting
-more time is spent low pressure than high pressure

41
Q

what is hypertension?

A

where the systolic blood pressure is getting very high

42
Q

what is hypotension?

A

where systolic and diastolic blood pressure is getting very low

43
Q

what does the equation Q= ΔP/R

A

flow= pressure difference/resistance

44
Q

what is the systemic circuit in terms of pressure and resistance?

A
  • high pressure

- high resistance

45
Q

what is the pulmonary circuit in terms of pressure and resistance?

A
  • low pressure

- low resistance

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