Pressure and Flow in Arteries Flashcards

1
Q

How can you measure arterial pressure?

A

By inserting an arterial line (thin catheter) into an artery

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2
Q

When measuring arterial pressure, where would you usually insert the arterial line (thin catheter)?

A

Radial artery at the wrist
or
Brachial artery at the elbow.

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3
Q

What are the advantages and disadvantages of using an arterial line?

A

Advantages- continuously measures BP, very accurate
Disadvantage- invasive

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4
Q

As using an arterial line is invasive, how would we usually measure someone’s arterial pressure?

A

Auscultation of Korotkoff sounds using a sphygmomanometer and stethoscope

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5
Q

What are the advantages and disadvantages of using Korotkoff sounds?

A

Advantages- non-invasive, cheap
Disadvantages- discontinuous, less accurate, requires skill and care.

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6
Q

Auscultation?

A

Listening w a stethoscope

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7
Q

What are Korotkoff sounds?

A

Turbulent blood flow

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8
Q

What does a sphygmomanometer measure?

A

BP

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9
Q

When using a sphygmomanometer, what will you here on the brachial artery before inflating the cuff?

A

Nothing as there is no turbulent blood flow.

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10
Q

What do you hear when you inflate the cuff to beyond systolic pressure?

A

You hear nothing as you completely occlude the vessel so no turbulent blood flow.

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11
Q

When will you start to hear Korotkoff sounds?

A

When the pressure in the cuff falls below systolic pressure as blood starts flowing back into the artery

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12
Q

What is the pattern of sounds you will hear in your stethoscope when manually taking blood pressure?

A

Silence -> Tapping -> Thumping -> Muffled -> Silence

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13
Q

What is the point at which you first hear the tapping sound known as?

A

Systolic blood pressure

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14
Q

What is the point where the sounds completely disappear known as?

A

Diastolic blood pressure.

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15
Q

What are oscialltions?

A

Vibrations generated from turbulent blood flow.

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16
Q

Do automatic machines measure Korotkoff sounds or oscillations?

A

Oscillations

17
Q

Describe some of the advantages and disadvantages of using Oscillatory blood pressure measurement.

A

Advantages- non-invasive, cheap, easier to use
Disadvantages- discontinuous, accuracy, needs care

18
Q

What happens to the aorta when the left ventricle contracts during systole?

A

Blood is ejected into the aorta and the walls of the aorta stretch.
Aorta acts as a pressure reservoir.

19
Q

What happens to the aorta during diastole?

A

Elastic recoil from the walls of the aorta which pushes on the blood and closes the aortic valve.

20
Q

What is the pressure wave affected by?

A

Stroke volume
Velocity of ejection
Elasticity of arteries
Total peripheral resistance

21
Q

What is the value of normal arterial pressure?

A

120/80

22
Q

What happens when the aorta acts as a pressure reservoir?

A

Damps down pressure variations

23
Q

What can cause arteries to lose their elasticity?

A

Age

24
Q

What is the effect of arteries losing their elasticity?

A

Systolic pressure will rise
Diastolic pressure will fall

25
Q

What happens to arterial pressure overall with age?

A

It increases

->elderly more likely to have hypertension etc.

26
Q

What happens to pressure throughout the vascular tree?

A

It drops

27
Q

Quantify the drop in pressure as blood travels through the artery

A

Small drop… from 95 to 90 mmHg

28
Q

Quantify the drop in pressure as blood travels through the arterioles.

A

Large drop (from ~90 to 40 mmHg)

29
Q

Therefore, what is pressure like when the blood reaches the arteries?
Is this good or basd?

A

Low bp
Good as very thin walls

30
Q

What pressure is the blood when it reaches the venules?

A

About 20 mmHg

31
Q

What happens to the bp when the blood goes into the right atrium?

A

Drops to about 5 mmHg

32
Q

Which system requires a lower BP for blood to be pumped- systemic or pulmonary?

A

Pulmonary

33
Q

Where is velocity high?

A

In the aorta

34
Q

What happens to velocity as blood travels through the arteries and arterioles?

A

It decreases

35
Q

What happens to velocity when blood reaches the vein and venules?

A

It increases

36
Q

What is velocity related to?

A

Cross-sectional area

37
Q

Why is velocity fastest in the aorta?

A

Small cross-sectional area so has to be quick to get all the blood through

38
Q

Where is velocity slowest?

A

Capillaries