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Cardiovascular system SA > Pressure and flow in arteries and veins*** > Flashcards

Pressure and flow in arteries and veins*** Flashcards

1
Q

How is arterial pressure physically measured

A

auscultation using stethoscope which is applied to the brachial artery (biggest brachial artery) distal to the cuff of a sphygmomanometer (blood pressure cuff) that change in pressure measuring and listening for the systolic and diastolic blood pressure which represents the arterial pressure

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2
Q

Why can no sound be originally heard in auscultation

A

As there is no blood flow due to high pressure

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3
Q

when pressure is gradually reduced what kind of sound can be heard, and why is this

A

A tapping sound, caused by the turbulence of blood now able to pus past due to reduced pressure

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4
Q

What does the tapping heard represent

A

systolic pressure

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5
Q

What is the next sound heard on the auscultation

A

A Thumping sound after tapping

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6
Q

What is the sound heard in the next stage which represent diastolic pressure

A

A Muffled sound

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7
Q

What is arterial pressure measured with

A

Auscultation of Korotkoff sounds using sphygmomanometer

& stethoscope

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8
Q

What is the disadvantages of measuring arterial pressure

A

Variation of around 10mmHg -quite alot
Can get a continuous read of pressure changing
can cut out the background sound in auscultation

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9
Q

What is the advantage of measuring arterial pressure

A

Non invasive

cheap

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10
Q

What is normal systolic and diastolic pressure

A

120mmHg

80mmHg

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11
Q

What do the elastic arteries act as

A

pressure reservoirs

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12
Q

What does the filling stage caused by systolic depend on

A

the elasticity of the arteriole wall

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13
Q

What affects the pressure wave of the filling stage into the arterioles from there arteries

A
  • stroke volume
  • velocity of ejection
  • elasticity of arteries
  • total peripheral resistance
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14
Q

What causes a change in normal arterial pressure

A

ageing as arteries become less elastic

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15
Q

What is a benefit of the pressure fall when blood flows from arterioles to venules

A

prevents blood being expelled backwards

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16
Q

Where does the pressure always remain high in the blood vessels

A

in the elastic arteries

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17
Q

What is the pressure change from elastic to muscular arteries

A

small pressure drop of 95-90mmHg

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18
Q

Why is there a massive pressure change in the blood from the arteries to the arterioles (e.g. roughly 90mmHg-40mmHg)

A

As the arterioles are resistance vessels

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19
Q

What happens to pressure passing down vascular tree

A

a continual decrease

20
Q

The small pressure difference pushing blood back through the veins is called what

A

a systemic filling pressure

21
Q

What is the drop in pressure for the systemic filling pressure

A

20-5mmHg

22
Q

How much of pulmonary circulation pressure makes up systemic circulation pressure

A

1/5th

23
Q

What happens to the velocity as the total cross section of BV increases

A

The velocity proportionally decreases

24
Q

Where is velocity the quickest

A

the aorta,

Vena cava

25
Q

What has the biggest cross section therefore the slowest velocity

A

the capillaries

26
Q

Why does the velocity increase for BV of smaller cross section

A

as must increase in speed to maintain the same flow rate of those BV with bigger cross section

(which means more blood is moving at a pace, so smaller must increase space to make up for lack of volume moving)

27
Q

What does the low pressure in the veins allow

A

the pressure difference to drive blood back to the heart

28
Q

What is the two characteristics of veins that allow external influences to affect the flow

A

Veins are distensible & collapsible

29
Q

What is external forces that affects veins flow rate

A 
Gravity 
skeletal muscle pump 
respiratory pump 
venomotor tone 
systemic filling pressure
30
Q

What condition can the effects of gravity cause

A

orthostatic postural hypotension
venous distension - swelling of legs
venous collapse

31
Q

What affect does gravity have on the pressures of your body as you stand up

A

Pressure in the legs increases (20+80=100mmHg) as the pressure in your head decreases 20-40= -20mmHg)

32
Q

How does orthostatic postural hypotension lead to you fainting

A

The increased pressure swelling in legs results in a decreased venous return which decreases EDV, therefore reducing the preload, then the stroke volume, and further cardiac output and mean arterial pressure , the decreased pressure to the brain and lack of oxygen due to decreased cardiac output propels you to faint

33
Q

How does gravity cause venous collapse (jugular vein)

A

Due to the decrease mean arterial pressure, pressure becomes sub atmospheric, therefore pressure outside is higher than inside so results in a collapse

34
Q

How can CVP be measured from jugular vein

A

as the jugular vein will become visible if CVP increase above sub atmospheric e.g. 20mmHg is high

35
Q

What does a bulging jugular vein indicate

A

raised blood pressure e.g. angry

36
Q

What is the importance of the skeletal muscle pump

A

each time skelteal msucle contract its squeezes the vein directing the blood back to the heart and increasing venous return

37
Q

What affect does static exercise have on the ability of the skeletal muscle pump and cardiac out put

A

Means there is a long contraction of muscle, so there is cut off of blood flow due to compression on the vein, meaning less venous return by skeletal pump and less preload so decreased cardiac output

38
Q

What is the affect of rhymic exercise on the skeletal pump and the cardaic output

A

The contractions are periodic, so in only compressed for short periods of time therefore skeletal pump maintains venous return and preload

39
Q

What is the venmotor tone

A

state of contraction of smooth muscle surrounding veules and veins

40
Q

What does a venmotor tone enable

A

mobile capacitance - giving veins the ability contract and push blood back to the heart (increasing EDV)

41
Q

What happens to the systemic filling pressure during exercise

A

It increases

42
Q

What is the affect of deep vein thrombosis on the pressure and flow in the veins

A

Deep vein thrombosis causes a pooling of blood in the veins - blood clot - which prevents the flow of blood and causes an increase pressure in the legs

43
Q

What causes deep vein thrombosis

A

Immobility

44
Q

What is the affect of varicose veins on blood flow and pressure on the veins

A

Stops blood flowing properly due to the formation of enlarged (dilated) sections of veins - this can result in an increase in pressure

45
Q

What does the respiratory pump aid the flow of blood in the veins

A

The harder and the more frequent you breath, increases the venous return to the heart maintaining preload

Cardiovascular system SA (43 decks)

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