Pressure and flow in arteries and veins***

Question 1

How is arterial pressure physically measured

Answer 1

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

Question 2

Why can no sound be originally heard in auscultation

Answer 2

As there is no blood flow due to high pressure

Question 3

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

Answer 3

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

Question 4

What does the tapping heard represent

Answer 4

systolic pressure

Question 5

What is the next sound heard on the auscultation

Answer 5

A Thumping sound after tapping

Question 6

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

Answer 6

A Muffled sound

Question 7

What is arterial pressure measured with

Answer 7

Auscultation of Korotkoff sounds using sphygmomanometer

& stethoscope

Question 8

What is the disadvantages of measuring arterial pressure

Answer 8

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

Question 9

What is the advantage of measuring arterial pressure

Answer 9

Non invasive

cheap

Question 10

What is normal systolic and diastolic pressure

Answer 10

120mmHg

80mmHg

Question 11

What do the elastic arteries act as

Answer 11

pressure reservoirs

Question 12

What does the filling stage caused by systolic depend on

Answer 12

the elasticity of the arteriole wall

Question 13

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

Answer 13

• stroke volume
• velocity of ejection
• elasticity of arteries
• total peripheral resistance

Question 14

What causes a change in normal arterial pressure

Answer 14

ageing as arteries become less elastic

Question 15

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

Answer 15

prevents blood being expelled backwards

Question 16

Where does the pressure always remain high in the blood vessels

Answer 16

in the elastic arteries

Question 17

What is the pressure change from elastic to muscular arteries

Answer 17

small pressure drop of 95-90mmHg

Question 18

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

Answer 18

As the arterioles are resistance vessels

Question 19

What happens to pressure passing down vascular tree

Answer 19

a continual decrease

Question 20

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

Answer 20

a systemic filling pressure

Question 21

What is the drop in pressure for the systemic filling pressure

Answer 21

20-5mmHg

Question 22

How much of pulmonary circulation pressure makes up systemic circulation pressure

Answer 22

1/5th

Question 23

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

Answer 23

The velocity proportionally decreases

Question 24

Where is velocity the quickest

Answer 24

the aorta,

Vena cava

Question 25

What has the biggest cross section therefore the slowest velocity

Answer 25

the capillaries

Question 26

Why does the velocity increase for BV of smaller cross section

Answer 26

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)

Question 27

What does the low pressure in the veins allow

Answer 27

the pressure difference to drive blood back to the heart

Question 28

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

Answer 28

Veins are distensible & collapsible

Question 29

What is external forces that affects veins flow rate

Answer 29

``` Gravity skeletal muscle pump respiratory pump venomotor tone systemic filling pressure ```

Question 30

What condition can the effects of gravity cause

Answer 30

orthostatic postural hypotension venous distension - swelling of legs venous collapse

Question 31

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

Answer 31

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

Question 32

How does orthostatic postural hypotension lead to you fainting

Answer 32

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

Question 33

How does gravity cause venous collapse (jugular vein)

Answer 33

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

Question 34

How can CVP be measured from jugular vein

Answer 34

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

Question 35

What does a bulging jugular vein indicate

Answer 35

raised blood pressure e.g. angry

Question 36

What is the importance of the skeletal muscle pump

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

What is the venmotor tone

Answer 39

state of contraction of smooth muscle surrounding veules and veins

Question 40

What does a venmotor tone enable

Answer 40

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

Question 41

What happens to the systemic filling pressure during exercise

Answer 41

It increases

Question 42

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

Answer 42

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

Question 43

What causes deep vein thrombosis

Answer 43

Immobility

Question 44

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

Answer 44

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

Question 45

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

Answer 45

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