Pressure and flow in arteries and veins

Question 1

How is Korotkoff sounds auscultated ?

Answer 1

Using a sphygmomanometer and stethoscope

Question 2

What are the advantages and disadvantages of using a sphygmomanometer ?

Answer 2

Disadvantages:
    - accuracy 
    - discontinuous 
    - needs care 
Advantages:
    - non-invasive 
    - cheap

Question 3

What is the effect of high diastolic pressure on the aorta ?

Answer 3

There is a higher total peripheral resistance so the aorta finds it harder to release blood

Question 4

What is the effect of elastic vessels on pressure variations ?

Answer 4

Dampens them down

Question 5

What is the pressure wave affected by ?

Answer 5

Stroke volume
Velocity of ejection
Elasticity of arteries
Total peripheral resistance

Question 6

Define pulse pressure ?

Answer 6

Pulse pressure is the difference between the systolic and diastolic pressure readings

Question 7

What is normal arterial pressure ?

Answer 7

120/80mmHg

Question 8

What feature of arteries allows maintenance of high pressure during high systolic pressure ?

Answer 8

Elastic fibres

Question 9

What is name given to the blood pressure left to bring the blood back to the heart ?

Answer 9

Systemic filling pressure

Question 10

Why is flow constant throughout the systemic circulation ?

Answer 10

Because everything is in series

Question 11

What is the pressure drop through the arteries ?

Answer 11

Arteries (from ~ 95 to 90 mmHg)

–low resistance conduit

Question 12

What is the drop in blood pressure through the arterioles ?

Answer 12

Large drop through arterioles (from ~ 90 to 40 mmHg)

– the resistance vessels

Question 13

Why is it good that blood pressure is low when blood reaches the capillaries ?

Answer 13

good, because they are thin-walled

Question 14

What is the small pressure difference pushing blood back through the veins ?

Answer 14

(from ~ 20 to 5 mmHg)

–the systemic filling pressure

Question 15

What is the pulmonary pressure in relation to the systemic pressure ?

Answer 15

Pulmonary circulation is 1/5th of the systemic

Question 16

Where is velocity fastest ?

Answer 16

In the aorta and the vena cava - slowest in the capillaries

Question 17

What is the pressure in veins ?

Answer 17

Pressure is low:

- therefore difference in pressure driving blood back to the heart is low

Question 18

Vessels of veins are distensible and collapsible what does this mean ?

Answer 18

External influences affect flow

Question 19

Does gravity affect driving pressure from arteries to veins ?

Answer 19

No

Question 20

What is the effect of gravity in venous blood in the leg ?

Answer 20

Cause venous distension in legs:

- decreased EDV, decreased preload, decreased SV, decreased CO, decreased MAP (orthostatic hypotension)

Question 21

What is the effect of gravity in the neck ?

Answer 21

Causes venous collapse in the neck:

- can be used to estimate central venous pressure

Question 22

If pressure in the arteries always remains constant what does this mean for the driving force of the blood ?

Answer 22

Always remains the same

Question 23

What is the purpose of skeletal muscle pump ?

Answer 23

Rhythmic contraction increases venous return and EDV
Significance re:
- rhythmic vs static exercise
- deep vein thrombosis

Question 24

What is meant by the respiratory pump ?

Answer 24

Increased respiratory rate and depth increases venous return and EDV

Question 25

What is meant by Venomotor tone ?

Answer 25

State of contraction of the smooth muscle surrounding the venues and veins
Mobilises the capacitance

Question 26

What are all the factors that affect venous pressure and blood flow in veins ?

Answer 26

Gravity
Skeletal muscle pump
Respiratory pump
Venomotor tone
Systemic filling pressure

Question 27

What does clotting involve ?