Pressure and flow in arteries in veins

Question 1

What is systolic pressure?

Answer 1

Ventricles contracting

Maximum during one heart beat

Question 2

What is diastolic pressure?

Answer 2

Heart refilling with blood

Minimum pressure while heart at rest

Question 3

What is pulse pressure?

Answer 3

Difference between systole and diastole

Question 4

What are the Korotkoff sounds?

Answer 4

Turbulent flow in the blood

Question 5

Explain the Korotkoff sounds

Answer 5

The tappy sound is systolic pressure. Some blood is able to pass though when the pressure in the artery is in systole
The thumping sound is because the artery pressure keeps rising above and dropping below the cuff pressure
Silence is diastole because the cuff no longer provides any restriction to blood flow

Question 6

Why would diastolic pressure increase?

Answer 6

High TPR

Constricted arterioles

Question 7

How do systolic and diastolic pressure vary in exercise?

Answer 7

Systolic pressure increases

Diastolic pressure decreases due to blood flowing to skeletal muscle

Question 8

How do elastic arteries manage the pressure wave?

Answer 8

They act as a pressure reservoir

Damps down pressure variations

Question 9

What is the pressure wave affected by?

Answer 9

Stroke volume
Velocity ejection
Elasticity of arteries
Total peripheral resistance

Question 10

What is ‘normal’ arterial pressure?

Answer 10

120/80 mmHg

Question 11

How does arterial pressure change with age?

Answer 11

Increases, especially pulse pressure

Question 12

What happens to pressure throughout the vascular tree?

Answer 12

Pressure falls throughout

Question 13

What happens to pressure as it goes through the arteries?

Answer 13

Small drop
From ~95 mmHg to ~90 mmHg
It’s a low resistance conduit

Question 14

What happens to pressure as it goes through arterioles?

Answer 14

Large drop
From ~90 to 40 mmHg
They’re resistance vessels

Question 15

What happens to pressure as it goes though capillaries?

Answer 15

It’s already low

They’re thin walled so pressure needs to be low

Question 16

What is the pressure difference pushing blood back through the veins? What is the term for this?

Answer 16

~20 to 5 mmHg

Systemic filling pressure

Question 17

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

Answer 17

~1/5 of systemic pressure

Question 18

What is the velocity relationship from aorta to capillaries?

Answer 18

It’s related to cross-section
Fastest in aorta and vena cava
Slowest in capillaries

Question 19

Why is there a velocity relationship from aorta to capillaries?

Answer 19

Flow remains the same throughout
TOTAL cross-sectional area increases
Means velocity has to drop

Question 20

What factors affect pressure and flow in veins?

Answer 20

• Gravity
• Skeletal muscle pump
• Respiratory pump
• Venemotor tone
• Systemic filling pressure

Question 21

Why are veins affected by external influences?

Answer 21

They’re distensible and collapsible

Question 22

How does gravity affect venous flow?

Answer 22

• Distension in legs, blood pools in venules in feet due to thin, floppy walls, increases pressure in venules and veins -> lower EDV, lower preload, lower SV, lower CO, lower MAP
• Orthostatic hypertension ->if you’re super tall
• Causes venous collapse in neck -> if you can see jugular collapse then there’s been an increase in CVP

Question 23

How does the skeletal muscle pump affect venous flow?

Answer 23

• Rhythmic vs. static exercise -> in rhythmic exercise, you get periodic contraction -> in static exercise there is sustained muscle contraction -> weightlifting can stop blood getting back to the heart
• Hot guardsman -> blood pooling as they’re not contracting their muscles
• DVT -> static blood pooling
• Varicose veins -> valves not working well, greater column of blood

Question 24

How does the respiratory pump affect venous flow?

Answer 24

• Negative pressure in thorax

- Positive pressure in the abdomen so the harder and more frequently you breathe, the more bloods gets back to the heart

Question 25

How does venemotor tone affect venous flow?

Answer 25

• State of contraction of the smooth muscle surrounding venules and veins
• Mobilises capacitance

Question 26

How does systemic filling pressure affect venous flow?

Answer 26

Pressure created by ventricles and transmitted through vascular tree to the veins