Blood Pressure

Question 1

BP usually means??

Answer 1

systemic arterial pressure.

BP term is quite variable, if over whole circuit, BP would be more ~7mmHg!

Question 2

One modifiable factor that has the biggest effect on health and life expectancy

Answer 2

BP

Question 3

What are the set values for high BP

Answer 3

There are none realistic one, it is a continuum. Increases CVD risk

Question 4

Systolic BP (peak P)
mean BP
diastolic BP (minimum P)

Answer 4

Systolic BP: ~120
mean BP: ~100
diastolic BP: ~90

These tend to increase with age!!!

Question 5

What does nun study show?

Answer 5

Effects of lifestyle: low stress, healthy diet, sleep etc leads to low BP that DOESN’T increase with age

Question 6

MAP calculation?

Answer 6

1)
MAP = P(D) + 1/3 (Ps- PD)

MAP = Pd + 1/3PP

2)
MAP = CO x TPR

Question 7

Pulse pressure (PP)

Answer 7

PP= Psys - Pdias

Question 8

Whats so special about 100mmHg

Answer 8

is a relatively constant value for MAP for most mammals

**exception giraffes who have to push blood up neck

-Optimal pressure required at the capillary level to get sufficient fluid/blood drive for nutrient exchange.

Question 9

If BP to high?

Answer 9

We increase resistance, but also get more fluid driven out of capillaries.

Leads to tissue damage and swelling

Question 10

Draw BP = CO x PR diagram

Answer 10

…

Question 11

Main determinants of systolic pressure

Answer 11

• SV (and ejection rate)

- aortic compliance

Question 12

Main determinants of diastolic pressure

Answer 12

• Diastolic runoff: determined byHR, TPR

- Aortic compliance

Question 13

Does arterial pressure get to zero?

Answer 13

NO. arterial pressure NEVER gets to zero, whereas ventricular pressures do! Need to maintain the pressure gradient!

Question 14

Aortic Pulse Pressure

Answer 14

During systole: blood flows in, some moves on but due to the compliant nature of the vessel, it expands and some will be stored within the aorta

Aortic valve shuts: vessel springs back to shape and you still have flow continuing

SO flow through the WHOLE cycle, and this becomes non-pulsitile by the time it reaches the small arterioles.

Question 15

THerefore one of the major determinants of aortic pulse pressure is compliance.

Answer 15

C= change V / change P

Low compliance = for every volume increase a bigger pressure increase occurs.

Question 16

Why does pulse pressure increase with age

Answer 16

Due to lowering compliance

Systolic increases
Diastolic decreases (less left over)

Question 17

How does SV affect pressure

Answer 17

The bigger the stroke volume, the higher the systolic pressure

• preload
• afterload
• chronotropy
• inotropy

this is why Systolic pressure can increase in exercise

Question 18

How can be change diastolic pressure/runoff?

Answer 18

TPR.

incr TPR > Less rapid runoff > inc diastolic pressure > decr PP

TPR can decrease in exercise.

Question 19

What is the “pulse” you feel in arteries

Answer 19

PRESSURE WAVE not blood flow!!

• stretch of ascending aorta caused by LV ejection initiates a pressure wave thats propagated through the arterial system.
• Pulse (4ms) travels faster then blood itself (0.3ms)

Question 20

Why does pulse pressure increase in larger conducting vessels

Answer 20

• decreasing compliance
• decreasing radius
• reflected wave

Question 21

Ways to measure BPs

Answer 21

1) Palpation method (could only get systolic!)

2) Ausculatory method (both dia and sys): listen for Korotkoff sounds
No flow >(sys)> turbulent >(dias)> laminar

Question 22

Above P>120

Answer 22

no flow = no sound

Systolic = first sound heard

Question 23

120> P>80

Answer 23

turbulent flow= korotkoff sounds

Question 24

P

Answer 24

laminar flow = no sound

Diastolic= last sound heard

Question 25

Effect of Gravity and BP

Answer 25

Reference height = right atrium

Gravity does affect BP
Hydrostatic Pressure P = pgh

Rigid tubes: would have no pooling effect BUT we aren’t rigid tubes!!! So this can occur

Question 26

Venous Pooling

Answer 26

After standing for an extended period of time.

Leads to Reduced Venous Return > postural hypertension and people faint.

Question 27

What happens in renal artery stenosis?

Answer 27

• Reduced renal blood flow
• It thinks BF is low
• Increases blood volume (fluid retention)
• Increases arterial pressure