Lecture 2: Variations in BP

Question 1

What is the population distribution of BP?

Answer 1

Unimodal, skewed towards upper values

Question 2

What is the equation for MAP?

Answer 2

MAP = diastolic + ⅓ pulse pressure (systolic – diastolic)

Question 3

What does high BP predispose to?

Answer 3

Stroke, heart failure, CHD, cardiac hypertrophy, kidney failure

Question 4

Why does high BP cause stroke?

Answer 4

Stress on arteries supplying brain

Question 5

Why does high BP cause cardiac hypertrophy?

Answer 5

Heart has to work harder to overcome high pressure

Question 6

Why does high BP cause heart failure?

Answer 6

Myocardial cells fail under stress

Question 7

Why does high BP cause kidney failure?

Answer 7

Kidney receives 25% of blood in the body - need high pressure for filtration to occur - when MAP increases, capillary pressure increases (can’t usually take this high pressure) so they fail - no filtration - kidney failure

Question 8

How does BP vary between populations?

Answer 8

Populations vary in the mean rather than the spread of BP

Question 9

What are the male and female average Bps?

Answer 9

F - 89 M - 94

Question 10

What is BP at birth?

Answer 10

At birth BP is 60mmg

Question 11

What happens to BP during childhood?

Answer 11

Rises rapidly due to increase in body size - male and female levels are the same

Question 12

What happens to BP during puberty?

Answer 12

Female BP rises above males as they enter puberty first and then as males enter they overtake female BP

Question 13

What happens to BP in adulthood?

Answer 13

Rise

Question 14

What is BP like for hunter gatherers?

Answer 14

More active lifestyle - less processed foods - BP stable through adulthood, not constant rise like westernised people

Question 15

What happens to systolic and diastolic pressures in adulthood?

Answer 15

Systolic BP rises and diastolic BP falls after 60 (pulse pressure rises after 60)

Question 16

What does increased body size do to BP?

Answer 16

Increased

Question 17

What is BP tracking?

Answer 17

If you start life with a higher BP, you will have a higher BP in adulthood (tracking is messed up during puberty but gets back on track)

Question 18

How does BP vary throughout the day?

Answer 18

When you wake BP is high and then goes up and down throughout the day, then falls during the afternoon and night and is low and stable when sleeping (sympathetic NS off during sleep)

Question 19

What happens to BP during summer?

Answer 19

Drops 3mmHg - lose weight, sweat (lose ECF), more exercise (tone down sympathetic NS)

Question 20

What are the correlation factors for BP of MZ twins, DZ twins and sibs?

Answer 20

MZ-0.46
DZ-0.32
Sibs-0.30