A L1.2 variation in BP Flashcards Preview

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Flashcards in A L1.2 variation in BP Deck (10):
1

Blood pressure equation

  • BP = DBP + 1/3 (Pulse Pressure)

2

How is population variation of BP modelled?

  • Population of BP is unimodal 

3

High blood pressure predisposes:

  • Coronary heart disease
  • Stroke (Could cause a hemorrhage in the brain, ↑ level of stress by ↑ BP)
  • Cardiac hypertrophy (↑size as a result of facing ↑demands)
  • Heart failure
  • Kidney failure
  • Kidneys receive 25% of cardiac output
    • ↑BP → ↑ glomerular pressure → damage glomerular capillaries → kidney failure
  • Blindness from diabetes (accentuated by ↑  in BP)

4

3 ways of variation within a population

Sex, Age, Body Size

5

Within population: Sex

  • Males > Females BP (Men generally weigh more - relates to body size)

6

Within population: Age

  • BP rises with age
    • ~60 mmHg at birth, ~120mmHg at adulthood
  • But DBP falls after 60yo, as a result of ↓compliance of arteries (arteries hardening)
    • Results in ↑ in pulse pressure with age
  • Females > Males during puberty (earlier puberty for girls)

7

Within population: Size

  • ↑BMI →  ↑BP
  • E.g.:
    • Tracking BP from birth:
      • If you have a higher BP, there is a tendency to have a higher BP at adulthood
        • BUT BP during puberty fluctuates (Height plays an important factor)
    • Westernised vs 'unacculturated' (hunting for own food)
      • BP increases with age for westernised, but stay generally constant with 'unacculturated'
      • Constant physical activity for unacculturated → ↓mean body size → ↓BP 

8

Variations within inidividuals: diurnal

  • High variations/fluctuations of BP during the day
    • Often associated with stress & Strain, ↑ up to 200mmHg
  • Low variation during night
    • Sympathetic activity is dulled, ~20mmHg less than day

9

Variations within individual: seasonal

  • Summer < Winter (~3mmHg)
    • ↑Temp
      • ↓TPR
      • ↑Sweat → ↓ECF → ↓V.R → ↓SV → ↓CO
  • Different diets during summer

10

Relationship b/w Na reabsorption & H+

↑Na reabsorption → ↑H+ lost