Basic maths used in medicine

Question 1

What is the SI derived units?

• Rate in Hz
• Force in N
• Pressure in Pa
• Work in J
• Power in W
• Electrical charge in C
• Electrical potential difference in V

Answer 1

• Hz = s^-1
• N = m kg s^-2
• Pa = N m^-2
• J = N m
• W = J s^-1
• C = A s
• V = J C^-1

Question 2

pH = ?

Answer 2

pH = -log₁₀[H⁺]

pH must always be worked out in moles not mM or uM etc.

Question 3

Pressure

• What is pressure?
• 1 atm (atmosphere) = ?
• How many metres further down in water gives an increase of 1 atm?
• What is normal blood pressure?
• A column of liquid exerts pressure in all directions this is hydrostatic pressure

Answer 3

Pressure

• Force per unit area
• 101,000 Pa (N m^-2)
• For every 10 metres of depth in water, another atmosphere of pressure is added
• Normal blood pressure = 120/80 mm Hg
• • Blood pressure changes further down the body, due to hydrostatic pressure exerted by the blood higher in the vessels. .^.. blood pressure should be measured at heart level*