levo

Medical Physics

Blood pressure readings and the sphygmomanometer

  • 3 things to know
  • A2 3

Overview

mmHg and kPa conversion, Korotkoff sounds, mercury, aneroid and digital sphygmomanometers, cuff size and reliable readings, white coat hypertension, low readings and pulse pressure.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

What unit is blood pressure measured in, and where does the unit come from?

Key term

Convert a systolic pressure of 120 mmHg into kilopascals, given that 1 mmHg is 133.3 Pa.

Key term

What are Korotkoff sounds?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What unit is blood pressure measured in, and where does the unit come from?

    Model answer

    Blood pressure is measured in millimetres of mercury, mmHg. The unit is the height of a mercury column that the pressure would support.

  2. 2

    Convert a systolic pressure of 120 mmHg into kilopascals, given that 1 mmHg is 133.3 Pa.

    Model answer

    A pressure of 120 mmHg is about 16.0 kPa. The working is 120 × 133.3 Pa = 15 996 Pa, which is 16.0 kPa.

  3. 3

    What are Korotkoff sounds?

    Model answer

    Korotkoff sounds are the tapping sounds heard through a stethoscope as blood spurts through a partly squeezed artery. The sounds are heard over the brachial artery just below the cuff.

  4. 4

    How are Korotkoff sounds used to read systolic and diastolic pressure?

    Model answer

    The cuff pressure at which the first tapping sound is heard is the systolic pressure. The pressure at which the sounds disappear is the diastolic pressure.

  5. 5

    Why must the cuff first be inflated above systolic pressure?

    Model answer

    A cuff pressure above systolic pressure squeezes the brachial artery shut. Blood cannot flow, so no sound is heard until the pressure is let down.

  6. 6

    How does a mercury sphygmomanometer display the pressure?

    Model answer

    The cuff is connected to a column of mercury in a glass tube with a millimetre scale. The cuff pressure pushes the mercury up to a height equal to the pressure in mmHg.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Experimental Techniques
Human Body Systems
Physical Chemistry in Industrial Processes
Brain Science

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

One cubic equals 1000 cm³.
decimetremetrecentimetre

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe energy of all bonds broken is added up.
BThe energy of all bonds formed is subtracted.
CA negative answer shows an exothermic reaction.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Acidosis means blood pH falling below 7.35.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Medical Physics, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.