Unit 4 > Unit 4 > Blood pressure


Blood pressure

Function of the heart

The heart is a muscle that pumps blood around the body.   It’s job is to:

  • Pump blood low in oxygen to the lungs
  • Pick up fresh oxygen in the lungs
  • Oxygenated blood is pumped around the body to be used by the muscles and cells

Blood pressure

Blood pressure is the amount of force it takes to push blood around the body in the arteries.

Example: Blood pressure is like a garden water hose.  If you turn on a water hose and point it upwards, how far the water travels tells us how much water pressure there is.  If it flies upwards the water pressure is high.  If it just falls in front of you then the water pressure is low.

The two measurements that are used;

  • Systolic  pressure is exerted near the end of the cardiac cycle, when the ventricles are contracting  and forces blood around the body
  • Diastolic  pressure occurs near the beginning of the cardiac cycle  when the ventricles are filled with blood.

The systolic pressure is the first number then the diastolic pressure e.g. 120/80 mmHg. means a systolic pressure of 120mmHg. and a diastolic pressure of 80mmHg. this is considered a normal reading for a normal healthy heart.

Variations in blood pressure readings

A variety of factors can affect the normal blood pressure of individuals

  • Age
  • Gender
  • Exercise
  • Emotions
  • Sleep
  • Digestion
  • Time of the day
  • Hormones
  • Stress
  • Illness e.g. diabetes
  • Cholesterol
  • Anxiety
  • Smoking

Average  blood pressure in mmHg. according to age

Age 1 year old 6-9 years old Adults
Blood pressure reading 95/65 100/65 110/65 – 140/90


Children have a lower blood pressure than adults.  An elderly adults blood pressure tends to be  above an adults normal range due to less flexibility  in their arteries.

High blood pressure(hypertension)

Higher pressure in the heart results in the heart having to work harder which thickens the wall of the heart and eventually becomes weaker.  Unhealthy tissue(artheroma) is pushed further along the arteries towards the heart.


  • Stroke
  • Heart attack
  • Heart failure

Low blood pressure(hypotension)

Low blood pressure results in less blood reaching the brain.  Consequently the symptoms are:

  • Dizziness
  • Fainting
  • Lightheadedness
  • Weakness
  • Shock

Low blood pressure  often occurs when an individual stands up from sitting.


  • Check that the individual does not have a condition  that may be affected by taking blood pressure
  • Ensure individual is relaxed physically and emotionally
  • The individual must give their consent for their blood pressure to be taken
  • Make sure they are not frightened to have their blood pressure taken

Measuring blood pressure

Blood pressure is measured by using a sphygmomanometer.

  • A cuff is placed over bare skin just below the elbow
  • The arm is raised to heart level
  • The cuff is inflated until the pulse cannot be felt in the wrist
  • The  pressure is slowly lowered
  • When the heart is able to overcome the pressure of the cuff, this is the systolic blood pressure.
  • At a lower pressure the heart easily overcomes the pressure of the cuff, this is the diastolic blood pressure.

Adult blood pressure in mmHg.

Normal Less than 130/85
High normal 130 – 139/85-89
Mild high blood pressure 140-159/90-99
Moderate high blood pressure 160-179/100-109
Severe high blood pressure 180-209/110-119
Very severe high blood pressure Greater than 210/120