
Define heart rate, stroke volume &
cardiac output

List the main factors affecting blood
pressure

Measure & accurately record heart rate
& blood pressure, using equipment
safely
On your mini
whiteboards,
summarise what you
remember about this!
Challenge: can you
write these as
numeric equations?
Heart rate = # beats
 Heart rate: number of heartbeats per
minute
minute

3)
Stroke
volume:
volume
of
blood
(cm
3
Stroke Volume = blood cm
pumped by heart in 1 beat
beat
 Cardiac
output:
stroke
multiplied
by
X # beats
Cardiac
Output
= blood
cm3volume
= blood
the heart rate gives
of blood
beatthe amount
minute
minute
(cm3) pumped by heart in 1 minute
 Can
be changed by a number of
factors:
› Cardiovascular centre in brain
› Hormones e.g. adrenaline
› Stretching of cardiac muscle
Parasympathetic & sympathetic nerves
to smooth muscle of arterioles
Get out your
calculators!
Heart rate
(beats/min)
Stroke
Volume
(cm3/beat)
At rest
75
75
During
exercise
180
120
Cardiac
Output
(cm3/min)
5,625
21,600
Blood needs to flow through vessels at a
certain pressure. If pressure is too low,
exchange of nutrients and gases within
the tissues will not happen efficiently.
 This is why blood pressure is a vital
measurement taken by doctors and
nurses.
 Blood pressure is measured using a
sphygmomanometer and is recorded in
mmHg (millimetres of mercury)


Measured in blood vessels (artery)

Determined by cardiac output and
resistance to flow of blood in vessels

Resistance to flow affected by diameter
of blood vessels

Narrower vessels (vasoconstriction)

Wider vessels (vasodilation)





Cardiovascular centre
› Diameter of blood vessels controlled by
stimulation of sympathetic and parasympathetic
nerves
Smoking
› Nicotine causes vasoconstriction
› Build up of fatty deposits in vessels
Diet
› High fat diet leads to build up of fatty deposits in
blood vessels
Adrenaline
› Causes selective vasoconstriction & vasodilation
Increase in blood viscosity
› Excess water loss (sweating/excessive urination)

Get out your mini-whiteboards

Write down the meanings of the words
‘systolic’ and ‘diastolic’.

Compare your answers with the others
on your table.

Systolic blood pressure:
› Maximum blood pressure
› Occurs when ventricles are contracting (at the
end of the cardiac cycle)

Diastolic blood pressure:
› Minimum blood pressure
› Occurs when ventricles are relaxed and filled with
blood (at the beginning of the cardiac cycle)

We record blood pressure as: Systolic
BP/Diastolic BP
› e.g. 120/80 mm Hg
Diastolic pressure gives clearest indication of
resistance to flow in blood vessels
 Rough estimate of systolic BP is your age +100

Sphygmomanometer
1. Place
the stethoscope ear pieces around your neck and wrap the cuff of
your sphygmomanometer tightly around your upper arm.
2. Locate the pulse of your brachial artery by tracing your finger down your
bicep down toward the crook, or inside elbow, of your arm. You should
find the brachial pulse about an inch or so above this crook.
3. Put the ear pieces of the stethoscope into your ears and place the
round, metal end of the stethoscope over the pulse of your brachial
artery.
4. Tighten the stopcock on the sphygmomanometer bulb and squeeze the
bulb of your sphygmomanometer multiple times to inflate the cuff
around your upper arm. The cuff should be inflated until you've reached
180 mm of pressure. You will be able to determine how much pressure
you've pumped into the sphygmomanometer cuff by reading the
blood-pressure meter in front of you.
5. Release the bulb stopcock slowly and gradually. This will let the air out of
the cuff, allowing you to make a blood pressure reading.
6. Note the number on the meter when you first hear your pulse through the
stethoscope. Then note the number when the last pulse sound comes
through the stethoscope. Record these two numbers by placing the
higher number over the lower number to determine your current blood
pressure.
Carotid artery
Radial artery
Watch the demonstration of how to use
the sphygmomanometer
 In your book, record:

› Your blood pressure three times and average
the results
› Your heart rate three times and average the
results
A person’s blood pressure should be
measured when they are resting and
relaxed. Explain why.
2) People with high blood pressure sometimes
have swelling in their legs and feet. Explain
how this happens
3) Low blood pressure can cause fainting.
Explain why.
4) Nicotine in cigarette smoke causes the
muscle fibres in arteriole walls to constrict.
Explain how this causes blood pressure to
increase.
1)

Define heart rate, stroke volume &
cardiac output

List the main factors affecting blood
pressure

Measure & accurately record heart rate
& blood pressure, using equipment
safely