The Cardiovascular
System
The circularity system or cardiovascular system includes
the heart, blood and blood vessels. The circularity
system as four main functions, they include:
 Maintaining the body’s core temperature (homeostasis).
 Removing waste products from the cells (co2).
 Fighting infections.
 Transporting oxygen and nutrients to the cells.
BLOOD
Each person has approximately 4 – 5 litres of blood which
take about 20 seconds to circulate the body at rest.
Blood is made up of blood cells, the solid component
(Hermatocrit 45%) and the blood plasma (final 55%).
The blood cells include red cells, white cells and
platelets.
RED BLOOD CELLS give blood there red colour due to
the haemoglobin content. Haemoglobin is essential in
the transportation of oxygen from the lungs to the cells.
Red blood cells are produced in the long bones marrow.
WHITE BLOOD CELLS fight infection by absorbing and
digesting disease causing organisms. White blood cells
are produced in bone marrow of long bones, lymph
tissue and the spleen.
PLATELETS are produced in
bone marrow and clot the
blood to prevent excessive
bleeding.
BLOOD PLASMA is mostly
made up of water (about 90%).
It is the fluid that blood cells,
nutrients and waste float in.
Vessels
The vessels that make
up the circularity
system include
arteries, arterioles
(smaller arteries),
capillaries, venules
(smaller veins) and
veins.
 Arteries / Arterioles: carry blood away from the heart.
With the exception of the pulmonary artery they carry
oxygenated blood. Arteries have muscular walls and a
pulse. The pressure in arteries is great.
 Veins / Venules: carry blood to the heart. With the
exception of the pulmonary vein they all carry
deoxygenated blood. Veins have thin elastic walls and
valves that prevent the back flow of blood.
 Capillaries: link arterioles with venules. They are 1 cells
thick which allows them to diffuse oxygen, carbon
dioxide, nutrients and other waste.
The Heart
The heart is the size of your clenched fist and is made of
cardiac muscle specific to the heart. The heart is
comprised of two separate pumps. One to the lungs and
the other to the rest of the body. The heart beats 60 – 80
times per minute at rest. It has four chambers, the left
atrium, right atrium, left ventricle and right ventricle.
 http://www.smm.org/heart/heart/pumping.htm
Superior
vena
cava
Pulmonar
y
vein
Inferior
vena
cava
Bicuspid
valve
Heart rate
Resting heart rate can vary from 45 – 85 beats per minute.
Heart rate is affected by a number of factors, these
include:
 Gender
 Age
 Body size
 Body Position
 Aerobic capacity
 Stress
 Anxiety
 Tension
 Excitement
 Level of food digestion
Maximum Heart = 220 beats – Age
What is yours?
The blood exerting pressure against the
artery walls as the heart contracts
measures pulse. The amount of blood
expelled in a beat is known as the stroke
volume. Pulse can be measured most
efficiently at the carotid artery (neck) of
the radial artery (wrist).
When taking your pulse, two fore fingers
should be used, Never you thumb as it
has its own weak pulse.
Blood
pressure
Blood pressure is measured as systolic or diastolic.
Systolic is the pressure
of blood against the
artery walls while the
atria and ventricles
contract.
Diastolic is the pressure
of the blood on the
artery walls while the
heart relaxes.
Blood Pressure is the force exerted by blood against the blood vessel walls
Cardiac output
Cardiac output is the volume of blood pumped
by the heart each minute.
Cardiac output (Q) = Heart rate (HR) x Stroke
volume (SV)
A-VO2 difference
A-VO2 differences the amount of oxygen
taken in and used by the tissues of a muscle.
It is the difference in oxygen concentrations in
the artery compared to the vein of a muscle.
SUMMARY OF CHANGES DURING
EXERCISE
Factor
Acute
Chronic
Heart rate (HR)
Increase
Decrease
Stroke volume (SV)
Increase
Increase
Cardiac output (Q)
(Q) = (HR) x (SV)
Increase
increase
A-VO2 difference
Increase
Slight increase
Blood flow to working
tissue, heart and lungs
Increase
Blood flow to non essential
regions
decrease