Transcript GCSE Physical Education

GCSE Physical Education
The Circulatory System
At the end of this topic you
should know the following…







The role and components of the circulatory
system;
The structure of the heart;
How the circulatory system works;
Definitions of…
 Heart rate, stroke volume, cardiac output;
The roles and characteristics of the 3 types of
blood vessels;
The functions of blood cells;
How the circulatory system is affected by
exercise.
The Circulatory System
Components are…
1 The heart
2 Blood vessels
3 Blood
Major functions include…
1 Transport of 0² & CO² to & from the
muscles
2 Temperature regulation
3 Preventing infection
The Heart
1.
2.
3.
4.
5.
The heart is a special
type of muscle
called…?
Why is it special?
What is its main job?
Why is the heart often
described as a ‘double
pump’.
Approximately how big
do you think the heart
is?
Answers
1.
2.
3.
4.
5.
Cardiac muscle
Because it never tires
Pump blood around the body
There are 2 circuits, the pulmonary
and the systemic
Size of a fist
The Structure of the Heart
Labelling of the Heart;
The Circulatory System
Using diagram of heart on previous slide describe the flow of blood
through the circulatory system.







Deoxygenated blood from the body enters the right atrium via the
vena cava.
Following its journey through the body, the blood has now collected
a number of waste products including CO².
From the atrium the blood is now forced into the right ventricle
through the tricuspid valve
Blood is then forced up into the pulmonary artery which leads to the
lungs
Here blood picks up O² and deposits CO²
The newly oxygenated blood is then forced back to the heart
through the pulmonary vein into the left atrium.
Blood is then forced into the left ventricle through the bicuspid valve
and then into the aorta to supply oxygenated blood to all parts of
the body.
Blood vessels
Blood vessels are needed to transport blood
around the body
 Arteries: carries oxygenated blood away
from the heart to the organs & muscles
 Veins: carry de-oxygenated blood back to
the heart. This blood carries excess CO²
 Capillaries: the smallest blood vessels. Lie
close to the muscle allowing O² & CO² to
pass to & from the blood & the muscles.
Blood Vessels
Vessels
Arteries
Characteristics





Capillaries



Veins
Connective tissue and smooth muscle (elastic)
Blood travels under high pressure
Oxygenated blood away from the heart
Linked to arterioles
Have pulses & thick walls
One cell thick
Allow gaseous exchange
Linked to arterioles and venules
Smooth muscle (non-elastic)
 Blood travels under low pressure
 Deoxygenated blood to the heart
Thinner walls
 Linked to venules

Blood pressure
Blood Pressure
Pressure under which the blood travels as
it is ejected from the left ventricle
Blood vessel constriction increases BP;
dilation reduces BP

1. DIASTOLE:
Heart is relaxed, BP is reduced
2. SYSTOLE:
Heart contracts, BP is increased
BP during aerobic exercise;

Systolic BP increases in direct
proportion to increased exercise
intensity

Diastolic BP changes little if any
during endurance exercise, regardless
of intensity


Muscles help
squeeze the blood
through the veins
back to the heart.
Note how valves
work together.
Blood – what is it??
Blood accounts for __8__%
of total body weight.
 It is made up of cells &
platelets, which are
suspended in plasma.
 There are 3 parts to the
blood:
1. Red & White Blood cells
2. Platelets
3. Plasma

Blood cells, Platelets & Plasma;






Red blood cells (erythrocytes) are extremely small and give
the blood its red colour. A typical adult has about 4.8 to 5.4
million red blood cells.
The main function of these cells is to transport O² & CO²
around the body
Oxygen is transported via a chemical called Haemoglobin
White blood cells (leukocytes) have the function of
protecting the body from bacteria, viruses, infections & foreign
bodies
Platelets (thrombocytes) are small cell fragments which help
blood clotting
Plasma is mainly made up of water, but also includes waste,
hormones, glycogen and nutrients.
Heart Rate
Heart rate defines as ……..
‘The number of times the heart beats per
minute’
RHR averages 60 to 80 beats per minute (bpm); can
range from 28 bpm to above 100 bpm.
 HR tends to decrease with age and with increased
cardiovascular fitness.
 Therefore resting heart rate is often used to indicate a
person’s fitness levels.
 HR is also affected by environmental conditions such
as altitude and temperature

Stroke volume
Stroke Volume defines as ....
‘The amount of blood pumped out of the heart by
each ventricle during 1 beat/contraction’
 SV increases with increasing rates of work.
 It also influences aerobic endurance capacity when
working maximally.
Stroke Volume Increases During Exercise
 Frank Starling mechanism—more blood in the ventricle
causes it to stretch more and contract with more force.
Cardiac output
Cardiac Output is defined as ..…
‘The amount of blood pumped out of the heart by each
ventricle in one minute.’
 Resting value of cardiac output (Q) is approximately 5.0 L/min.
 Q increases directly with increasing exercise intensity to between
20 to 40 L/min.
 Value of increase varies with body size and fitness level
How can you calculate the Cardiac Output?
Q = HR x SV
 When exercise intensity exceeds 40% to 60% of maximum, further
increases in Q are more a result of increases in HR than SV.
CHANGES IN HR, SV, AND Q
The Heart in Action
Heart Rate
[beats per minute]
Stroke Volume
[mls per beat]
Cardiac Output
[litres per minute]
Homer
Flanders
100
65
90
70
Complete the table [remember there are 1000ml in a litre!]