Blood vessels 2
What you will learn about
in this topic:
1. What blood vessels are and what
they do
2. Arteries
3. Veins
4. Capillaries
Blood vessels 3
Learning objectives
By the end of this presentation you
should be able to:
•Understand the different types of
blood vessel
•Describe how blood vessels work
•Explain the effects of exercise
and inactivity on blood vessels
Blood vessels 4
Task 1
Starting and finishing with the right
ventricle, put the following in the
correct order to describe blood flow
around the body:
•
•
•
•
•
Left ventricle
Right atrium
Aorta
Pulmonary vein
Pulmonary artery
•
•
•
•
Vena cava
The lungs
The body
Left atrium
Blood vessels 5
Task 1 answers
Pulmonary vein
•
•
•
•
Left atrium
Right ventricle
Right ventricle
•
•
•
•
•
Pulmonary artery
The lungs
Left ventricle
Aorta
The body
Vena cava
Right atrium
Blood vessels 6
Recap of the heart:
Aorta
Superior
vena cava
Pulmonary
artery
Pulmonary
veins
Left atrium
Right atrium
Semi-lunar
valve
Mitral value
Tricuspid value
Septum
Right ventricle
Left ventricle
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Recap of the
circulatory
system:
Blood vessels 8
The blood vessels
There are three main types of blood
vessel:
• Arteries
• Veins
• Capillaries
Blood vessels 9
Arteries
Arteries carry oxygenated blood
from the heart to the rest of the
body (apart from the pulmonary
artery where deoxygenated blood
goes to the lungs).
The longest artery in the body is the
aorta.
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An artery:
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Smaller arteries branch off the
aorta, they then divide into smaller
arterioles and then into even
smaller capillaries.
The outer layer of an artery is tough
and fibrous, the inner liner is elastic.
The blood stretches the walls, the
walls contract and force the blood
along.
Blood vessels 12
Arteries have small passageways for
blood (internal lumen – the open
space inside a blood vessel that
blood travels through).
Blood in the arteries is bright red
due to the presence of oxygen
(apart from in the pulmonary
artery).
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Veins
Veins carry deoxygenated blood
from the body to the lungs (apart
from the pulmonary veins where
oxygenated blood travels from the
lungs to the heart).
Blood vessels 14
A vein:
Blood vessels 15
Veins have a large lumen and the
blood flows slower, at a lower
pressure. Veins have much thinner
walls than arteries.
Blood in the veins is dark red due to
the presence of carbon dioxide and
the lack of oxygen (apart from in
the pulmonary veins).
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Veins contain valves to stop the
blood from flowing backwards and
pooling, avoiding problems like
varicose veins.
Veins eventually split into venules
and then into capillaries.
Blood vessels 17
Capillaries
Capillaries are microscopic blood
vessels, much thinner than a human
hair; most let only a single blood
cell through at a time.
They are found in the muscles and
lungs.
Blood vessels 18
Blood vessels 19
Gas exchange takes place through
the walls of the capillaries. Oxygen
and nutrients are passed into
tissues and carbon dioxide and
waste products pass from the
tissues into the blood.
Blood vessels 20
At the end of the capillaries blood
flows back into veins and returns to
the heart via the vena cava at a
very low pressure.
There are over 100,000 km of
capillaries in the body.
Blood vessels 21
Task 2
List as many differences and
similarities between arteries, veins
and capillaries as you can.
For example, the arteries carry
oxygenated blood as do the veins
whereas the capillaries carry both
oxygenated and deoxygenated
blood.
Blood vessels 22
Effects of inactivity
Oxygen is not exchanged as easily
between muscles during inactivity
due to the cooler blood vessel and
blood temperature.
Blood vessels 23
Inactivity can lead to storing energy
around the body as fat. Storing fat,
like cholesterol, in the blood vessels
reduces the space for the blood to
flow through them, which raises
blood pressure.
This can put great stress on the
heart and blood vessels and can
lead to problems such as a heart
attack.
Blood vessels 24
Effects of exercise on
blood vessels
When blood in the veins flows close
to the working muscles, the ‘skeletal
pump’ effect helps move blood
around the body.
Blood vessels 25
The blood vessels increase in size to
allow more blood to flow to the
working muscles.
An increase in blood temperature
helps blood to flow better.
Oxygen is exchanged with the
muscles more easily when blood is
warm.
Blood vessels 26
Exam questions
1. Which of the following best describes a
vein?
A. Works at lower pressure than other blood
vessels, has semi-permeable walls
B. Has valves, works under high pressure,
transports oxygenated blood
C. Walls are thin, has valves, works at a low
pressure, transports deoxygenated blood
D. Transports deoxygenated blood, divides into
arterioles, walls are one cell thick
Blood vessels 27
What you have learnt
in this topic:
1. What blood vessels are and what
they do
2. Arteries
3. Veins
4. Capillaries
Blood vessels 28
Learning objectives
You should now be able to:
•Understand the different types of
blood vessel
•Describe how blood vessels work
•Explain the effects of exercise
and inactivity on blood vessels