Download 8 Cardiovascular System SB Powerpoint

Unit 5 – Anatomy &
Physiology
Circulatory System
Sophie Bevan
Objectives
• By the end of the lesson you will be
able to:• Identify the gross structures of the
CV system;
• Describe, in detail, the flow of blood
around the body:
• Discuss the structure & function of
different types of blood vessels.
The Circulatory System
The circulatory system is also known as the cardiovascular system.
It consists of…
1. Blood
2. Blood Vessels
3. The Heart
The three main types of blood vessels
are arteries, veins and capillaries.
What does Blood do?
Blood does the job of a non-stop courier service - it collects chemicals
from one part of the body and delivers them to other parts, for use or
disposal.
What is Blood made of?
If blood is spun in a centrifuge it will separate into 4 parts…
Blood spinning in a centrifuge.
White blood cells help
to fight infection.
Red blood cells make up
about 45% of the total
volume of the blood
Plasma is a straw-coloured
liquid. It is mostly water
with dissolved nutrients,
salts, hormones and
proteins.
Platelets are cell
fragments.
Blood Structure
A photomicrograph of a blood smear showing
the appearance of blood as seen with the
light microscope (1000 x Magnification).
Platelets
White blood
cells
Red blood
cells
Plasma
PLASMA
This is the liquid part of blood - it is straw coloured.
Function
Its main role is the transport of:
A. Carbon dioxide away from cells to the lungs
for removal from the body.
B. Glucose from the small intestine to the
cells for use in energy production.
C. Nutrients from the small intestine to the
cells for use in growth and repair.
D. Other waste products away from cells for
removal from the body, e.g. urea and heat
when the body is hot.
White Blood Cells
These have a nucleus (control centre) and vary in shape and size.
Function
Their main role is to protect the body from disease by:
A. Engulfing any invading microbes, defending
the body from disease.
B. Producing antibodies which help the body
attack disease.
Platelets
These are tiny pieces of cell which have no nucleus.
Function
Their main role is to:
Clump together when blood vessels are
damaged and help to clog a ‘meshwork’ of
fibres which create a clot, to help stop
bleeding.
Red Blood Cells
These have no nucleus and are very flexible so they can pass through
the extremely tiny capillaries of the body.
Function
Their main role is to:
A. Collect and carry oxygen to all the cells of
the body so they can create energy.
B. In order to do this, red blood cells contain
Haemoglobin, which combines with oxygen
to become Oxyhaemoglobin.
Red Blood Cells
A scanning electron micrograph of human red blood
cells showing the biconcave disc shape that gives
these cells a large surface area to volume ratio.
(x6000 Magnification).
Blood Vessels
Non-elastic fibres
Arteries
Non-elastic fibres
Lumen
Muscle + elastic
fibres
Muscle + elastic
fibres
Non-elastic fibres
Veins
Lumen
Muscle + elastic
fibres
Capillaries
Arteries carry blood
away from the
heart and have a
thick, elastic,
muscular wall.
They stretch as
blood is pumped in
and the muscle wall
contracts to force
blood along.
Veins have a
relatively thinner
and less muscular
wall than arteries.
The blood is under
a lower pressure
than in the arteries.
Capillary walls are
one cell thick.
Exchange of
nutrients and
respiratory gases
occurs across
their surface.
Veins - Valves
The blood pressure is lower in
the veins than the arteries.
To ensure that blood does not
flow back towards the heart ,
between heartbeats, valves are
present every few centimetres.
The valves only allow blood to
flow in one direction.
Valve Open
Valve Closed
Muscle contraction and
relaxation also squeezes the
walls of the veins to help
blood flow back towards the
heart.
Arteries
The Major Blood Vessels
Veins
The Heart - Structure
Aorta
Vena cavae
Semilunar valves
Right atrium
Tricuspid valve
Right ventricle
Septum
(dividing wall)
Pulmonary artery
Pulmonary veins
Left atrium
Bicuspid valve
Left ventricle
Cardiac muscle
How Blood is Pumped around the Body



Blood flows around the body in a
‘figure of eight’ circuit, passing
through the heart twice on each
circuit.
Blood travels away from the heart
through arteries (A).
Lungs
(A)
(A)
(V)
(V)
Blood returns to the heart through
veins (V).
Heart
There are 2 separate ‘loops’ to the circuit:

The top loop – carries blood from
the heart to the lungs and back.

The bottom loop – carries blood from the
heart to all over the body and back.
Body
How the Heart Pumps Blood
The heart is divided into 2 parts. Each part is a pump, so the heart is
a double pump.
To
To
the lungs the body
From
the body
The right side
pumps deoxygenated
blood to the lungs to
pick up oxygen.
From
the lungs
The left side
pumps oxygenated
blood to the rest of
the body for use.
The Cardiac Cycle - How the Heart Beats
Every time the heart beats it goes through a 3-part cycle:
Stage 1
 The top chambers (atria) relax and fill up
with blood from the veins.
Stage 2
 The atria contract and the blood is forced
into the relaxing bottom chambers
(ventricles).
Stage 3
 The ventricles contract and the blood is
forced out of the heart into the arteries.
The Cardiac Cycle - How the Heart Beats
Blood Flow around the Body – Top Loop
1. Blood leaves the right side of the heart via the pulmonary artery
and goes to the lungs where it is oxygenated.
Lungs
Pulmonary
artery
Pulmonary
vein
Heart
Body
2. It then travels
back to the left
side of the heart
via the pulmonary
vein.
Blood Flow around the Body - Bottom Loop
Lungs
3. The left side of the
heart then pumps the
oxygenated blood
around the rest of the
body for use, via the
aorta.
Vena Cava
4. Once the
oxygen has
been used, the
blood becomes
deoxygenated
and returns to
the right side
of the heart via
the vena cava.
Aorta
Heart
Body
Circulatory System Functions - Transport
All the cells of the body require energy in order to work properly, e.g.
muscle cells would not be able to contract without a supply of oxygen
and fuel.
The circulatory system is therefore the body’s ‘transport system’.
It carries…

Blood from the heart
to all the cells of the
body, providing them
with fuel and oxygen.
It is a delivery service…

Waste products
away from all the
cells of the body,
including carbon
dioxide and urea.
…and a waste disposal unit!
End of Show