Transcript File - singhscience

Why Does Our Heart
beat?
• To pump blood around the
body.
Why do we need to pump
blood around the body?
•To get oxygen to all the
organs and tissues in our
bodies.
What happens when we
run out of oxygen?
•We need to get more
How do we get more?
• The blood is pumped back to
our lungs.
• Where it is oxygenated again.
Where does it go from
here?
• Back to the heart.
Where does it go from
here?
• To the rest of the body.
Double circulatory system
The heart pumps both oxygenated and
deoxygenated blood at the same time.
lungs
body’s
cells
This is
often
shown in a
diagram
like this
Double Circulation
• So we have two things going on in the
heart, this is known as double
circulation.
• The blood is being pumped to the body
to give it oxygen AND the blood is being
pumped to the lungs to get more oxygen.
• So we say that the heart is spilt into
two sections, the left and the right.
So what is the structure of
the heart?
The Heart
•The heart is made of very
special muscle, CARDIAC
muscle. It must keep beating all
the time for the rest of a
persons life! If you tried to do
the same action repeatedly (like
the heart) your muscles would
get tired and, after a while,
they would stop working.
•For example if you clench and
unclench your hand continuously,
it will get tired, and may even
start to cramp.
4 Chambers
• Each side has two
chambers:
1. Atria at the top,
2. Ventricles are the
bottom.
What are their functions?
• Atria – Let blood pour into
heart and down into
ventricles.
• Ventricles - Blood from
ventricles pumped out of
heat when muscle
contracts.
How do we stop the
blood from flowing
backward?
• Valves stop the flow of blood once
it has entered the ventricles.
• And also once the blood has been
pumped out the valves stop it from
coming back into the heart.
Why is the left side of the
heart thicker?
• Left ventricle muscle wall is thicker
that the right ventricle as it has to
pump blood all around the body, whilst
the left only send it to the lungs.
The Circulatory
System
The circulatory system is made
up of:
• Blood
• Arteries
• Veins
• Capillaries
• The Heart
An organ system is a group of organs that work together to carry out a
particular function in the body. The circulatory system is an organ
system that consists of the heart, the blood vessels and the blood. Its
function is to transport materials around the body. Below is an overview
of the circulatory system.
There are 3 types of blood vessel:
1. Arteries
2.Veins
3.Capillaries
• Arteries carry blood Away from
the heart
• Veins carry blood towards the
heart
• Capillaries have thin walls to
allow oxygen to pass into nearby
cells and tissues
Describe what blood vessels are
• carry blood away from the heart
• blood is under high pressure generated by the hear
• thick outer walls and small lumen
• thick layers of muscle and elastic fibres
•carry blood back to the heart
• blood is under low pressure
• have thin walls and larger lumen
• have thin layers of muscle and elastic fibres
• have one-way valves
• Tiny, thin-walled vessels
• Carry blood close to all the body's cells in its tissues and
organs.
• Only one cell thick and has a very small lumen.
• Where gas exchange takes place. Oxygen passes through
the capillary wall and into the tissues, carbon dioxide passes
from the tissues into the blood
Describe what blood vessels are
Blood vessel
Function
Artery
carry blood away from
heart at high pressure
Capillary
allow exchange of
materials between
blood and tissues
Thin permeable walls
return low pressure
blood to
heart
Large diameter to offer
least flow resistance.
Valves to prevent back
flow.
Vein
Adaptations
Thick, elastic, muscular
walls to withstand
pressure and to exert
force (pulse)