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Blood, circulation, and the Heart.
The beat goes on…
Your Blood Vessels…
• Many years ago, people thought we
were just walking sacs of liquid, with
blood just sloshing freely inside of us
(Ugly bags of mostly water).
• Eventually, however, it was discovered
that blood flowed through a tubing
system of arteries and veins all through
our body.
Arteries
• Are the vessels that carry oxygenated
blood away from our heart to our body
or lungs.
• One exception – the Pulmonary artery
carries deoxygenated blood to the lungs.
• Very Muscular, thick walls, under great
pressure
• Main artery leading from the heart is the
‘Aorta’.
Veins
• Are the vessels that carry deoxygenated
blood back to our heart.
• One exception – the pulmonary vein
carries oxygenated blood from the lungs
to the heart.
• Thinner walls, stretchy, with valves to
control back-flow of blood.
• Under less pressure than arteries.
• ‘Varicose Veins’ happen when valves
break down.
Capillaries
• Arteries and Veins are connected by a
system of very tiny blood vessels called
capillaries.
• These are so small, only one blood cell
can fit through at a time.
• Very thin walls that allow diffusion of
nutrients and oxygen to the cells, and
waste products out of the cells.
• Every cell in your body needs access to a
capillary.
Only flow in one direction
• Valves prevent the backflow of blood
into our heart or in our veins. They are
flaps that allow the flow of blood in only
one direction.
• Found in veins and in the heart.
ARTERIES-ARTERIOLES(GET SMALLER)
Capillaries to Body Cells – diffusion
of nutrients and gases
VEINS – BACK TO HEART
Each cell in the body is serviced by a
capillary where…
- Carbon Dioxide (and other waste) is
taken out, and replaced with Oxygen.
- Nutrients enter the cells.
• Artery walls are thick, muscular, and not
very stretchy. They are designed to help
push the blood flow along, and do not
allow nutrients to pass through easily.
• These vessels get continuously smaller
(arterioles), until they become
capillaries – which have very thin walls,
and exchange nutrients and gases more
easily to your cells.
• The blood then drains into your veins
which are much more stretchy and much
less muscular than your arteries.
• The blood is then pushed back to your
heart by the movement of your muscles
Eg. When you walk, your leg muscles
push the blood back up to your heart.
• The Valves make sure that the blood
flows in only one direction – towards
your heart. If one is standing or sitting
too long without moving their legs, the
valves can start to break down, blood
starts pooling in the veins in the legs,
and they get a condition known as
-Varicose Veins.
• Once the deoxygenated blood gets back
to the heart, it is transported to the
lungs, where it exchanges the Carbon
Dioxide wastes for fresh Oxygen. It
then goes back to the heart where it is
pumped back to the body to revisit the
cells.
Back to heart (Left
Atrium)
To body (from left ventricle)
Back to heart (right atrium)
To lungs (from right
ventricle)
Blood
• Blood is a very important fluid in your
body. It transports Nutrients and
Oxygen to the cells, and then transports
Waste Products away from them to the
appropriate organs for
removal/excretion.
• Men have approx. 5 L of blood in their
bodies, and women have approx 4 – 5 L
• If any part of the body is deprived of
blood for any length of time, waste
products build up in the cells, and they
eventually die.
What is Blood?
• Blood is made up of two parts; a liquid
part, and a solid part.
• The Solid matter is mainly made up of
tiny blood cells and platelets.
• The liquid part is clear and yellowish,
and is called ‘Plasma’.
Plasma
• Plasma is 92% water, and 8% dissolved
solids:
– Eg. Glucose
– Amino Acids
– Minerals/Vitamins
– Carbon Dioxide
Plasma also carries Blood Proteins – there are
three types that we will learn about…
• Antibodies – Fight infection – your body
makes very specific antibodies for
specific infections
• Hormones – Direct certain actions and
processes in your body
eg. Thyroxin – controls how fast you
burn energy (metabolism)
Adrenalin – released when you
need to respond quickly to something
(fight or flight)
• Clot forming Proteins – work to repair
broken blood vessels.
The Solid Part of Blood Conisists of…
• Red Blood Cells
- Carry oxygen to all cells in the body
- Contain ‘Hemoglobin’ – the molecule
in the red blood cells that ‘grabs’ the
oxygen and ‘lets go’ of it in places where
it is needed.
- 1 hemoglobin can carry 4 oxygen
molecules
- In order to make Hemoglobin, your
body needs iron, which you get from
dark, green, leafy veggies like spinach
and broccoli.
• Red blood cells live for about 120 days,
and when they die, they go to the liver
to be recycled into ‘bile’.
• The iron is removed and used in the new
blood cells which are produced in the
marrow of your bones.
• Iron deficiency = anemia
• Leukemia is ‘blood cancer’ which
prevents you from properly making new
blood cells. Treated with a ‘marrow
transplant’.
White Blood Cells (Leukocytes)
• Work with antibodies to fight off
invaders like viruses and bacteria.
• There are different types – some made
in the bones, spleen, and tonsils.
Platelets
• Collect where there is damage to blood
walls (a cut)
• Release chemicals that activate the ‘clot
forming proteins’.
• Hemophelia – your blood doesn’t clot
properly.