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BIOLOGY CHAPTER 6 - BLOOD AND
CIRCULATION
Contains:
Parts of the heart and functions
Heartbeat
Double circulation
Blood vessels
Parts of the blood
Blood pressure
Blood groups
Diseases

Parts of the heart and functions:

Blood enters the heart through the vena cava (inferior and superior, superior
is above and inferior below), emptying oxygen-poor blood from the body into the
right atrium of the heart
...

When the ventricle is full, the tricuspid valve shuts
...

As the ventricle contracts, blood leaves the heart through pulmonary valve
to the pulmonary artery and to the lungs where it is oxygenated
...

As the atrium contracts, blood flows from your left atrium into your left
ventricle through the open bicuspid / mitral valve
...
This prevents blood from
flowing backward into the atrium while the ventricle contracts
...


Functions:
1
...
Vena cava: The vena cava is a vein that carries blood from the lower body to the
heart
...

3
...
Tricuspid valve: The function of the Tricuspid valve is to prevent back flow of
blood into the right atrium
5
...
Pulmonary valve: The pulmonic valve is one of two valves that allow blood to
leave the heart via the arteries
...
Aorta: The aorta is the largest artery in the body
...
The heart pumps
blood from the left ventricle into the aorta through the aortic valve
...
Pulmonary vein: Pulmonary veins are responsible for carrying oxygenated blood
from the lungs to the left atrium of the heart
...
Left atrium: Oxygen-rich blood from the lungs enters the left atrium through the
pulmonary vein
...

10
...

11
...
Blood flows through into the left ventricle as
the heart expands (diastole)
...

12
...

13
...
Septum: This is an important function since the right side of the heart carries
oxygen-poor blood from the extremities to the heart, and the left side of the
heart oxygenates the blood and passes it through the veins
...



Heartbeat:
A heartbeat has 3 steps:
Da, dum and … (break)
Da: left and right atria contract, bicuspid and tricuspid valves open and blood
flows into the left and right ventricles (systole)
Dum: Left and right ventricle contract, bicuspid and tricuspid valves close, blood
flows into the Pulmonary artery, left and right atria relax
...
In a first order
circulatory circuit, blood is pumped to the lungs, thus acquiring oxygen while
simultaneously releasing carbon dioxide
...
Have a thick wall
...
No valves
...
Walls are very thin
...
No valves
...
Have a thin wall
...
Valves stop back flow of blood
...
It transports things from one part of the body to another part of the body, like
oxygen or nutrients
...
It helps protecting your body from diseases
Your blood is made of Plasma and Cells
Plasma : Water (most), glucose, amino acids, vitamins, carbon dioxide, urea,
hormones, salt, red bloodcells
Cells : Platelets, white bloodcells
1
...
They carry the oxygen around
your body, the shape of the cell is like a disc but there is a push-in in the
middle, they have a large surface area to volume ratio, this helps them to
absorb a lot of oxygen
...

Red cells also carries a bit of carbon dioxide, but most of this is in the plasma
...
White cells: The white cells fight diseases, there are way less of them than the
red cells
...

The white blood cells are also made in the bone marrow
...

There are two types of white cells: Lymphocytes and Phagocytes
...
The lymphocytes make chemicals called antibodies
...

Phagocytes (hulk)
These are like the 'cell-eaters'
...
When the pathogens
come into the body the white cells move towards them, the white cells can go
through the capillary walls of the pathogens
...
Platelets: Platelets are small fragments of cells, they are important if clotting is
taking place
...
They
change the fibrinogen to fibrin
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The red cells get
trapped in the threads and they make a clot
...
When the skin is healed the scab falls of
...
Drugs and alcohol can thin the blood and
prevent a clot being made
...

Systolic is the dum, when the heart contracts, and Diastolic is … + da, when the
heart refills with blood
...
Antibodies are chemicals floating around in the bloodcells to protect
our body, when an unknown antigen is in our blood the antibodies stick to them
and kill them
...
You can
bleed to death (even from a paper cut)
- Anaemia - Lack of iron, because of this your body can’t make much red
bloodcells
...
If there’s not enough oxygen in your brain you can
even faint
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When bloodcells
go to thin capillaries it gets blocked
...
A side effect is that they can’t get malaria because the virus
doesn’t recognize the red bloodcells
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Because one part of the brain dies,
one side of the body is paralyzed
...

- High blood pressure - Blood vessels that can pop

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