Biology 4 you blood and circulation

blz. 88

Your blood system (also called your circulatory system) consist of two things, blood vessels and your heart.

Your blood vessels transport useful things like:

Oxygen from the lungs to the rest of the body in the red cells
Carbon dioxide from the body to the lungs in the plasma
Dissolved food from the gut to the rest of the body in the plasma
Urea from the liver to the kidneys in the plasma
Hormones from the hormone glands to the rest of the body in the plasma
Heat from the liver and muscles to the rest out body in all parts of the blood


Many small animals don't need a blood system.
They can get things (like oxygen) just by diffusing in and out.
Their having a larger surface compared to their volume. So diffusing in and out is easier.
(Small animals like amoeba and flatworms)
We need a blood system cause our body is to large and it would take too long.

Blz. 89

your heart (the pump of your blood system) is at the centre.
The rest of the blood system is made up out blood vessels, you have two main types.
1. Arteries -> carry blood away from the heart
2. Veins -> carry blood to the heart

Arteries branch many times when they got to an organ. The smallest form is the capillaries, they swop gasses and then they form veins again.
Capillaries are very narrow and red blood cells can only squeeze trough.

Arteries:
- they have very thin walls
- they have a larger surface

- body cells are never far from a capillary
- blood flows through them very slowly

Blz. 90

Right side <-, pumps the blood to your lungs and then back to the left side of your heart.
In your lungs the blood gets rid of carbon dioxide and picks up oxygen.
We say the blood get oxynated.

Left side ->, pumps the blood to the rest of the body and back to the right side of your heart.
The blood gives up it oxygen to your cells and takes up the carbon dioxide.
We say the blood gets deoxynated.

It's called a double circulation because the blood passes twice trough the heart.

Blz. 91

when the heart muscles contracts it force the blood into your arteries, so the pressure in the arteries is very high.
The artery walls are elastic and stretch to take the blood, and then they contract and force the blood further. (A pulse)

Veins are wider then capillaries and have thinner walls, but they have got the same construction.

The pressure in the veins is much lower, but the blood flows much slower, the blood is often squeezed along by your muscles.
So your veins are helped with valves. (Double doors which only open in 1 direction)
valves stops blood flowing backwards.

Blz. 92
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Blz. 93

Diastole = when the heart muscle relax, the blood flows from the veins into the atria.
Systole = when the heart muscle contract...
1. First the atria contract and force the blood into the the ventricles.
(Trough valves, so that it don't streams back.)
2. Then the ventricle contracts and force the blood into the arteries.
(Trough valves, so that it don't streams back.)

Pulmonary artery = from the heart to the lungs
Pulmonary vein = from the lungs to the heart
Vena cava = from the rest of the body to the heart
Aorta = from the heart to the rest of body


Blz. 94

The beating of the heart is controlled by the pacemaker (group of cells in the right atrium)
the pacemaker sends electrical messages to the heart, these messages stimulate the heart muscles to contract.
The heart also receives information from the brain.
It lets the heart beats faster and slower.
So the brain affects your heart rate, but why?
During exercise you need more oxygen and you need to get rid of your CO2 faster.

Your heart need oxynated blood also for itself, coronary arteries carry oxynated blood to the heart muscle.

Blz. 95

you need a healthy heart to pump the heart around your body, but your heart needs food and oxygen for itself to keep contracting. These get to the heart in the coronary arteries.
If these get blocked it causes heart diseases. (Like this)

Normally the blood can flow through the arteries easily, but if you eat too much saturated fat, there comes a thick layer of cholesterol in the arteries.
Because your body tries to solve this problem they try to make it (los). If they (loslaten) a too big peace cholesterol, it gets stuck, and it blocks the artery. (A thrombosis). Now can happen 2 things:


1. if the artery is partly blocked it can cause heart pain. (This is called angina)
2. A total blockage of the artery can cause a heart attack.
It causes several pains in the chest and the affected part of the heart is damaged.
(The heart may stop beating all together (cardiac arrest) if it doesn’t starts beating again after a view minutes it causes death.)

Blz. 96

Why
Heart diseases causes by things you can't avoid:
- inherited germs (runs in your family)
- age (how older how more chance)
- sex (m/v)

Heart diseases causes by things you can avoid:
- eating fatty foods (increase cholesterol in your blood)
- being over-weight
- smoking
- taking little/no exercise

what can you do about it?
- Take care of your diet (more fish, no fried food, less red meat, more fruits)
- no smoking
- take regular exercise

Blz. 97-99

replace blood = blood transfusion

important things that your blood does :

1. transport things from one part of your body to another part.
2. It helps to protect you against diseases.

Your blood is separated into 2 parts:
1. plasma
2. (Blood) cells

1. Plasma (yellow liquid) is mainly water with chemicals dissolved in it. (Dissolved food, waste chemicals like urea, blood proteins like antibodies and hormones-chemicals which control things like our growth)

2. There are 3 main types of blood cells:
1. red cells (Look red cause they have a red pigment called hemoglobin, no nucleus)
2. white cells (have a nucleus, no heamoglobin. 2 main types: lymphocytes/phagocytes)
3. platelets (tiny bits of cells)

1. red cells are made in bone marrow, and carry oxygen.
they are disc shaped so they have a larger surface area then their volume. (helps to absorb much oxygen)
Red cells have no nucleus, but a haemoglobin (contains iron).
Haemoglobin-->oxygen = oxyhaemoglobin


(oxygen in the blood, comes into the red blood cell, and combines with haemoglobin and forms oxyhaemoglobin) --> (red blood cells carry the oxyhaemoglobin to cells that need it) --> (the oxyhaemoglobin gets oxygen and haemoglobin again)--> (red cells return to the lungs again to catch new oxygen)

The red cells carry little co2 too, but most of the co2 is dissolved into the plasma.

2. white cells fight diseases, you have more red cells then white cells.
(white cells: no haemoglobin, not red, have a nucleus, and are also made in bone marrow)

When a virus or a bacterium enters the body the white cells recognise that is shouldn't be there.

1. The lymphocytes makes antibodies. The antibodies attacks the germs with the following things:
-first they make them stick together
-then they dissolve them
-destroy the toxic that the germs make

after you had a disease, the antibodies stay in your blood they make you immune to a disease.

2. The phagocytes destroy the germs too like this:
Phagocytes are cell-eaters. they swallow up cells and take them into the cell. then they digest them and kill them.

Blz. 100

Clot = 1. skin is cut open and blood starts leaking out the body.
2. the protein fibrinogen is in the blood, and when the platelets come in contact with the air they turn the fibrinogen into threads of fibrin, they make a net over the cut
3. the red blood cells caught in the net and make a blood cot which covers the cut

4. the clot dries to make a scab. and new skin grows under the scab

if you didn't make a clot germs will get in the cut and you would have more diseases.

Platelets are small fragments of cells, and they are also made in bone marrow.
platelets are important if clotting takes place.

Many chemicals are needed if clotting takes place, sometimes people can't make one of those chemicals. Haemophilia is a disease like this. (factor 8)