Biology Presenation

Content:
1 What’s blood made off
2 What do red and white blood cells do?
3 Blood clotting
4 Types of blood and the blood bank
5 Blood diseases
6 The circulator
7 Tissue fluid

1. What’s blood made of and what does it do?
Blood does two important things:
» It transports stuff from one place in you body to another
» It helps your body to protect itself from and fight diseases
Blood also keeps your body temperature steady (around 37 degrees). When a person becomes overheated, more blood starts flowing through the skin, which allows the heat to escape. When a person is cold, the vessels narrow to keep more heat.
If you would put blood in a tube, after some days you’ll see two different “parts” in the blood; a transparent, and a red part. The transparent part is called plasma. Plasma contains the important things of blood which are:
» The red blood cells
» The white blood cells
» The platelets, which are tiny bits of cells

2. What do the red and white blood cells do?
---Red Blood cells---
There are about a million red blood cells in one drop of blood. Red blood cells are made in the bone marrow.
The red blood cells carry around the oxygen your muscles need to work. They have no nucleus (“kern”), and look red because of the red pigment called haemoglobin.
Red blood cells have a special form; you can see it in the picture. Because of this shape they have a large surface area in comparison with their volume. This is essential, because the more surface area they have, the more oxygen they can carry. They have the smallest possible volume, so the blood can carry a lot in a small area.
Red blood cells don’t have a nucleus, but instead they are filled with haemoglobin, which is a protein that contains iron. Red blood cells need iron to make enough haemoglobin.
Haemoglobin easily combines with oxygen, which makes oxyhaemoglobin.
Red blood cells also carry the carbon dioxide, but most of that is dissolved in the plasma.
---White blood cells---
You don’t have as much white blood cells as red blood cells in your body. There are two different tupes of white cells that protect the body in their own way. White blood cells do have a nucleus, but no haemoglobin. That’s why they look white. You have two different types of white blood cells; Lymphocytes and Phagocytes.

» Lymphocytes:
Lymphocytes protect the body by detecting diseases. As soon as they indicate a germ that does not belong in the body, they start making antibodies. Antibodies work like this:
A. They make the germs stick together
B. They dissolve them
C. They destroy the poison that the germs make
After the antibodies have done their work, they stay in the body, which makes you immune to that particular disease. There is a different antibody for each type of disease.

» Phagocytes:
The Phagocytes have a different way of fighting diseases; they simply eat the germs. First they swallow them, than digest and kill them.

When diseases come into the body the white blood cells squeeze through the capillary walls to kill them.

3. Blood clotting
The blood has its own way to keep cuts clean, and to seal a wound. Blood contains a protein called fibrinogen. When you have a wound, the platelets come to action. They turn the fibrinogen into fibrin as soon as it touches the air. Fibrins are thin threads, which cover the wound and keep the red blood cells together. They make a kind of net, in which the blood cells are captured. When the red blood cells are captured, they stick to the fibrin, and start to dry up, or cloth. This seals the cut. When the blood is entirely dried up, it forms a scab which covers the wound and keeps it clean. Then a new skin can grow underneath the scab.

4. Types of blood and the blood bank
We have different types of blood, and often two types can’t be mixed together, because then the blood won’t work properly anymore, which can cause diseases and even death.
The different types of blood are:
» A+ (A positive), can be combined with A-, AB and O
» A- (A negative) can be combined with A+, AB and O
» B+ (B positive) can be combined with B-, AB and O
» B- (B negative) can be combined with B+, AB and O
» AB can only be combined with O
» O can only be combined with O
The most common type of blood is A+. Most people have it. O is the rarest of all blood types.

A blood bank is usually a department in a hospital where people can give their blood to give to others who need it. Because of that, a hospital usually has a large collection of tubes containing blood. These tubes are kept safe inside a fridge.
A lot of people go to a blood bank once in a month, they are called blood donors. They can survive with less blood than their body produces, so they go to a blood bank to get an injection. Anybody can be a blood donor, except when they have a blood disease, or when they are younger than 18 years old. When giving blood the first time, you have to fill in a form with your name, address and blood group. When you don’t know your blood group, you can test it at the hospital.

5. Blood diseases
There are a lot of things that can happen to the blood cells, which can cause a disease. There are too many diseases, so we won’t give them all.
» Haemophilia
Haemophilia means that a person who has the disease can’t produce all the chemicals needed for blood clotting, or at least one of them. With this disease, the sufferer can’t make a chemical called factor 8.
This disease is not very helping, because whenever a person who has the disease gets cut or something like that, the bleeding won’t be stopped by the fibrin and blood is lost.

» Anaemia
Anaemia is when someone has a shortage of red blood cells, or a shortage of haemoglobin. The most common symptom of this disease is fatigue, which means that a person is tired easily. This is caused by the shortage of oxygen, which occurs when a person doesn’t have enough red blood cells or not enough haemoglobin. This disease can be caused by eating less nutrition than what’s good for you, or by an infection.

» Leukaemia (blood cancer)
This is a disease which occurs in the white blood cells. When a person has blood cancer, the bone marrow makes too many white blood cells, which are unpractised (not finished). This can cause death, because the unpractised white blood cells can’t protect the body. This disease is caused by a lot of things, but often it won’t be inherited. One of the causes is a too high dose of radiation, another is chemical gas. There are other unknown causes, which makes this disease extremely difficult too control.
However, there are treatments. The most common treatment is chemotherapy, which means that strong drugs are used to kill the Leukaemia cells, but leaving the normal cells to regenerate.
Another treatment is bone marrow transplants. In one type of childhood Leukaemia, there is a cure, which has caused 80 percent of the patients to get rid of the disease.

6. The circulator
In the table below you can check what the blood carries around.

What it carries Where it is carried How it is carried
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 of the body In all parts of the body

7. Tissue fluid
Plasma goes through the capillary walls, where is surrounds the body cells, than it is called a tissue fluid. Tissue fluids help substances to go in and out of the cells (diffusing).