Blood and It's Elements - T6C

8/6/2019 Blood and It's Elements - T6C

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Science Faculty Mr. Jos Novoa Vsquez

The Blood and its elementsThe blood consists of a suspension of special cells in a liquid called plasma. In an adult man, the blood isabout 1/12th of the body weight and this corresponds to 5-6 litres. Blood consists of 55% plasma and 45%

by cells called formed elements.

The blood performs a lot of important functions. By means of the hemoglobin contained in the

erythrocytes, it carries oxygen to the tissues and collects the carbon dioxide (CO2). It also conveys

nutritive substances (e.g. amino acids, sugars, mineral salts) and gathers the excreted material which will

be eliminated through the renal filter. The blood also carries hormones, enzymes and vitamins. It

performs the defense of the organism by mean of the phagocitic activity of the leukocytes, the

bactericidal power of the serum and the immune response of which the lymphocytes are the

protagonists.

What are the blood elements ?

Blood has four key elements:

1.Plasma

Plasma is a pale yellow sticky liquid. It makes up 55% of the bloods volume. The components of plasma

are water 92%, dissolved protein 8%, glucose, lipids, amino acids, vitamins, minerals, urea, uric acid, CO2,

hormones, antibodies. Plasma carries dissolved materials such as glucose, amino acids, minerals,vitamins,

salts, carbon dioxide, urea, and hormones. It also carries heat energy, carbon dioxide and waste.


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2.Red blood cells

Red Blood Cells, also called erythrocytes, are tiny biconcave disc-shaped cells. This design helps them tofold over when traveling through the small space of a capillary. They do not have a nucleus. They

transport oxygen because their cytoplasm is rich in hemoglobin. This hemoglobin contains iron, which

attracts oxygen molecules (O2). So oxygen attaches to the hemoglobin and is carried to living cells of

the body, where the oxygen is released to the cells through the capillaries.

Red blood cells are made in the bone marrow. They survive for about three to four months and then die.

They are destroyed and recycled by the liver and spleen. When they die the hemoglobin is stored in the

liver and used to make new blood cells in the bone marrow. They are very small. There are about 5

million red blood cells in 1 cc. of blood. The rest that is not stored is converted into bile pigments.

Anaemiais the lack of hemoglobin or red blood cells. The symptoms of anaemia are pale skin colour and aloss of energy.

3.White blood cells

White blood cells or leucocytes are colourless cells and possess a nucleus. They are larger than red cells

and their main function is to defend body against pathogens or germs. Bacteria and viruses, which are

commonly known as germs, can enter the body through cuts, the nose, throat, and intestines. Germs

can cause infections. Blood will quickly carry white blood cells to an area of the body at which germs


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are invading. Finally, white blood cells attack germs. There are different types of white blood cells.

Some of them feed on pathogens by phagocytosis. These white blood cells are called phagocytes.

Others, the lymphocytes produce antibodies, the specific defense proteins, that attach to the germ andeither break them apart or clump them so that other white cells can eat the germs . Some white blood

cells live only a few hours, while others can live for years. They are made in bone marrow like red blood

cells. White blood cells are an important part of our bodies immune system.

What are the different types of white blood cells?

Neutrophils

The most common (54-62%)

Nucleus have 2-5 lobes

First to arrive to an infection site

Ingest bacteria, virus, particules, protozoa,fungi

Monocytes

2-8% of the white blood cells

Twice the size of the red blood cells

Oval or kidney-bean-shaped nucleus.

Big eaters

They developed into macrophages

Phagocytose bacteria and debris in the tissues.

Basophils

Less than 1% of the white blood cells

Numerous blue granules in the cytoplasm.

Response to various allergens.

Discharge their granules containing histamine and heparin

Produce hypersensitivity.

This can result in hay fever, some forms of asthma,

urticaria (nettle rash) and most seriously anaphylactic shock

Lymphocyte

25-33% of the white blood cells

Slightly bigger than red blood cells

Large nucleus that occupies most of the cell

T cells, B cells and NK cells

T cells: Secretion of chemical signals and destroy abnormal cells.

B cells: Responsible for antibody production.

NK cells:Natural killer cells.They kill cells by releasing small proteins that destroy the targetcell. They do not require activation in order to kill cells.


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Eosinophils

3% of the leukocytes

Bilobed nucleus

Red uniform cytoplasm granules.

Granules contain a chemical which is toxic to many parasites.

Defend our body against parasitic infestations.

They also increase in number in some allergic states. For example their numbersincrease in the nasal and bronchial mucosal linings in hay fever and asthma and in

some adverse drug reactions. It is thought that they may neutralise the effect of

histamine.

4.Platelets

Platelets, also called thrombocytes are not true cells; they are tiny fragments of other cellsmegakaryocytes that were formed in the bone marrow; their life-span is 7-11 days.

Platelets play an important role in blood clotting, by adhering to the site of the wound and releasing

clotting factors.

Unwanted clotting of blood within blood vessels can block the flow of blood a thrombosis. If this

happens in the brain, brain cells may die, causing a stroke; in the coronary artery, it may cause the

death of heart cells a coronary thrombosis.

What is the blood clotting process ?

Blood clotting process

When we are injured with a cut, the platelets immediately

help to begin a series of chemical reactions that stop the

bleeding. There are chemicals called clotting factors found

in the plasma. One forms fibrin, which is made up of long

threads that form a net-like mesh that traps blood cells and

platelets to seal the break. This eventually becomes a clot

that seals the wound while the vessel is repaired.

When the cut is on the skin, the clot becomes a scab

because it hardens in air. In consequence, this is the bodys

way of stopping the loss of blood when you are injured.


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What is the bone marrow?

Blood cells are made in the bone marrow. The bone marrow is the spongy material in the center of the

bones that produces about 95 percent of the body's blood cells.

The production and development of new cells is a process called hematopoiesis. Blood cells formed in

the bone marrow start out as a stem cell. A "stem cell" (or hematopoietic cell) is the initial phase

of all blood cells. As the stem cell matures, several distinct cells evolve such as the red blood cells,

white blood cells, and platelets. Immature blood cells are also called blasts. Some blasts stay in the

marrow to mature and others travel to other parts of the body to develop into mature, functioning

blood cells.

What is the blood test?

A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein

in the arm using a needle, or via fingerprick .

Blood tests take an internal and dynamic 'snapshot' of you. Blood tests are used to determine the

evidence of infection, disease or abnormality. In a blood tests the amount, shape and colour of red

blood cells are studied. Also the amount of each type of white blood cells as well as platelets. In

plasma o serum chemical substances are studied such as: glucose, cholesterol, triglycerides, urea,

proteins, etc.


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What are ABO blood groups?

Blood types are classified in several ways. The most basic system is called ABO, which divides blood

into four groups, or types: A, B, AB and O. The ABO blood system was established by an American

scientist, Karl Landsteiner. He grouped the four human blood types according to the proteins on the

outer coat of their red blood cells. He ran a series of experiments that showed that when mixing red

blood cells from one person with the plasma of another person, sometimes things went smoothly and

other times the blood clotted and clumped up. This clotting would be a dangerous situation because it

could mean blood vessels might be blocked leading to series consequences. He ran further experiments

and found that not all red blood cells contain the same proteins on their outer coatings. He also found

that plasma may contain two different proteins that are needed for clumping cells. This clumping or

clotting is necessary when there is a threat of a foreign invader, such as bacteria or germs. Lansteiner

named the proteins on the red blood cells "A" and" B."

Antigens A and B are two distinct proteins present on the surface of some people's red blood cells.

Each person's blood contains a specific and inherited set of these. So in the ABO system, one antigen

is labeled "A" and the other "B." If the red blood cell has only A antigen on it, that blood is called "type

A". If the red blood cell has B antigen only, that blood is called "type B". If the red blood cell has both

A and B antigens, the blood is called "type AB". If the red blood cell has neither antigen, the blood is

called "type O".

Also, he named the proteins in the plasma anti-A and anti-B, depending on how they reacted with

the A and B proteins from the blood. For instance, if a person with type A blood receives blood from a

type B donor, the anti-B chemicals in the plasma of the type A person will identify the type B red blood

cells as foreign. The anti-B chemicals will cause the type A red cells to clump. So as you can see, it is

important that during a transfusion a person only receives blood that is compatible with his or her blood

type. The chart below shows the ABO blood system.

In addition, type AB is known as a universal recipient, meaning that they can receive any type blood,

whilst O is the universal donor, meaning they can donate blood to anyone.


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Rhesus system or Rh factor

The "Rhesus factor is a protein that an individual either has, or does not have on the surface oftheir red blood cells. People can be Rh positive (Rh+, does have the D antigen) or Rh negative(Rh-,

does not have the D antigen) in addition to the ABO blood type.

If an Rh- person receives a transfusion of blood that has Rh+ antigens, anti-Rh+ antibodies will be

formed and will react with the Rh+ antigen and agglutination (clumping) will occur.

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http://www.biologymad.com/resources/Ch%206%20-The%20Circulatory%20System.pdf

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Blood and It's Elements - T6C

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