What is blood?

• Blood is a mixture of several different components that are responsible for circulating nutrients, gases, and wastes– It contains enzymes, cells, proteins,

hormones, and inorganic substances as well as many other substances

• Fluid portion of blood is called plasmaMostly water (55% of blood volume)

What makes up our blood?• RED BLOOD CELLS (Erythrocytes) – The most abundant

cells in our blood; they are produced in the bone marrow and contain a protein called hemoglobin that carries oxygen to our cells.

• WHITE BLOOD CELLS (Leukocytes) – They are part of the immune system and destroy infectious agents called pathogens.

• PLASMA – This is the yellowish liquid portion of blood that contains electrolytes, nutrients and vitamins, hormones, clotting factors, and proteins such as antibodies to fight infection.

• PLATELETS (Thrombocytes) – The clotting factors that are carried in the plasma; they clot together in a process called coagulation to seal a wound and prevent a loss of blood.

Blood Characteristics

• Plasma is the fluid portion of the blood (55%)

• Cells (45%)– Erythrocytes are red blood

cells. They are responsible for oxygen distribution.

– Leukocytes are the white blood cells; they are responsible for “cleaning” the system of foreign invaders.

– Thrombocytes or platelets are responsible for blood clotting

• Serum is the liquid that separates from the blood when a clot is formed.

Red blood cells

• Contain antigens on their surfaceProteins attached to the cells surface that

stimulate the body to produce antibodies against it

• Humans have several different types of antigens on their blood– Most common = A or B

Historical Perspective of Blood Typing

Around 1900, Karl Landsteiner discovered that there are four different types of human blood based on the presence or absence of specific antigens found on the surface of the red blood cells.

In 1940, Landsteiner and Weiner reported the discovery of the Rh factor by studying the blood of the Rhesus monkey. 85% of Caucasians, 94% of Black Americans and 99% of all Asians are Rh positive.

Blood Terminology• ABO blood groups based on having an A, B, both or no

antigens on red blood cells• Rh factor may be present on red blood cells; positive if

present and negative if not• Antigen a substance that can stimulate the body to make

antibodies. Certain antigens (proteins) found in the plasma of the red blood cell’s membrane account for blood type.

• Antibody a substance that reacts with an antigen• Agglutination clumping of red blood cells; will result if

blood types with different antigens are mixed

A-B-O blood typing

• Fundamental principle in blood typing is that for every antigen, there exists a specific antibody

• Antibody – produced by the body’s immune system when exposed to “foreign” proteins (antigens)– Found in the serum

A-B-O blood typing

• Antibodies are specific to the antigen (protein) which elicited their formation– Will not fight other antigens

• Works like a lock and key Once antigen and antibody unite, creates a

antigen-antibody complex which is detectable in the lab

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

There are 3 alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations.

Blood Types

AA or AO = Type ABB or BO = Type B

OO = Type OAB = Type AB

Blood Typing

• Blood type A has antigen A on the surface of the cell and will agglutinate with blood type B.

• Blood type B has antigen B on the surface of the cell and will agglutinate with blood type A.

• Blood type AB has antigens A and B on the surface of the cells and will not agglutinate with either type A or B blood.

• Blood type O has neither antigen A or B and will not agglutinate.

Blood Groups

Type Antigen Antibody Can GiveBlood To

Can GetBlood From

A

B

AB

O

A

B

A and B

NeitherA nor B

B

A

NeitherA nor B

A and B

A, AB O, A

B, AB O , B

AB

A, B, O, AB

A, B, O, AB

O

How common is your blood type?

46.1%

38.8%

11.1%

3.9%