Blood groups and blood types

Blood is characterized into different blood groups

based on the

presence or absence of glycoprotein and glycolipid antigens

(agglutinogens) on the surface of red blood cells

There are 24 blood groups

more than 100 antigens

A and B antigens

are glycoproteins found on

the surface of red blood

cells

AB

is co-dominant

Type O does not have

these antigens

O like zero

Blood plasma usually contains

immune system antibodies

(agglutinins)

that identify and

bind with A or B antigens from

blood that does not match

Antibodies

An individual will not have

antibodies against their own

blood type

Blood plasma usually contains

immune system antibodies

(agglutinins)

that identify and

bind with A or B antigens from

blood that doesn’t match

An additional antigen, sometimes called Rh(D) antigen,

is present on RBCs in 85% of humans

If present: Rh positive (like A+)

• If absent: Rh negative (like O-)

Rh positive

can give to Rh positive

Rh negative

can give to Rh negative or positive

Rh negative

can only receive from other Rh negative

Typing and cross-matching are performed to determine

a person’s blood type

A drop of blood is mixed with an antiserum containing

antibodies that will agglutinate (clump) RBCs that

possess specific A or B antigens that bind with it

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While whole blood transfusions do sometimes happen,

they are not as common

Type B could give to Type B

Vs fractionation, where the blood components are

separated, is more common

Red blood cells to one person, plasma to another,

platelets to someone else

If blood types incompatible

recipient’s antibodies

agglutinate donor’s RBCs

Type O is “universal donor”

because lacks A and B

antigens

• Recipient’s antibodies won’t agglutinate donor’s Type O

RBCs

Type AB is “universal recipient

because doesn’t

make anti-A or anti-B antibodies

• Won’t agglutinate donor’s RBCs

If the fetus is Rh+ and the parent is Rh−,

the parent will

develop antibodies to the Rh factor

Current fetus won’t be attacked

The antibodies will attack next Rh+ fetus

For next Rh+ fetus

Anti-Rh antibodies (or sometimes called

anti-D antibodies) enter the fetus’ bloodstream and attack

their RBCs, causing agglutination and hemolysis. Usually

fatal for the fetus

Rh− parents (who would carry the fetus) can

now receive a shot, called RhoGAM

Prevents anti-Rh

antibodies being created in the first place.

• GAM stands for gamma globulin

Hematocrit

is the measure of what percentage of your blood

is red blood cells

After centrifuging it

ed blood cells gather at the bottom of

the tube

average 38-53% hematocrit is typical

For cisgender men: 41-53%

• For people who menstruate: 36-46%

• For post-menopausal cisgender women: 38.3 ± 2.4%1

(tends to increase from 40-65 as menstruation becomes

more irregular)

Heparin

“blood thinner” = anticoagulant

Blood into heparinized tube

This way blood can get properly centrifuged without

clotting first

A dark red column should fill the bottom portion of the tube

This area contains red blood cells (erythrocytes; RBCs), the heaviest blood components

A thin white layer called the buffy coat should be directly above the RBCs.

This area contains white blood cells (leukocytes; WBCs) and platelets (thrombocytes).

A pale, straw-colored fluid, blood plasma

should appear above the buffy coat

Use a hematocrit reader card to ascertain the percentage of RBCs in the subject’s blood sample

(packed cell volume; PCV