Blood


Functions of Blood:

1) Transports things. (Oxygen/Carbon Dioxide, nutrients, water, hormones)
2) Defends against toxins (harmful chemicals) and pathogens (harmful biologicals)
3) Stabilizes body temperature

Anatomy of Blood:

Plasma: mostly water, with some proteins.
  • Albumins: contribute towards osmotic pressure. This allows water to move into cells from the plasma.
  • Immunoglobulins: Antibodies that help fight toxins and pathogens.
  • Fibrinogen: functions in blood clotting.

Hematocrit: The percentage of whole blood occupied by cellular elements.
http://saypeople.com/wp-content/uploads/2011/06/Red-blood-cells.jpg
http://saypeople.com/wp-content/uploads/2011/06/Red-blood-cells.jpg

  • Erythrocytes: Red blood cells (RBC's). Transports oxygen and carbon dioxide through the use of a protein known as hemoglobin. Erythrocytes have no nucleus and a bi-concave disc shape (see picture).









  • Leukocytes: White blood cells
    http://www.bacteria-world.com/white-blood-cell.jpg
    http://www.bacteria-world.com/white-blood-cell.jpg
    (WBC's). Help defend the body against toxins and pathogens.
    • Neutrophils: Most common. These cells phagocytize (eat) bacteria. Neutrophils die from this process and release chemical signals that attract more neutrophils to the area.
    • Eosinophils: Attack and phagocytize substances that have already bonded to an antibody.
    • Basophils: Release heparin (prevents blood clotting) and histamine (encourages inflammation). These changes increase the number of other leukocytes that visit the area.
  • Platlets: Fragments of a type of blood cell. These cell bits aid in blood clotting.

Blood Clotting
  1. Vascular Phase: After an injury occurs, smooth muscle in the blood vessel walls contracts. This makes the opening of the would smaller and slows the loss of blood.
  2. Platelet Phase: Platelets stick to the epithelial tissue near the wound. This may form a plug that stops blood from leaving the break in the blood vessel.
    http://www.bss.phy.cam.ac.uk/~jrb75/fibrin.jpg
    http://www.bss.phy.cam.ac.uk/~jrb75/fibrin.jpg
  3. Coagulation Phase: Circulating fibrinogen (dissolved in the plasma) turns into fibrin (insoluble in water). This fibrin looks like a spiderweb (in blue-green in photo) and forms a network that seals off the damaged area of the blood vessel.

Blood Types and Transfusions

Human blood (and most other tissues) have many 'factors' that a mammalian immune system can detect and build antibodies against. First some vocab:
http://www.emc.maricopa.edu/faculty/farabee/biobk/antigenAB.gif
http://www.emc.maricopa.edu/faculty/farabee/biobk/antigenAB.gif

Antigen: Any thing with a molecular shape that the body can potentially make antibodies against.

Antibodies: A chemical with a complimentary shape to a specific antigen.

Gene: A specific area of DNA common to all members of a species (eye color in humans).

Allele: A type of a gene. (brown or blue colored eyes)

Genotype: The specific alleles that each parent donated.

Phenotype: How the genotype appears in the physical world in the organism.

Human Blood Types
ABO System
Blood Type
Phenotype
Genotype
A
A
AO, AA
B
B
BO, BB
AB
AB
AB
O
O
OO
Rh System

Blood Type
Phenotype
Genotype
+
+
++, + -
-
-
--
Each type of blood has the following characteristics:
ABO
Blood Type
Antigen
Antibody
A
A
Anti-B
B
B
Anti-A
AB
A and B
none
O
none
Anti-A and Anti-B
Rh
Blood Type
Antigen
Antibody
+
+
none
-
none
none, unless previously exposed to + blood. After exposure to + blood it will have Anti-+ Antibodies
Blood Transfusions
Transfusing blood means moving blood products from a donor (one who gives the blood products away) to a receipient (one who gets the blood products).

In order to prevent the recipient's body from attacking and destroying the blood, a blood match must be found. The following rules will help:

  1. Consider the Antigen of the blood (its type) from the donor.
  2. Consider the Antibody of the blood of the recipient.
  3. If the Antigen and Antibody are complimentary that means there will likely be an immune response and the blood will be rejected.

By applying the above rules we can begin matching for blood transfusions. Example, Recipient AB is receiving B blood. Is it a match? Rule 1: Antigen of B type blood is B. Rule 2: Antibody status of recipient is none. Rule 3: No antibodies in recipient means they cannot reject the B antigen. No complimentary antigen/antibody match means it's a good transfusion.

Using all the information above, one can develop the following table:

ABO

Donor A
Donor
B
Donor
AB
Donor
O
Recipient A
Match



Recipient
B

Match


Recipient
AB


Match

Recipient
O



Match

Rh


Donor +
Donor -
Recipient +
Match

Recipient -

Match