A. Function of Blood is to transport needed materials such as
1. Oxygen
2. Carbon Dioxide
3. nutrients (glucose)
4. waste products
5. Hormones
6. antibodies
B. amount of blood is 4-6 liters
C. Blood is composed of
1. formed elements
a. Red Blood Cells-Erythrocytes
b. White Blood Cells-Leukocytes
c. Platelets-Thrombocytes
2. Plasma - liquid portion
of blood; contains
a. water
b. proteins
c. electrolytes
d. nutrients
e. wastes
D. RBC's
1. Biconcave disc; about same size in
diameter as capillaries are wide
2. No nucleus means
a. can't repair damage
b. lifespan of about 120
days
3. filled with molecules
of Hemoglobin
- an iron containing molecule that binds and transports Oxygen
- responsible for the color of blood
4. The process of making new RBCs to replace those that die is known as erythropoiesis
a. 2.5 millionRBCs are lost per second
b. dead cells removed by liver and spleen
c. erythropoieses takes place in
bone marrow
1) ribs
2) cranial bones
3) sternum
4) proximal limb bones
5. The rate in which RBCs are produced is controlled by Oxygen levels in the kidney
a. low oxygen ( hypoxia )
- caused by a loss of RBCs means that there are not
enough cells to transport O2
b. the kidney will release a hormone called erythropoietin into the blood.
c. this hormone stimulates starter cells, hemocytoblasts, to divide more rapidly thus producing more RBCs
d. our bodies make about 2.52
million RBCs per second
E. WBCs
2. two types
a. Granular - lobed nuclei with cytoplasmic granules.
1). Neutrophils-phagocytosis
2). Eosinophils-phagocytosis of antibody-marked bacteria, allergic reactions
3). Basophils-anticoagulent
b. Non-granular - unlobed nuclei without cytoplasmic granules.
1). Lymphocytes-immune response, antibody production
2). Monocytes-phagocytosis
F. Platelets-
1. Important in blood clotting
2. When blood vessel is cut platelets clump together called platelet aggregation
3. Release a clotting chemical called serotonin
4. Serotonins cause local vasoconstriction
5. Contain contractile proteins
6. In the coaggulation phase of the blood clot, fibrinogen is converted to fibrin. This covers the platelet plug and passing blood cells become trapped in the fibrin causing a blood clot to form.
G. Blood Types
1. RBCs may have molecules
(antigens) on the surface of their membranes that are not
found on the membranes of other cells
2. two categories of molecules
a. ABO
b. Rh
3. ABO system
a. two possible antigens
1). A
2). B
b. the presence or absence of these 2 antigens in the membranes of RBCs
determines an individual's blood type
c. antigens not found on an individuals RBCs are "foreign" molecules and
that
individuals immune system will produce antibodies
against it
Blood Type
Antigen Present
Antibodies Present
1. A
A Anti-B
2. B B Anti-A
3. AB A,B none
4. O neither Anti-A, Anti-B
!!! If transfuse the wrong blood type, it will be attacked and will clump, which blocks the system. Called a glutination reaction!!!!
H. Rh system
1. consists of one type of molecule that is either present or not present
on the membrane of RBCs
a. if present = Rh+ (85% of US population)
b. if not present = Rh-
2.
Rh negative individuals do not have the Rh molecule (antigen) on their
RBCs, so if exposed to the Rh antigen their immune system will
produce antibodies.
!! Erythroblastis fetalis - condition of in utero baby where baby is
Rh+
and
mother is Rh-
. First time around everything is ok, but when the placenta
breaks, the baby's Rh antigen
causes the mother's body to produce antibodies.
So, when the mother becomes
pregnant again the mother's body will view baby's
blood as foreign and attack
it.
Useful links:
Human Physiology: Blood & Body Defenses I
Human
Physiology: Blood & Body Defenses II