Blood
Blood composition (Connective tissue that has several components) Hematocrit – the total composition
in percentages of the components of blood volume.
A. Plasma – approximately 55% of whole blood. This is a non-living matrix and is the least dense
component of blood, and does contain fibrous proteins that become visible during clotting.
Composed of about 90% water. Albumin, a plasma protein is a carrier of molecules and is an
important blood buffer.
a. Solutes in plasma:
Proteins – albumin, globulins, fibrinogen
Non-proteins nitrogenous substances
Organic nutrients – from digestion
Electrolytes – sodium, potassium, calcium, magnesium, chloride, phosphate, sulfate,
Respiratory gasses – Oxygen, Carbon Dioxide
Hormones- steroid and thyroid hormones
B. Buffy coat - <1% of whole blood. Contains leukocytes (white blood cells) and platelets
C. Erythrocytes – (red blood cells) about 45% of whole blood, and is the densest component.
Erythrocytes do not have a nucleus or significant organelles. They are essentially bags of
hemoglobin (97%). The biconcave shape increases surface area for gas exchange.
a. Hemoglobin is made of a protein (globin)and a heme group. Heme pigment has iron as
it’s center. Oxygen binds to the hemoglobin and turns the heme group bright red.
When oxygen leaves the heme group it turns dark red.
b. Disorders with erythrocytes
i. Anemia – abnormally low O2 carrying capacity. Results in fatigue, paleness,
short of breath and chills. Caused by:
1. Low number of red blood cells.
2. Low hemoglobin – low iron content
3. Abnormal hemoglobin – sickle-cell anemia
ii. Polycythemia – many blood cells – excess of red blood cells.
1. Too much EPO (erythropoietin)
2. Bone marrow cancer
3. Blood doping
D. Leukocytes – white blood cells ( Never Let Monkeys Eat Bananas )
a. Neutrophils – bacteria slayers by phagocytosis
b. Lymphocytes – Two types T and B
i. T – lymphocytes – attack virus infected cells and tumor cells
ii. B – lymphocytes – give rise to plasma cells which produce antibodies.
c. Monocytes – largest leukocyte. When they migrate from the blood they morph into
macrophages with big appetites for viruses, parasites, and infections in general.
d. Eosinophils – lead the counterattack against parasitic worms that are too large to be
phagocytized by the monocytes.
e. Basophils - cytoplasm contains histamine that attracts other leukocytes.
E. Platelets – the broken down pieces of a megakaryocyte. These fragments are essential for blood
clotting. They are not cells any longer and typically degenerate in 10 days unless they are
involved with clotting.
Hemostasis – the stoppage of bleeding (blood clotting)
A. Vascular Spasm – vessel responds to injury by constricting
B. Platelet Plug formation – platelets become sticky and form a clot that temporarily seals off the
break in the vessel wall. This is done with positive feedback. Until coagulation
C. Coagulation – fibrin threads reinforce the platelet plug and act as molecular glue.
After the clot is no longer needed (repair has occurred) fibrinolysis occurs - (break down of the clot
with plasmin, a fibrin digesting enzyme.)
Disorders with Blood clotting
A. Thrombus – an unbroken down clot within a vessel
B. Embolus – a thrombus that has broken free from the vessel and is moving through the blood
vessels.
C. Embolism – a stuck embolus
D. Thrombocytopenia – platelet deficiency – failure to clot, results in body wide bruising
E. Liver impairment can reduce procoagulants. Without enough clotting factors, the blood fails to
clot
F. Hemophilia – genetic lack of clotting factors. Results in inability to clot after damage to vessels.
Blood Groups A B O Each type has different glycoproteins on the surface of the blood cell and act as
antigens and cause clotting or agglutination. If the wrong type of blood is transfused into a person, the
immune system sees this blood as foreign and attacks it, causing the blood to clot up. This can be fatal.
A. Blood typing is based on the presence or absence of two agglutinogens (Type A and Type B)
B. Type A will only have the A agglutinogen, Type B will have the B Agglutinogen, Type AB will have
both agglutinogens, Type O will have neither.
Rh factor
A. There are 45 different types of Rh agglutinogens called Rh factor.
B. Most Americans are Rh positive (85%)
C. Rh factor is written with the blood type ( A+ or B- etc. )
D. Transfusing positive blood into a person who is Rh- will eventually result in destruction of the
donor’s blood if transfused more than once.
Transfusion Reactions –
A. Agglutination – blood clotting
B. Hemolysis – destruction of donor blood cells