Chapter 10 Lecture Notes
Composition and functions of blood (10.1)
Blood is the only fluid tissue.
Formed Elements: living blood cells
Plasma: Nonliving fluid matrix
Physical Characteristics and Volume
Blood is heavier than water and about 5 times thicker, or more viscous
Blood is slightly alkaline, pH between 7.35 and 7.45
Temperature is always slightly higher than the body. 100.4 degrees
Approximately 8% of body weight, in males 5-6 liters
Plasma
90% water
Over 100 different substances dissolved in fluid
i.e. Nutrients, metal ions (salts), respiratory gases, hormones, plasma proteins and
various wastes and products of cell metabolism
Composition of plasma varies continuously as cells remove or add substances to the blood
Formed Elements (10.2)
Erythrocytes: RBC’s
Function primarily to transport oxygen to all cells of the body
Anucleate and contain very few organelles
Contain Hemoglobin: an iron-containing protein.
Hemoglobin transports the bulk of the O2 carried in the blood
RBC’s outnumber WBC’s by about 1000-1
5 million RBC’s / cubic millimeter of blood
Anemia: The decrease in the oxygen-carrying ability of the blood.
Lower than normal # of RBC’s
Abnormal or deficient hemoglobin content
Polycythemia: An excessive or abnormal increase in the # of RBC’s
May result from bone marrow cancer
May be physiological response to living at high altitudes
Leukocytes: WBC’s
Crucial to the body’s defense against disease
4000-11,000 WBC’s/cubic millimeter
Account for less than 1% of total blood volume
Locate areas of tissue damage and infection by responding to chemicals that diffuse
from the damaged cells (positive chemotaxix)
Unable to synthesize proteins, grow or divide
As they age they become more rigid and begin to fragment (100-120 days)
Leukocytosis: Total WBC count above 11,000/cub. mm. which indicates a
bacterial/viral infection.
Leukopenia: Abnormally low WBC count-commonly caused by corticosteroids and
anticancer agents
Leukemia: (“white blood”) Excessive production of abnormal WBC’s. The bone
marrow becomes cancerous and huge numbers of WBC’s are turned out rapidly. The
body becomes easy prey for disease causing bacteria and viruses.
Platelets: Fragments of bizarre multinucleate cells called megakaryocytes which rupture releasing
thousands of anucleate pieces that seal themselves off from the surrounding fluids.
Platelets are needed for normal blood clotting
Hematopoisis: Blood cell formation
Occurs in the red bone marrow (myloid tissue)
In adults the flat bones of the skull and pelvis, ribs, sternum and proximal epiphyses of the
humerus and femur
Hemostasis: Stoppage of blood flow
3 stages
Vascular spasms
Platelet plug formation
Coagulation (blood clotting)
Thrombus: A clot that develops and persists in an unbroken blood vessel. If large enough it may
prevent blood flow to the cells beyond the blockage
Embolus: A thrombus that breaks away from a vessel wall and floats freely in the blood stream.
May lodge in a blood vessel too narrow to pass through (i.e. Cerebral embolus may cause a
stoke).
Thrombocytopenia: Insufficient number of circulating platelets
Normal movements may cause spontaneous bleeding from small blood vessels
Characterized by small purplish blotches on the skin (petechiae)
Can arise from any condition that suppresses myeloid tissue (bone marrow cancer, radiation,
certain drugs).
Hemophilia: A lack of any of the factors needed for clotting
Hereditary
Minor tissue trauma can cause prolonged bleeding and can be life threatening
Patients are given transfusion of fresh plasma or an injection of purified clotting factor they
lack.
Blood Groups:
Plasma membranes of RBC’s bear genetically determined proteins (antigens)
Antigen is a substance that the body recognizes as foreign and stimulates the immune
system to release antibodies.
Most antigens are foreign proteins, such as those that are part of viruses or bacteria
that have managed to invade the body.
One person’s RBC proteins will be recognized as foreign if transfused into another person
with different RBC antigens
The “recognizers” are antibodies present in plasma that attach to RBC’s this causes the
RBC’s to clump (agglutination). Which leads to clogging of small blood vessels of the
body.
ABO blood groups: (table 10.3)
Based of which of two antigens, type A or B a person inherits
Absence of both results in type O
Presence of both results in AB
AB= universal recipient
O= universal donor
Rh blood groups:
Most Americans are Rh+
RBC’s carry the Rh antigen.
If an Rh- person receives mismatched blood, the immune system becomes sensitized and
begins producing antibodies against the foreign blood type
Problems begin to occur at second transfusion of mismatched blood
Rh- mom and Rh+ baby= mom must be treated with RhoGAM shortly after giving birth.
This is an immune serum that prevents the sensitization and the subsequent immune
response.