BLOOD AND DISORDERS
BIO 238
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Blood is confined within the heart and blood vessels
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Functions of blood

Carry substances throughout the body
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Examples: oxygen and wastes
Regulate pH of body tissues
 Prevent excessive blood loss due to hemorrhage
 Fight infections
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GENERAL CHARACTERISTICS OF BLOOD
Blood is a fluid connective tissue
 It is heavier and more viscous then water
 Blood pH ranges between 7.35 and 7.45
 Male blood volume: 5-6L
 Female blood volume: 4-5L
 Blood is ~8% of body weight

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55% of blood volume
consists of plasma
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Liquid matrix of blood
45% of blood volume
consists of formed
elements
Most are red blood cells
 1% are white blood cells
and platelets

RED BLOOD CELLS
Also called erythrocytes
 Transports oxygen and carbon dioxide
 Biconcave shape allows for maximal surface area
for gas diffusion
 Mature RBCs lack a nucleus
 Most numerous formed element
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HEMOGLOBIN
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Forms 33% of RBC volume
Red pigment
Components
Heme: iron containing pigment
 Globin: protein
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Binds oxygen (to a small degree carbon dioxide)
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Oxygen-carrying hemoglobin is called oxyhemoglobin

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Bright red color
Oxygen-deficient hemoglobin is called
deoxyhemoglobin

Dark red color
CONCENTRATION OF RBCS
Most abundant formed element
 Red blood cell count: clinical test to
determine RBC number in a mm3 of blood
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Adult males>Adult females
Males have higher metabolism; needs more O2
Increases with higher altitude
Hematocrit: the percentage of RBC per
volume of blood
PRODUCTION

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Prior to birth, RBCs are produced by liver and
spleen
After birth, RBCs are produced by red bone
marrow
If blood oxygen level is low, erythropoietin is
released by liver and kidneys
 Stimulates red bone marrow to make more
RBCs

Other factors required for production
Iron is required for hemoglobin production
 Folic acid and vitamin B12 are needed for DNA synthesis
during RBC formation

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B12 absorption from diet requires intrinsic factor secreted by the
stomach lining
All RBCs develop from hemocytoblasts in red bone
marrow
LIFE SPAN AND DESTRUCTION

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Live ~120 days
Worn out RBCs are removed by phagocytes in
liver and spleen
Break down of heme

Breaks into iron-containing compound and bilirubin
Iron is recycled to form more hemoglobin
 Bilirubin is secreted by liver into bile, which enters the
small intestine

WHITE BLOOD CELLS
Also called leukocytes
 Formed from hemocytoblasts in bone marrow
 Cells retain their nuclei
 ~4,500 to 10,000 per mm3 of blood
 WBC count increases whenever the cells encounter
disease causing organisms or chemicals

 Function

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Provide defense against disease organisms or
promote and decrease inflammatory responses
Cells perform their functions within tissues
 Cells can migrate from blood into tissue
 Cells then follow a chemical trail to the site of
damage
TYPES OF LEUKOCYTES

Grouped into two broad categories
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Granulocytes: possess cytoplasmic granules
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Neutrophils, eosinophils, basophils
Agranulocytes: lack cytoplasmic granules
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Lymphocytes, monocytes
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Neutrophils
Most abundant
 First WBCs to respond to tissue damage
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Number increases with acute bacterial infections
Eosinophils
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Functions
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Perform phagocytosis and release the enzyme lysozyme
Neutralize histamine released during allergic reactions
Destroy parasitic worms
Number increases during allergic reactions and parasitic worm
infections
Basophils
Those that move into tissues are called mast cells
 Functions in damaged tissues and during allergic reactions
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Release histamine, which dilates blood vessels to increase blood flow
Release heparin, which inhibits clot formation
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Lymphocytes

Two types
T lymphocytes
 Attack and destroy pathogens
 B lymphocytes
 Produce antibodies that attack bacteria and bacterial toxins
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Monocytes

Function

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Phagocytosis of bacteria and cellular debris
Once in tissues, they are called macrophages
PLATELETS
Also called thrombocytes
 Cytoplasmic fragments of megakaryocytes that
develop from hemocytoblasts
 ~150,000 to 400,000 per mm3 of blood
 Functions

Plug breaks in blood vessels
 Begin the clotting process
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PLASMA
Straw-colored fluid portion of blood
 90% water containing dissolved solutes and formed
elements
 Contains a variety of solutes that are kept in a state
of dynamic balance
 Plasma Proteins
 Most abundant solutes
 Most are produced by the liver
 Three types of plasma proteins
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Albumins
 Globulins
 Fibrinogen
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Albumins
Most abundant protein
 Buffers to maintain pH of blood
 Maintain osmotic pressure of blood
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Globulins
Alpha and beta globulins carry lipids and fat soluble vitamins in
blood
 Gamma globulins are antibodies involved in immunity
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Fibrinogen
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Vital role in blood-clotting process
 Converted into insoluble fibrin to form blood clots
 Nonprotein
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Substances
Amino acids: nutrients
Urea and uric acid: waste products of protein
Electrolytes
Ions absorbed from intestine or released from cells
 Most common are Na+, K+, Ca++, Cl-, HCO3-, PO4—
 Help maintain osmotic pressure and plasma pH
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HEMOSTASIS
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Hemostasis is the stoppage of bleeding
Involves three processes
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Vascular Spasm
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Platelet Plug Formation
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Platelets are attracted to damage site and adhere to exposed
connective tissue
Coagulation
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Constriction of the damaged vessel
 Restricts blood loss and lasts several minutes
Clot formation
After clot formation, fibrins contract and pull damaged tissues closer
together
Fibroblasts migrate into clot and repair the damage
Later, tissue plasminogen activator (t-PA) converts plasminogen into
plasmin
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Plasmin breaks down fibrin and dissolves blood clot
HUMAN BLOOD TYPES
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Blood types are determined by specific antigens on RBC
plasma membranes

Antigen: special protein

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Common blood types involve the ABO blood group and the Rh factor
Antibodies in blood will recognize antigens not
found normally on the RBCs of that person
Agglutination occurs when the antibodies bind
foreign antigens

Causes the foreign RBCs to clump together
ABO BLOOD GROUP
Type depends on the presence of antigen A
and antigen B on RBCs
 Four types of blood are possible
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A, B, AB, and O
Blood type will possess antibodies against the
antigens NOT present on the RBCs
 Type AB blood is considered to be a
universal recipient
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It possesses no antibodies so it will not react with
any donated RBCs
Type O is considered to be a universal
donor
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It possesses both antibodies and will react with
all donated RBCs except those of another type O
Transfusion:
donation of whole
blood to an individual
 Blood
is usually of same type
 Care must be taken to ensure blood is
compatible with recipient blood
Incompatible blood can result in
widespread agglutination and fatality
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RH BLOOD TYPE
Rh (D) antigen, first discovered in the
Rhesus monkey
 If the antigen is present, blood is Rh+
 If the antigen isn’t present, blood is Rh

Erythroblastosis Fetalis
 Disorder in newborn infants resulting from
destruction of fetal RBCs by maternal
antibodies
DISORDERS OF THE BLOOD
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Disorders can be grouped as
Erythrocyte disorders
 Leukocyte disorders
 Clotting disorders
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ERYTHROCYTE DISORDERS
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Anemia
Decreased oxygen-carrying capacity of blood
 Most common blood disorder
 Caused by decrease in RBC count or insufficient
hemoglobin
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Nutritional anemia: insufficient iron and vitamin B12 in
diet
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Hemorrhagic anemia: excessive loss of RBCs through
bleeding
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Pernicious anemia: due to deficiency of intrinsic
process
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Prevents absorption of B12
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Hemolytic anemia: premature rupture of RBCs
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Aplastic anemia: due to destruction of red bone
marrow or its inability to produce enough RBCs
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Sickle-cell anemia: due to abnormal
hemoglobin that cannot carry enough
oxygen
Sickled RBCs rupture easily, causing hemolytic
anemia
 Inherited disorder common in African blacks who
lived in malarial regions

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Erythroblastosis fetalis
Due to destruction of fetal Rh+ RBCs by a Rh+ mother’s
anti-Rh antibodies
 Causes anemia, jaundice and presence of erythroblasts in
fetal blood
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Polycythemia
Excessive numbers of RBCs
 Increases blood volume and viscosity, which impairs
circulation
 Possibly due to cancer of RBC forming cells
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LEUKOCYTE DISORDERS
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Infectious mononucleosis
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Contagious disease of lymphoid tissue by the EpsteinBarr virus
Primarily in young adults
Kissing is common mode of transmission
Infects B lymphocytes
Symptoms include fever and sore throat
Lasts from four weeks to months to years
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Leukemia
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Cancers of the cells forming WBCs in bone marrow
Excessive WBC production that inhibits RBC and platelet
production
Acute forms: children or young adults
Chronic forms: adults
Treatments include chemotherapy and bone marrow
transplants
CLOTTING DISORDERS

Hemophilia
Inherited diseases that are more common in males
 Involved spontaneous bleeding and reduced ability to
clot blood
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Due to lack of a clotting factor
Treatment involved transfusion containing missing
clotting factor
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Thrombocytopenia
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Extremely low platelet number that permits spontaneous
bleeding to occur
Thrombosis
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Formation of a clot in an unbroken blood vessel
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If an artery is blocked, tissues are deprived of oxygen
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In areas roughened or damaged
Thrombophlebitis
Embolus: clot that breaks free and floats in blood
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Embolism: free-floating clot lodges in a vessel of the body and blocks
blood flow