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Blood
Chapter 12 - Blood
Introduction
A) Blood, a type of connective tissue, is a complex mixture of cells,
chemicals, and fluid.
B) Blood transports substances throughout the body, and helps to
maintain a stable internal environment.
C) The blood includes red blood cells, white blood cells, platelets,
and plasma.
Introduction
D. Blood Volume and Composition
• Plasma is a mixture of water, amino acids, proteins, carbohydrates,
lipids, vitamins, hormones, electrolytes, and cellular wastes.
• A blood hematocrit (HCT), is normally 45% cells and 55% plasma.
• An average-sized adult has a blood volume of about 5.3 quarts (5
liters).
Blood Cells
A. Red Blood Cells
1. Red blood cells (erythrocytes)- are biconcave discs that contain one-third
oxygen-carrying hemoglobin by volume.
2. When oxygen combines with hemoglobin, bright red oxyhemoglobin results.
3. Deoxygenated blood (deoxyhemoglobin) is darker.
4. Red blood cells discard their nuclei during development and so cannot
reproduce or produce proteins.
Red Blood Cells
Red Blood Cell Counts
1. Typical red blood cell count is 4.6-6.2 million RBC’s per
mm^3 for males and 4.2-5.4 million cells per mm^3 for
females.
2. Number of RBCs is a measure of the blood’s oxygencarrying capacity.
Red Blood Cell Production
1. In the embryo and fetus, RBC production occurs in the yolk sac,
liver, and spleen; after birth, it occurs in the red bone marrow.
2. Average RBC life span = 120 days
3. Stages of RBC formation from hematopoietic stem cells is
displayed in the figure on the next slide.
• Hematopoietic stem
cells in bone marrow
produce RBC’s, WBC’s,
and platelets.
RBC Production and Control
4. Total number of RBC’s remains relatively constant
due to a negative feedback mechanism utilizing
the hormone erythropoietin, which is released from
the kidneys and liver in response to the detection
of low oxygen levels.
• Low blood oxygen causes
the kidneys, and to a lesser
degree, the liver to release
erythropoietin.
• Erythropoietin stimulates
target cells in red bone
marrow to increase the
production of RBCs that
carry oxygen to the tissues.
Dietary Factors Affecting RBC Production
• Vitamins B12 and Folic Acid are needed for DNA
synthesis, so they are necessary for the reproduction of
all body cells, especially in hematopoietic tissue.
• Iron is needed for hemoglobin synthesis.
• A deficiency in RBCs or quantity of hemoglobin results
in anemia.
Destruction of RBCs
• With age, RBC become increasingly fragile and are damaged by
passing through narrow capillaries.
• Macrophages in the liver and spleen phagocytize damaged RBCs.
• Hemoglobin from the decomposed RBCs is converted into heme
and globin.
• Heme is decomposed into iron which is stored or recycled and
biliverdin and bilirubin which are excreted in bile.
• Life cycle
of a red
blood cell
White Blood Cells
White Blood Cells
1. White blood cells (leukocytes) help defend the body against
disease.
2. They are formed from hemocytoblasts (hematopoietic stem cells).
3. Hormones that stimulate WBC production fall into two
categories, interleukins and colony-stimulating factors (CSF’s).
White Blood Cells
4. Five types of WBCs are in circulating blood and are distinguished by size,
granular appearance of the cytoplasm, shape of nucleus, and staining
characteristics.
5. The types of WBCs are…
• Granulocytes = neutrophils, eosinophils, and basophils
• Agranulocytes = monocytes and lymphocytes
Granulocytes
• Neutrophils –
• Red staining
• Fine cytoplasmic granules
• Multi-lobed nucleus
• Compromise 54-62% of leukocytes
Granulocytes
• Eosinophils –
• Deep red staining
• Course granules
• Bi-lobed nucleus
• Make up only 1-3% of
circulating leukocytes
Granulocytes
• Basophils –
• Blue staining
• Few granules
• Account for fewer than 1% of
leukocytes
Agranulocytes
• Monocytes –
• Largest blood cells
• Variably shaped nuclei
• Make up 3-9% of circulating
leukocytes
Agranulocytes
• Lymphocytes –
• Long-lived (years)
• Large, round nucleus
• 25-33% of leukocytes
Functions of WBCs
• Leukocytes can squeeze between cells lining walls of blood vessels by diapedesis
and attack bacteria and debris.
• Neutrophils/Monocytes – Both are phagocytic; the monocytes engulf larger
particles.
• Eosinophils – moderate allergic reactions as well as defend against parasitic
infections.
Functions of WBCs
• Basophils – Migrate to damaged tissues and release
histamine to promote inflammation and heparin to inhibit
blood clotting.
• Lymphocytes – Major players in specific immune
reactions and some produce antibodies.
WBC Counts
• Cubic milliliter of blood = 4,000 to 11,000 WBCs
• Leukocytosis – (higher than 11,000) occurs after an infection when excess
numbers of leukocytes are present. (Bacterial Infection)
• Leukopenia – (lower than 4,000) occurs from a variety conditions, including
AIDS, Measles, Influenza. (Viral Infection)
• A differential WBC count (DIFF) helps pinpoint the nature of an illness
• Lists the percentages of types of leukocytes in a blood sample
Blood Platelets
• Blood platelets (thrombocytes) - fragments of megakaryocytes,
developed from hematopoietic stem cells in response to
thrombopoietin.
• Platelets help repair damaged blood vessels by adhering their
broken edges
• Normal platelet counts vary from 130,000 to 360,000 platelets per
mm^3
Blood Plasma
Blood Plasma
• Plasma – clear, straw colored fluid portion of the blood.
• Contains mostly water (92%) but contains a variety of
substances
• Functions: transports nutrients and gases, regulate fluid and
electrolyte balance, and maintain a favorable pH.
Plasma Proteins
• Plasma proteins are the most abundant dissolved
substances in the plasma.
• Plasma proteins are not used for energy.
• Fall into three groups – albumins, globulins, and
fibrinogen.
Plasma Proteins
• Albumins – help maintain osmotic pressure of the blood, account
for 60% of the plasma proteins
• Globulins – compromise 36% of plasma proteins. Designated as
alpha, beta, and gamma globulins.
• Alpha and Beta globulins – transport lipids and fat-soluble vitamins.
• Gamma globulins – type of antibody
• Fibrinogen – 4% of proteins, Primary role in blood coagulation
Gases and Nutrients
• Most important gases – Oxygen and Carbon Dioxide
• Plasma nutrients include: Amino Acids, Monosaccharides,
Nucleotides, and Lipids
• Lipids are not soluble in the water of the plasma. They
are surrounded by protein molecules for transport
through the bloodstream as lipoproteins.
Non-protein Nitrogenous Substances
• Nonprotein nitrogenous substances generally include
amino acids, urea, and uric acid, creatine, and creatinine.
• Urea and uric acid are the by-products of protein and nucleic
acid catabolism.
Plasma Electrolytes
• Plasma Electrolytes are absorbed by the intestine or are by-products of
cellular metabolism.
• Include: Sodium, Potassium, Calcium, Magnesium, Chloride, Bicarbonate,
Phosphate, and Sulfate Ions,
• Some of these are important in maintaining osmotic pressure and pH of
plasma.
Hemostasis
• Hemostasis – stoppage of bleeding
• Following injury to a vessel, three types of hemostasis can
occur
• 1. Blood vessel spasm
• 2. Platelet plug formation
• 3. Blood coagulation
Blood Vessel Spasm
• Cutting a blood vessel causes the muscle in its walls to contract in
a reflex, or engage in vasospasm.
• This reflex only lasts a few minutes, but it lasts long enough (30
minutes) to initiate the second and third steps of hemostasis.
• Platelets release serotonin at this time = constricting smooth
muscles in the blood vessels (vasoconstriction).
Platelet Plug Formation
• Platelets stick to the exposed edges of damaged blood
vessels, forming a net with spiny processes protruding
from their membranes.
• A platelet plug is most effective on a small vessel.
Platelet plug
formation
Blood Coagulation
• Blood coagulation is the most effective means of hemostasis.
• Very complex – Uses clotting factors
• Damaged tissues release a chemical called tissue thromboplastin,
which activates the first in a series of factors leading to the
production of prothrombin activator.
Blood Coagulation Process
1. Damaged tissues release a chemical called tissue thromboplastin, which activates
the first in a series of factors leading to the production of prothrombin activator.
2. Prothrombin activator converts prothrombin in the plasma into
thrombin. This in turn catalyzes a reaction that converts fibrinogen
into fibrin.
3. The major event in blood clot formation is the conversion of soluble
fibrinogen into net like insoluble fibrin causing the blood cells to catch.
4. Serum is the plasma minus the clotting factors.
5. The amount of prothrombin activator formed is proportional to the
amount of tissue damage.
Blood Coagulation Process
6. Once a blood clot forms, it promotes more clotting through
a positive feedback system.
7. After a clot forms, fibroblasts invade the area and produce
fibers throughout the clots.
• A clot that forms abnormally in a vessel is a thrombus; if it
dislodges, it is an embolus.
• Clotting cascade
Blood Groups
Blood Groups and Transfusions
• After mixed success with transfusions, scientists
determined that blood was of different types and only
certain combinations were compatible.
Antigens and Antibodies
• Clumping of RBCs following transfusion is called agglutination.
• Agglutination is from interaction of proteins on the surfaces of
RBCs (antigens) with certain antibodies, proteins carried in the
plasma.
• Only a few of the antigens on RBCs produce transfusion reactions.
• These include ABO group and Rh group.
ABO Blood Group
• Type A blood has A antigens on RBCs and anti-B antibodies in the plasma
• Type B blood has B antigens on RBCs and anti-A antibodies in the
plasma
• Type AB blood has both A and B antigens, but no antibodies in the
plasma (Universal recipient)
• Type O blood has neither antigen, but BOTH (anti-A & anti-B) antibodies
in the plasma (universal donor)
ABO Blood Group
• Adverse transfusion reactions are avoided by preventing the
mixing of blood that contains matching antigens and antibodies
• Adverse reactions are due to the agglutination of red blood cells.
Rh Blood Group
• Rh blood group – named after rhesus monkey
• If the Rh factor surface protein is present on red blood cells, the
blood is Rh positive; otherwise it is Rh negative (not present).
• There are no corresponding antibodies in the plasma unless a
person with RH-negative blood is transfused with Rh-positive
blood; the person will then develop antibodies for the Rh factor.
Rh Blood Group
• Erythroblastic Fetalis - Rh-negative woman who becomes pregnant with an Rh•
•
•
•
•
positive fetus sometimes develops anti-bodies against the Rh factor in the fetus.
This development usually causes no problem during the woman's first pregnancy,
since the number of anti-bodies produced tends to be small.
By the time a second pregnancy occurs, the situation has changed!
The number of Rh antibodies produced by the mother's body has become large
enough to cause destruction of red blood cells in the fetus.
Can result in complications for fetus such as anemia, jaundice, or premature birth.
Today, this reaction can be controlled by immunizing Rh negative women after their
first pregnancy with a drug known as RhoGam.