Download Lecture Suggestions and Guidelines

CHAPTER 14
BLOOD
LEARNING OBJECTIVE 1: Describe the general characteristics of blood and discuss
its major functions.
Lecture Suggestions and Guidelines
1. Discuss blood volume and composition.
2. Introduce the terms hematocrit, plasma, and buffy coat.
3. Describe the general functions of blood and its role as a transportation medium.
Application Question(s)
1. Ask students to develop a table of the major constituents of blood plasma and
their major functions.
Answer: The table should include a discussion of electrolytes, albumin,
fibrinogen, globulins, nutrients, respiratory gases, hormones, waste products, and
water.
Critical Thinking Issue(s)
1. Describe the meaning of the terms PCV, MCV, MCH, and MCHC.
Answer: PCV, or packed cell volume, is synonymous with hematocrit. PCV is
the percentage of red blood cells in a sample of whole blood. MCV, or mean
corpuscular volume, is the volume per red blood cell. MCV assists in the
determination of classifying red blood cells as macrocytic or microcytic. MCH, or
mean corpuscular hemoglobin, gives the weight of hemoglobin in an average
erythrocyte. MCHC, or mean corpuscular hemoglobin concentration, relates the
size of a red blood cell to its hemoglobin content, and assists in the detection of
hypochromic or hyperchromic red blood cells.
LEARNING OBJECTIVE 2: Distinguish among the formed elements of the blood.
Lecture Suggestions and Guidelines
1. Discuss the origin of blood cells, from stem cells to eventual differentiation.
2. Introduce the terms hematopoeisis, erythropoeitin, thrombopoeitin, and colony
stimulating factors.
3. Describe the characteristics of red blood cells, white blood cells, and platelets.
4. Lecture on the functions of each type of blood cell.
Application Question(s)
1. Students should be able to trace each type of blood cell from its origin as a
hemocytoblast to its mature form. Wall charts, slides, and textbook flowcharts are
helpful.
Answer: Identifying immature forms of blood cells is crucial. This ability is
developed through practice and experience.
Critical Thinking Issue(s)
1. Discuss situations in which one would expect to find a decreased white blood cell
count (leukopenia) and an elevated white blood cell count (leukocytosis).
Answer: Leukopenia is usually due to a decrease in the number of neutrophils
(but not always). Conditions would include acute infections, poisoning, radiation,
hematopoietic diseases, or shock. Leukocytosis may be the result of an increase in
any one or more types of white blood cells. Examples include: 1) neutrophilia—
pneumonia, meningitis, labor, strenuous exercise; 2) eosinophilia—allergic
reactions; 3) basophilia—myeloproliferative diseases; 4) lymphocytosis—acute
infectious mononucleosis, tuberculosis, whooping cough; and 5) monocytosis—
typhoid fever, malaria, Hodgkin’s disease, or infectious mononucleosis.
LEARNING OBJECTIVE 3: Explain the significance of red blood cell counts and how
they are used to diagnose disease.
Lecture Suggestions and Guidelines
1. Introduce the normal ranges of blood cell counts for adults and children.
2. Briefly discuss the current technologies used to perform blood cell counts.
3. Describe various parameters recorded during the performance of a complete blood
count.
4. Define a differential white blood count.
Application Question(s)
1. Apply information from this learning objective to perform an accurate assessment
of a human peripheral blood smear.
Answer: The analysis should include an accurate differential white blood cell
count, a determination of red blood cell morphology, and an estimate as to normal
platelet morphology and count.
Critical Thinking Issue(s)
1. Ask students to report on current technology used to perform blood cell counts.
They may schedule a visit to a local hospital or other medical facility, or directly
contact vendors who sell this technology. Compare/contrast the technological
principles behind each instrument.
Answer: Responses will vary. This is an excellent opportunity to schedule a site
visit for the class to observe actual technology used in the field.
LEARNING OBJECTIVE 4: Discuss the life cycle of a red blood cell.
and
LEARNING OBJECTIVE 5: Explain the control of red blood cell production.
Lecture Suggestions and Guidelines
1. Reiterate the origin of red blood cells.
2. Discuss the roles of the spleen and liver in the destruction of red blood cells.
3. Introduce the terms bilirubin and biliverdin.
4. Summarize the major events in red blood cell destruction.
Application Question(s)
1. What are the major forms of anemia? Ask students to develop a table, which
summarizes the names, causes, and treatments of each.
Answer: The table should include anemias caused by increased rates of
destruction, inadequate hemoglobin content, blood loss, impaired production, and
abnormal maturation.
Critical Thinking Issue(s)
1. What may cause some newborns to appear jaundiced?
Answer: Often, as fetal hemoglobin is converted to a mature form, newborns
appear to be jaundiced as a result of bilirubin, a yellow pigmented byproduct of
red blood cell destruction. Newborns are placed under an ultraviolet light, which
helps to dissociate the bilirubin.
LEARNING OBJECTIVE 6: Distinguish among the five types of white blood cells and
give the function(s) of each type.
Lecture Suggestions and Guidelines
1. Introduce the five major types of white blood cells.
2. Discuss the function of each of the five types. Compare and contrast these
functions.
3. Describe how a total white blood cell count is performed, including a differential
count.
Application Question(s)
1. Ask students to examine a variety of human blood slides. Perform a differential
count for various normal and abnormal white blood cell counts.
Answer: In addition to some normal slides, examine slides of cancer patients,
leukemia patients, patients with allergies/asthma, and patients with bacterial
infection.
Critical Thinking Issue(s)
1. Compare and contrast various types of leukemia.
Answer: Responses should include a discussion of acute and chronic forms. Also,
compare and contrast the differential displayed by myelogenous and lymphocytic
leukemias.
LEARNING OBJECTIVE 7: List the major components of plasma and describe the
functions of each.
Lecture Suggestions and Guidelines
1. Introduce three main plasma protein groups: albumins, globulins, and fibrinogen.
Discuss the functions of each.
2. Describe plasma lipoproteins, including chylomicrons, VLDLs, LDLs, and HDLs.
3. Lecture on the nonprotein nitrogenous substances found in blood plasma.
4. List the major plasma electrolytes and their sources.
Application Question(s)
1. What various blood components and products are commercially available?
Answer: This question provides an excellent opportunity to schedule a site visit
for the class with a local Red Cross office. Products include whole blood, packed
cells, platelets, fresh frozen plasma, etc. Reagents, controls, and supplies related
to blood banking are available from several nationally recognized vendors.
Critical Thinking Issue(s)
1. Why are some plasma lipoproteins considered “good”, while others are
considered “bad”?
Answer: High-density lipoproteins (HDL) are considered “good” lipoproteins
because they transport chylomicron remnants to the liver for processing. On the
other hand, low-density lipoproteins deliver cholesterol to various cells, and are
thus sometimes referred to as “bad” lipoproteins.
LEARNING OBJECTIVE 8: Define hemostasis and explain the mechanisms that help
to achieve it.
Lecture Suggestions and Guidelines
1. Introduce the terms hemostasis and coagulation.
2. Discuss various hemostatic mechanisms, including blood vessel spasms, platelet
plug formation, and blood coagulation.
3. Describe the extrinsic and intrinsic clotting mechanisms.
Application Question(s)
1. Apply the hemostatic mechanisms to a real situation, for instance, a cut finger.
Answer: The textbook mentions three major hemostatic mechanisms: 1) the
blood vessel spasm; 2) platelet plug formation; and 3) blood coagulation.
Discussions should include the stimulus and effect for each mechanism.
Critical Thinking Issue(s)
1. Discuss the consequences of the failure of a formed clot to dissolve.
Answer: Responses should include the danger of a thrombus, in which the clot
continues to adhere to the vessel wall resulting in possible blood circulation
occlusion, and secondly, the danger associated with an embolus, in which the clot
dislodges into the circulation where it may cause a blockage in the kidneys, lungs,
or brain.
LEARNING OBJECTIVE 9: Describe the major steps in hemostasis.
and
LEARNING OBJECTIVE 10: Explain how to prevent coagulation.
Lecture Suggestions and Guidelines
1. Reiterate the major steps in blood coagulation, utilizing both the extrinsic and
intrinsic clotting mechanisms.
2. Introduce thirteen clotting factors, their sources, and mechanisms employed.
3. Describe prothrombin time and partial thromboplastin time.
4. Compare a thrombus to an embolus.
5. Discuss a variety of ways in which coagulation may be prevented.
Application Question(s)
1. Compare and contrast the extrinsic and intrinsic clotting mechanisms. Ask
students to develop flow charts for each mechanism from tissue damage to blood
clot formation.
Answer: The extrinsic and intrinsic blood clotting mechanisms are detailed in the
textbook.
Critical Thinking Issue(s)
1. Discuss the hemorrhagic disorder known as hemophilia.
Answer: Hemophilia is an inability to clot normally, however, platelets are
normal in the hemophiliac. This disease results from a deficiency of a normally
functioning Factor VIII, a plasma protein. Hemophilia occurs primarily in males
and is a hereditary disease, being transmitted by females. Bleeding into the joints
is painful and debilitating. Transfusions and the administration of clotting protein
concentrates are possible treatments.
LEARNING OBJECTIVE 11: Explain blood typing and how it is used to avoid adverse
reactions following blood transfusions.
Lecture Suggestions and Guidelines
1. Introduce antigens, antibodies, and their role in agglutination.
2. Discuss the concept of ABO blood groups.
3. Describe the Rh antigen.
4. Summarize the antigens and antibodies associated with Type O, Type A, Type B,
and Type AB blood.
5. Discuss compatible blood types, universal donors, and universal recipients.
Application Question(s)
1. Apply the concepts of this learning objective by typing the students’ blood. If
class size is a limitation, select a few volunteers. The concepts of ABO/Rh blood
typing are more readily understood when the students have a vested interest.
Answer: Discuss the results of the blood typing demonstration.
Critical Thinking Issue(s)
1. What complications might arise for patients who have multiple transfusions over
a prolonged period of time?
Answer: A major concern is that these patients may develop antibodies resulting
from a history of transfusions. It then becomes a more complicated process to find
compatible blood for that patient, should the need for future transfusions arise.
LEARNING OBJECTIVE 12: Describe how blood reactions may occur between fetal
and maternal tissues.
Lecture Suggestions and Guidelines
1. Discuss the Rh blood group.
2. Describe a scenario in which an Rh-negative mother gives birth to a second Rhpositive baby.
3. Discuss complications, which may arise by receiving Rh-incompatible blood.
4. Explain the use of RhoGam.
Application Question(s)
1. Give real-life examples of Rh-negative mothers who gave birth to a second Rhpositive baby. Discuss the consequences of this situation being ignored.
Answer: It is surprising to find how many students have never heard of RhoGam
and its application in the prevention of HDN.
Critical Thinking Issue(s)
1. Compare the adverse blood reactions, which may occur between maternal and
fetal tissues with possible adverse reactions of an Rh-negative patient receiving
Rh-positive blood.
Answer: The final results are similar. If an Rh-negative individual receives Rhpositive blood, he will likely begin to accumulate anti-D antibodies. Upon
repeated transfusions of Rh-positive blood, the newly formed antibodies are likely
to recognize the transfused red blood cells (containing D antigen) as foreign and
destroy them. Likewise, during HDN, the fetal Rh-positive cells will be attacked
by the anti-D antibodies, which had previously been formed maternally, and are
now crossing the placenta.
RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Anemia—A decrease in the total amount of hemoglobin in a given volume of
whole blood. It is caused from defects in the synthesis of components of the red
blood cell, increased destruction of the red blood cell, and/or a loss of red blood
cells that is greater than the synthesis.
2. Disseminated Intravascular Coagulation—Complication of many disorders
ranging from cancer to infections. It involves an abnormal clotting mechanism
with generalized hemorrhaging.
3. Acute Lymphocytic Leukemia—Known primarily as a children’s disease, it is the
most common cancer in children. Onset occurs between the ages of 2–14 years,
with an abrupt onset and fast progression. The prognosis with radiation therapy
and chemotherapy is generally good.
SUGGESTIONS FOR ADDITIONAL READING
Antman, Karen. September 1996. When Are Bone Marrow Transplants Considered?
Scientific American.
Blaese, R. Michael. June 1997. Gene Therapy for Cancer and Aids. Scientific American.
Blood. 1993. An excellent collection of wonderfully illustrated articles, available from
the Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase,
Maryland, 20815-6789.
Edginton, Stephen M. October 1992. New horizons for stem cell bioreactors.
Bio/Technology. Cultured stem cells could treat many disorders.
Gillis, Anna Maria. September 1993. As good as blood? BioScience. Blood substitutes
would be a breakthrough.
Morgan, Kendall. January 18, 2003. Blood-clot surprise: finding may explain a danger of
Viagra. Science News, vol. 163, no. 3, pg. 38.
Radetsky, Peter. March 1995. The mother of all blood cells, capable of generating an
endless supply of red cells, white cells, and platelets, have also generated a heated
scientific controversy—and millions of dollars for the man who claims to have found
them.
Rutherford, C. J. and H. S. Kaplan. March 16, 1995. Autologous blood donation—can we
bank on it? New England Journal of Medicine, vol. 332. Because of the risk of
infection and a blood storage, many people donate their own, for future needs.
Seppa, Nathan. December 14, 2002. First-Line Treatment–Chronic leukemia drug clears
a big hurdle. Science News.