The blood volume in an adult averages approximately
The hormonal stimulus that prompts red blood cell formation is
All of the following are true of RBCs except
A)biconcave disc shape
B)life span of approximately 120 days
The most numerous WBC is the
Blood proteins play an important part in
C)maintenance of blood volume
D)all of the above
D)all of the above
The white blood cell that releases histamine and other inflammatory chemicals is the
The blood cell that can become an antibody-secreting cell is the
Which of the following does NOT promote multiple steps in the clotting pathway?
The normal pH of the blood is about
Suppose your blood was found to be AB positive. This means that
A)agglutinogens A and B are present on your red blood cells, there are no anti-A or anti-B antibodies in your plasma, and your blood is Rh+
B)there are no anti-A or anti-B antibodies in your plasma
C)all of the above
C)all of the above
(a) Define formed elements and list their three major categories.
(b) Which is least numerous?
(c) Which compromise(s) the buffy coat in a hematocrit tube?
a. The formed elements are living blood cells. The major categories of formed elements are erythrocytes, leukocytes, and platelets.
b. The least numerous of the formed elements are the leukocytes.
c. The buffy coat in a hematocrit tube is comprised of the white blood cells and platelets. (p. 632)
Discuss hemoglobin relative to its chemical structure, its function, and the color changes it undergoes during loading and unloading of oxygen.
Hemoglobin is made up of the protein globin bound to the pigment heme. Each molecule contains four polypeptide chains (globins) and four heme groups, each bearing an atom of iron in its center. Its function is to bind oxygen to each iron atom. When oxygen is loaded (bound to hemoglobin), the hemoglobin becomes bright red. When oxygen is unloaded from the iron, the hemoglobin becomes dark red. (p. 635)
If you had high hematocrit, would you expect your hemoglobin determination to be high or low? Why?
With a high hematocrit, you would expect the hemoglobin determination to be high, since the hematocrit is the percent of blood made up of RBCs, which contain hemoglobin. (p. 632)
What nutrients are needed for erythropoiesis?
In addition to carbohydrates for energy and amino acids needed for protein synthesis, the nutrients needed for erythropoiesis are iron and certain B vitamins. (p. 638)
(a) Describe the process of erythropoiesis.
(b) What name is given to the immature cell type released to the circulation?
(c) How does it differ from a mature erythrocyte.
a. In the process of erythropoiesis, a hemocytoblast is transformed into a proerythroblast, which gives rise to basophilic, then polychromatic erythroblasts, orthochromatic erythroblasts, and reticulocytes.
b. The immature cell type released to the circulation is the reticulocyte.
c. The reticulocyte differs from a mature erythrocyte in that it still contains some rough ER. (p. 636)
Besides the blood's ability to move by amoeboid motion, what other physiological attributes contribute to the function of White blood cells in the body?
The physiological attributes that contribute to the function of white blood cells in the body include exhibition of positive chemotaxis enabling them to pinpoint areas of tissue damage, diapedesis (moving through capillary walls), and the ability to participate in phagocytosis. (p. 640)
(a) If you had a severe infection . would you expect your WBC count to be close to 5000, 10,000, or 15,000/ul
(b) What is this condition called?
a. With a severe infection, the WBC count would be closest to 15,000 WBC/mm3 of blood.
b. This condition is called leukocytosis. (p. 640)
(a) Describe the appearance of platelets and state their major function.
(b) Why should platelets not be called cells?
a. Platelets appear as small discoid fragments of large, multinucleated cells called megakaryocytes. They are essential for the clotting process and work by clumping together to form a temporary plug to prevent blood loss.
b. Platelets should not be called “cells” because they are only fragments of cells. (p. 645)
(a) Define homostasis.
(b) List the 3 major steps of coagulation. Explain what each phase and what the phase accomplishes.
(c) In what general way do the intrinsic and extrinsic mechanisms of clotting differ?
(d) Which ion is essential to virtually all stages of coagulation.
a. Literally, hemostasis is “blood standing still” because it refers to clotted blood. It encompasses the steps that prevent blood loss from blood vessels. (p. 646)
b. The three major steps of coagulation include the formation of prothrombin activator by a cascade of activated procoagulants, the use of prothrombin activator enzymatically to release the active enzyme thrombin from prothrombin, and the use of thrombin to cause fibrinogen to form fibrin strands. (pp. 647–648)
c. The intrinsic pathway depends on substances present in (intrinsic to) blood. It has many more steps and intermediates, and is slower. The extrinsic mechanism bypasses the early steps of the intrinsic mechanism and is triggered by tissue factor (thromboplastin) released by injured cells in the vessel wall or in surrounding tissues. (pp. 647–648)
d. Calcium is essential to virtually all stages of coagulation. (p. 647)
(a) Define fibrinolysis.
(b) What is the importance of this process?
a. Fibrinolysis is the disposal of clots when healing has occurred.
b. The importance of this process is that without it, blood vessels would gradually become occluded by clots that are no longer necessary. (p. 649)
(a) How is clot overgrowth usually prevented?
(b) List two conditions that may lead to unnecessary (and undesirable) clot information.
a. Clot overgrowth is usually prevented by rapid removal of coagulation factors and inhibition of activated clotting factors. (pp. 649–650)
b. Two conditions that may lead to unnecessary (and undesirable) clot formation are roughening of the vessel wall endothelium and blood stasis. (p. 650)
How can liver dysfunction cause bleeding disorders?
Bleeding disorders occur when the liver cannot synthesize its usual supply of procoagulants. (p. 650)
(a) What is a transfusion reaction and why does it matter?
(b) What are its possible consequences?
a. A transfusion reaction involves agglutination of foreign RBCs, leading to clogging of small blood vessels, and lysis of the donated RBCs. It occurs when mismatched blood is transfused.
b. Possible consequences include disruption of oxygen-carrying capacity, fever, chills, nausea, vomiting, general toxicity, and renal failure. (pp. 663–664)
How can poor nutrition lead to anemia
Among other things, poor nutrition can cause iron-deficiency anemia due to inadequate intake of iron-containing foods or to pernicious anemia due to deficiency of vitamin B12. (pp. 638–639)
What blood-related problems are most common in the aged?
The most common blood-related problems for the aged include chronic types of leukemias, anemias, and thromboembolic disease. (p. 654)
Cancer patients being treated with chemotherapy drugs designed to destroy rapidly dividing cells are monitored closely for changes in their RBC and WBC counts.
Hematopoiesis is a process involving fairly rapid cell production. Because chemothera-peutic drugs target cells exhibiting rapid turnover (rather than other specific properties of cancer cells), hemopoiesis is a target of chemotherapeutic drugs and must be carefully monitored. (p. 636)
Mary Healy, a young woman with severe vaginal bleeding is admitted to the emergency room. She is three months pregnant, and the physician is concerned about the volume of blood she is losing.
(a) What type of transfusion will be probably be given to this patient?
(b) What blood tests will be performed before starting the transfusion?
a. Mary would probably be given a whole blood transfusion. It is essential that she maintain sufficient O2-carrying capacity to serve fetal needs and blood volume to maintain circulation.
b. The blood tests that would be performed include tests for ABO and Rh group antigen and cross matching. (pp. 652–653)
Alan Forsythe, a middle-aged college professor from Boston, is in the Swiss Alps studying astronomy during his sabbatical leave. He has been there for two days and plans to stay the entire year. However, he notices that he is short of breath when he walks up steps and tires easily with any physical activity. His symptoms gradually disappear, and after two months he feels fine. Upon returning to the US, he has a complete physical exam and is told his erythrocyte count is higher than normal.
(a) Attempt to explain this finding.
(b) Will his RBC’s remain at this high level? Why or why not?
a. Polycythemia accounts for his higher erythrocyte count because of the need to produce more RBCs to increase his O2 binding and transport ability in the high-altitude (thinner air) environment of the Alps. Enhanced production of RBCs was prompted by an increased production of erythropoietin, in response to chronic hypoxia.
b. His RBC count will, with time, return to normal. This is because the conditions at lower altitudes make it easier for oxygen to enter the blood, resulting in elevated plasma O2. Elevated plasma O2, coupled with the high number of RBCs, inhibits erythropoietin production by the kidneys. (p. 640)
A young child is diagnosed as having acute lymphocytic leukemia. Her parents cannot understand why infection is a major problem for Janie when her WBC count is so high.
Can you provide an explanation for Janie’s parents?
As a consequence of acute lymphocytic anemia, Janie’s leukocytes are immature or abnormal and are incapable of defending her body in the usual way. (p. 639)
Mrs. Ryan, a middle-aged woman, appears at the clinic complaining of multiple small hemorrhagic spots in her skin and severe nosebleeds. While taking her history, the nurse notes that Mrs. Ryan works as a rubber glue applicator at a local factory. Rubber glue contains benzene, which is known to be toxic to red bone marrow.
Using your knowledge of physiology, explain the connection between the bleeding problems and benzene.
Red bone marrow is the site of hemopoiesis, and if it is destroyed by benzene, hemocy-toblasts will not be produced, which will reduce the production of megakaryocytes (the progenitor cells of platelets, which are involved in clotting). (p. 636)
A reticulocyte count indicated that 5% of Tyler’s red blood cells were reticulocytes. His blood test also indicated he had polycythemia and a hematocrit of 65%.
Explain the connection between these three facts.
Tyler is turning out a high rate of reticulocytes (immature red blood cells), which accounts for his polycythemia and high hematocrit. (p. 636)
In 1998, the US Food and Drug Administration approved the nation’s first commercial surgical glue to control bleeding during certain surgeries. This glue called Tisseel forms a flexible mesh over an oozing blood vessel to help stem bleeding within five minutes. This sealant is made from two blood proteins that naturally cause blood to clot when they react together.
Name these two proteins.
Based on the description of the roles of various proteins in the clotting process, the two blood proteins are thrombin and fibrinogen. (p. 648)
Jenny, a healthy young woman, had a battery of tests during a physical for a new job. Her RBC count was at the higher end of normal range, but four weeks later it was substantially elevated beyond that. When asked if the circumstances had changed in her life she admitted to taking up smoking.
How might her new habit explain her higher RBC count?
An elevated RBC count could be related to smoking, due to the frequent hypoxia that results from inhalation of oxygen-poor cigarette smoke. Chronic hypoxia is a stimulus for the release of erythropoietin, which promotes RBC formation. (p. 640)
Mr Chu has been scheduled for surgery to have his arthritic hip replaced. His surgeon tells him he must switch from aspirin to acetaminophen for pain control before his surgery.
Aspirin is a mild anticoagulant, which could cause excessive bleeding during or after surgery. (p. 650)