40 Questions
What percentage of cells are reticulocytes among all red blood cells?
About 1%
What is the function of growth inducers?
To promote growth but not differentiation of cells
What is the term for the process by which reticulocytes pass from the bone marrow into the blood capillaries?
Diapedesis
What is the final stage of development for a red blood cell?
Erythrocyte
What is the function of differentiation inducers?
To cause differentiation of cells
What triggers the growth, differentiation, and production of greatly increased numbers of RBCs?
Exposure to a low oxygen level
What happens to the basophilic material in the reticulocyte?
It normally disappears within 1 to 2 days
What is the role of factors outside the bone marrow?
To control the formation of growth inducers
What is the effect of increased blood viscosity on venous return to the heart?
It decreases the rate of venous return
Why does the body partially compensate for anemia?
Increased cardiac output
What happens to the cardiac output in polycythemia?
It remains nearly normal
Why does anemia lead to tissue hypoxia during exercise?
The heart cannot pump enough blood
What happens to the arterial pressure in most people with polycythemia?
It is normal
What effect does increased blood viscosity have on peripheral resistance?
It increases peripheral resistance
What is the result of the compensatory mechanisms in polycythemia?
Normal arterial pressure
What is the consequence of the heart's inability to pump more blood during exercise in anemia?
Acute cardiac failure
What is the molecular weight of Hemoglobin A?
64,458
What type of chains are found in Hemoglobin A?
Two alpha chains and two beta chains
What is the primary function of leukocytes in the body?
To provide a rapid and potent defense against infectious agents
Where are granulocytes and monocytes formed?
Partially in the bone marrow and partially in the lymph tissue
What is the type of bond between oxygen and the iron atom in hemoglobin?
Coordination bond
What is the form of oxygen that is carried to the tissues?
Molecular oxygen
What is the normal range of platelets per microliter of blood?
150,000 - 450,000
What is the approximate percentage of neutrophils in the total WBCs?
62.0%
What is the function of the heme moiety in hemoglobin?
To bind to oxygen in the lungs
What is the term for the ability of granulocytes and monocytes to 'seek out and destroy' a foreign invader?
Chemotaxis
What is the significance of the loose bond between oxygen and the iron atom in hemoglobin?
It allows oxygen to be released in the peripheral tissue capillaries
How many major lineages of WBCs are formed from the multipotential hematopoietic stem cell?
Two
What is the function of hemoglobin in the body?
To carry oxygen from the lungs to the peripheral tissue capillaries
What is the term for the stem cells that are committed to form specific types of WBCs?
Committed stem cells
What is the result of the oxygen combining with the iron atom in hemoglobin?
The oxygen becomes molecular oxygen
What is the approximate percentage of lymphocytes in the total WBCs?
30.0%
What is the typical blood count of a person with polycythemia vera?
6 to 7 million/mm3
What is the cause of polycythemia vera?
A genetic aberration in the hemocytoblastic cells
What is the typical hematocrit of a person with polycythemia vera?
60% to 70%
What is the main difference between polycythemia vera and physiological polycythemia?
The cause of the condition
What is the typical appearance of a person with polycythemia vera?
Ruddy complexion with a bluish tint to the skin
What is the main benefit of having polycythemia vera at high altitudes?
Ability to perform high levels of continuous work
What is not a characteristic of polycythemia vera?
Vitamin B12 deficiency
What is the typical altitude at which physiological polycythemia occurs?
14,000 to 17,000 feet
Study Notes
Erythrocytes (Red Blood Cells)
- The nucleus of the erythrocyte condenses to a small size and is absorbed or extruded from the cell during the final stage of development.
- The cell at this stage is called a reticulocyte, which still contains remnants of cytoplasmic organelles like the Golgi apparatus, mitochondria, and others.
- Reticulocytes pass from the bone marrow into the blood capillaries by diapedesis, and normally disappear within 1-2 days, becoming mature erythrocytes.
- Growth inducers promote growth but not differentiation of stem cells, which is the function of differentiation inducers.
- Formation of growth inducers and differentiation inducers is controlled by factors outside the bone marrow.
Hemoglobin
- Hemoglobin is composed of a polypeptide portion (globin) and four heme chains, which bind together to form the hemoglobin molecule.
- The most common form of hemoglobin in adults is hemoglobin A, consisting of two alpha chains and two beta chains.
- Hemoglobin A has a molecular weight of 64,458.
- Oxygen binds loosely with the iron atom in the heme moiety, forming molecular oxygen that is carried to the tissues.
Anemia and Polycythemia
- In anemia, the cardiac output increases to partially offset the reduced oxygen-carrying effect, but during exercise, extreme tissue hypoxia results and acute cardiac failure may ensue.
- In polycythemia, the blood volume is greatly increased, but the cardiac output is not far from normal due to increased blood viscosity.
- Arterial pressure is usually normal in polycythemia, but may be elevated in about one-third of cases.
- People with polycythemia vera have a ruddy complexion with a bluish tint to the skin.
Leukocytes (White Blood Cells)
- Leukocytes are the mobile units of the body's protective system, formed partially in the bone marrow and partially in the lymph tissue.
- The six types of WBCs normally present in the blood are neutrophils, eosinophils, basophils, monocytes, and lymphocytes.
- The normal percentages of different types of WBCs are: neutrophils (62.0%), eosinophils (2.3%), basophils (0.4%), monocytes (5.3%), and lymphocytes (30.0%).
- WBCs are specifically transported to areas of serious infection and inflammation, providing a rapid and potent defense against infectious agents.
Learn about the process of cell maturation, including the role of growth inducers and differentiation inducers, and the final stages of cell development.
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