32 Questions
What is the approximate volume percentage of erythrocytes in the total blood volume of healthy adults?
44%
Which of the following is NOT a function of blood in the human body?
Production of hormones
What is the primary component of blood that carries oxygen to cells throughout the body?
Erythrocytes
What is the term for the process by which blood proteins react to form a clot when blood leaves the circulatory system?
Coagulation
Which of the following is a function of serum in the human body?
Confering biological properties
What is the primary function of platelets in the blood clotting process?
Releasing growth factors
What is the term for the liquid portion of blood that remains after clotting has occurred?
Serum
Which of the following is a characteristic of blood in the human body?
It is a specialized connective tissue
What is the percentage of the volume of the buffy coat in the centrifugation tube?
1%
What is the primary function of albumin in the blood?
To maintain the osmotic pressure of the blood
What is the purpose of the complement proteins in the plasma?
To defend against inflammation and microorganisms
What is the name of the largest plasma protein?
Fibrinogen
What is the pH of the plasma?
7.4
What is the function of the globulins in the plasma?
To transport various substances in the blood
What is the location of the highest O2 pressure in the blood?
Arteries
What is the name of the protein that polymerizes to form fibrin during blood clotting?
Fibrinogen
What is the approximate percentage of lipid in the erythrocyte plasmalemma?
40%
What is the primary function of erythrocytes in the vasculature?
To provide a large surface-to-volume ratio for gas exchange
Which of the following proteins is NOT an integral membrane protein in the erythrocyte plasmalemma?
Hemoglobin
What is the purpose of using azures in blood smear stains?
To stain cytoplasmic granules containing charged proteins and proteoglycans
What is the primary mechanism by which erythrocytes generate energy?
Anaerobic glycolysis
What is the characteristic shape of human erythrocytes suspended in an isotonic medium?
Flexible biconcave discs
What is the average lifespan of human erythrocytes in the circulation?
120 days
What is the normal concentration of erythrocytes in blood in women?
3.9-5.5 million/μL
What is the primary reason for the removal of senescent erythrocytes from the circulation?
Both A and B
What is the advantage of the biconcave shape of erythrocytes?
It increases their surface-to-volume ratio for gas exchange
What is the primary symptom of anemia?
All of the above
Why are erythrocytes useful as an internal standard in histology?
Because they can be used to estimate the size of other nearby cells or structures
What is the property of certain biological materials of staining a different color from that of the stain used?
Metachromasia
What is the underlying cause of sickle cell anemia?
A mutation in the gene for hemoglobin
What is the primary function of macrophages in the spleen, liver, and bone marrow?
To remove senescent erythrocytes from the circulation
What is the term for the stacks of erythrocytes that form in larger blood vessels?
Rouleaux
Study Notes
Blood: A Specialized Connective Tissue
- Blood is composed of cells and fluid extracellular material called plasma, totaling approximately 5 liters in an average adult.
- When blood leaves the circulatory system, plasma proteins react to produce a clot, including formed elements and a pale yellow liquid called serum.
Blood Function
- Erythrocytes (44% of total blood volume in healthy adults) transport O2, CO2, metabolites, hormones, and other substances to cells throughout the body.
- Nutrients are distributed from their sites of synthesis or absorption, while metabolic residues are collected and removed by excretory organs.
- Blood participates in heat distribution, regulates body temperature, and maintains acid-base and osmotic balance.
Composition of Blood and Plasma
- Plasma is an aqueous solution (pH 7.4) containing substances of low or high molecular weight, making up 7% of its volume.
- Plasma components include plasma proteins, nutrients, respiratory gases, nitrogenous waste products, hormones, and inorganic ions (electrolytes).
Major Plasma Proteins
- Albumin: maintains osmotic pressure of blood, made in the liver.
- Globulins (α- and β-globulins): transport factors, coagulation factors, lipoproteins, and other proteins, made in the liver and other cells.
- Immunoglobulins (antibodies or γ-globulins): secreted by plasma cells in many locations.
- Fibrinogen: polymerizes as insoluble, cross-linked fibers of fibrin during clotting, made in the liver.
- Complement proteins: comprise a defensive system important in inflammation and destruction of microorganisms.
Blood Cells
- Erythrocytes (red blood cells [RBCs]):
- Terminally differentiated structures lacking nuclei, completely filled with hemoglobin.
- Flexible biconcave discs, approximately 7.5 μm in diameter, 2.6-μm thick at the rim, and 0.75-μm thick in the center.
- Normal concentration in blood: approximately 3.9-5.5 million/μL in women and 4.1-6.0 million/μL in men.
- Can be used as an internal standard to estimate the size of other nearby cells or structures.
Erythrocyte Characteristics
- Flexibility allows RBCs to bend and adapt to small diameters and irregular turns of capillaries.
- In larger blood vessels, RBCs may adhere to one another loosely in stacks called rouleaux.
- Erythrocyte plasmalemma is composed of 40% lipid, 10% carbohydrate, and 50% protein.
- Integral membrane proteins include ion channels, band 3 protein, and glycophorin A.
Erythrocyte Lifespan and Medical Application
- Erythrocytes undergo terminal differentiation, losing nuclei and organelles before release into circulation.
- Lacking mitochondria, RBCs rely on anaerobic glycolysis for energy needs.
- Normal lifespan: approximately 120 days, after which defects in the membrane’s cytoskeletal lattice or ion transport systems produce abnormalities.
- Medical application: anemia is a condition of having a concentration of erythrocytes below the normal range, causing symptoms such as lethargy, shortness of breath, fatigue, skin pallor, and heart palpitations.
This quiz covers the basics of blood as a specialized connective tissue, its composition, and its role in the circulatory system.
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