BSCI202 Lab Practical 1

Formed elements

Erythrocytes, leukocytes, and platelets.

Erythrocytes

Red blood cells (RBCs); use hemoglobin to transport oxygen and are the most abundant formed element.

Leukocytes

White blood cells (WBCs) with various immune functions.

Granulocytes

Leukocytes with visible granules; include neutrophils, eosinophils, and basophils.

Agranulocytes

Leukocytes without visible granules; include lymphocytes and monocytes.

Diapedesis

Movement of leukocytes out of blood vessels and into tissues.

Platelets

Cytoplasmic fragments of megakaryocytes that are important for blood clotting.

Neutrophils

Granulocytes with a multilobed nucleus and pale granules; phagocytize pathogens and debris.

Eosinophils

Granulocytes with a bilobed nucleus and red granules; kill parasitic worms and are involved in allergies and asthma.

Basophils

Granulocytes with large blue-purple granules; release histamine and other inflammatory mediators.

Lymphocytes

Agranulocytes with a large round or indented nucleus; involved in immune responses through direct cell attack or antibody production.

Monocytes

Large agranulocytes with a U-shaped or kidney-shaped nucleus; develop into macrophages and phagocytize pathogens and debris.

Erythrocyte appearance

Biconcave, anucleate disc; about 7–8 µm in diameter.

Erythrocyte concentration

About 4–6 million cells/µL of blood.

Neutrophil appearance

Multilobed nucleus with pale red and blue granules; about 10–12 µm.

Neutrophil relative concentration

About 50–70% of leukocytes; the most abundant leukocyte.

Eosinophil appearance

Bilobed nucleus with prominent red cytoplasmic granules; about 10–14 µm.

Eosinophil relative concentration

About 2–4% of leukocytes.

Basophil appearance

Lobed nucleus with large blue-purple granules; about 10–14 µm.

Basophil relative concentration

Less than 1% of leukocytes; the least abundant leukocyte.

Lymphocyte appearance

Spherical or indented nucleus with pale blue cytoplasm; about 5–17 µm.

Lymphocyte relative concentration

About 20–40% of leukocytes.

Monocyte appearance

U-shaped or kidney-shaped nucleus with gray-blue cytoplasm; about 14–24 µm.

Monocyte relative concentration

About 3–8% of leukocytes.

Platelet appearance

Small, deep-purple-staining cytoplasmic fragments; about 2–4 µm.

Platelet concentration

About 150,000–400,000/µL of blood.

Hematocrit

Percentage of total blood volume occupied by erythrocytes.

Hematocrit formula

Height of RBC layer ÷ height of all blood components × 100.

Erythrocyte layer

Bottom layer after centrifugation; normally about 45% of blood.

Buffy coat

Thin whitish middle layer containing leukocytes and platelets; less than 1% of blood.

Plasma layer

Top layer after centrifugation; normally about 55% of blood.

Normal adult female hematocrit

37–47%.

Normal adult male hematocrit

42–52%.

Normal newborn hematocrit

49–61%.

Leukocytosis

Abnormally high leukocyte count; buffy coat may make up more than 1% of blood; can result from infection or some leukemias.

Anemia

Abnormally low erythrocyte count resulting in a below-average hematocrit.

Aplastic anemia

Bone marrow does not produce enough new erythrocytes; lowers hematocrit.

Iron-deficiency anemia

Anemia in which erythrocytes are smaller; lowers hematocrit.

Hemolytic anemia

Anemia in which erythrocytes are destroyed too quickly; lowers hematocrit.

Sickle cell anemia

Anemia characterized by sickle-shaped erythrocytes; lowers hematocrit.

Hemorrhagic anemia

Anemia caused by blood loss; according to the lab slide, it is NOT detected by hematocrit.

High altitude effect on hematocrit

Lower oxygen causes increased erythrocyte production, resulting in a higher hematocrit.

Dehydration effect on hematocrit

Loss of water decreases plasma volume, making the hematocrit percentage higher.

How do you perform a hematocrit?

Draw blood into a capillary tube → centrifuge → measure total blood height and each layer → calculate the percentages.

What is the order of blood layers after centrifugation from bottom to top?

Erythrocytes → buffy coat → plasma.

Which formed element is the most abundant?

Erythrocytes.

Which leukocyte is the most abundant?

Neutrophils.

Which leukocyte is the least abundant?

Basophils.

Lymphatic system

Consists of lymphatic vessels and lymphoid tissues/organs; returns escaped fluid to the blood and plays roles in immunity and digestion.

Lymph

Fluid within bodily tissues that leaks out of cardiovascular capillaries and is picked up by lymphatic vessels.

Lymphatic vessels

One-way vessels that carry lymph back toward the heart.

Skeletal muscle pump

Squeezing of skeletal muscles that helps move lymph through lymphatic vessels.

Lymphatic valves

Structures that prevent the backflow of lymph.

Lymph nodes

Structures that filter lymph before it is returned to the blood.

Macrophages in lymph nodes

Engulf and destroy foreign substances.

Lymphocytes in lymph nodes

Provide immune responses to antigens.

Lymph node cortex

Outer portion of a lymph node containing follicles that house collections of lymphocytes.

Lymph node medulla

Inner portion of a lymph node containing macrophages.

Afferent lymphatic vessels

Vessels through which lymph enters a lymph node.

Efferent lymphatic vessels

Vessels through which lymph exits a lymph node.

Lymph node sinuses

Spaces inside a lymph node through which lymph flows.

Flow of lymph through a lymph node

Afferent lymphatic vessels → sinuses → efferent lymphatic vessels.

Slowed lymph flow through lymph nodes

Caused by having fewer efferent vessels than afferent vessels.

Lymphatic vessels

Collect lymph from lymphatic capillaries, carry it toward and away from lymph nodes, and eventually return fluid to veins near the heart.

Right lymphatic duct

Lymphatic duct that returns lymph to the circulatory system near the heart.

Thoracic duct

Lymphatic duct that returns lymph to the circulatory system near the heart.

Primary lymphoid organs

Bone marrow and thymus.

Secondary lymphoid organs and tissues

Spleen, lymph nodes, tonsils, adenoid, appendix, and Peyer's patches.

Bone marrow

Site of lymphocyte production where B cells mature.

Hematopoietic stem cells

Precursors of all blood cells.

B lymphocytes

Lymphocytes that mature in bone marrow.

T lymphocytes

Lymphocytes that originate in bone marrow and migrate to the thymus to mature.

Thymus

Primary lymphoid organ where T lymphocytes mature; produces hormones that help program lymphocytes.

Thymosin

Example of a thymic hormone involved in programming lymphocytes.

Spleen

Secondary lymphoid organ that filters blood, destroys worn-out blood cells, acts as a blood reservoir, and forms blood cells in the fetus.

Tonsils

Small masses of lymphoid tissue around the pharynx that trap and remove bacteria and other foreign material.

Peyer's patches

Lymphoid tissue in the wall of the small intestine that captures and destroys bacteria.

Appendix

Lymphoid organ that serves as a reservoir for gut bacteria and may assist in B-cell maturation.

Secondary lymphoid organ function

Traps microorganisms and foreign particles and exposes them to high concentrations of leukocytes.

Antibody

Immunoglobulin produced by plasma cells that binds to a specific antigen and aids in its inactivation or destruction.

Immunoglobulin

Another name for an antibody.

Plasma cells

Effector B cells that produce antibodies.

Five major antibody classes

IgM, IgG, IgD, IgA, and IgE.

Antibody shape

Y-shaped.

Antibody structure

Four amino acid chains linked by disulfide bonds: two heavy chains and two light chains.

Heavy chains

Two identical chains forming part of an antibody.

Light chains

Two identical chains forming part of an antibody.

Disulfide bonds

Bonds that link the amino acid chains of an antibody.

Antigen-binding sites

Two sites on the arms of an antibody that bind a specific antigen.

Variable region

Region of an antibody that gives the antigen-binding site its specificity.

Constant region

Region that is the same within a class of antibodies.

Antigen

A substance that can be recognized as foreign by the immune system.

Antibody function

Binds a specific antigen and aids in its inactivation or destruction.

Neutralization

Antibody action that masks dangerous parts of bacterial exotoxins or viruses.

Agglutination

Clumping of cells or other particles caused by antigen-antibody interactions.

Precipitation

Antibody-mediated precipitation of soluble antigens.

Complement activation

Antibody action that fixes and activates complement, which can lead to cell lysis.

Human blood groups

Classifications based on genetically determined antigens on red blood cells.

RBC antigens

Genetically determined proteins on the plasma membrane of erythrocytes that determine blood type.

ABO blood group

Classification based on the presence or absence of A and B antigens.