BIOL 441 LECTURE SLIDES 8: Blood amd Hematopoiesis

Comprehensive vocabulary flashcards covering blood composition, cellular histology, erythrocytes, leukocytes, platelets, and hematopoiesis.

Blood

A specialized connective tissue with an entirely fluid intercellular material (plasma), originating from the undifferentiated embryonic mesenchyme.

Plasma

The liquid extracellular matrix of blood, constituting the fluid fraction that suspends the formed elements.

Plasma Water Content

The solvent component that accounts for approximately $92\%$ of blood plasma by weight.

Plasma Proteins

The major organic solutes making up $7\%$ of plasma by weight, consisting of albumins, globulins, fibrinogen, and regulatory proteins.

Albumin

The most abundant plasma protein, comprising $58\%$ of total plasma proteins, essential for maintaining colloid osmotic pressure and transporting various substances.

Globulins

The second most abundant group of plasma proteins, accounting for $37\%$ of total plasma proteins, which includes antibodies and transport proteins.

Fibrinogen

A large plasma protein constituting $4\%$ of total plasma proteins that serves as a soluble precursor critical for the blood-clotting cascade.

Regulatory Proteins (Plasma)

A minor protein fraction comprising $1\%$ of plasma proteins, consisting of enzymes, proenzymes, and circulating hormones.

Other Plasma Solutes

Solutes making up $1\%$ of plasma by weight, including electrolytes, nutrients, respiratory gases, and metabolic waste products.

Formed Elements

The cellular components suspended within blood plasma, consisting of erythrocytes, leukocytes, and platelets.

Buffy Coat

The narrow, cream-colored layer that forms between plasma and erythrocytes upon centrifugation of whole blood, composed of leukocytes and platelets.

Hematocrit

The percentage of whole blood volume composed of erythrocytes (red blood cells).

Normal Male Hematocrit

The normal physiological percentage of packed red cell volume in adult men, ranging from $42\%$ to $52\%$.

Normal Female Hematocrit

The normal physiological percentage of packed red cell volume in adult women, ranging from $37\%$ to $48\%$.

Normal Erythrocyte Count

The physiological concentration of red blood cells in human peripheral blood, typically ranging from $3.5 \times 10^6$ to $5.5 \times 10^6\,\text{per mm}^3$.

Erythrocyte Primary Function

Facilitating gas exchange between the lungs and tissues, specifically transporting oxygen ($O_2$) and carbon dioxide ($CO_2$).

Biconcave Disc Shape

The physiological morphology of mature mammalian erythrocytes that provides a $20\text{--}30\%$ increase in surface area compared to a sphere, maximizing gas diffusion efficiency.

Acidophilic Staining of Erythrocytes

The histological staining property of mature red blood cells caused by their dense cytoplasmic packing of basic hemoglobin molecules, which affinity-bind acidic dyes like eosin.

Anaerobic Respiration in Erythrocytes

The exclusive metabolic pathway utilized by mature red blood cells to generate ATP due to their complete absence of mitochondria, ensuring they do not consume the oxygen they transport.

Erythrocyte Lifespan

The approximate survival period of circulating mammalian red blood cells, limited to roughly $120\,\text{days}$ due to the absence of nuclei and the inability to synthesize new proteins.

Nucleated Erythrocytes

Red blood cells that retain functional nuclei throughout maturity, a feature characteristic of non-mammalian vertebrates including birds and reptiles.

Rouleaux

Aggregated stacks of red blood cells resembling stacks of coins, observed in thick regions of blood smears or as a non-specific indicator of diseases such as multiple myeloma and diabetes.

Crenation

The shrinkage of erythrocytes leading to irregular, spiny margins, typically caused by drying artifacts on a slide or exposure to hypertonic anticoagulants.

Hemoglobin ($Hb$)

A specialized oxygen-transporting tetrameric protein that densely fills the cytoplasm of erythrocytes, comprising four globin polypeptides and four iron-containing heme groups.

Globin

The protein component of a hemoglobin molecule composed of four polypeptide chains that carries a small portion of circulating carbon dioxide ($CO_2$).

Heme Group

An iron-containing ($Fe^{2+}$) porphyrin complex embedded within each globin subunit that directly and reversibly binds a molecule of oxygen ($O_2$).

Sickle Cell Anemia

A hereditary hemoglobinopathy primarily affecting individuals of African descent, causing hemoglobin to polymerize at low oxygen tensions and deform red blood cells into rigid, pointed crescents.

Sickle Cell Molecular Mutation

A point mutation changing the DNA codon from GAG to GTG in the $\beta$-globin gene, replacing a negatively charged glutamic acid (Glu) with a neutral valine (Val).

Plasmodium falciparum Immunity

The selective evolutionary survival advantage against severe malaria exhibited by individuals who are heterozygous carriers of the sickle cell trait.

Leukocytes

The nucleated white blood cells that retain standard organelles for protein synthesis and defend the body against infectious pathogens and foreign particles.

Normal Leukocyte Count

The normal physiological white blood cell count in human peripheral blood, ranging from $4{,}500$ to $11{,}000\,\text{per mm}^3$.

Ameboid Movement of Leukocytes

The dynamic motility that enables white blood cells to migrate out of the circulation across blood vessel walls into surrounding connective tissues.

Differential White Blood Cell Count

A diagnostic hematological profile identifying the relative percentage of each leukocyte subtype within the total circulating white blood cell population.

Granulocytes

A classification of leukocytes possessing prominent specific cytoplasmic granules and segmented or lobed nuclei, including neutrophils, eosinophils, and basophils.

Agranulocytes

A classification of leukocytes that lack specific cytoplasmic granules and possess non-segmented nuclei, consisting of lymphocytes and monocytes.

Granulocyte Functional Properties

Short-lived white blood cells that act nonspecifically against infective agents, rapidly proliferating upon infection and dying off once the insult is resolved.

Neutrophils

The most abundant circulating leukocytes ($54\text{--}62\%$ of total WBCs), featuring a characteristic $3\text{--}5$ lobed nucleus and faint, barely visible cytoplasmic granules.

Polymorphonuclear Leukocytes (PMNs)

A synonym for neutrophils describing their distinctive, highly variable multi-lobed nuclear morphology.

Acute Inflammatory Infiltration (Neutrophils)

The rapid recruitment of neutrophils, designating them as the first white blood cell type to arrive at sites of infection or acute tissue damage.

Neutrophil Phagocytosis

The primary defense mechanism by which neutrophils internalize and degrade invading bacteria using specialized lysosomal enzymes.

Neutrophil Extracellular Traps (NETs)

Extracellular web-like structures composed primarily of ejected neutrophil genomic DNA and antimicrobial peptides that trap and neutralize extracellular pathogens.

Azurophilic Granules (Neutrophils)

Primary cytoplasmic granules appearing dark red-purplish that represent specialized lysosomes loaded with antimicrobial proteins and enzymes.

Specific Granules (Neutrophils)

Secondary, faintly pink-staining cytoplasmic vesicles containing biochemical compounds involved in producing toxic reactive oxygen species.

Barr Body (Neutrophil)

A small, condensed, drumstick-like nuclear projection present on a nuclear lobe of neutrophils in genetic females, representing the inactive X chromosome.

Eosinophils

Granulocytes comprising $1\text{--}3\%$ (approximately $3\%$) of circulating leukocytes, identifiable by a bilobed nucleus and large acidophilic cytoplasmic granules.

Eosinophil Specific Granules

Large, membrane-bound granules that stain bright red/pink with acidic eosin, representing specialized lysosomes packed with DNAses, RNAses, and lipases.

Eosinophil Functions

The degradation of antigen-antibody complexes and targeted defense against parasitic infections and allergic reactions.

Eosinophilia

An abnormal elevation in circulating or tissue eosinophils, commonly seen in allergic conditions, insect bites, parasitic infestations, and diseases of the spleen or CNS.

Basophils

The rarest circulating leukocytes ($0\text{--}0.75\%$, or roughly $1\%$ of WBCs), characterized by an S-shaped nucleus obscured by coarse, dark blue-staining granules.

Histamine

A chemical mediator stored within basophil granules that triggers inflammation by causing vasodilation and increasing vascular permeability.

Heparin

A glycosaminoglycan anticoagulant stored inside basophil granules that prevents localized blood clotting to maintain microvascular blood flow to injured tissues.

Lymphocytes

Agranulocytes constituting $25\text{--}33\%$ of circulating leukocytes in humans ($50\%$ in birds, $70\%$ in rodents) that coordinate antigen-specific adaptive immunity.

Lymphocyte Histological Appearance

A leukocyte featuring a prominent, round or ovoid dark violet nucleus with a thin, slightly basophilic rim of agranular bluish cytoplasm.

B Lymphocytes

Adaptive immune cells that differentiate into antibody-producing plasma cells upon antigen presentation and activation.

T Lymphocytes

Adaptive immune cells that mediate cell-mediated immunity by directly destroying virus-infected cells, intracellular bacteria, and neoplastic cells.

Natural Killer (NK) Cells

Innate cytotoxic lymphocytes that perform immune surveillance, destroying virally infected and transformed tumor cells without prior sensitization.

Small Lymphocytes

Circulating inactive lymphocytes displaying a compact, darkly condensed heterochromatic nucleus with minimal discernible cytoplasm.

Large Lymphocytes

Activated lymphocytes possessing more abundant cytoplasm and a lighter, vesicular euchromatic nucleus, predominantly localized in lymph nodes rather than blood.

Monocytes

The largest circulating white blood cells ($3\text{--}8\%$ of WBCs), distinguished by a kidney- or horseshoe-shaped nucleus and pale blue-gray cytoplasm containing fine azurophilic granules.

Monocyte Progenitor Function

Circulating precursors that extravasate into target tissues to differentiate into macrophages, osteoclasts, microglia, and other cells of the mononuclear phagocyte system.

Macrophages

Tissue-resident phagocytes differentiated from blood monocytes that actively ingest and degrade bacteria, cellular debris, and foreign particles.

Antigen-Presenting Cell (APC)

An immune cell, such as an activated macrophage, that ingests antigens, cleaves them in lysosomes, and displays peptide fragments on surface MHC proteins to stimulate T cells.

Class II MHC Molecule

A surface protein on antigen-presenting cells that binds internalized antigen fragments and presents them to helper T ($T_H$) cells to initiate adaptive immune responses.

Monocytosis

An elevated circulating monocyte count typically associated with systemic viral infections and chronic inflammatory disorders.

Leukemia

A hematological malignancy characterized by the uncontrolled, abnormal proliferation and accumulation of white blood cells or their precursors in the blood and bone marrow.

Platelets

Small, anucleate, membrane-bound cytoplasmic fragments ($150{,}000\text{--}400{,}000\,\text{per mm}^3$) derived from megakaryocytes that initiate blood clotting.

Megakaryocyte

A giant polyploid hematopoietic cell located in the red bone marrow whose cytoplasmic extensions fragment to produce circulating platelets.

Proplatelets

Long, branching cytoplasmic ribbons extended by megakaryocytes through sinusoidal endothelial fenestrations, which break apart into functional platelets under vascular shear stress.

Hematopoiesis

The physiological process of blood cell generation and replacement from precursor stem cells within the bone marrow.

Multipotent Hematopoietic Stem Cell (HSC)

A self-renewing, multipotent stem cell in the bone marrow that gives rise to all circulating blood cell lineages.

Common Lymphoid Progenitor

A committed progenitor cell originating from hematopoietic stem cells that selectively gives rise to B cells, T cells, and NK cells.

Common Myeloid Progenitor

A committed progenitor cell derived from hematopoietic stem cells that generates erythrocytes, megakaryocytes, granulocytes, and monocytes.

Thrombopoietin

A humoral growth factor produced primarily by the liver that stimulates hematopoietic stem cells and promotes megakaryocyte differentiation and platelet production.

Erythropoietin (EPO)

A hormone secreted predominantly by the kidneys (and liver) in response to hypoxemia that stimulates red bone marrow to accelerate erythropoiesis.

Red Bone Marrow

Active hematopoietic tissue containing stem cells and blood, found throughout the fetal skeleton and confined to spongy bone cavities in adults.

Yellow Bone Marrow

Inactive, adipose-rich marrow residing in medullary canals of adult long bones that retains the capacity to revert to red marrow under severe hematological demand.

Bone Marrow Sinusoids

Specialized, highly permeable vascular channels lined by endothelial cells in red bone marrow through which mature formed elements migrate into the bloodstream.

Erythroid Island

A histological microenvironment in red bone marrow consisting of developing erythroblasts clustered around a central macrophage.

Reticulocyte

An immature, anucleate erythrocyte that has extruded its pyknotic nucleus but retains residual ribosomal RNA, which stains as a reticular network.

Normal Adult Reticulocyte Count

The standard diagnostic range representing recent bone marrow erythropoietic output, typically constituting $0.5\text{--}1.5\%$ of circulating red blood cells.