Blood and Hematopoiesis Flashcards
what are the most common protein in the plasma & what is its role?
albumin
most important: regulating osmotic pressure
also, carries:
- thyroxine
- bilirubin
- drugs
what is hematocrit?
clinical relevance?
hematocrit: the percentage of blood that is composed of cells relative to the total volume
- normal: 47-78%
- anemia: < 30%
- polycthemia: >60%
what are the m/c clotting factors found in blood? what are their roles?
- prothrombin: becomes thrombin, which
- facilitates platelet aggregation
- converts fibrinogen → fibrin in presence of Ca++
- fibrinogen: becomes fibrin, which polymerizes dense networks at sites of blood vessel damage
what is prothrombin?
what are its roles?
a clotting factor
- becomes thrombin, which:
- facilitates platelet aggregation
- converts fibrinogen → fibrin in presence of Ca++
what is fibrin?
what are its roles?
a clotting factor
- becomes fibrin, which polymerizes dense networks at sites of blood vessel damage
what are erythrocytes and their major role?
= RBCs
- bio-concave cells that carry hemoglobin, which transports oxygen
describe the structural elements of erythrocytes
- have a flexible plasma membrane that rests on a skeleton made of 3 main components
- spectrin
- a peripheral membrane protein that forms a network of fibers
- is bound to
- ankrin
- actin complex
- ankyrin
- binds spectrin filaments to integral membrane proteins (ex: 3 band protein)
- actin complex
- binds spectrin filaments to glycophorin
- spectrin
what is spectrin? what are its roles?
a erythrocyte cytoskeletal protein
- a peripheral membrane protein that forms a network of fibers
- is bound to
- ankrin
- actin complex
what is ankryin? what are its roles?
an erythrocyte cytoskeletal protein
- binds spectrin filaments to integral membrane proteins (ex: 3 band protein)
what is the actin copmlex what are its roles?
an erythrocyte cytoskeletal protein
- binds spectrin filaments to glycophorin
what is hereditary spherocytosis?
- a condition where RBCs go from bioconcave → spherical when their cytoskeleton is compromised d/t a spectrin mutation
leukocytes
prevalence in the blood stream
less prevalent than RBCs
- normal: 5000-9000
- leukocytosis: > 12,000
- leukopenia: < 5000
categorize leukocytes (WBCs)
two main categories
- granulocytes: contain specific granules + azurophilic granules
- neutrophils
- eosinophils
- basophils
- agranulocytes: contain azurophilic granules only
- lymphocytes
- monocytes
what are the types of granules found in leukocytes (WBCs)? in which leukocytes are each granule type found?
two types
-
specific granules
- found in granulocytes (neutrophils, basophils, eosinophils)
-
azurophilic granules = lysosomes
- found in granulocytes (neutrophils, basophils, eosinophils) + agranulocytes (monocytes, lymphocytes)
neutrophils
- what kind of cell
- describe their structure
- describe their characteristics
- granulocytes (lymphocytes)
- structure
- multilobed nuclei
- contain 3 types of granules
- neutrophilic granules (specific granules): that contain bactericidal proteins
- azurophilic (non-specific): aka lysosomes
- tertiary granules: gelatinase + glycoproteins
what induces the release of the each neutrophil granule & what does each granule do?
chemotactic agents release of:
- neutrophilic (specific) granules: contain bactericidal agents
-
tertiary granules: contain
- gelatinase: degrades basal lamina allowing neutrophil migration
- glycoproteins: aid in phagocytosis
what is neutropenia?
what does it lead to?
what is it most commonly associated with?
- abnormally low neutrophils in the blood
- leads to bacterial infections
- often d/t immunodeficiency conditions (AIDS)
what is diapedesis?
= extravasation
the process by which neutrophils migrate through to damaged tissue through endothelium
outline the process of diapedesis
macrophages trigger neutrophils to travel thru post capillary venules to damage site - extravasation occurs in 3 phases:
- rolling: neutrophil carbohydrate adhesion molecules (Sialyl Lewis) bind to endothelial cell selectins (E and P selectin) → neutrophil rolls through venules
- tight adhesion: neutrophil integrins bind to endothelial surface Igs (ICAM-1 and VCAM) → neutrophils adhere to site on vessel wall
- transmigration: neutrophils squeeze through endothelial cells by extending a pseudopod
what is the major function of neutrophils?
phagocytosis of bacteria
(part of cell mediated immunity)
discuss the means by which neutrophils perform selective phagocytosis of bacteria
via various surface receptors:
- Fc receptors: bind Fc portion of IgG
- Complement receptors: bind to 3Cb complement coating bacteria
- Scavenger receptors: bind to modified LDLs found on the surface of gram + and gram - bacteria
-
toll like receptors (TLRs): bind PAMPs on bacterial surface, inducing
- phagocytosis
- release of IL-1, IL-3 and TNF-a from neutrophils
what are complement receptors and their role?
found on neutrophils
facilitate selective phagocytosis
- bind to bacteria coated by C3b complement, allowing → opsonization of bacteria
what are scavenger receptors and their role?
found on neutrophils
facilitate selective phagocytosis
- bind to modified LDLs found on the surface of gram + and gram - bacteria → phagocytosis
what are toll like receptors (TLRs) and their role?
found on neutrophils
facilitate selective phagocytosis
- bind PAMPs on bacterial surface, inducing
- phagocytosis
- release of IL-1, IL-3 and TNF-a from neutrophils → inflammatory response
eosinophils
- what kind of cell
- describe their structure
- describe their characteristics
- are granulocytes (WBCs)
- structure
- have a bilobed nucleus
- contain eosinophilic granules, which are made of:
- cytotoxins: peroxidases, ribonucleases
- histaminase
what are the major functions of eosinophils
eosinophils increase in the blood during
- parasitic infections (helminths, protozoa)
- allergic reactions
what triggers eosinophil degranulation?
what do the granules to?
- triggered by: binding of the Fc portion of antigen bound IgE antibodies to Fc receptors on the eosinophil surface
- cytotoxic granules (ribonuclease / peroxidase → ROS) destroy protozoan/helminth parasites
- histaminase: destroys histamine → dec allergic rxn
basophils
- what kind of cell
- describe their structure
- describe their characteristics
- granulocytes (WBCs)
- structure
- have a lobed nucleus
- contain basophilic granules, which are made of
- histamine
- heparin
what are the main roles of basophils?
- histamine release - main function
- phagocytic (slightly)
what triggers basophil degranulation?
what do these granules do?
- triggered by binding of antigen bound anti-IgE antibodies to Fc receptors on basophils
- basophilic granules cause Type I allergic reaction → vasodilation / bronchoconstriction
- histamine
- heparin
characterize the granulocytes in terms of
- size
- nuclear shape
- size: neutrophils > eosinophils > basophils
- nucleus:
- neutrophil - multilobed
- eisonophil - bilobed
- basophil - lobed
discuss the Fc receptors on each granulocyte and
- what they bind
- what this binding leads to
- neutrophils - bind IgG Fc
- these IgG Ab are bound to bacterial antigens, and IgG-neutrophil binding → bacterial phagocytosis
- eosinophils - bind IgE Fc
- these antigen bound IgE induce release of eosinophilic granules → cytotoxins, anti-histamines
- basophils - bind IgE Fc
- these antigen bound IgE induce release of basophilic granules → histamine
which granulocyte behaves like mast cells?
how does it do this?
basophils
binding of IgE Fc to Fc receptors induces histamine release → Type I allergic rxn
lymphocytes - nuclear shape
large spherical OR slightly indented heterochromatic nucleaus surrounded by a tiny rim of cytoplasm
lymphocytes are
- what kind of cell?
- composed of what cell subtypes?
- are agranulocytes (WBCs)
- include
- T-cells
- helper T-cells (CD4)
- killer T-cells (CD8)
- regulatory T-cells
- B-cells
- NK cells
- T-cells
T-cells
- are what kind of cells?
- have what distinguishing characteristics?
- have what major role?
- are made of what subtypes?
- are lymphocytes (agranulocytic WBCs)
- all produce cytokines
- have specific markers:
- all have
- TCR (T-cell receptor)
- CD3
- further distinguished by presence of either CD4, CD8, CD25
- T-helpers: have CD4+
- regulatory T-cells: have CD4+, CD25+
- cytotoxic T-cells: have CD8+
- all have