Patho-Exam 2

Virus

A protein coat surrounding a nucleic acid core that lacks its own metabolic enzymes and relies on a host.

Bacteria

Prokaryotic cells that do not have membrane-bound organelles and can live independently.

Fungi

Infections most commonly occur on the surfaces of the body and require cooler temperatures than the human core body temperature.

Protozoa

Organisms like malaria, amoebic dysentery, and giardiasis.

Helminths

Examples include roundworms, tapeworms, and flukes.

Arthropods

Ticks, mosquitoes, mites, lice, and fleas which can be vectors for pathogens.

Suffix: …itis

Indicates inflammation or infection.

Bacterial septicemia

The presence of bacterial toxins in the blood.

Virulence

The capability of a pathogen to cause disease, making an infection more likely to occur or be severe.

Adhesion factors

Substances that help an infective organism stick to the body.

Opportunistic pathogens

Normally non-pathogenic microflora that can cause disease when the host's health or immunity is weakened.

Antigen

A foreign substance that serves as a marker for the immune system to identify harmful elements.

Epitopes

Small part of an antigen (e.g., spike protein).

Passive immunity

Occurs when antibodies are given to a person from another source rather than being produced by their own immune system.

Cytokines

Primary means of communication between cells in the immune system.

Chemokines

Subset of cytokines that direct movement of leukocytes.

Opsonin / Opsonization

Marks or targets a substance/pathogen for phagocytosis.

Innate immunity

Nonspecific immune response involving myeloid line cells.

Adaptive immunity

Specific immune response involving lymphoid line cells.

B cells

They eliminate extracellular microbes and create memory for faster response upon subsequent exposures.

T cells

CD4 helper cells recognize antigens presented by APCs, while CD8 cytotoxic cells destroy nucleated cells presenting non-self antigens.

Antigen-Presenting Cells (APCs)

Cells that display foreign antigens on their surface to T cells, examples include macrophages, dendritic cells, and B cells.

MHC proteins

Serve as self-recognition markers on cell surfaces which are crucial in transplant acceptance or rejection.

Acute stage of an infection

Maximum manifestations of the infection occur, including tissue damage and inflammation.

Physical barriers against infection

Skin, stomach acid, mucus, and tears protect from infection.

Anaphylaxis

Systemic response to inflammatory mediators (Type 1), characterized by difficulty breathing, rapid swelling, rash, and a drop in blood pressure.

Anergy

Body fails to react to an antigen.

IgE

Antibody mediated in Type 1 allergic reactions; coats mast cells.

IgG or IgM

Antibodies mediated in Type 2 reactions (attack antigens on cell surfaces).

Type 1 Hypersensitivity

Allergic reaction; IgE mediated; involves mast cell degranulation and release of histamine.

Type 2 Hypersensitivity

Tissue-specific reactions where antibodies attack antigens present on cell surfaces (e.g., Graves disease, transfusion reactions).

Type 3 Hypersensitivity

Immune complex mediated; antigen-antibody complexes float in plasma and trigger inflammation wherever they attach (e.g., Glomerulonephritis, systemic lupus, chronic rejection).

Type 4 Hypersensitivity

Cell mediated (delayed); involves CD4 or CD8 cytolysis; the only hypersensitivity that does not involve antibodies (e.g., Contact dermatitis, TB test, chronic rejection).

Molecular mimicry

Foreign antigen closely resembles a self-antigen, leading to antibodies attacking the self-antigen.

HLA (Human Leukocyte Antigen)

Unfamiliar proteins displayed on MHC that trigger organ rejection.

Graft vs. Host disease (GVHD)

Donor T cells and NK cells attack host cells with incompatible HLA antigens (typically occurs following bone marrow transplant in immunocompromised patients).

Pruritic

Itchy (symptom of GVHD affecting the skin).

HIV (Human Immunodeficiency Virus)

A retrovirus that uploads into host DNA and attacks CD4 cells.

AIDS (Acquired Immunodeficiency Syndrome)

Defined by a CD4 count <200 cells/mL (normal is 500-1500).

Reverse transcriptase

Enzyme used by HIV to change single-strand RNA to double-strand DNA.

Integrase

Enzyme used by HIV to integrate new DNA into the host cell's nucleus.

Protease enzyme

Enzyme used by HIV to cleave the viral protein chain into parts that make new viruses.

Seroconversion

Immune system response where antibodies against HIV appear (1-6 months after primary infection).

Common symptoms of uncontrolled HIV infection

Fever, night sweats, weight loss, and lymphadenopathy.

Examples of local Type 1 hypersensitivity

Urticaria (hives), Rhinitis (hay fever), Atopic dermatitis, Bronchial allergic asthma, food allergies.

Sensitization

The process by which an individual's immune system develops a heightened reactivity to an antigen upon initial exposure, particularly in Type I hypersensitivity where IgE antibodies bind to the surface of mast cells or basophils.

Degranulation

The emptying of granules from the interior of a mast cell into the extracellular environment.

Megakaryocytes

Cells from which platelets originate; also make Von Willebrand factor.

Thrombopoietin

Activating factor that causes platelet production; regulated by the number of platelets in circulation.

Thrombocytes (platelets)

Fragments of megakaryocytes; live 8-9 days; main function in clotting.

Thrombocytopenia

Abnormally low number of thrombocytes.

Thrombocytosis

Too many thrombocytes.

Thromboxane A2 (TXA2)

Signaling molecule that triggers aggregation and vasoconstriction.

Fibrinogen

Key component leading to fibrin mesh formation.

Plasminogen

Triggers dissolution of clots.

Hemostasis

The process of stopping blood loss.

Coagulation cascade

Involves 13 blood clotting proteins.

Intrinsic pathway

Activated by intravascular trauma (damage in the vessel); slower.

Extrinsic pathway

Activated by damaged external surfaces (damage to surrounding tissues); faster; triggered by tissue factor.

Common pathway (Coagulation)

Begins with Factor X; converts prothrombin to thrombin, which converts fibrinogen to fibrin.

Von Willebrand factor (vWF)

Made by megakaryocytes and endothelium; binds to platelets; carries Factor 8.

Hypercoagulability

Too much clotting resulting in unwanted thrombus.

Factor V Leiden

Inherited cause of hypercoagulability.

Von Willebrand's disease

Most common hereditary bleeding disorder; deficiency or defect in vWF, leading to reduced platelet adhesion.

Hemophilia

X-linked recessive disorder; impaired ability to make clots due to insufficient Factor 8.

ITP (Immune Thrombocytopenic Purpura)

Autoimmune disorder where antibodies form against platelets, leading to excessive destruction and bleeding.

TTP (Thrombotic Thrombocytopenic Purpura)

Combination of thrombocytopenia, hemolytic anemia, renal failure, and neurologic dysfunction; absence of enzymes leaves unusually large vWF molecules, causing intravascular clotting.

Plasmapheresis

Treatment for TTP.

DIC (Disseminated Intravascular Coagulation)

Caused by massive activation of coagulation, leading to widespread intravascular coagulation and subsequent severe hemorrhage due to consuming all available clotting factors.

Purpura

Bleeding into tissues, often associated with low platelet counts.

Reticulocytes

Immature RBCs.

Erythropoiesis

Production of RBCs.

Erythropoietin

Released from the kidney when blood oxygen decreases; stimulates bone marrow to produce RBCs.

Hemoglobin (Hgb)

Carries $O_2$ to cells via iron.

Transferrin

Support protein in blood plasma that carries iron.

Ferritin

Protein that stores iron in the liver and bone marrow.

Byproducts of heme destruction

Heme is broken down to bilirubin.

Unconjugated bilirubin

Not bound to another molecule.

Conjugated bilirubin

Bound to another molecule.

Jaundice

Results from excess bilirubin (unconjugated) in the blood, causing yellowing of skin and eyes.

Rh factor

Expressing the D antigen means RH POSITIVE; antibodies are acquired through exposure.

Anemia

An abnormally low number of RBCs or hemoglobin, which reduces the blood's oxygen-carrying capacity.

Normal lifespan of a red blood cell

Approximately 120 days.

Hemolysis

Cells die early (less than 120 days).

Iron deficiency anemia

Most common cause is chronic blood loss; manifestations include spoon-shaped nails and pica (craving non-food items).

Megaloblastic anemias

Anemias caused by B12 (Pernicious) or Folic acid deficiencies.

Pernicious anemia

Vitamin B12 deficiency; often due to lack of intrinsic factor (produced by parietal/chief cells) needed for B12 absorption.

Aplastic anemia

Bone marrow is not producing enough of ALL blood cells (WBCs, platelets, RBCs).

Hereditary spherocytosis

Hemolysis due to a defective RBC membrane.

Sickle cell disease

Inherited chronic hemolytic anemia caused by a mutation in the beta-chain of hemoglobin (HbS), leading to elongated, inflexible cells that block capillaries.

Thalassemia (alpha and beta)

Hemoglobinopathy caused by a mutation in the gene directing synthesis of chains.

Pica

Craving non-food items, often associated with iron deficiency anemia.

Microcytic hypochromic anemia

Anemia characterized by small, pale red blood cells, typically seen in iron deficiency anemia.

Normocytic normochromic anemia

Anemia characterized by normal-sized and normally colored red blood cells, often seen in acute blood loss or anemia of chronic disease.

Macrocytic (Megaloblastic) anemia

Anemia characterized by abnormally large red blood cells, typically due to Vitamin B12 or Folic Acid deficiency.

Polycythemia vera (Primary polycythemia)

Neoplastic disease of bone marrow stem cells resulting in increased blood volume and viscosity.

Acute hemolytic reaction (Transfusion)

Rare but life-threatening reaction due to host antibodies attacking donor cells, causing lysis (often ABO incompatibility).

Delayed hemolytic reaction (Transfusion)

Symptoms appear 1-2 weeks after transfusion.

Febrile reactions (Transfusion)

Host antibodies react to donor WBCs.

Allergic reactions (Transfusion)

Host antibodies attack donor proteins.