Immunology Exam 1
Normal Bone Marrow
incubator of all formed elements in different ages
Cells that have Segmented nucleus vs mononuclear
polysegmented: Neutrophil Mononuclear: Monocyte and Lymphocyte -All have granules in cytoplasm=> used to kill bacteria, virus, or parasite
bone marrow produces -Once differentiation begins
produces the erythrocytes, granulocytes, monocytes, and platelets and supplies stem cells for the lymphocyte subpopulations to the thymus and other lymphoid organs. Once differentiation begins, the RBC's and granulocytes go thru a series of transformations leading to mature cells, which leave the marrow and enter into the circulation.
Complement system purpose
purpose is to go through center of it and spill everything out- lyse-> kills organism ● Large group of independent proteins secreted by hepatocytes and monocytes ● These complement/help antibody response ● Essential for host defense against infectious agents and inflammatory process ● 20 plasma proteins with cell-surface receptors for inflammatory and innate immune system cells
Boards First organ/ tissue in hematopoeisis
yolk sac- first hematopoeitic tissue Early in embryonic development, it begins in the yolk sac islands. (mesenchyme) A little later, the liver becomes the major site, and after further development, the spleen and lymph nodes supplement this activity As the bones develop during the 4th and 5th months of intra-uterine life, it begins in the marrow cavities, and by birth, becomes the major organ of hematopoiesis. yolk sac-> liver-> spleen-> bone marrow
Interferons
• A group of glycoproteins which inhibit the spread of viral infections by blocking the translation of viral proteins. • They are produced in human cells after a viral infection (leukocytes, fibroblasts, and lymphocytes) to limit the spread of virus. • Thought to be produced a few hours after viral replication. Antibodies begins to appear in the blood several days after infection and both combat the viral infection.
Primary Response
• After rising for several weeks (IgM first followed by IgG), both then declines to very low levels. • The first antibodies to appear are IgM followed by IgG or IgA. • The IgM levels decline earlier than the IgG levels.
Acquired (Adaptive) Immunity
• Displays a high degree of memory and specificity and incorporates cells and molecules of the innate immune system and its fight against harmful pathogens. • Comprises two main types of leukocytes known as T and B Lymphocytes. • Lymphocytes are regulators of immunity, and are considered the hallmark cells of chronic inflammation.
Eosinophils -have what? -phagocytic or nah? -attracted to what?
• Found to have a variety of inflammatory and immune responses, often in conjunction with other leukocytes. • They are highly phagocytic for antigen-antibody complexes and exhibit some phagocytic activity of neutrophils. • They are attracted to sites of inflammation by substances released from basophils and mast cells (connective tissue analogs of basophils).
Plasma Proteins-Globulins and Fibrinogens
• Globulins are a diverse group of proteins, separated into the Alpha-1, Alpha-2 and Beta Globulins, all important in the transport of hormones, metal ions, and lipids. Gamma Globulins = antibodies (5 total= GAMED) -2 light chains-> kappa and lambda • Fibrinogen is a soluble protein which polymerizes to form the insoluble protein Fibrin during blood clotting.
Basophil Granules
• Histamine: Involved in the increase of vascular permeability, which allows the other leukocytes to migrate out of the circulation into the connective tissue during an inflammatory response (can cause local swelling or anaphylaxis). • Heparin: is an anticoagulant and its role in inflammation is unclear.
Agranulocytes -often referred to as? -contains?
• Often referred to as Mononuclear leukocytes because of the singular structure of the nuclei • Frequently contains a number of non-specific azurophillic granules (stains with azure dyes) which are characteristic of primary lysosomes. • They contain no specific granules like granulocytes.
Hemoglobin Synthesis -requires
• Requires iron, Vitamin B12, Vitamin B6, and Folic Acid. • Deficiencies of these nutrients can result in anemias. Anemia may also develop because the nutrient is not available in food because it cannot be absorbed, or because the loss exceeds the intake.
Macrophages -phagocytic or nah? -shape? -life span?
• Termed phagocytes or histiocytes when in tissue and monocytes when circulating in the blood. • These are large cells with a horseshoe-shaped nucleus that functions in phagocytosis. • Unlike neutrophils, which are short-lived, these are seen in chronic inflammation as they are long- lived cells.
Erythrocyte Breakdown parts go ?
• The iron is reutilized in the bone marrow for developing RBC's. • The globin is reutilized for the production of amino acids. • The heme is converted to Bilirubin, which is excreted in the bile into the intestines, where it is either reutilized or metabolized and excreted in the form of urobilinogen and stercobilinogen in the urine and feces. -released iron is complexed with protein and stored as Ferritin or Hemosiderin and then reincorporated into the hemoglobin of developing erythrocytes in the bone marrow.
Basophils -% -structure? -resemble what?
• The least common leukocyte, constituting less than 1% of leukocytes in circulating blood. • Also have a bilobed nucleus with numerous large basophilic (blue) specific granules that contain either Histamine or Heparin • Resemble the connective tissue Mast Cells in structure and function and are the same cell involved in increasing vascular permeability during inflammation.
Neutrophils -% -most prominant feature -The cytoplasm of neutrophils
• The most common type of leukocytes in blood (constitutes from 40-75%). • The most prominent feature is the multilobated nucleus, the mature cell has up to five lobes, connected by fine strands of nuclear material. • The cytoplasm of neutrophils is lightly stippled with purplish granules called Azurophilic granules which are large lysosomes also called Specific granules. Hallmark- board
Molecules of the Innate System
• There are many molecules that work in concert with the cells of the Innate Immune System. • Three major molecules: 1. Complement 2. Acute Phase Proteins (Reactants) 3. Interferon
Primary vs. Secondary Antibody Response-Primary Response
• When an antigen is first encountered, antibodies are detectable in the serum after a longer lag period than occurs in the secondary response. • The lag period is typically 7-10 days but can be longer depending on the nature and dose of the antigen. • A small clone of both B-cells and plasma cells specific for the antigen is formed and the serum antibody concentration continues to rise for several weeks.
Neutrophil names
•Because of their variability in nuclear shape, they are often referred to as "PMN's" or Polymorphonuclear Leukocytes or Poly's, Neuts
band neutrophils
•When they are first released into the blood, their nuclei are unsegmented, and thus they are known as "band neutrophils" (bands).
3 sequential steps: "RAM"
○ 1. Recognition unit ○ 2. Activation unit ○ 3. Membrane attack unit ○ Each contains certain numbers of complement proteins (for target cell lysis)
Complement system Activated by 2 different pathways:
○ Classical (antibody dependent) - activated by binding of antibodies (IgG + IgM) to foreign particle ○ Alternate - can operate without antibodies; may be activated by microorganism itself or secreted substances (ex. Bee venom, snake bites, etc.)
Cell-mediated + humoral immunity characterized by 3 important features:
○ Diversity - can respond to millions of antigens ○ Memory - can respond many years after initial exposure ○ Specificity - actions specifically directed against antigens that initiated response
4 types of immunologic reactions:
○ I - anaphylaxis or immediate hypersensitivity ○ II - cytotoxic antibody reactions (complement) ○ III - immune complex mediated reactions ○ IV - cell mediated reactions Types I, II and III require formation of specific antibody against exogenous or endogenous antigen Several immunologic diseases mediated by more than one type of hypersensitivity reaction
Natural killer (NK) cells
○ Large granular lymphocytes in circulation - IgG ○ Attack virally infected cells via enzymes in granules ○ Can secrete interferon ■ Prevents healthy host cells from becoming infected, augments T-cell response to virally-infected cells
Dendritic cells
○ Skin - langerhans cells ○ Lymph nodes - interdigitating cells ○ True "antigen presenting cells" - help body present antigenic peptides on viruses to T-helper cells for destruction and memory of viral antigens ○ Bridge between innate and adaptive immunity
IgA antibodies -% -found where? -also known as?
● 10-15% of immunoglobulins ● "Secretory antibody" - secreted in tears, saliva, lumen, nasal cavity, etc. (boards) ● Secreted in milk - protects neonate
IgM antibodies -% -shape? -function
● 5-10% of immunoglobulins ● Pentameric shape - up to 5 binding sites ● Activates complement like IgG antibody (only 2 that do) ● First isotope formed in primary immune response ○ Aka. Acts as quickly as neutrophils in primary infection
IgE antibodies -% -also known as ? -function
● <1% of immunoglobulins ● "Reagenic antibody" - facilitates release of histamine/inflammation mediators ● Attaches to exposed surface of basophils/mast cells - causes degranulation when suitable antigen attaches ● Elicits hypersensitivity reactions + help eiosinophils kill parasites (boards)
IgD antibodies
● <1% of immunoglobulins ● On surfaces of B-cells - helps recognize antigens ● Activates B-cells → plasma cells
Anaphylaxis
● Immediate hypersensitivity response inducible with antigenic exposure (sensitization) ○ Either systemic (anaphylactic shock) or local response ○ Smooth muscle constriction and increased capillary permeability - due mediators from mast cells or basophils ○ Causes immediate laryngeal swelling with constriction ● Ex. Hay fever, asthma, food or drug allergies (PCN)
Type I - anaphylaxis or immediate hypersensitivity reaction
● Immediate reactions involving release of active mediators or substances from mast cells or basophils ○ Mechanism triggered by antigens (allergens) reacting with preformed IgE molecule receptors ● Active chemical mediators (ex. Histamine, bradykinin, SRS-A) cause bronchial smooth muscle contraction and increased capillary permeability -> urticaria, asthma, and angioedema
Macrophages of liver, lungs, brain
● Liver = kupffer cells ● Lungs = dust cells, heart failure cells ● Brain = microglial cells
B-cell lymphocytes -vital in
● Not all proliferating B-cells develop into plasma cells ○ Remain as Memory B-cells via clonal selection ● Vital in eliminating antigen if re-exposed in future ● Both T and B cells can recirculate from blood → tissue ○ Increases efficiency in fighting antigen
Secondary Response -second encounter, what happens
● Second encounter with same antigen (months/years after primary response) - rapid antibody response ○ Lag period ~3-5 days with higher antibody levels than for primary response ● Due to persistence of antigen-specific memory cell ○ Form large clone of specific B and plasma cells that mediate secondary antibody response ● IgM levels are similar to those of primary contact BUT produce more IgG that persists longer
Recognition unit -3 components
● Trimolecular complex → C1 ● Recognizes certain classes of antibody aggregated on surface of antigen-bearing cell ● 3 components of C1 → C1q, C1r, and C1s ○ C1q - recognizes antibody and binds to immunoglobin's Fc portion ■ Aka. Binds first → then C1r → then C1s
Eosinophils -% -structure -function?
(boards) -have own preferences of numbers-> Numbers increase in the circulation in parasitic infections and certain hypersensitivity reactions (hay fever and anaphylaxis). -• The most characterisitic ultrastructural feature are the large, ovoid, specific granules which contain a variety of hydrolytic enzymes including Histaminase, and the characterisitic bilobed nucleus.
Reticulocytes
- <1% of peripheral RBCs that exhibit basophilia (blue stain) due to residual RNA ○ Immature erythrocytes ○ Mature ~1 day after release ○ Rate of release into circulation = rate of removal of aged erythrocytes by spleen/liver (homeostasis!!) ○ Cresyl blue - stains reticulocytes blue (doesn't work on mature erythrocytes) When severe depletion of RBC's occurs (hemorrhage), the rate of erythrocytes and retic- ulocytes production in the bone marrow increases, and thus reticulocytosis may be used as measure of the rate of RBC formation in the marrow.
Hemoglobin -most common anemia
-most common= iron deficiency anemia Hemoglobin is a complex molecule that consists of four heme groups and four globins. • Heme is composed of four pyrrole rings held together with a centrally placed iron in a ferrous form (Fe++). • The heme portion of the hemoglobin is the oxygen-binding part of the molecule, and cannot be synthesized without iron.
Types of Acute Phase Reactants
1. C-reactive protein: useful marker of inflammation, usually opsonizes bacteria. 2. Complement factors: opsonization and lysis of bacteria and viruses and chemotaxis 3. Plasminogen: degrades blood clots. 4. Alpha-1-antitrypsin: downregulates inflammation 5. Serum Amyloid A: recruits immune cells 6. Fibrinogen and Prothrombin: clotting factors that trap microbes in their clots 7. Alpha-2-macroglobulin: alternating inhibitor of coagulation or fibrinolysis
-As the child matures, the red bone marrow of the long bones is replaced by ? -Only the __________ bones produce blood during adulthood
1. Fat 2. Only the flat bone, like the ribs, sternum and pelvic bones, produce blood during adulthood. • The thymus and lymph nodes remain sites of lymphocytopoiesis in infancy and childhood. The thymus usually involutes after puberty, and the lymph nodes continue to form lymphocytes.
Hematopoietic Stem Cell
1. Lymphoid: The lymphoid stem cell give rise to B-Cells, which finally mature into immunoglobulin-secreting plasma cells, and T- Cells, which assume their function in mediating cell-mediated immunity. 2. Erythromyeloid: These stem cells are all the precursors of mature erythrocytes, monocytes, neutrophils, eosinophils, basophils and megakaryocytes.
Granules of granulocytes
1. Neutrophils 2. Eosinophils 3. Basophils • The specific granules of Neutrophils have little affinity for either acidic or basic dyes whereas those of Eosinophils are stained strongly by acidic dyes such as Eosin, and those of Basophils are stained intensely by basic dyes, such as Hematoxylin or Methylene Blue.
Phagocytosis Part 1 + 2
1. cells arrive at the site of inflammation by chemotaxis and attach to the microorganism, either by recognition of the bacterial wall sugars or by complement/antibodies which is bound to the pathogen -> 2. Opsinization- tags bacteria that are reciprocal to receptors on the phagocyte (lock and key- chemotaxis)- boards
Granules of Neutrophils
1• The specific granules comprise the most abundant population (80%) and these granules contain two bacteriocidal substances: Phagocytin and Lysozyme. 2•The non-specific granules are larger and consists of lysosomes that contain peroxidases, acid hydrolases, and acid phosphatase, all involved with antibacterial digestive functions.
Phagocytosis Part 3
3. Phagocytes' cell surface invaginates ... microbe is internalized (via pseudopodia) into a phagosome -Phagosome fuses with multiple vesicles containing free oxygen radicals/toxic proteins (lysosomes) to form phagolysosome ... microbe destroyed
Plasma
A connective tissue composed of free cells in a fluid interstitium
Acquired immunity
Acquired immunity (adaptive) = after exposure to agent; improves with repeated exposure; is specific ○ Mediated by antibodies + T-lymphs (T-cells) ○ Long-term memory for specific antigen ○ Either active or passive
Acquired immunity- active
Active - resistance induced after contact with foreign antigens ● Host actively produces immune response (Ab + activated T-lymphocytes) ● Long-term (years) ● Slow onset ● Ex. Live attenuated viral vaccines (mumps, rubella, measles)
Platelets -AKA
Aka. Thrombocytes ● Cytoplasmic fragments in shapes of discs ● Derived from megakaryocytes (gigantic multinucleated cells in bone marrow) ● Appear in small clusters in blood - naturally clump together ● Granules contain serotonin (vasoconstrictor) ○ Shuts down small blood vessels during vascular injury
Plasma Proteins -most prominant protein
Albumin: constitutes the bulk of these proteins, and binds insoluble metabolites such as fatty acids and thus serves as trans- port proteins. It also functions to maintain the colloid blood pressure so that the blood does not lose an excess of fluid to the connective tissues at the capillary level. (prevents edema) -helps keep plasma inside blood vessels
Angioedema
Angioedema (due to IgE or anaphylactic) - hypersensitivity caused by degranulation of mast cells sensitized to specific antigen ■ Similar to hives but worse ■ Edema of deep dermis and/or subcuticular tissue ... egg-like swelling ■ Rapid onset ■ Wide range: Localized lesions → life-threatening with laryngeal + tongue swelling
Immunoglobulins -consist of -produced in?
Antibodies = immunoglobulins composed of glycoproteins Inactivate antigens (including viruses) + elicit extracellular response Produced in large numbers by plasma cells ... released into lymph or blood Humans have 5 isotypes (classes) - G, A, M, E, D ->only IgM and IgG produce compliment
Monocytes -are what? -phagocytic or nah?
Are immature macrophages that are in transit into the connective tissues. • They too are highly phagocytic, and also have pseudopodia. • The nucleus in usually indented (kidney or horseshoe shape) and pale in color. • They circulate in the blood for a day or two and upon entering the connective tissue, differentiate into macrophages.
Review questions
Boards
Immune mechanisms of tissue injury -Hypersensitivity reaction
Boards Same immunologic mechanisms that defend the host can cause damage to own tissues ... may cause death Hypersensitivity reaction - immune response leading to tissue injury or disease ○ Common ○ Include: asthma, hives, arthritis, hepatitis, etc.
IgG antibodies -% -found where -functions
Boards ● 80% blood immunoglobulins ● Crosses placenta - protects fetus with passive immunity ● Secreted in milk - protects neonate with passive immunity ● Activates the complement cascade ○ 2 binding sites ... need 2x to bind an antigen! ● Functions as opsonin (coating for antigen, increasing phagocytosis by neutrophils/macrophages)
Compliment opsonins
C-Bs and IgG
C1q attachment to antigen-antibody complex activates ?
C1q attachment to antigen-antibody complex activates entire C1 complex ○ C1q alters C1r to active molecule ○ Each of the 2 original C1r chains is cleaved after attachment to antigen-antibody complex ... expose active sites ○ After 1st enzymatic cleavage in complement sequence, now-active C1r chains activate C1s ○ NOTE: C1q activates C1r → binds, cleaves → active C1r activates
Granulocytes
Characterized by prominent cytoplasmic granules and a single multilobed nucleus. • The highly variable shape of granulocyte nuclei has given rise to the common names of PMN's, Polymorphonuclear Leukocytes, Poly's, or Seg's. (for segmented nuclei) • There are three different types of granulocytes named according to the staining characteristics of their specific granules.
Lymphocyte types
Divided into: ○ T-cells (cell mediated) ○ B-cells (humoral mediated) - mature into plasma cells; produce antibodies
Each globin chain is synthesized under the control of a Mutations cause? Sickle Cell Anemia is characterized by ?
Each globin chain is synthesized under the control of a specific gene. Mutations of these genes cause hemoglobin- opathies marked by abnormal hemoglobins. -Sickle Cell Anemia is characterized by an abnormal "A" chain known as Hgb S due to a gene defect in the synthesis of the beta chain.
Lymphocyte life span
Either short-lived (few days) or long lived (months - years) ○ Memory cells = long lived
Eosinophils and parasites
Eosinophils have a direct destructive effect on some parasites provided that specific antibodies (IgE) are present.
Unipotential Stem Cells
Erythrocytes, granulocytes, lymphocytes, monocytes and megakaryocytes (platelets). -referred to as "Unipotential Stem Cells", divide at a rapid rate to provide precursors soon to be a mature cell type.
Extramedullary hematopoiesis -If the hematopoietic bone marrow is destroyed
Extramedullary hematopoiesis in the liver and spleen subsides normally after birth, and the bone marrow remains the primary blood-forming organ. • If the hematopoietic bone marrow is destroyed, extramedullary hematopoiesis may continue or resume in the liver and spleen.
Fc portion must be either -needs
Fc portion must be either IgG or IgM ○ Needs: ■ 2x IgG Fc fragments to bind/activate C1q ■ 1x IgM (pentameric shape - has 5x Fc binding sites for C1q)
Hemopoeisis
Formed element cells are formed in the bone marrow by a process called "Hemopoiesis". The process by which mature blood cells develop from precursor cells. • In the human adult, it takes place almost exclusively in the bone marrow of certain bones, mainly the flat bones of the skull, ribs, sternum, the vertebral column, the pelvis, and the proximal ends of some long bones.
Heparin centrifuge
If clot formation is prevented by Heparin, the blood cells settle freely, comprising 45% of the total blood volume. The plasma comprises the remaining 55%. Serum is plasma minus the clotting factors when centrifuged (clot can form)
Lymphocytes -different sizes
Large lymphocytes (in lymphoid organs) → medium/small lymphocytes (in bloodstream) ● Small lymphocytes recirculate back to lymphoid organs, and under antigenic stimulation can transform into large lymphocytes (blastogenic transformation)
B-cell lymphocytes + antibodies -where produced? -activated? -secrete what?
Lymphocytes that produce antibodies or immunoglobulins (bind specific antigens) ● Produced: bone marrow → specific lymphoid tissues (Humoral immunity) ● When activated: B-cells proliferate and mature into antibody secreting plasma cells ○ Can secrete protein antibodies (Ig - G (80%), A, M, E, D) -> IgG only one that can pass the placenta (boards) ■ These are heavy chains
Natural immunity
Natural immunity (innate) = resistance not acquired through antigen contact ○ Nonspecific - host defences like skin/mucous membranes, neutrophils + macrophages, complement (proteins) ○ Does not improve after exposure to organism ○ No memory
Acute infection
Neutrophil skyrockets means acute infection some place
Phagocytic cells
Neutrophils (acute), monocytes, macrophages and eosinophils
all come from Granulocyte Precursors
Neutrophils, basophils, and eosinopbils
Lymphocytes - nuclei
Nuclei = heterochromatic; usually nearly round with slight indent on 1 side ○ Surrounding small rim of cytoplasm = basophilic (due to # of free ribosomes)
Acquired immunity- passive
Passive - resistance based on antibodies preformed in another host ● Short duration ● Ex. Immune globins (Hep B)
Lymphocytes function
Perform central function in immune response - involves antigenic interaction with lymphocyte membrane receptors ● Other functions: (all inactivate/eliminate invaders) ○ Interact with macrophages ○ Transformation + proliferation with lymphoid tissues ○ Release of chemical mediators ● Lymphs + plasma cells = common in chronic inflammation ... indicate immunological response
Platelets and Erythrocytes
Platelets= thrombosites
Immune system protection
Protection provided by 3 types of immunity: ○ Cell-mediated immunity - primarily T-lymphocytes in conjunction with other cells ○ Humoral (antibody-mediated) - B-cell produce antibodies ○ Complement - complements other 2 types of immunity
Acute Phase Reactants -what are they -produced by?
Proteins whose plasma concentrations increase in response to inflammation. • Produced by the liver in response to injury. The inflammation causes inflammatory cells (neutrophils and macrophages) to secrete "cytokines" into the bloodstream. -Cytokines like Interleukins (IL-1, IL-6, and IL-8) and Tumor Necrosis Factor-alpha (TNF-a) • These proteins have certain physiologic functions of the immune system.
Erythrocyte Breakdown
Red Blood Cells live in the peripheral circulation about 120 days. • The aging cells are sequestered in the spleen, which removes the old and defective RBC's from the circulation. • The phagocytic cells in the spleen digest the main components of the RBC's and release them into the circulation for reutilization and excretion from the body.
Activation unit
Serum contains active C1s and inactive C4, C2 and C3
Formed Elements
The cells of the blood are of three major functional classes: 1. Erythrocytes (RBC's), 2. Leukocytes (WBC's) 3. Thrombocytes (Platelets) -> Granulocytes (Neutrophils, Eosinophils, and Basophils) -> Non-Granulocytes- mononuclear (Monocytes, Lymphocytes and Macrophages [monocytes in tissue]).
globin part of the hemoglobin consists
The globin part of the hemoglobin consists of four polypeptide chains designated by the Greek letters alpha, beta, gamma, and delta. -Alpha chains are present in all Hemoglobins. -Two alpha and two beta chains form Hgb A -Two alpha and two delta chains form Hgb A2 -Two alpha and two gamma chains form Hgb F
Neutrophil function -phagosome
The hallmark cell of acute inflammation, and while fighting infection, they die in large numbers, producing pus. (board) -•Neuts are chemotactically attracted to areas in which bacteria and other foreign substances are present. •Their presence indicates acute inflammation in that the neutrophils phagocytize bacteria in large numbers. •The phagosomes fuse with the two types of granules and their enzymes degrade the bacteria.
mature blood cells are descendants of..... The mother stem cell differentiates into.....
The mature blood cells are descendants of developmentally pluripotent (cells that can differentiate and develop into more than one mature cell type) hematopoietic stem cells. The mother stem cell differentiates into several developmentally committed stem cells, which are the precursors of distinct cell lineages, the ultimate product of which are the mature blood cells.
Elements of Hematocrit
The percentage of packed volume of cellular elements is called the Hematocrit. Of the 45% value of normal persons, erythrocytes comprise 44%. The 1% remaining is composed of WBC's which settle on top of the RBC's (Buffy Coat).
The red color of RBCs is derived
The red color is derived from Hemoglobin, an iron-containing pigment that constitutes 90% of the dry weight of each erythrocyte.
Leukocytes -classes
There are five cell types of WBC's and these are subdivided into two main classes: Granulocytes and Agranulocytes, according to the granularity of their cytoplasm and general nuclear characteristics.
T-cell lymphocytes -derived from -life span -divided into
Thymus derived lymphocytes have long lifespan (months - years) ● Divided into T-helper cells, cytotoxic T cells + memory cells (based on surface receptor) ● Helper cells (CD-4) - recognize specific antigen + activate other cells (ex. Other lymphocytes, macrophages, B cells (Ab)) ● Cytotoxic cells (CD8) - destroy infected viral cells + activate other cells (ex. Lymphocytes, macrophages) ● Memory cells - recognize antigen + participate in amnestic response sensitized)
Serum
When blood is exposed to air, a clot rapidly forms, trapping the cells in it's fibrous matrix, the remaining clear fluid -plasma minus the clotting factors when centrifuged -An aqueous solution of inorganic salts which is constantly exchanged with with the extracellular fluid medium of all body tissues. • Also contains the plasma proteins, Albumins, Globulins, and Fibrinogen, and collectively, these plasma proteins exert a colloidal osmotic pressure within the circulatory system which helps to regulate the exchange of aqueous solu- tion between the plasma and extracellular fluid.
When platelets degranulate...
When degranulate, release clotting substances (thromboplastin + plasmin) ○ Local damage to vascular endothelium attracts platelets ... adhere to exposed collagen ● Both thombroplastin + plasmin result in production of blood clot (thrombus) composed of fibrin, platelets, trapped RBC ○ Prevent further blood loss from injured blood vessel site
Immunoglobulins structure
Y-shaped molecule ○ 2 long, identical polypeptides - heavy chains ○ 2 shorter, identical polypeptides - light chains ○ 4 chains bound by several disulfide bonds ○ Stem of Y = heavy chains ■ Fc fragment ('c for complement') ○ Diverging arms of Y = light + heavy chains ■ Fab fragments (antigen binding region)
multipotential stem cell
derive All of the blood cell types These cells divide and give rise to five discrete cell types, each committed to a different developmental fate. Each of the five cell types stem cells is capable of giving rise to only one of the following cell types: Erythrocytes, granulocytes, lymphocytes, monocytes and megakaryocytes (platelets)
Urticaria
due to hypersensitivity reaction Urticaria (hives) - common skin disorder of localized mast cell degranulation causing pruritic edematous plaques (wheals) ■ 20-40yrs susceptible ■ Lesions last ~24hrs but large plaques may last for days-months ■ Usually from antigen-induced release of vasoactive mediators from mast cell granules ● Ex. Pollen, food, drugs, insect venom
