Microbio Unit 4

Zone of inhibition

distance (mL) from edge of paper disk to where it stopped

larger zone: more effective antibiotic is/effacious the antibiotic is

First Line Barriers

Skin: keratin (water proofing), shedding skin cells, sweat: pH, salt

Mucus: cilia (traps pathogen, movement of pathogens/allergens)

Stomach acid

Tears: salty, lysozyme, rinses and hydrates the eye

Saliva

Microbes

Second-Line Cellular Defenses

Eosinophils: parasite, histamine —> allergy (eosinophilic, asthma)

Basophils/Mast cells: histamine, kill bacteria

Neutrophils: phagocytic, bacteria + virus killers

Dendritic cells: phagocytic, help present antigens to helper T cells

Monocytes: circulate, phagocytic, turn into macrophages when exits circulation

Second-Line molecular Defense

Cytokine: signal that acts locally or at a distance

Example of cyotkins

leukotriences/prostoglandins (fever, pain)

interferons: antiviral molecules

interleukins (signal from T helper cells, goes to B cells, cytotoxic t cells, memory cells)

Histamine: major inflammatory molecule, baggy/sticky/leaky

4 cardinal signs of fever

swelling, redness, pain, heat

B cells and T cells origin and maturation

B cells originate and mature in bone marrow

T cells originate in bone marrow and mature in thymus

Primary and Secondary Lymphoid organs

Primary: bone marrow and thymus, cells develop and mature

Secondary Lymphoid organs: tonsils, appendix, MALT, peyers patch, lymph nodes, spleen. function: immune surveillance

Lymphocytes

B cells: humoral response

plasma cells: makes antibodies

memory cells

T cell: cellular response

cytotoxic cells: Tc, CD8, kill virus infected cells

helper cells: Th, CD4, coordinate immune activity

Characteristics of lymphocytes

1. specificity: each B cell receptor (BCR) or TCR on1 cell is specific for one pathogen/antigen

2. Inducibility: upon targeting and interacting with a specific antigen, lymphocytes mobilize a immune response

3. Clonality: rapid cell division

4. Non-responsiveness to self: no autoimmunity

5. Memory cells

B cells response steps

1. naive b cell binds to an antigen (usually a protein) on a specific pathogen

2. naive b cell becomes activated, makes clones, and differentiates into memory/plasma cells (primary response, 14-20 days)

3. memory cells respond to 2nd exposure of same pathogen (1-2 days)

4. plasma cells: differentiate from the naive B cells and exocytose/release BCRs or immunoglobulins/antibodies

Immunoglobin Isotypes (5 types)

IgD: not well characterized

IgA: secreted antibody, saliva and breast milk

IgE: made due to allergic response, type 1 hypersensitivity

IgM: made in early immune response/primary response

IgG: made in secondary responses

Antibody Function

Opsonins: tag pathogens

stimulate complement system and inflammation

agglutinate: clumping

cytolysis: cells burst/lyse