2a

Question 1

what are the bodies defences?

Answer 1

skin, mucous membrane, iron-binding proteins, phagocytosis

Question 2

what defense is skin? how does the skin act as a defense?

Answer 2

mechanical barrier
-acid pH: sebaceous secretion and sweat contain unsaturated fatty acids
-lower temp that is suboptimal for some bacteria

Question 3

what defense is mucous membrane? function?

Answer 3

mechanical barrier
- cilia of respiratory tract eliminate particles larger than 5 microns (e.g., large bacteria carrying dust particles).
- lysozymes (antibacterial substance e.g., in tears)
- pH - e.g., gastric juice pH, acid pH in vagina, urine.

Question 4

iron-binding proteins

Answer 4

that bind the iron necessary for growth
e.g transferrin, lactoferrin

Question 5

phagocytosis

Answer 5

polymorphonuclear white blood cells and monocytes as well as fixed macrophages
in the tissues engulf and eventually destroy bacteria

Question 6

what is specific immunity? what types are there?

Answer 6

mechanism aimed at particular infecting organisms
- humoral immunity (specific circulating antibodies)
- cell mediated immunity (cells to attack invading specific organism)

Question 7

humoral immunity

Answer 7

antibodies which are modified serum
globulins, physico-chemically tailored to react with particular chemical components of previously
encountered invading organisms and produced only in response to these encounters

Question 8

what are antiboies produced by?

Answer 8

B-lymphocyte’s; also known as B-cells

-In order to produce antibodies, B lymphocytes need antigen-presenting cells

Question 9

how is antibody production regulated

Answer 9

T-helper and Tsuppressor cells

Question 10

when is humoral immunity an important role in preventing infections?

Answer 10

-involves production of toxins
- presence of a capsule
-some viral infections

Question 11

what are antigens

Answer 11

stimulate the production of antibodies; foreign invaders

Question 12

important aspects of antigen

Answer 12

1. must be recognized by body as foreign
2. stimulates the production of antibodies
3. usually a protein, but can be glycoprotein, lipoprotein, polysaccharide
4. molecular weight at least 10,000 to trigger an immune respons
   -can be particulate or soluble
   -bacterial cells contain antigenic materials (capsular substance, flagell, cell wall)
   – viruses often have polypeptide antigens

Question 13

general properties of antibody

Answer 13

• referred to as immunoglobulin (Ig);
• produced by the body in response to stimulation by antigen;
• synthesized by specific B lymphocytes (plasma cells);
• ability to distinguish foreign macromolecules (NON-SELF) from ‘normal’ body constituents
  (SELF);
• high specificity in combination with antigens;

Question 14

what are the 5 classes of immunoglobins (antibody)?

Answer 14

IgG, IgA, IgM, IgE and IgD

Question 15

which Ig are involved in defense mechanisms

Answer 15

IgG, IgA, IgM,

Question 16

where is igE involved

Answer 16

hypersensitivity states

Question 17

basic shape found in igG

Answer 17

Y-shaped molecule

Question 18

IgG

Answer 18

-two combining sites
-combine specifically with antigens (lock and key)
-bind phagocytes and macrophages
-cross placenta and protect newborn
-y shaped

Question 19

IgM

Answer 19

-5 units joined together
-MAIN immunoglobin
-produced early in immune response
-doesn cross placenta

Question 20

IgA

Answer 20

-2 units
-found in secretion
-mucosae (reformatory)
-tears
-milk

Question 21

the serological reaction

Answer 21

-presence of antibodies in a serum sample (blood screening)
-observable antigen-antibody reaction
-titration of antibody
- unknown microorganisms can be identified with known diagnostic antisera

Question 22

Cell-Mediated Immunity (CMI)

Answer 22

exposure to an antigen induces
production of “trained” cells active against that antigen or any organism that carries it

Question 23

main difference between cmi and humoral

Answer 23

• soluble antibodies are not involved
• based on a large number of T-cell subpopulations and a complex system of interactions
• active in most microbial infections and is essential in the defense against intracellular organisms, parasites, and tumor cells and foreign cells (transplants)

Question 24

what is the importance of APC’s?

Answer 24

• mediate the response upon exposure to an antigen
• display the antigen on its surface and, along with major histocompatibility complexes
  -drive cellular or humoural immune
  responses by interacting with Th1 or Th2 cells

Question 25

what affects the quality and intensity of the immune system?

Answer 25

age, race, stress, nutritional status

Question 26

4 ways immune response can be harmful to the system

Answer 26

1. Allergy and hypersensitivity states (overreaction to antigens; anaphylaxis) 2. Auto-immune diseases (immune system believing itself to be foreign) 3. Immunodeficiency states (lack antibody, CMI, or both.) 4. Graft rejection (kidney, bone-marrow, heart, etc; foreign supress rejection by drugs)

Question 27

passive immunization? IgG in animals? Humans?

Answer 27

- preformed antibody injection -IgG of animals cleared from recipient in 10 days -risk of IgE antibodies (serum sickness and anaphylaxis) - IgG of human disappears after several weeks no risk of hypersensitivity -short lived

Question 28

immune serum globulin or gamma globulin

Answer 28

- IgG fraction pooled from a large group of blood-donors -antibody for naturallly occuring disease

Question 29

Hyperimmune globulins

Answer 29

IgG fractions from human subjects with high titers of antibody to a specific disease that have resulted from natural exposure or hyperimmunization.

Question 30

Active immunization

Answer 30

-Antigen injection stimulate antibody -long lasting

Question 31

Major active immunization strategies (Live attenuated vaccines, Killed vaccines, subunits vaccines and toxoids,

Answer 31

1) Live attenuated vaccines mild illness, limited extent, disease prevention provide IgA and IgG (develop faster in live than killed) 2) Killed vaccines, subunits vaccines and toxoids no infectivity, administered multiple times for satisfactory secondary response 3) Recombinant vaccines produced by DNA recombinant technology avoids chance if live virus surviving inactivation process e.g. hepatitis B vaccine 4) Adsorbed vaccines mixed with inorganic salts absorbed by tissue ensures prolonged effect 5) Conjugate vaccines capsular material is attached (conjugated) to an altered, non-toxic protein. In this form, the polysaccharide becomes immunogenic. 6) Combined vaccines several vaccines administered together 7) Schedule of immunizations orderly time-table under which several routine immunization procedures are carried out in infancy and childhood.

Question 32

Combined active-passive immunization? examples? site of injection?

Answer 32

-used in a few situations potential exposure to a given microbial agent, it is desirable to provide the patient with immediate protection e.g. tetanus, hepatitis B, rabies exposure - injected at two diff sites and syringes

Question 33

what antibiotic was hailed as a miracle drug in 1940s to 1950s?

Answer 33

penicillin

Question 34

what has been dramatically reducing the efficacy of antibiotics

Answer 34

antibiotic resistance

Question 35

Reasons underlying the marked increase in antibiotic resistant bacteria

Answer 35

(a)Use and misuse of antibiotics in agriculture and aquaculture. (b) Use and misuse of antibiotics in the human population (mainly in developing countries). (c) With advances in medical therapies, many more immunocompromised patients are remaining alive longer and are serving to harbour and transmit antibiotic resistant bacteria.

Question 36

what is Antibiotic Resistance? most common in who?

Answer 36

-develop resistance to virtually any antibiotic given sufficient time - Resistance common & more quickly in immunocompromised patients resulting in increased morbidity, increased length of hospital stay and higher mortality

Question 37

Antibiotic resistance is generally classified into two major types

Answer 37

1) Intrinsic resistance- predictable form of resistance based on the mechanism(s) of action of the antibiotic and the characteristics of the microorganisms 2)Acquired resistance - described as a previously susceptible organism becoming resistant to an antibiotic's action. This type of resistance is clinically more important and involves three main mechanisms of resistance: (i) Alteration in drug target (ii) Production of inactivating enzymes (iii) Decreased antibiotic uptake

Question 38

Genetics of Antibiotic Resistance

Answer 38

Antibiotic resistance genes can be encoded by the bacterial chromosome or by extrachromosomal entities such as plasmids

Question 39

Ways bacterias exchange info

Answer 39

Conjugation (plasmid) Transformation Transduction Transposition

Question 40

Conjugation (plasmid)

Answer 40

This mode of exchange requires cell-to-cell contact as well as specialized bacterial structures known as conjugative pili for the transfer of DNA molecules usually in the form of plasmids, which are extrachromosomal DNA elements that replicate in bacteria

Question 41

transformation

Answer 41

uptake of free or naked DNA from the environment, its incorporation into the bacterial genome and subsequent gene expression

Question 42

transduction

Answer 42

This involves the transfer of genetic material among bacterial cells using a bacteriophage as vector or carrier -random; accidental incorporation of bacterial DNA within a phage particle - high host specificity and host restriction/modification systems

Question 43

Transposition

Answer 43

Conjugative transposons can jump from the chromosome of one organism to the chromosome of another thus circumventing plasmid-host range restrictions intregrons, is a mobile DNA element with a specific structure consisting of two conserved segments flanking a central region in which "cassettes" that encode functions such as antibiotic resistance may be inserted.

Question 44

how do chromosomes effect antibiotic resistance

Answer 44

(i)encoding the target site of the antibiotic, rendering the site functional but nonsusceptible. (ii) being a regulatory element which controls alternative pathways or efflux mechanisms. (iii) controlling cell permeability and regulating the uptake of the antibiotic and, consequently, the intracellular concentration of the drug.

Question 45

What is the primary response

Answer 45

-Exposed to antigen for first time -Triggers productions of antibody by B cell -5-10 days circulation -max 3 weeks then drops

Question 46

2nd response

Answer 46

Basis of immunization -occurs when Ab is introduced -less lag rapid Ab increase 2-3 days, slow decrease -booster to maximize Ab levels -3-5 injections for full immunity

Question 47

role of APC cell on humoral or cmi if activated?

Answer 47

APC cells -take in antigen presents it on surface -bunds special receptor on t helper cells -receptors are mhci or mhcii -T helper we th1(CMI) or th2 (humoral)

Question 48

What do mutation lead to

Answer 48

Change in site of antibiotic target Regulator gene (turn on alternative path or turn in efflux mechanism)

Question 49

How to decrease microbial resistance

Answer 49

-Withhold antibiotic (not use for viral infection they don’t work) -right concentrations by classifying organism first -prevent infection (hygiene) -educate ( when,how, proper duration) -early detection of therapeutic failure