Human Bio- Immunity

What are antibiotics

• they are drugs that are used to fight infections of microorganisms (bacteria)

• they cant be used with viral infection

• each antibiotic is specific to certain type of infection

what do antibiotics do

some interfere with protein synthesis in the cells of target cell others interfere with synthesis of cell wall

what are the 2 types of antibiotics and what do they do

1. Bactericidal: kill bacteria by changing structure of of cell wall/membrane or by disrupting action of essential enzymes

2. Bacteriostatic: stop bacteria from reproducing usually disrupting protein synthesis

what is multiple drug resistance

when bacteria become resistant to to many antibiotics due to changing antibiotics to many times due to bacteria growing resistant to them.

what is broad spectrum antibiotics

they target a wide range of bacteria

what is narrow spectrum antibiotics

they target specific bacteria

what is total drug immunity

when bacteria is resistant to all drugs

what causes resistance in antibiotics

caused by the overuse of drugs and doctors prescribing antibiotics to prevent rather than treat the infection

what slows down resistance

by preventing the misuse and abuse of antibiotics

how do you overcome resistance

they produce new antibiotics that bacteria have no resistance to. They combine original antibiotics with new substances so the bacteria will turn off the genes for resistance.

what are antivirals

• used for treating viral infections

• antibiotics cant treat viruses so there is no treatment for common aliments (cold, chickenpox)

• this led to finding chemicals to use as antivirals

• they inhibit the development of the virus

how do viruses work

• virus enter host cell and their DNA or RNA induces cell to produce new virus particles

• these particles then leave cell and infect new host

why is it hard to find a way to treat viruses

due to the way they replicate. this is because the drug interferes with the replication and is likely to be toxic to host

what is research aimed at for antivirals

aimed at identifying viral proteins that can be disabled by special chemicals.

difference between specific and non specific immunity

• specific immunity is a genralised response (same response)

• specific is directed against a specific pathogen.

What are the key cells in Specific defense

B and T cells

describe the differences between B and T cells

• B cells mature in bone marrow and T cells are made in Thymus

• they are both white blood cells

• both produced in bone marrow

• they both migrate to Lymphoid tissue (connective tissue) found in lymph nodes

Describe Antigens

• any substance capable of causing an autoimmune disease

• they can be proteins, carbs, lipids, nucleic acids or whole or parts of microorganisms, viruses, bacterial cell walls, and capsules.

• they have specific active sites with particular shape and can only be acted unpin by complimentary antibody

where are Antigens found

on the surface of foreign RBCs or allergens

name and describe the 2 types of antigens

• self antiens: produced by own body

• non self antigens: foreign invading agents

what are antibodies

• found in plasma

• they are proteins produced in response to presence of antigens.

• they are Y shaped

what are the groups if Immunoglobins that Antibodies belong to

• IgA

• IgD

• IgE

• IgG

• IgM

what are the other key cells with Specific immunity

• macrophages and antigen presenting cells

what do macrophages do

they are a type of WBC produced in bone marrow and perform phagocytosis

what to antigen presenting cells do

• they are cells such as macrophages, dendritic cells and undifferentiated Bcells

• they detect the presence of and engulf the pathogens

• they then digest it and break it into smaller fragments

• they present the antigens from the pathogen on the surface of their own cell membrane to be recognised by lymphocytes (B and T cells)

what are the 2 types of immune response

• antibody mediated

• cell mediated

what does antibody mediated transport do

it provides resistance before pathogen enters cell

describe how antibody mediated response works

• they present antigen

• they present it to specific B cells in lymphoid tissue and activate them

• they present to helper T cells which release cytokines (proteins released by cells to act as messengers to immune system)

• this causes helper T cells to clone them selves and release different cytokines which activate more B cellls

• the activated B cells enlarge and divide into clones

• majority become plasma cells that secrete antibodies into blood, lymph and extracellular fluid, or memory cells that spread around all tissues of body. they allow response to be more rapid if second exposure occurs.

describe primary response

• first exposure to antigen

• immune systems responds slowly

• could take several days

• this is because time is needed for B-cells to multiply and differentiate into plasma cells before secreting antibodies.

• once levels of antibodies peak it begins to decline. you now have memory of antigen due to creation of memory cells

describe secondary response

• occurs when a second or subsequent exposure response occurs from the same non-self antigen

• response is much faster as memory B-cells recognise non-self antigen

• plasma cells produced very quickly and begin to secrete antibodies

• antibody levels rise faster, get to higher level, and last longer

• secondary response often so quick antigen has little time to produce effect on body so no illness result.

what is cell mediated immunity

• it provides resistance after pathogen has entered the cell and provides resistance to fungi, parasites, fighting cancer, and rejecting foreign tissue transplants

• involves the use of T cells (no B cells)

what is the process of cell mediated immunity

• antigen presenting cells engulf foreign pathogen. they digest the non self antigen in surface of cell membrane

• antigen presenting cells present antigen to specific T cells

• T cells become senstised (activated), they enlarge and divide and produce clones of themselves

• most T cells become Helper T cells, killer T cells or suppressor cells

• some of T-cells remain in Lymphoid tissue as memory cells that quickly recognise antigen of reinfected

what are the 2 types of immunity and describe them

• Natural: occurs without human intervention

• Artificial: results from giving people an antibody or antigen

• both can be passive or active

describe passive immunity

• when a person is given antibodies produced by someone else

• own body plays no role in producing antibodies

• given via blood from placenta or breastmilk

• immunity established immediately but it is short lived response

• antibodies are broken down so no memory cells

describe active immunity

• when body is exposed to foreign antigen and manufactures own antibodies in response

• antibodies form from an actual infection (natural active)

• injection of antigens to stimulate antibody response (artificial active)

• long lasting response and produces memory cells

what are the main ways to prevent disease

• immunisation: programming immune system so that the body can respond rapidly to the pathogen

• Vaccination: artificial introduction of antigens of pathogens so the ability to generate appropriate antibodies occur without person having to get infected

what are the types of vaccinations

1. attenuated: contain microorganism with reduced virulence (ability to produce disease symptoms) e.g polio, tuberculosis, mumps

2. Inactivated: vaccinations that offer short time frame of immunity than attenuated e.g whooping cough, cholera, typhoid

3. toxoid: for bacterial infections where toxins cause damage e.g tetanus, diphtheria

4. sub-unit: fragment of organisms used e.g HPV, hepatitis B

should everyone get vaccinated

no, people with chronic illness, weak immune systems cant cope with the extra stress. but if everyone around them is vaccinated then they are protected (Heard immunity)

describe Helper T cells and describe the process

involved in both antibody mediated response and cell mediated

• they bind to antigen on antigen presenting cell

• this stimulates secretion of cytokines which:

  • attract lymphocytes to site of infection which become sensitised to intensify response

  • attract macrophages to site of infection so they destroy invading cells through phagocytosis and intensify phagocytic activity of macrophages

  • promote action if killer T cells

Describe Killer T cells

• they migrate to site of infection

• attach to the antigen on invading cells

• they secrete chemicals (cytokines) to destroy cells (cytotoxins destroy cells)

• then detach and search for more foreign invaders

describe suppressor T cells

• they act when infections have been dealt with or when immune activity becomes excessive

• release substance which inhibit T and B cell activity and slow doen/ suppresses immune response.

how antibodies act

1. bind to pathogen to inhibit reactions with other cells

2. bind to surface of viruses stopping them from entering cells

3. agglutinate bacteria to enhance phagocytosis

4. react with soluble substances to make them soluble for phagocytosis to occur easier