Immunity Flashcards
Bacterial Structural features
Cell Wall
No membrane bounding organelles
Rings of DNA
Virus structural features
Flagellum
Protein spikes
Protein sheath
Contains RNA
Difference between bacteria and a Virus
Virus can infect widespread whereas bacteria is localised
Virus is non-living whereas bacteria is a unicellular living organism
Bacteria can be beneficial whereas viruses cannot be beneficial
Contact transmission of pathogens
Indirect contact - touching something an infected person has touched
Direct contact - touching an infected person
EXAMPLE - STIs
Transfer of bodily fluids of pathogens
Bodily fluids come into contact with mucous membranes of an uninfected person so the pathogen can enter the body
EXAMPLE - HIV
Transfer of pathogens via droplets
Droplets of moisture containing pathogen emitted when sneezing or coughing can be breathed in by another or settle on food
EXAMPLE - Measles
Transmission of pathogens via ingestion
Consumption of food or drink contaminated with pathogen allowing it to enter via the digestive tract
EXAMPLE - Salmonella
Transmission of pathogen via airborne transmission
When moisture in exhaled droplets evaporates, some bacteria and viruses remain viable which cause infection when inhaled
Transmission of pathogens by vectors
Transfer of pathogen via an animal
EXAMPLE - Malaria
Skin as external defence
Impervious barrier prevents entry
Secrete sebum containing antibacterial substances
Sweat glands produce lysozyme
Cilia as an external defence
Beating motion moves mucous upwards where it can be expelled
Hair as an external defence
Traps particles
Mucous as an external defence
Traps microogranisms
Acids as an external defence
In stomach, kill pathogens which have been ingested
In vagina which reduce growth of microorganisms
Lysozyme as an external defence
Enzymes that kill bacteria
Flushing action as an external defence
Urine flowing prevents bacterial growth
Cerumen as an external defence
Earwax, protects outer ear against infections
Sneezing as a protective reflex
Forceful expulsion of air from lungs
Carries foreign particles out nose and mouth
Coughing as a protective reflex
Forces mucous upwards and out
Vomiting as a protective reflex
Expels contents of stomach
Diarrhoea as a protective reflex
Contractions of large intestine muscles allow pathogen to be removed quickly
Steps of the inflammatory response as a non-specific defence
- Damage tissues stimulate mast cells to release histamine and heparin into the tissue fluid
- Histamine causes vasodilation of blood vessels to increase blood flow to damaged area, it also causes the increase of permeability of the capillaries which allows fluid to be filtered from the blood, this causes redness and heat
- Heparin prevents clotting in the area
- Other chemicals attract macrophages and leukocytes to consumed microorganisms and debri via phagocytosis
- Pain receptors are stimulated to feel pain
- Phagocytes collect all bacteria and debri to form pus as dead cells begin to die
- New cells are formed by mitosis and repair of damaged tissue takes place in formation of a scab
Fever as a non-specific defence
- Set point rises
- WBC release pyrogens, this causes the hypothalamus to change its set point at a higher than normal temperature this causes the body to seem coler than it is, this causes vasoconstriction and shivering to try and warm the body up - Fever break
Once the pyrogens stop being released by the WBCs, the hypothalamus resets its set points to 36 degrees which causes the body to vasodilate and profuse sweating to cool the body temp
Why is high temperatures beneficial for pathogens?
- Increases production of killer T-cells = speeds up cell-mediated response
- Increases metabolic to allows an increase in tissue repair
- Creates non-optimum environment for pathogens so it inhibits them
- Inhibits bacterial growth
How to maintain good hygiene, prevent pathogens from entering the body
Washing hands
Covering mouth
Wiping surfaces
Steps of the antibody mediates immune response / humoral response
- Macrophages detect a microorganism with a foreign antigen
- They engult it and display the antigen on the surface of its cell membrane
- The macrophage then presents the antigen to a b-cell
- The antigen then binds to the surface of the B-cell membrane at antigen receptor site, causing the b-cell to become sensitised
- The macrophage also presents the antigen to a t-cell
- The helper t-cell than matures and is induced to release substances = cytokines
- These activate B-cells to enlarge and divide into a group of cells = clones
- These clones further develop into plasma cells which secrete the complimentary antibody which is capable of attaching to the antigen active site
- These circulate in blood, lymph and extracellular fluid to reach the microorganism of foreign material and inactivate it
What is the secondary response of the humoral response
B-cells clones which don’t develop into plasma cells become memory cells which allow the immune response to occur more rapidly if the same froegn material enter the body again
Why are memory cells beneficial
- Allows more antibodies to be produced at a faster rate
- Antibody concentration remains higher for longer
- Symptoms of foreign antigen are minor to none at all
How do antibodies inactive the pathogen
- Binds to surface of viruses to prevent entering cell
- Coat bacteria so more easily consumed by phagocytes
- Inhibit reactions with other cells which causes cell breakdown
- React with soluble substances to make insoluble to be consumed by phagocytes
Steps of the cell-mediated immune response
- Foreign antigen enters the body
2 Macrophage detects it and present the antigen to a helper t-cell - The helper t-cell binds to the antigen and secretes cytokines which activate and sensitise the T-cell
- Sensitised T-cells that don’t become memory cells develop further into specialised T-cells known as helper t-cells, suppressor t-cells or killer t-cells
- Intracellular pathogen infection will stimulate the T-cells to become inactivated by non-self antigen
Types of immunity
- Natural, mothers antibodies across the placenta
- Artificial, someone else’s antibodies injected
- Passive, only lasts as long as the antibodies are in the body
- Antibodies can be produced quickly, results in no/slight symptoms
Live attenuated vaccine
contains live microorganism with reduced virulence
EXAMPLE - Measles
Inactivated vaccine
Contains dead microorganisms
EXAMPLE - Influenza
Toxoid vaccine
Inactivated toxins produced by bacteria
EXAMPLE - Tetanus
Biosynthetic Vaccine
Contain synthetic substances
EXAMPLE - HIB
Social Factors for Vaccinations
FOR
Following health advice of health professionals
Helps to create herd immunity
Negative side effects are rare
AGAINST Lack of availability of the vaccine Perceived health concerns Parents don't see the importance Can encourage sexual activity Ethical concerns
Cultural factors for vaccinations
FOR
Historically always done in families
AGAINST
Ethical objection to medical interventions with religious beliefs
Economic factors for Vaccinations
FOR
Immunisation bonus paid to participants
Reduced health care costs for treating the sick
No loss of family tax benefits
AGAINST
Cost of visiting a doctor to abstain
Cost prohibitive for some governments
Interests of commercial enterprise that manufacture the vaccine can affect its use
Vaccine Delivery
Via a syringe
Sprays, skin patches and ingestion are continuously being tested
Types of antibiotics
- Bacterial antibiotics: Kill bacteria by changing structure of cell wall or membrane
- Bacteriostatic: Stop bacteria from reproducing, usually by disrupting protein synthesis
- Broad-spectrum: Affects many types of bacteria
- Narrow-spectrum: Affects only a particular type of bacteria
Two types of antibiotic resistance
- Multiple drug resistance: Resistance of some strains of bacteria to most of the available antibiotics
- Total drug resistance: Resistance of some strains to bacteria to all antibiotics
How do antivirals help viruses
It inhibits the development of the virus by interfering with reproduction
EXAMPLE - HIV, Herpes
Whats the difference between antibiotics and antivirals
Antivirals are harder to make because viruses replicate which makes it difficult to find drugs that will treat viral infections
Antivirals are often toxic to the host
Antibiotics are used to treat bacterial infections whereas antivirals treat viral infections
