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Human Biology Unit 3 + 4 > Immunity > Flashcards

Flashcards in Immunity Deck (43)
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Bacterial Structural features

Cell Wall
No membrane bounding organelles
Rings of DNA


Virus structural features

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



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



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

1. Damage tissues stimulate mast cells to release histamine and heparin into the tissue fluid
2. 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
3. Heparin prevents clotting in the area
4. Other chemicals attract macrophages and leukocytes to consumed microorganisms and debri via phagocytosis
5. Pain receptors are stimulated to feel pain
6. Phagocytes collect all bacteria and debri to form pus as dead cells begin to die
7. New cells are formed by mitosis and repair of damaged tissue takes place in formation of a scab


Fever as a non-specific defence

1. 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

2. 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?

1. Increases production of killer T-cells = speeds up cell-mediated response
2. Increases metabolic to allows an increase in tissue repair
3. Creates non-optimum environment for pathogens so it inhibits them
4. 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

1. Macrophages detect a microorganism with a foreign antigen
2. They engult it and display the antigen on the surface of its cell membrane
3. The macrophage then presents the antigen to a b-cell
4. The antigen then binds to the surface of the B-cell membrane at antigen receptor site, causing the b-cell to become sensitised
5. The macrophage also presents the antigen to a t-cell
6. The helper t-cell than matures and is induced to release substances = cytokines
7. These activate B-cells to enlarge and divide into a group of cells = clones
8. These clones further develop into plasma cells which secrete the complimentary antibody which is capable of attaching to the antigen active site
9. 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

1. Allows more antibodies to be produced at a faster rate
2. Antibody concentration remains higher for longer
3. Symptoms of foreign antigen are minor to none at all


How do antibodies inactive the pathogen

1. Binds to surface of viruses to prevent entering cell
2. Coat bacteria so more easily consumed by phagocytes
3. Inhibit reactions with other cells which causes cell breakdown
4. React with soluble substances to make insoluble to be consumed by phagocytes


Steps of the cell-mediated immune response

1. Foreign antigen enters the body
2 Macrophage detects it and present the antigen to a helper t-cell
3. The helper t-cell binds to the antigen and secretes cytokines which activate and sensitise the T-cell
4. 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
5. Intracellular pathogen infection will stimulate the T-cells to become inactivated by non-self antigen


Types of immunity

1. Natural, mothers antibodies across the placenta
2. Artificial, someone else's antibodies injected
3. Passive, only lasts as long as the antibodies are in the body
4. 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



Social Factors for Vaccinations

Following health advice of health professionals
Helps to create herd immunity
Negative side effects are rare

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

Historically always done in families

Ethical objection to medical interventions with religious beliefs


Economic factors for Vaccinations

Immunisation bonus paid to participants
Reduced health care costs for treating the sick
No loss of family tax benefits

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

1. Bacterial antibiotics: Kill bacteria by changing structure of cell wall or membrane
2. Bacteriostatic: Stop bacteria from reproducing, usually by disrupting protein synthesis
3. Broad-spectrum: Affects many types of bacteria
4. Narrow-spectrum: Affects only a particular type of bacteria


Two types of antibiotic resistance

1. Multiple drug resistance: Resistance of some strains of bacteria to most of the available antibiotics
2. 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



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