Module 7 - Biology - Ruby

Define a Disease

any process or condition that adversely affect the normal functioning of a living thing or parts of a living thing.

• infectious of non-infectious

Define and infectious Disease

caused by an organism or infective agent (called a pathogen) and can be transmitted, either directly or indirectly, from one person to another

Define Incidence

the number of newly diagnosed cases of a disease

Define Prevalence

the total number of live cases of a disease or proportion of a population that have a disease

Define mortality

Mortality – number of deaths or proportion of a population that die from a disease.

Define Endemic level of disease

the baseline rate (incidence of prevalence) of a specific disease in a certain population

Define Epidemic

a widespread increase in the prevalence of a particular disease (sometimes also called an “outbreak”) above the endemic rate.

Define Pandemic

Pandemic – an epidemic which has spread across multiple countries or continents.

Methods of Disease Transmission? and examples of each?

Direct:

• a disease is passed directly from one human or animal to another human or animal

  • person to person

  • droplet

Indirect:

• a disease is transmitted from person to person - even though the two individuals have not been in contact.

  • fecal-oral

  • airborne

Vector:

• another organism to transfer a disease between individuals - type of zoonotic transmission.

  • insect bite

What are the types of Pathogens?

Living (Cellular Pathogens)

• Bacteria

• Fungi

• Protists

• Macroparasites

Non-living (Non-Cellular Pathogens)

• Viruses

• Prions

What are Prions and how are they transmitted?

Prion:

• They are incorrectly folded proteins

• Convert adjacent brain proteins to the misfolded ‘prion’ form.

• results in holes in the brain → to neurodegeneration and eventually death.

• Composed only of protein and do not contain a nucleic acid.

Transmission:

• Ingestion of infected tissue

• There is concern that plants can take up prions from contaminated soil and that animals that graze on these plants.

• Contaminated:

  • surgical equipment

  • injections from infected animals

  • transplanted tissue or organs.

2 examples of diseases caused by a prion pathogen?

1. ‘Mad Cow Disease’ (BSE)

   • a disease in cattle that humans can catch from eating beef contaminated with brain or spinal cord tissue from an infected cow.

   • can also be caught from a contaminated blood transfusion.

2. Chronic Wasting Disease

   • affects deer/elk/moose

What are Viruses and how are they transmitted?

Viruses:

• Non-cellular so technically not living organisms.

• They can only reproduce and metabolise in a host cells.

  • Attach to the host cell and inject their nucleic acid

  • The cell’s resources are used to copy the viral RNA or DNA and replicate the virus within the host cell.

  • Eventually the viruses burst out of the host cell (killing it) and being released to invade more host cells.

• The structure can vary → they all contain a nucleic acid (either DNA or RNA) enclosed by a protein coat.

• Can affect animals, plants and bacteria.

Transmission:

• Some viruses are airborne

• Some can only be transmitted via bodily fluids (e.g. HIV, ebola).

• Indirectly through contamination of fomites (objects), in some cases through contaminated food, or contaminated blood donations.

• Some viruses can be vector transmitted.

2 examples of diseases caused by a Virus pathogen?

Influenza

• causes fever and chills, sneezing, coughing and a sore throat

• Transmission

  • Airborne droplets – from coughing, sneezing, or talking.

  • Direct contact – touching an infected person (e.g. handshake).

  • Indirect contact – touching contaminated surfaces (fomites).

Ebola

• fever, fatigue, vomiting, internal and external bleeding.

What are Bacteria and how are they transmitted?

Bacteria

• Cellular and living.

• Prokaryotic.

• Able to reproduce quickly through binary fission.

• Most bacteria are not pathogenic and play important roles within organisms.

• Bacteria are the only pathogens which are affected by antibiotics.

Transmission:

• Directly through close contact

• Indirectly through air, contamination of food, water or another object.

2 examples of diseases caused by a Bacteria pathogen?

Salmonella:

• fever, headaches, nausea, vomiting

• ingestion of food or water that has been contaminated with animal faeces

• disease that affects the intestinal tract

Chlamydia:

• painful urination, vaginal discharge, painful sex

What are Protists and how are they Transmitted?

Protists;

• Unicellular eukaryotes

• They reproduce via binary fission.

• Many protozoa do not cause disease

Transmission

• faecal/oral

• Eating contaminated meat

2 examples of diseases caused by a Protist pathogen?

Malaria:

• fever, chills, headache

• Caused by a protozoan called Plasmodium

• First reproduces in the liver cells, then burst out of the liver cells (destroying them) and moving into the red blood cells to reproduce and cause the cells to burst releasing the pathogen into the blood.

• Then if Anopheles mosquito bites this host, the plasmodium (protist) will be transmitted to a healthy person if bitten by this same mosquito.

• Only transmitted by the Anopheles mosquito Vector

Giardiasis:

• gas, nausea, weight loss.

• Transmitted through contaminated water.

• The pathogen binds to the wall of the bowel, causing a range of digestive issues and interference with absorption of nutrients.

What are Fungi and how are they Transmitted?

Fungi:

• Eukaryotes, unicellular or multicellular.

• Fungi are heterotrophic so will absorb nutrients from their host in order to grow and reproduce.

• Some pathogenic fungi grow on or under the skin, hair and nails. Others can cause severe lung diseases if spores are inhaled.

Transmission:

• transferred via direct contact

• Indirectly → the floor of a public shower

2 examples of diseases caused by a Fungi pathogen?

Athlete’s Foot (Tinea):

• tiny white patches between toes, red skin, sore flake skin

• grow on the floor of a public shower and be transmitted to new hosts with bare feet.

Thrush (Candidiasis):

• naturally inhabit the mucous membranes of the mouth, respiratory tract, digestive system and female reproductive tract (vaginal itching/burning).

• transmitted through direct contact or contact with contaminated bodily fluids.

What are Macroscopic parasites and how are they Transmitted?

Parasites:

• Are multicellular so they are the largest of the pathogen types.

• Endoparasites

  • live inside the host.

• Ectoparasites

  • live outside the body

  • Can cause disease

    • directly by injecting toxins into the blood

    • indirectly as vectors.

Transmission:

• Endoparasites

  • infected individual to pass the eggs in their faeces, which are then ingested by another host through contaminated water or infected soil.

• Ectoparasites

  • can move

2 types of Macroscopic parasite pathogen?

Endoparasites

• roundworms, tapeworms and flukes are all worm-like parasites called helminths.

• They attach to the host’s gastrointestinal tract and interfere with digestion and absorption of nutrients.

Ectoparasites

• include parasitic arthopods such as fleas, lice, mites, flies and mosquitos.

• Directly impact the host by benefiting from sucking the blood from their hosts, feed on skin flakes, or injecting toxins, or skin irritation.

• They can also indirectly spread other diseases by acting as vectors.

Whats is Aristotle Theory pertaining to disease?

Spontaneous Generation

• Life is able to arise from nonliving matter if it contained some vital energy

What is Miasma Theory?

That disease and decay were examples of spontaneous generation from “bad air”

What experiment did Pasteurs use to refute spontaneous generation?

Swan Neck Flask Experiment

• The curve of the flask allows exposure to air, but particles (dust and microbes) get trapped in the bottom so they can’t get to the broth

• broth is boiled to kill any lingering microbes

• When the neck of the flask is broken and bacteria can reach the sterile broth, bacterial growth occurred

What can be drawn from Pasteurs experiment?

• Air or the broth itself had no “life force”, but the air did carry microorganisms

• Decay was caused by this microbial contamination of the air and not “spontaneous generation”.

• Spoilage of beer and wine was also due to microbial contamination and developed the process of ‘pasteurisation’ which involves heating liquids to kill microbes. It is still used today in the dairy industry.

• He rescued the silk industry after discovering that a silk worm disease was caused by bacteria.

• Influenced other scientists who introduced antiseptics to hospitals

• his work also inspired Koch to develop a method to determine which specific microbe is responsible for a disease.

What do Koch’s Postulates do and what are they?

statements that can be used to determine if a particular microbe is responsible for a specific diseases. (based on experimental work with anthrax).

A microorganisms is responsible for a disease if:

1. The specific microorganism must be present in every host with the disease

2. The specific microorganism must be isolated from the host and grown in a pure culture

3. A healthy host, when inoculated with the microorganism, must develop the same symptoms as the original host

4. The specific microorganism must be able to be isolated from the second host and identified as the same species as originally cultured.

How did Koch Discover his postulates?

• able to isolate disease causing bacteria from the blood of dying animals

• Compared the blood of sick and healthy animals, sick = microorganisms, heathy = clear

• injecting contaminated blood can transmit microbes

• isolating the microbe and transmitting it caused disease

What did Pasteur use Koch’s discoveries to create?

Pasteur used Koch’s work on anthrax to develop a vaccines for anthrax, cholera and rabies by using an attenuated (weakened) version of the microbe responsible for each disease.

both scientists discoveries laid the foundation for germ theory

What is the problem with agricultural disease, for the industry?

Significant costs:

• reduced productivity

• higher production costs

• negative impacts on international and local trade

• detrimental impacts on the environment and biodiversity

What are Types of Animal Agricultural diseases?

Anthrax:

Caused by bacterium Bacillius anthracis

Can affect a wide range of animal species including humans

Previous outbreaks have caused significant amounts of cattle die.

Spores can survive in deep alkaline soil for many years and grazing animals can become infected

Business costs:

• livestock deaths

• treatment and vaccination costs

• human health risks

Flystrike:

caused by several species of blow flies, most common is Lucilla cuprina.

the flies attacks leave a damaged wound which other flied lay eggs in → maggots then feed on the animals flesh.

Treatments/preventions:

• removing tails

• shearing

• chemical treatments

Same economic impacts..

What are Types of Plant Agricultural diseases?

Citrus Canker:

Caused by the bacterium Xanthomonas citri

The bacteria forms lesions on stems → leaves and fruit die back

high economic impact to the farmers and the government who lose tree plantations

Potato Moth:

Phthorimaea operculella

Destructive pest of potatoes in NSW → can also interfere with tomatoes, tamarilloes and eggplant

caterpillars feeds on leaves and tubers

Insecticides used to kill caterpillars and stop moths laying eggs

infestations can severely affect crops and productivity.

Define an Adaption

Adaptations are structures, behaviours or physiological responses that help an organism to survive and/or reproduce in its environment.

to successfully establish an infection a pathogen must…

1. enter the host

2. multiply in host tissues

3. resist or not stimulate host defence mechanisms

4. damage the host

In order to colonise a new host the pathogen must…

1. Exit original host

2. be transmitted to another host either directly or indirectly

3. repeat the steps to establish infection in new host.

Bacterial Cell Adaptions

1. Varied Transmission Route

   eg: air, water, food, bodily secretions

2. Attachment to surfaces

   surface adaptions to attach to other cells (fimbriae/glycoalyx)

3. Rapid Reproduction

   rapid multiply in/on host

4. Mobility

   some have flagellae to allow greater mobility.

Methods of entry of prions? and an adaption that aids in entry?

Oral route

•Prions can enter a new host via the gut -contaminated tissue

- Skin

Can enter the body through open lesions to skin.

Prions are able to retain their infectious properties in soil for long periods of time.

Protein can “adapt” and change shape to the most infectious form for a particular host cell in the absence of a nucleic acid

How do prions suppress host immune system?

They invade specialized white blood cells found in the lymph nodes and spleen and replicate and eventually invade nervous tissue.

Methods of entry of Viruses? and 3 adaptions that aids in entry?

Adaptations:

1. Entry via receptor mediated endocytosis

Spikes which usually cover Viruses cause the host cell to form a vesicle bringing the virus into the host.

Eg influenze

2. Fusion:

Use their spike proteins to bind to host cells surface proteins, "tricking" the host cell to fuse its membrane, allowing the virus to enter.

• SARS

3. Entry via Genetic Injection
Use surface proteins to attach then inject their genetic information.

Similarities and Differences of Viruses to other pathogens

Similar to bacteria and fungi, they have to stick to their host cell prior to invasion

Differences: → Surface proteins on capsid or envelope adhere to the host cell

Do Viruses suppress the host immune response?

Due to high rate of mutation, their surface proteins can change so host immunity – specific memory  B and T cells against one strain are ineffective against new strains of the same virus

Bacteria Similarities and Differences

Similar to viruses and fungi they have to stick to their host cell prior to invasion

Differences → Chemicals called adhesins or Pilli and Fimbria stick to the host cell.

Bacterial cells can also stick together forming a biofilm, which aids adhesion.

Do Bacteria suppress the host immune response?

Release of chemicals destroy or suppress the hosts immune defences.

→ so do Bacteria, fungi and macroparasites

distinguishing adaptation of bacteria to aid in entry to host

Bacterial cells can stick together forming a biofilm which are inherently highly antibiotic resistant.

An adaption of protozoa that benefits them in infecting hosts.

Some protozoans can conceal or change their surface antigens, which delays detection by the immune system

Fungi Similarities and differences…

Similar: to bacteria and viruses, they have to stick to their host cell prior to invasion

Differences:

Cell wall or capsule molecules permit adhesion to cells

An adaption of fungi that benefits them in infecting hosts.

Some fungi can produce chemicals which suppress the host immune system.

Difference of macroparasites

Specialised mouth to attach to the host (internally or externally)

An adaption of macroparasites that benefits them in infecting hosts.

Some macroparasites (e.g. ticks and hookworms) secrete molecules that supress the host immune response

many have specialised mouth parts which hook onto the hosts skin eg: ticks

Prion Adaption for Transmission

Prions are able to retain their infectious properties in soil for long periods of time.

Viruses Transmission Adaption

able to live in a range of bodily fluids which enable them to be transmitted through the blood and other bodily fluids

Bacteria Transmission Adaption

horizontal gene transfer where bacteria can share genetic information

→ This paired with their high mutation rate allows for beneficial mutations to be shared.

• eg antibiotic resistance

These large colonies of resistant bacteria are more difficult for the host to destroy, giving bacteria more time for the infected host to pass on the pathogen.

Protozoa Transmission Adaption

Transmitted through food + water

• have adaptations enabling them to survive and replicate outside a host and are well adapted to move through water.

Fungi Transmission Adaption

fungi that cause tinea and ring worm can thrive anywhere that is warm and moist so they can be transmitted through direct contact or indirectly

Macroparasite Transmission Adaption

vary widely

• Ticks have adaptations that enable them to detect animals´ breath and body odors, or by sensing body heat, moisture, and vibrations.

Symptoms of Plant Viruses and Responses + example

Symptoms

• discolouration in the leaves

  • Watermarking

  • Vein Banding

  • discolouration

Example:

• mosaic plant virus = discolouration in mung beans

Symptoms of Plant Fungi and Responses + Example

Symptoms:

• discolouration in leaves

• thin fungi hairs on plant

• rotted roots

Example:

Armillaria Lutobubalina - causes root rot in eucalypts and other australian plants

Physical Plant barriers and responses and why

• Cell wall

  • strength and flexibility

• Bark

  • protects plant

• Waxy cuticle

  • is a structural feature but can change cuticle as a behavioural feature to thicken cuticle to respond to a pathogen

    • strengthens cell wall and closes stomata

• Stomatas

• Spikes and Thorns

Chemical Plant barriers and responses and why

• Chemical Cues emitted

  • warn nearby pants

  • deter herbivores

• Contain or Release Toxin

  • repel or cause harm to insects

• Produce a toxin or enzyme

  • breaks down pathogens

• Atoptosis

  • sometimes undergone by plant cells near infection site

  • prevents further infection

  • plant as a whole can survive by stopping the spread.

Plant Pathogen Response Example

Myrtle Rust Pathogen:

Myrtle Rust Pathogen:

Plants Affected:

• Plants in the myrtaceae famile

  • Eucalyptus

  • Bottle Brush

  • Tea Trees

What is the Pathogen?

• Fungal Infection

• attacks soft new growth

• spreads through spores

• high transmission rate

Symptoms:

• Purple Spots

• bright yellow spores form inside bulbous pustules

Host Responses:

• thick bark, cell wall

• cell wall increases at site of infection

• and develop defensive substances

• chemical response example:

  • eucalyptus oil produced by eucalyptus plants

• non-specific immune responses

Epidemiology Definition

A study to determine the distribution and determinants of diseases and/or health related states.

• can be applied to both infectious and non-infectious diseases, as well as accidents and suicide.

Application of epidemiology

• to help control disease spread

• to help develop treatments and prevention measures

• to develop a control strategy to manage outbreaks

• help to determine the severity of an outbreak

• determine where it may have originated

• determine who is still susceptible and most vulnerable

  • which can help focus quarantine efforts and prioritise who to vaccinate (if a vaccine exists).

• Accurately identifying the cause and effect relationship between a risk factor and disease

  • helps with treatment or prevention

Consequences of not doing epidemiological studies

• disease may be misidentified because people mistake correlation for causation. I

  • which is essential in order to establish effective, evidence based strategies to prevent or treat the disease

    • eg stop smoking for lung cancer.

Example of an effective epidemiological study

Smoking causes lung cancer

• reduced the number of smokers and cigarette sales, which is expected to result in a long-term reduction in lung cancer cases in the future.

How to establish cause and effect relationship within epidemiological studies.

Correlation: is the extent to which the change in two variables is related

• there may be correlation but no causation

• a correlation might be displayed but that might be due to a 3rd factor

for epidemiology causation must be established not just correlation.

What are the Types of Epidemiological Studies

• Descriptive

• Analytical

  • Case control

  • Cohort

• Intervention

What are Descriptive Epidemiological Studies

Descriptive: describe disease patterns in populations including:

• Incidence

• prevalence

• mortality

• Geographical distribution

• Demographic information

• Lifestyle factors

Should be:

• cross-sectional - involve large numbers of people

Descriptive Studies can help generate hypotheses as to the cause of the disease.

Eg: lung cancer + smoking

What are Descriptive Epidemiological Studies

Analytical: statistical analysis of data collected in descriptive studies and additional data collected to test hypotheses regarding the likely cause(s) of the disease.

• Case Control: studies comparing diseased people (case) with healthy people (control) to see if a factor (or set of factors) is more common in the group with the disease than those without. - statistical comparisons used to pin point factors contributing to disease.

  • what makes a good case:

    • large sample

    • case and controls from a diverse range of backgrounds

• Cohort Study: compares similar groups of healthy people with a group exposed to a risk factor, and the others not exposed to see if the exposed group has a higher incidence, and/or mortality from the disease.

  • What makes a good cohort Study

    • long period of time

    • very large sample sizes

    • groups as similar as possible to each other except for their exposure to the risk factor

Epidemiological Study Case

Richard doll - lung cancer

• patients in London hospital

• compared patients with lung cancer to patients without

• collected lifestyle and other data

• smoking more lung cancer then control group of non-smokers

What are Intervention Epidemiological Studies

to help to evaluate the effectiveness of a treatment or a campaign.

• includes clinical trials of drugs

• Studies before and after an prevention/treatment initiatives → to determine if the initiative was successful

Errors in epidemiological studies

Random errors – unpredictable variations in data, usually due to individual differences.

avoided by:

• large sample sizes

• groups are as similar as possible besides variable

Systematic errors (bias) —

Selection bias - subjects in a study are not representative of the whole population

Information bias – errors in taking measurements or recording information, or subjects can’t correctly recall information

What is an antigen?

There are marker molecules on the outside of cells.

• Cells with self markers → Normally not attacked by immune system. Every individual has unique markers

• Foreign markers → attacked by immune system.

Antigen: Any foreign molecule that your body recognises as ‘non-self’ and that triggers an immune response. Surface molecules on pathogens act as antigens.

Where are antigens found?

Antigens can be found:

• on non-cellular objects in the body, (eg snake venom, bacterial toxins, viruses),

• parts of broken cells (eg dead bacteria)

• on protein fragments (eg dead viral DNA).

Antigens in blood and donated tissue.

Donated Tissue:

Marker molecules from donated tissues and organs are matched to recipient to a certain extent → never an exact match (except identical twins).

→ Therefore → imuno-supressents are needed.

Blood antigens:

• The A and B antigens are surface molecules, specific to red blood cells.

• a person can only receive blood from same blood type or type O

  • as foreign and blood cells would be attacked by the recipient’s immune system.

Innate immune system definition & what it encompasess.

The innate immune system is made of defenses against infection that can be activated immediately once a pathogen attacks. → not specific

The innate immune system includes:

• First Line of Defense:

  • Physical Barriers

  • Chemical barriers

• 2nd Line of Defence → Non-specific Internal Immune Responses:

  • Phagocytosis

  • inflammation

  • lymph system

  • complement

  • fever

  • cell death.

Innate Immune Response – Physical barriers (1st line of defence)

SKIN:

• largest organ in body

• physical barrier to pathogens and contains natural microflora

• dry so that pathogen settlement/growth is slowed

• able to be quickly sealed if broken

MUCOUS MEMBRANES:

• line the respiratory, digestive, reproductive and urinary systems and contain natural microflora

• produce mucus as a sticky trap for pathogens and other particles

CILIA:

• cilia tiny hair-like structures that line the trachea and bronchi

• constantly beat in unison to carry mucus/particles/pathogens out of the lungs

• Pathogens are then swallowed, coughed out or sneezed out

Innate Immune Response – Chemical barriers (1st line)

CHEMICAL BARRIERS:

-stomach contains hydrochloric acid

- intestines have an alkaline environment

- skin, urinary and reproductive surfaces are slightly acidic

- oil and sweat glands produce chemicals that are antibacterial and/or antifungal

- urine is acidic so prevents microbial growth in the urinary system

- lysozymes are chemicals that destroy the cell wall of pathogens. - protect eyes/mouth

Physical responses to pathogen:

Vomiting and diarrhoea – response to pathogens in the gastrointestinal tract. → expel the pathogen

Increased urination – pathogens infecting the urinary tract → flush out the pathogen.

Coughing and sneezing – increased mucous production traps pathogens, exit via → respiratory tract (with the help of cilia)

Adaptive immune system definition & what it encompasess.

Adaptive immune response: Is carried out by specific lymphocytes called B cells and T cells. These B cells and T cells are highly specific against a specific pathogen (e.g. Specific B cells against influenza A would not recognize other pathogens, including other viruses or even other types of flu virus). This is sometimes referred to as the 3rd line of defense.

Prevention definition

enabling of individuals to avoid getting a disease

Control Definition:

avoiding the spread of a disease through a population. Successful control measures reduce the incidence, prevalence and mortality of a disease.

Treatment Definition

Curing or managing a disease after an individual is affected.

• can also help with control of a disease because once a person is treated, they cannot spread the disease to others.

Why is prevention important?

• help control the disease because the more individuals that are prevented from getting a disease in the first place, the less likely the disease will spread through a population, and fewer people will need to be treated.

Factors involved in monitoring and control

Humans today are more mobile than at any other time in history

• It is possible to travel via plane to anywhere in the world in a very short period of time

• Because of our increased mobility, it is also possible for diseases to spread globally in very short periods of time.

What are the three levels of Disease monitoring and control

1. Local

2. Regional

3. Global

What are local factors that influence the spread of disease

Relate to neighbourhood, town or city. Factors include:

• Sanitation: especially important in areas affected by typhoons and hurricanes

• Overcrowding: increasing the chance of exposure/infection

• Poor communication networks or roads: limiting access to medical treatment and/or information

• Animal husbandry practices: poor practices may aid transmission of some diseases from animal to human (e.g. bird flu) Local spiritual / cultural beliefs

What are regional factors that influence the spread of disease

• Mountain regions or islands have natural isolation factors that reduce spread.

• Coastal regions high coastal populations who rely on seafood which could harbour and transfer bacteria/viruses

• Seasonal variations may also influence types of vectors

  • e.g. monsoons mosquitos + malaria

• Increased trade between regions can lead to transmission of pathogens.  E.g. frozen berries from China = Australian’s contracting hepatitis A.

What are global factors that influence the spread of disease

Factors include:

• Increased mobility due to travel and work

• Migration of refugees (many have experienced lack of access to basic health care such as vaccinations)

• Misuse of antibiotics: led to rise in antibiotic resistant bacteria

4 examples of Pathogen Factors?

Pathogen factors may include:

•virulence

•natural reservoir (animal) + where found (eg waterborne)

•Method of transfer

•Incubation period

What are some personal hygiene practices that can reduce the risk of pathogens infecting an individual?

• Hand washing before preparing and eating food & after going to the toilet

• disinfecting surfaces - prevent fomites

• use of tissues

Examples of community hygiene which can help limit the spread of a disease.

• Sterilisation & disinfection of equipment in hospitals, ]

• City planning to avoid overcrowding

• Safe food practices

  • wearing gloves,

  • cleaning surfaces and utensils correctly,

  • storing food correctly

  • cooking food at correct temperatures.

What is quarantine and how is it effective in helping to limit the spread of a disease.

Quarantine is a period of isolation used to prevent the spread of infectious of infectious disease.

May include:

• Isolation and quarantine

• compulsory hospitalisation of infected people

• closing schools/workplaces

• surveillance/Border screening/isolation of animals or goods

Define Phagocytosis:

The process of specialised white blood cells called phagocytes, engulf and absorb foreign matter (physical), and digesting it (chemical), to destroy pathogens.

What is a neutrophil?

The most abundant white blood cell in your body. Particularly toxic to bacteria and fungi. They self-destruct following phagocytosis, forming “pus”.

What is a macrophage?

• Type of phagocyte

• Antigen presenting cell.

• Larger than neutrophils – can destroy pathogens and cancer cells → phagocytosis.

• After phagocytosis, they transfer part of the pathogen’s antigen to its own surface and “present” the antigen to a helper T cell activating the adaptive immune response

• can also release cytokines in order to signal and recruit other cells to an area with pathogens.

What is a Dendritic Cell

• antigen presenting cells

• located in tissue

• identify threats and act as messengers to the rest of the immune system

• bridge innate and adaptive immunity

What is a natural killer cell (NK cell)?

trigger apoptosis to kill cells and virus-infected cells → stops the spread of infection

identify infected cells by body cells which dont have MCH1 markers anymore

What is a basophil:

• target multicellular parasites.

• Release chemicals called histamines, triggering inflammation

• also responsible for some allergic reactions.

what is a Eosinophil

– target bacteria and multicellular parasites