communicable diseases

Define communicable disease

Illness caused by a pathogen than can be directly transmitted directly or indirectly between organisms.

What is cell mediated immunity

An immune response involving T lymphocytes that act on infected or abnormal cells

What type of pathogens does cell mediated immunity target

Intracellular pathogens (inside cells)

Outline cell mediated immunity

• T helper cell binds to antigen

• T helper cell activated

• Cytokines released

• Cytotoxic T cells activated (killer T cells)

• Cytotoxic T cells kill infected cells

• Memory T cells formed

How to cytotoxic T cells (killer T cells) kill infected cells

Release performing (creates pores)

Release enzymes →cell apoptosis

What is natural immunity

Immunity acquired without medical intervention

What is artificial immunity

Immunity gained through medical intervention

What is active immunity

Immunity resulting from activation of the immune system to produce antibodies

What is passive immunity

Immunity gained by receding antibodies from another source

What is the difference between active and passive immunity

Active - produces memory cells, long lasting

Passive - no memory cells, short term

What is natural active immunity

Immunity gained after infection and immune response

What is natural passive immunity

Antibodies passed from mother to child (eg placenta or breast milk)

What is artificial active immunity

Immunity gained through vaccination

What is artificial passive immunity

Injection of ready made antibodies

Why is artificial passive immunity used

Immediate protection

Used when exposure risk is high

Disadvantage of artificial passive immunity

• temporary

• No memory cells formed

What is personalised medicine

Treatment tailored to an individuals genetic makeup

Why is personalised medicine useful

• Improves effectiveness

• Reduces side effects

What is pharmacogenetics

The study of how genetic variation affects drug response

Why is pharmacogenetics important

• determines correct drug/dose

• Reduce adverse reactions

• Improves treatment success

What is synthetic biology

The design and construction of new biological parts or systems

How is synthetic biology used in medicine

• produces vaccines

• Engineering bacteria to produce drugs

• Developing new treatments

What are monoclonal antibodies

Identical antibodies produced from a single clone of cells

How are monoclonal antibodies used

• target specific antigens

• Used in diagnosis treatment

What is a pathogen

A microorganism that causes disease

Name the four main types of pathogen

Bacteria, viruses, fungi, parasites.

What is meant my primary pathogen

A pathogen that can cause disease in a healthy organism

What is an opportunistic pathogen

A pathogen that causes disease only when the hosts immune system is compromised

Name three methods of transmission of communicable disease

Direct contact

Indirect contact

Airborne transmission

Vector transmission

What is direct transmission

Transfer of pathogens through direct physical contact

What is indirect transmission

Transmission via an intermediate object (formite)

What is a vector

An organism that carries and transmits a pathogen (eg mosquito for malaria)

How to bacteria cause disease

Produce toxins

Damage host tissues

What are exotoxins

Toxins secreted by bacteria

What are endotoxins

Toxins released when bacteria die and break down

Give an example of pathogenic bacteria

Tuberculosis

Bacterial meningitis

Give examples of viral diseases

HIV

Influenza

How do viruses causes disease

Invade host cells

Replicate inside cells

Cause cell damage

Why are antibiotics ineffective against viruses

Viruses lack cellular structures targeted by antibiotics

Give an example of a plant viral disease

Tobacco mosaic virus

What are symptoms of tobacco mosaic virus

Mosaic discolouration of leaves

Reduced photosynthesis

Stunted growth

Describe structure/content of viruses

DNA or RNA

Protein coat (capsid)

How do viruses replicate

Enter host cell

Use host machinery

Replicate

Burst cell (lysis)

How do fungi cause disease

Grow on host tissue

Digest tissues using enzymes

What is a key feature of protoctists

Eukaryotic, often parasitic

How do protoctists cause disease

Live inside host

Damage cells Replicate

Use host nutrients

Define transmission

Transfer of pathogens between hosts

Describe airborne transmission

Pathogens spread via droplets in the air

Define direct transmission

Physical contact between individuals

What is indirect transmission

Transfer of pathogens via surfaces (fomites)

Describe vector transmission

Organism carries pathogen

Who is most at risk for contracting TB

Those in overcrowded conditions

Those with weakened immune systems

Who is most at risk for contracting bacterial meningitis

Babies, young children, teens, elderly

Who is most at risk for contracting HIV

Those who have unprotected sex

Those who share needles

Who is most at risk for contracting Influenza

Elderly, young children and the immune compromised

Who is most at risk for contracting malaria

Those in tropical regions

Those who traveled to endemic areas

Who is most at risk for contracting ring worm

Those in close contact, athletes and those who share towels

Who is most at risk for contracting athletes foot

Athletes, those using communal showers

What is tuberculosis‘ effect on the body

Damages lungs and suppresses immune system

What is bacterial meningitises effect on the body

Damages membranes of the brain and can cause blood poisoning

What is HIV/AIDS effect on body

Gradually destroys immune system

What is influenzas effect on body

Kills ciliated cells epithelial cells in gas exchange system

What is athletes foot effect on body

Causes cracking and scaling of skin between the toes

What is ringworms effect on the body

Causes circular, red rash

What is malarias effect on body

Damages red blood cells, liver and brain

Name example of fungi

Athletes foot

Ringworm

Name example of protoctist

Malaria

What are primary defences

Barriers preventing pathogen entry

Name examples of primary defences

Skin (physical barrier)

Mucous membranes

Lysozyme in tears

What is the role of mucus and cilia

Mucus - traps pathogens

Cilia - moves mucus out of airways

What is an antigen presenting cell

Cell that displays antigens on surface

What is the function of B cells

Produce antibodies

What is clonal selection

Only specific B cells activated

What is clonal expansion

Rapid mitosis of selected B cells

What is role of plasma cells

Produce antibodies

What is role of memory cells

Provides long term immunity

State two types of B cells

Plasma cells

B memory cells

What are steps of phagocytosis

• recognition of antigen

• Engulfment

• Lysosome fusion

• Digestion by enzymes

What are roles of helper T cells

Activate B cells

What is role of cytotoxic T cells (killer T cells)

Kills infected cells by making holes in cell surface membrane using preforins

What is role of T suppressor cells

Control adaptive immune response ensuring it ends after pathogen is cleared

What is role of T memory cells

Responsible for immunology memory

What are four types for T cells

T helper

T cytotoxic (killer)

T suppressor

T memory cells

Describe structure of antibodies

Y shaped region

Variable region binds to specific complimentary antigen

How do antibodies work

• bind to antigen

• Form antigen - antibody complex

• Causes agglutination

• Mark for destruction

Describe primary immune response compared to secondary immune response

Primary - slow, low antibody concentration

Secondary - faster, high antibody concentration

Why is secondary immune response faster

Presence of memory cells

Define a vaccine

Contains antigens to stimulate immune response

How do vaccines work

• introduce antigens

• Activate B cells

• Produce memory cells

• Faster secondary response on infection

Define antibiotics

Chemicals that kill/inhibit bacteria

How does antibiotic resistance arise

• mutation

• Resistance allele

• Selection pressure (antibiotic)

• Survival of resistant bacteria

• Reproduction

• Spread of resistance gene

State four methods to prevent disease spread

• vaccination

• Hygiene

• Isolation

• Vector control

State method of antibiotic testing

• agar plate

• Bacteria spread

• Antibiotic discs added

• Incubate

• Measure inhibition zones

What does a larger inhibition zone indicate in antibiotic testing experiment

More effective antibiotic

Why are viruses obligate intracellular parasites

Cannot reproduce without host cell machinery

Why are bacteria targeted by antibiotics

Different cells structure