Communicable Diseases Flashcards
What’s a pathogen
Organism that causes disease
What’s a host
Organism the pathogen lives in
Organisms that affect diseases
Bacteria
Viruses
Fungi
Protoctista
How do bacteria spread disease
They are prokaryotic cells that rapidly reproduce to spread disease -> no membrane bound organelles & nucleus
- most bacteria produce toxins that produce poison or damage the host cells, causing disease.
These toxins can damage / inactivate enzymes, cause cell-membrane breakdown etc. e.g. interfere with the host cell genetic material so cells can’t divide
Diseases caused by bacteria
TB & ring rot
How do viruses infect host cells and take over the generic machinery & organelles of cell
Diseases caused by viruses
How do fungi spread disease
Some fungi produce toxins which affect the host cells & cause disease
Fungi digest living cells & destroys them. This combined with the response of the body to the fungus damage gives symptom of disease
Fungi = hyphae from mycelium spread throughout host skin / vascular tissue -> release spores
Diseases caused by fungi
How do Protoctista spreads disease
Some take over the cells & break them open, digesting
Some need a vector to transfer them to their hosts, while some enter directly through polluted water
These are eukaryotes which aren’t animals, fungi, or plants + have overlapping features with all of the other eukaryotes
What diseases do Protoctista cause
Ways of direct transmission
Ways of indirect transmission e.g. using a vector etc
Factors that increase the likelihood of transmission
Why is spread of communicable diseases likelier in warmer / moist conditions
What is direct transmission
Direct contact of a healthy plant with any part of a diseased one
Ways of indirect transmission (NOT USING A VECTOR)
What are factors affecting plants pathogen transmission
- planting varieties of crops that are susceptible to disease
- over-crowding increases the likelihood of contact
- damp conditions = increased survival and spread of spores & pathogens
- poor mineral nutrition = reduced plant resistance
What are (plants) passive defences
Passive defences are always present, before infection, & prevent entry & spread of pathogen
Examples of main physical plant defences
Chemical defences in plants
What are non-specific defences in animals
What are the steps of skin keratinisation (~30 days)
Why does blood clot
- prevents excess blood loss
- prevent pathogens entering body & bloodstream through wound
- scab provides barrier which allows wound to heal
How does blood clot
Clotting factors activate the enzyme cascade, once a clot forms, blood cannot leak out of the body & pathogens cannot get in
Why does blood clot formation have to be complex
To prevent formation in blood vessels when not needed
Wound repair steps
What do mast cells do in the immune response
Detect the presence of pathogens in tissue, then release histamines (cell signalling substances)
What do histamines stimulate
- vasodilation to increase blood flow through capillaries to area
-> leaky capillaries allow WBC’s + plasma proteins to leave the blood & enter tissue fluid
-> that tissue fluid then enters tissues, leading to swelling
The excess tissue fluid is drained by the lymphatic system, where lymphocytes are stored, & pathogens come into contact with lymphocytes and imitate the immune response
What are expulsive reflexes
- Coughs & Sneezes - they eject the pathogen laden mucus from gas exchange
- Vomiting & Diarrhoea - expel the contents of the gut, & infective pathogens
How do mucus membrane work / what’s the action of mucus
Mucus secreted by goblet cells
Mucus traps pathogen
Cilia sweeps mucus upwards to top of trachea
Mucus swallowed -> enters digestive system -> traps pathogens -> killed by stomach acid
Where are mucus membranes found
Mucus membrane line the gut, airways and reproductive system, as these areas are less well protected as ifs where many things are taken into the body
What are antibodies
Y shaped (proteins) that are specific to 1 type of antigen
Antibody structure
4 polypeptide chains (two light & two heavy) held together by disulphide bonds
2 variable regions (these allow for the binding of more than 1 of the same antigen)
- has a complementary shape to a specific antibody
- variable regions of different antibodies allow for specificity to different antigens
Constant region (allows recognition by & attachment to phagocytes)
Hinge region (allows flexibility + binding of more than one antigen)
Function of the antibody
Produced by plasma cells to bind to specific antigens
Antibody diagram
Antibody diagram
Ways antibodies can function
Agglutinins
Opsonins
Anti-toxins
What do agglutinins do
Cause pathogens to stick together by agglutination
- clump together many pathogens
- clump too large to enter host cells
- increases likelihood of the clump being consumed by phagocyte & more pathogens can be consumed by phagocyte at once
How do opsonins work
These are protein molecules which attach to antigens on the surface of a pathogen -> increase the ability of the phagocyte to bind to & engulf the pathogen
How do anti-toxins work
They neutralise toxins released by pathogens
- cover binding site (antigen) on pathogen
Bind to toxins
Prevent entry of pathogen into host cell
Types of immunity
Active
Passive
Artificial
Natural
Types of each immunity explanation / examples
What is autoimmunity
When antibodies produced by the immune system attack its own antigens, damaging its body cells
Examples of autoimmune diseases
What are lymphocytes
White blood cells
Smaller than phagocytes
Have large nucleus which fills most of cell
Specific receptors on the cell surface membranes
2 types of lymphocytes
T and B
T cells vs B cells table
What do T cells differentiate into
What do B lymphocytes become
Differentiate into plasma cells e.g. to produce antibodies
B memory cells also stay in the blood to provide long term immunity
What occurs in the primary immune response (based on B cells & humoural immunity)
How does the secondary immune response differ from the primary one
Secondary…
Stars earlier than primary
Faster
Produces more antibodies + production starts sooner than primary
Due to memory cells
Functions of memory cells
Functions of memory cells
Vaccination definition
Deliberate exposure to harmless antigenic material in order to stimulate an immune response, produce antibodies, & memory cells in order to gain future immunity to a specific disease
Antigenic material = weakened dead pathogen
Epidemic vs pandemic
Epidemic = rapid spread of disease through a high proportion of population
Pandemic = worldwide epidemic
Herd vaccination vs ring vaccination
Why do vaccines have to be changed regularly
As different strains of the pathogen emerge due to the pathogen mutations -> these diff strains have diff antigens, so therefore antibodies produced must match the antigens of the new strain
Examples of vulnerable demographics in society e.g as they have compromised or immature immune systems
- young children
- elderly
- hiv infected
- on immunosuppressants
- leukomia
- under cancer treatments
Define ‘health’
Free from disease & physical, mental & social well-being & good nutrition & suitable housing
Sources of medicines & threats to these sources
Sources
- plants / micro-organisms esp those in traditional medicine (as already identified to be likely to have a medicinal effect
Threat
- reducing biodiversity
- new drugs coming from plants / animals fungi
Leads to habitat destruction via logging
How does antibiotic resistance develop
How does antibiotic resistance develop
What do phagocytes do + types of them
First line of secondary defence (after pathogen has entered the body)
E.g. macrophages, neutrophils, & mast cells
What are macrophages / what do they do (etc’
What do Antigen present cells do
Move around the body, increasing the likelihood that it will come into contact via specific cells (T-lymphocytes) which active the immune response
What do neutrophils do / their structure / their traits etc.
What do cytokines do
They’re cell signalling molecules which stimulate the immune response
- have specific shape
- complementary shape to receptor
- bind to receptor on membrane
- activate clonal expansion
What is the process of phagocytosis (a neutrophil engulfing a pathogen into a phagocyte)
