Communicable Diseases, Disease Prevention and the Immune System Flashcards
Different types of pathogen
Bacteria
Diseases caused by bacteria
Tuberculosis
Diseases caused by viruses
HIV/AIDS
Diseases caused by protoctista
Malaria
Diseases caused by fungi
Black sigatoka
Organisms affected by ring rot
Potatoes
Organisms affected by black sigatoka
Bananas
Organisms affected by ring worm
Cattle
Types of transmission of communicable pathogens
Direct
Direct transmission
The transfer of a pathogen directly from one individual to another
Methods of direct transmission in humans
Direct contact
Types of direct contact
Kissing
Things kissing and contact with bodily fluids can pass on
Bacterial meningitis
Things direct skin-to-skin contact can pass on
Ring worm
Things microorganisms from faeces can pass on
Diarrhoeal diseases
Types of inoculation
Break in the skin
Things breaks in the skin can pass on
HIV/AIDS
Things animal bites can pass on
Rabies
Things puncture wound/sharing needles can pass on
Septicaemia
Things ingestion can pass on
Amoebic dysentery
Methods of indirect transmission in animals
Fomites
Examples of fomites
Bedding
Things fomites can pass on
Athlete’s foot
Examples of droplet infection
Expulsion of saliva and mucus
Things droplet infections can pass on
Influenza
What do vectors do?
Transmit communicable pathogens from one host to another
Things vectors can pass on
Malaria
Examples of vectors
Mosquitoes
Factors affecting the transmission of communicable diseases in animals
Overcrowding living and working conditions
How can climate change affect transmission of communicable diseases?
Introduce new vectors and new diseases
Example of direct transmission in plants
Direct contact of a healthy plant with any part of a diseased plant
Things that direct contact in plants can pass on
Ring rot
Examples of indirect transmission in plants
Soil contamination
Things that soil contamination can pass on
Black sigatoka spores
Examples of vectors for plants
Wind
Things that wind as a vector in plants can pass on
Black sigatoka
Things that water as a vector in plants can pass on
Potato blight
Examples of animal vectors in plants
Insects
Examples of things humans do as vectors for plants
Hands
Things humans as vectors can pass on for plants
TMV
Factors affecting the transmission of communicable diseases in plants
Varieties of crops that are susceptible to disease
How does climate change affect the transmission of communicable diseases in plants?
Increased rainfall and wind promote the spread of diseases
General pattern of defence in plants
Receptors in cells respond to molecules from the pathogen or chemicals produced when the cell wall is attacked
Structure of callose
Beta 1
Roles of callose in plant defences
Deposited between cell walls to act as barriers to prevent pathogens entering cell walls around the site of infection
Why can plants react by sealing off and sacrificing?
They are continually growing at the meristems so can replace damaged parts
Examples of chemicals produced by plants in defence
Insect repellents
Examples of insect repellents produced by plants
Pine resin and citronella from lemon grass
Examples of insecticides produced by plants
Pyrethrins from chrysanthemums
Examples of antibacterial compounds produced by plants
Phenols
Examples of anti fungal compounds produced by plants
Phenols
Examples of anti-oomycetes
Glucanases
Glucanases
Enzymes made by some plants that break down glucans
Glucans
Polymers found in cell walls of oomycetes
Non-specific animal defences against disease
Skin
How does the skin defend against disease?
Prevents entry
How do mucuous membranes defend against disease?
Secrete mucus that traps microorganisms and contains lysozymes and phagocytes
Blood clotting cascade
The tissue is damaged
What does serotonin do in blood clotting and wound repair?
Makes the smooth muscle in the walls of the blood vessel contract so they narrow and reduce the supply of blood to the area
What happens after clotting in wound repair?
Clot dries out
Inflammatory Response
The localised response to pathogens
Characteristics of the inflammatory response
Pain
What happens in the inflammatory response?
Mast cells are activated in damaged tissue to release histamines and cytokines
What do histamines do?
Makes the blood vessels dilate to cause localised heat and redness
Oedema
Swelling
What do cytokines do in the inflammatory response?
Attract white blood cells
Phagocytes
Specialised white blood cells that engulf and destroy pathogens
Types of phagocytes
Neutrophils
What is in pus?
Dead neutrophils and pathogens
Stages of phagocytosis
Phagocytes recognise non-human proteins on the pathogen
How do macrophages work? (This is the antigen presenting cell stuff)
Macrophage digests a pathogen
General use of cytokines
Act as cell-signalling molecules to inform phagocytes that they need to move to the site of infection or inflammation
General use of opsonins
Chemicals that bind to pathogens and tag them so they can be recognised by phagocytes. Phagocytes have receptors in cell membranes that bid to opsonins so the phagocyte then engulfs the pathogen
Role of plasma cells
Produce antibodies for a particular antigen and release them into circulation
Role of T helper cells
CD4 receptors on the cell surface membrane will bind to surface antigens on antigen presenting cells
Role of T killer cells
To destroy the pathogen containing the antigen by producing perforin which kills the pathogen by making holes in the cell membrane
Role of T regulator cells
To suppress the immune system and regulate it
When are interleukins particularly important?
In preventing the set up of autoimmune responses
Role of T memory cells
To provide immunological memory
Role of B memory cells
To provide immunological memory
Process of cell mediated immunity
Macrophages engulf and digest pathogens in phagocytosis
What can the cloned T cells do in the cell mediated response?
Develop into T memory cells
Process of humoral immunity
Activated T helper cells bind to the B cell APC in clonal selection
Humoral immunity
When the body responds to antigens found outside the cells and APCs.
What does the humoral immune system do?
To produce antibodies that are soluble in blood and tissue fluid but aren’t attached to cells
General structure of antibodies
Made of two polypeptide chains called the heavy chains and two other chains called light chains
How antibodies defend the body
Antibodies in the antigen-antibody complex can act as an opsonin so the complex is more easily engulfed
How do agglutinins help?
They cause antigen-antibody complexes to clump together so they don’t spread through the body which makes it easier for the phagocytes to engulf a number of pathogens at the same time
How do anti-toxins help?
They bind to the toxins produced by pathogens which makes them harmless
How do opsonins help?
They bind to pathogens and tag them so they can be recognised by phagocytes as phagocytes have receptors on their cell membranes that bind to opsonins so they can engulf stuff
Important opsonins
Immunoglobulin G
Natural active immunity
The body has acted to produce its own antibodies and memory cells
How does natural active immunity develop?
Meet a pathogen for the first time
Active immunity
Body has acted to produce new antibodies and memory cells
Example of natural passive immunity
Breastfeeding
How does natural passive immunity develop?
First milk a mother makes is called colostrum which is high in antibodies
When does natural passive immunity last until?
Until the baby starts to make its own antibodies
How does artificial passive immunity develop (In the broadest sense of the word)?
Injecting antibodies into the bloodstream
Examples of diseases that need artificial passive immunity to fight
Tetanus
How does artificial active immunity develop?
Immune system of the body stimulated to make its own antibodies by a safe form of the antigen
Stages of a vaccination
Pathogen made safe
How can a pathogen be made safe?
Killed
Example of pathogen made safe by killing or inactivation
Whooping cough
Example of pathogen made safe by attenuated strain
Rubella
Example of pathogen made safe by altered toxins
Diphtheria
Example of a pathogen made safe by isolated pathogens
Influenza
Example of a pathogen made safe by genetically engineered pathogens
Influenza
Example of artificial active immunity
Routine vaccinations
Autoimmune disease
When the immune system stops recognising self cells and starts to attack healthy body tissue
Examples of autoimmune diseases
Type 1 diabetes
Body part affected by type 1 diabetes
Pancreas
Treatments for type 1 diabetes
Insulin injections
Body part affected by Rheumatoid Arthritis
Joints
Treatment for rheumatoid arthritis
No cure
Body part affected by lupus
Skin
Treatment for lupus
No cure
Reasons for changes to vaccines
Different strains of a pathogen may have mutated so the antigens are different shapes
Epidemic
When a communicable disease spreads rapidly to a lot of people at a local or national level
Pandemic
When a disease spreads rapidly across a number of countries or continents
Vaccines in epidemics/pandemics
Mass vaccination can prevent the spread of the pathogen into the wider population
Herd immunity
When a significant number of people in the population have been vaccinated
Why does herd immunity work?
There is minimal opportunity for an outbreak to occur
Examples of drugs derived from bioactive compounds
Penicillin
Source of penicillin
Mould growing on melons
Function of penicillin
Antibiotic
Source of docetaxel
Yew trees
Function of docetaxel
Treatment of breast cancer
Source of aspirin
Compounds from sallow bark
Function of aspirin
Painkiller
Personalised medicine
Combination of drugs that work with your individual combination of genetics and disease
How is personalised medicine done?
Human genome is analysed
Pharmacogenomics
Interweaving knowledge of drug actions with personal genetic material
Example of pharmacogenomics
Breast cancer with mutation of HER2 gene can be shut down by trastuzumab and lapatinib
Synthetic biology
Developing populations of bacteria or mammals that produce much needed drugs that would be too rare
Nanotechnology
When tiny non-natural particles are used to deliver drugs to a very specific site within cells
How penicillin was made an economically viable antibiotic
Grown from a mould by Alexander Fleming
How scientists design drugs
Build up 3 dimensional models of key molecules in the body
Examples of habitats being destroyed
Rainforests
Need for maintenance of biodiversity
To make sure that we don’t destroy an organism that could be used in a life-saving drug
Example of antibiotics being used to benefit society
At the beginning of the 20th century
Benefits of antibiotics
Selectively toxic
Selective toxicity
Interfering with the metabolism of bacteria without affecting the metabolism of human cells
Disadvantage of antibiotics
Development of antibiotic resistance
Causes of antibiotic resistance
Use in agriculture
Where is antibiotic resistance a particular problem?
Hospitals
Examples of antibiotic resistant bacteria
MRSA
What is MRSA?
Bacterium carried by 30% of population on skin or in the nose
Antibiotic used to treat MRSA
Methicillin
What is C. difficile?
Bacterium in the guts of 5% of the population
How is overuse of antibiotics causing problems with C. difficile?
Commonly used antibiotics will kill off gut bacteria so C. difficile can survive and reproduce and take hold
How does antibiotic resistance develop?
Chance mutation in one bacterium makes it antibiotic resistant
How to reduce antibiotic resistant infections
Minimise use of antibiotics
Implications of antibiotic resistant bacteria
Death
Site of production of B cells
Bone marrow
Site of maturation of B cells
Bone marrow
Site of production of T cells
Bone marrow
Site of maturation of T cells
Thymus gland
Structure of neutrophils
Multi-lobed nucleus
Structure of antigen-presenting cells
Antigens released from a pathogen in phagocytosis are on the cell surface membrane bound to the MHC
Major histocompatibility complex
Set of cell surface proteins used in recognising foreign molecules
Role of the hinge region
To allow the antigen to bind to more than one antigen
Role of the constant region
To bind to the phagocyte
Role of disulfide bridges
To hold the heavy and light chains together
Neutralisation
Antibody blocks binding sites to prevent the entry of the pathogen into a host cell
Why does the secondary immune response take less time than the primary immune response?
Time for antigen presentation and clonal selection not required
Why is there a gap in time between infection and appearance of antibodies?
Time for antigen presentation
Parasite
An organism that lives in a host and causes it detriment
Name of bacteria that causes tuberculosis
Mycobacterium
Immune response
Response to antigens that involves lymphocytes
How to identify a lymphocyte down a light microscope
Large nucleus
