4.1.1 Communicable Diseases, Disease Prevention and the Immune System COMPLETE Flashcards
DEFINITION- Health
A state of complete physical, mental and social wellbeing and not merely the absence of disease or infirmity
DEFINITION- Disease
Anything that impairs the normal functioning of the body/ mind
Disease Types
Infectious- Colds Non Infectious- Cancer Mental- Depression Inherited- Cystic Fibrosis Deficiency- Anaemia
Parasites
An organism that lives on or in a host organism, takes nutrition and causes harm.
ANIMAL- Flea
PLANT- Mistletoe
Pathogens
Microorganisms that cause disease, either produce TOXINS
Bacteria- breakdown plasma membrane, inactivate enzymes and prevent mitosis
Fungi- Produce toxins that damage host cell
or DIGEST living cells i.e. fungi and protoctista
DEFINITION- Epidemiology
The study of the spread of diseases and the factor affecting it
DEFINITION- Pandemic
A Worldwide epidemic
DEFINITION- Mortality
The number of people who die each year from a disease
DEFINITION- Prevalence
The number of people with a disease at a given time
DEFINITION- Incidence
The number of new cases of a disease in a population per year
DEFINITION- Endemic
A disease that is always present in the population
DEFINITION- Epidemic
A disease that spreads rapidly to a lot of people over a wide area
DEFINITION- Morbidity
The number of people with a disease as a proportion of the population
Examples of how health organisations help
- Education programmes
- Advertisement
- Screening programmes
- Vaccination programmes
- Target research for cures
Disease in Developing Countries
Mainly infectious disease, as well as deficiency diseases, accidents and deaths at birth.
CAUSES- poor sanitation, unsafe water, overcrowding, poverty, climate, lack of medical facilities
Disease in Developed Countries
Mainly Cardiovascular, cancer or road accidents, also more degenerative diseases.
CAUSES- Improved hygiene and vaccinations, however poor diets, smoking, too much alcohol and longer lives,
Bacteria
Belong to the Prokaryote kingdom, reproduce quickly and waste can be toxic.
ANIMAL- Meningitis
PLANT- Ring Rot
Viruses
Non living pathogen, also parasites, invade living cells and make copies before cell lyses and releases new viruses, evolve rapidly.
ANIMAL- HIV
PLANT- Tobacco Mosaic Virus
Protoctista
Eukaryotes, single celled organisms, sometimes parasites/ pathogens, some need vectors to transport them.
ANIMAL- Malaria
PLANT- Potato Blight
Fungi
Devastating for plants, multicellular eukaryotes, many are saprophytes, reproduces quickly releases millions of spores.
ANIMAL- Athletes foot
PLANT- Black Sigatoka
Bacterial Meningitis
CAUSE- Bacterial infection
TRANSMISSION- Direct physical contact
DETAILS- Blotchy red rash, causes blood poisoning and rapid death, antibiotics cure if early can get vaccine.
Influenza
CAUSE- Viral Infection
TRANSMISSION- Droplet infection
DETAILS- Infects the ciliated epithelium and leaves airway open for second infection, can be fatal
Ringworm
CAUSE- Fungal disease
TRANSMISSION- Direct Physical Contact
DETAILS- Causes grey white crusty infections, different fungi for different animal species i.e. Cattle, dogs, cats. Treated with anti fungal cream
Athletes Foot
CAUSE- Fungal infection
TRANSMISSION- Direct Physical Contact/Fomites
DETAILS- Digests warm moist skin between toes, causes cracking and itching, treated with anti fungal cream
Malaria
CAUSE- Protoctista
TRANSMISSION- Vector via female mosquito
DETAILS- Female sucks blood to make her eggs, plasmodium cells enter the bloodstream and invade RBC causing fevers.
Malaria details
SYMPTOMS- Repeated fevers, muscle aches
TREATMENT- Many strains have become resistant
GLOBAL IMPACT- Climate change makes it worse, difficult to vaccinate, increased resistance.
Prevention of Malaria
Avoid being bitten- repellant, long sleeves, sleep under nets
Reduce Mosquito Number- Fish ponds, oil on surface preventing larvae breathing, pesticide.
Tuberculosis
CAUSE- Bacteria
TRANSMISSION- Droplet infection
DETAILS- Affects the lungs, at greater risk if have HIV, if bacteria reaches the alveoli then macrophages engulf them but they’re not destroyed and instead divide
TB Details
SYMPTOMS- weight loss, night sweats, coughing blood.
TREATMENT- 6 month antibiotic course, DOT directly observed therapy.
GLOBAL IMPACT- leading killer of HIV positive people, common in south east Asia and Sahara Africa
HIV/AIDS
CAUSE- Virus
TRANSMISSION- Physical Contact, body fluids, sex, dirty needles, blood transfusions
DETAILS- Infects the T Helper cells and destroys them, leads to opportunistic diseases i.e. phneumonia
HIV/AIDS Details
TREATMENT- Drugs are available but are expensive, best to prevent using condoms and sterile needles
GLOBAL IMPACT- Major public issue claiming 35 million lives so far, WHO area in Africa most effect
Ring Rot
TYPE- Bacteria
AFFECTS- Potatoes, aubergines, Tomatoes
DETAILS- Decay of vascular tissue, causing wilting. Spread via direct contact, dirty water and equipment.
Tobacco Mosaic Virus
TYPE- Virus
AFFECTS- Tobacco plants
DETAILS- Causing decolorisation of leaves, only multiply in living cells, survive dormant in dead cells. Spread by workers hands, clothing and tools
Potato Blight
TYPE- Protoctist
AFFECTS- Potatoes
DETAILS- microscopic fungus like organism who’s spores break away easily, airborne in high temps, waterborne in lower temps.
Black Sigatoka
TYPE- Fungus
AFFECTS- Bananas
DETAILS- Attacks and destroys the leaf, spots result in lower yield, spread by wind, rain and irrigation water. Fungicides spreads using aeroplanes.
Transmission between animals
- Direct Contact
- Ingestion
- Droplet Infection
- Inoculation
- Fomites
- Vectors
Factors Affecting Transmission (Animal)
- Overcrowded living conditions
- Poor Nutrition
- Compromised immune system (HIV)
- Poor waste disposal
- Climate changes (introducing new vectors)
Transmission between plants
- Direct contact between healthy and infected plant
- Indirect contact via vectors (wind, water, animal, human) and soil contamination
Factors affecting Transmission (Plants)
- Plant varieties susceptible to disease
- Overcrowding
- Poor nutrition lowers resistance
- Damp warm conditions
- Climate change
Physical Defences in Plants
- Cellulose Cell Wall
- Lignin is waterproof
- Bark contains pathogen fighting bacteria
- Stomata Closure prevents entry
- No immune system but sacrifice parts, i.e. swelling that blocks xylem.
- Chemical defences
Primary Defences in Animals
- Skin acts as a barrier, also produces sebum that inhibits growth of pathogens
- Mucus membrane traps pathogens and get wafted up throat by ciliated epithelium.
- Hydrochloric acid in stomach denatures the pathogen
- Waxy ear canal traps pathogen
- Expulsive reflexes
- Blood clotting
Blood clotting
- Temporary platelet plug forms when the platelets bind to collagen after vessel wall is exposed
- Inactive thromboplastin is activated and becomes Thrombin when combined with Ca2+ and Prothrombin. Then combines with Fibrin/ Fibrinogen to produce another plug.
Wound Repair
Clots prevent the entry of microbes, serotonin also released to trigger vasoconstriction reducing blood flow. The scab shrinks once formed to pull sides together.
Collagen is deposited and stem cells in the epidermis undergo mitosis.
New blood vessels grow
The inflammatory response
Characterised by pain, heat, swelling.
Presence of microbes detected by mast cells that then release cytokines and histamine
Histamine
Causes Vasodilation, capillary becomes more permeable to WBC. Increases tissue fluid leading to swelling, this drains into the lymphatic system where lymphocytes are stored, pathogen then meets lymphocyte
Cytokines
Attract phagocytes that remove pathogens via phagocytosis
Fevers
- Cytokines stimulate the hypothalamus to reset bodies thermostat
- Higher temp will inhibit pathogen, immune system also works faster
Neutrophils
(phagocytes)
Small and squeeze through capillaries to patrol tissues, short lived
Macrophages
(phagocytes)
Leave bone marrow as monocytes, settles in an organ and becomes a macrophage, long lived cells.
Antigens
Protein on cell surface composed of glycoproteins and proteins, allows recognition of foreign pathogens and ‘self cells’
Opsonins
Chemicals that bind to pathogen to identify them, phagocytes therefore bind onto the antigen on the pathogen
Antigen Presentation
Antigens on the surface of foreign cells will be recognised by the immune system
Phagocytosis- Macrophages
- Antigen on pathogen attaches to receptor
- Pathogen is engulfed by phagocytosis and enclosed in a vesicle
- Lysosome fuses with phagosome forming a phagolysosome
- Pathogen is partially digested by hydrolytic enzymes
- Indigestible material is removed by exocytosis
Phagocytosis- Neutrophils
Same as with macrophages but pathogen is fully digested and all products absorbed by the cells.
T lymphocytes
Made in the bone marrow but develop in the Thymus gland. They have specific receptors for a particular antigen but only recognise when with a self protein. This could be a macrophage or a virus infected cell
T lymphocytes Activation
ANTIGEN PRESENTATION- Macrophage engulfs, processes and presents antigen with self protein
CLONAL SELECTION- When a complimentary receptor binds cytokines are released by macrophages that activate specific T lymphocytes.
CLONAL EXPANSION- Mitosis of the T Lymphocytes forming clones
T Helper Lymphocytes
Secrete cytokines called interleukins, they bind to receptors and act over short distances.
LEADS- stimulates B lymphocytes, production of other T cells, macrophages ingest pathogen
T Killer Lymphocytes
Destroys cells that they bind to, produce a chemical called Perforin, creates pores in the membrane so its freely permeable.
T Memory Cells
Remain in the blood, help body respond more quickly and effectively if same antigen enters again.
T Regulator Cells
Cells suppress the immune system, once pathogen has been removed, involves autoimmunity
B Lymphocyte
Made and mature in the bone marrow, have cell surface embedded antibodies which act as receptors. They’re specific for particular antigens. Can become antigen presenting cells b engulfing the pathogen.
B Lymphocyte Activation
CLONAL SELECTION- Specific B lymphocytes encounters an antigen with complimentary antibody and it becomes activated. T Helper cells also activate them.
CLONAL EXPANSION- Divide many times by mitosis
DIFFERENTIATION- Becomes a protein factory (Plasma Cell) increased number of organelles, Synthesise particular antibody and releases by exocytosis.
B Memory Cells
Remain in the blood so if same antigen invades they’ll be a quicker response, they develop into plasma cells to produce more antibodies.
Immune Response
Specific response to antigens on a pathogen, involving lymphocytes and antibodies.
Rheumatoid Arthritis
Autoimmune Disease
Effects joints especially hands and wrists. No cure but steroids and immunosuppressants
Lupus
Autoimmune Disease
Attacks organs like the kidneys, affects joints and causes fatigue
No cure but anti inflammatories help
Type 1 Diabetes
Autoimmune Disease
Affects insulin secreting cells in the pancreas, insulin injections
Antibodies
Composed of glycoproteins, consist of 4 polypeptide chains and a variable region that binds to specific antigens
Variable Region
Complimentary to the antigen, composed of varying amino acids
Constant region
Amino acid sequences are the same, receptors on phagocytes have receptors specific for this region, same on all antibodies
Hinge Region
Allows flexibility when binding to antigens
Disulphide Bridges (Antibodies)
Hold the polypeptides together
Opsonisation
Action of Antibodies
A group of antibodies that can bind to the antigen on a pathogen, also a binding site for phagocytes
Agglutination
Actions of Antibodies
Large antibodies binding pathogens together, makes bacteria easier to engulf and prevents viruses entering new hosts.
Anti toxins
Actions of Antibodies
Antibodies can act as antitoxins by binding to the toxin produced by pathogens making them harmless
Neutralisation
Actions if Antibodies
Antibodies binding to the surface of pathogens can prevent it binding to host cells
Primary immune response
Clonal Selection and expansion can take up to several days. During this time the pathogen multiplies and the person gets ill. Antibodies are produced slowly and over time kill the pathogen, after this antibody numbers drop
Secondary response
If the same pathogen invades again memory cells allow a faster response. Antibodies are produced quickly an din large numbers, pathogen is destroyed before any symptoms.
Forms of antigenic material in vaccines
- Inactive bacteria/ viruses
- Attenuated strains of live B/V (Weakened)
- Toxin molecules that’ve been altered
- Isolated antigens extracted from the pathogen
- Genetically engineered antigens
Natural Passive Immunity
Mothers milk
Natural Active Immunity
Memory cells
Artificial Passive Immunity
Extracted and injected directly into bloodstream
Artificial Active
Immune system stimulated to make its own antibodies, i.e. vaccine
Herd Vaccination
Significant number of people have been vaccinated so protect those without due to minimal break out chances
Ring Vaccination
Controls an outbreak by vaccinating and monitoring a ring of people around each infected individual
Sources of new medicine
- Accidental Discovery
- Traditional Remedies
- Observing wildlife
- Synthetic biology
Why new drugs are needed
- New diseases
- Many diseases still don’t have treatments
- Antibiotic resistance
