Topic 4 - Communicable diseases, disease prevention & the immune system Flashcards
What are communicable diseases
Communicable disease are caused by pathogens (viruses, bacteria, fungi & protoctista) and can be transmitted from one person to another. They are infectious.
What are the two types of ways in which pathogens can be transmitted
Pathogens can be transmitted directly (e.g. physical contact, ingestion, droplet infection) or indirectly (e.g. via vectors)
What type of cells are bacteria and how do they affect cells
Bacteria are prokaryotes that can usually damage cells directly or release toxins
What type of cells are protoctists
Protoctists are unicellular eukaryotic organisms, which can produce sexually and asexually
What type of cells are fungi
Fungi are eukaryotic organism which cannot photosynthesis therefore are parasties
What type of cells are viruses and how do they act and reproduce
Viruses are acellular, non-living particles, they can only replicate inside living host cells where they hijack the host machinery to replicate and then burst the cell to be released
Define infectious diseases and give an example
These are disedses caused by
organisms known as pathogens.
They are sometimes called
communicable diseases as they
are passed from infected to
uninfected people (they are
transmissible). Some also
affect animals and are passed
from animals to humans.
Eg. cholera, Malaria, HIV/AIDS, Tuberculosis (TB)
Define non infectious disease and give an example
These are long-term,
degenerative diseases that
are not caused by pathogens.
Examples include diseases of
the gas exchange and
cardiovascular systems,
inherited or genetic disedses,
deficiency diseases caused
by malnutrition, and mental diseases.
Eg.Lung cancer, Chronic obstructive
pulmonary disease (COPD), Sickle cell anaemia, Cystic fibrosis
Tuberculosis
Pathogen type
Pathogen
Method of transmission
Symptoms
Bacterium
M. tuberculosis
Direct - airborne droplets
Coughing with blood, chest pain, weight loss, fever, weakness, night sweats
Bacterial meningitis
Pathogen type
Pathogen
Method of transmission
Symptoms
Bacterium
N. meningitidis / H. influenzae
Direct - airborne droplets
fever, swelling of the meninges, neck pain, characteristic rash
Influenza
Pathogen type
Pathogen
Method of transmission
Symptoms
Virus
Influenza A, B or C
Direct - airborne droplets
fever, cough, headaches, fatigue, muscle/body aches
HIV / AIDS
Pathogen type
Pathogen
Method of transmission
Symptoms
Virus
Human immunodeficiency virus (HIV)
Direct - transfer of bodily fluids
Fever, chills, rash, night sweats, muscle aches, sore throat, fatigue, swollen lymph nodes
Malaria
Pathogen type
Pathogen
Method of transmission
Symptoms
Protoctist
P. falciparum
Indirect - female mosquitos
fever, flu like illness, nausea / vomiting, anaemia and jaundice = loss of RBCs
Cattle ringworm
Pathogen type
Pathogen
Method of transmission
Symptoms
Fungus
T. verrucosum
Direct - contact with infected cattle
Grey-white areas of skin with an ash like surface circular in outline and slightly raised, size of lesions can vary - can become very extensive
most commonly found around eyes, on ears and back in calves and more around chest and legs for adult cattle
Athlete’s foot
Pathogen type
Pathogen
Method of transmission
Symptoms
Fungus
E. Floccosum
Direct - contact with items touched by infected individuals
Itchy white patches between toes; sore and flaky patches on feet; skin may appear red / may crack or bleed
Ring rot
Pathogen type
Host
Pathogen
Method of transmission
Symptoms
bacterium
Potato, tomato
C. michiganensis
Direct - contact with other infected tubers
Vascular wilt in the above ground parts of the potato plant; discolouration and loss of texture/consistency notes in infected tubers
Mosaic
Pathogen type
Host
Pathogen
Method of transmission
Symptoms
Virus
Tobacco (and other)
Tobacco mosaic virus (TMV)
Direct - contact with leaves of infected plants and indirect - vectors (aphids)
Stunting; mosaic pattern of light and dark green on the leaves; malformation of leaves or growing points; yellow streaking
Black Sigatoka
Pathogen type
Host
Pathogen
Method of transmission
Symptoms
Fungus
Bananas
M. fijiensis
Direct - spores
Small reddish-rusty flecks on underside of leaf; evolve to form reddish brown leaf streaks running parallel to the leaf veins
Late blight
Pathogen type
Host
Method of transmission
Symptoms
Protoctist
Potato, tomato
P. infestans
Direct - spores
Leaf symptoms of late blight first appear as small, water-soaked areas that rapidly enlarge to form purple-brown, oily-appearing blotches. On the lower side of leaves, rings of grayish white mycelium and spore-forming structures may appear around the blotches.
What are autoimmune diseases and give 2 examples
Autoimmune diseases occur when the immune system mistakenly attacks its own antigens
- In Arthritis, antibodies attack membranes around the joints
- In Lupus antibodies attack proteins in the nucleus of cells.
What are the types of Phagocytes and what is their function
Macrophages + Neutrophils
Engulfs and digests pathogens by fusion of the phagosome with lysosomes
What are the types of T cells and what is their function
T helper cell
Stimulates B cells to divide and secrete antibodies
Cytotoxic T cells
Kill abnormal cells and infected body cells via perforin
T memory cell
Remain in the blood for years and provide long tern protection
What are the types of B cells and what is their function
Plasma cell
Secrete antibodies
B memory cell
Remain in the blood for years and provide long term protection
What is an antigen
Antigens are any part of an organism/substance which is recognised as foreign by the immune system and goes on to trigger an immune response.
What are antibodies and what do then do
Antibodies are a protein produced by lymphocytes in response to the presence of the corresponding antigen
Antibodies agglutinate pathogens by forming antigen-antibody complexes, leading to phagocytosis & neutralise toxins.
Draw a labelled antibody
Look at notes,
- receptor binding site
- constant region
- light chain 1
- light chain 2
- antigen binding site
- variable region
- heavy chain 1
- heavy chain 2
Describe the process of Cell Mediated Immunity
- Antigen from the pathogen is displayed on the cell surface of body cells or phagocytes after phagocytosis
- T cells with the correct specific receptor bind with the antigen and are activated
- They divide by mitosis (clonal expansion) and differentiate into T helper, cytotoxic and memory cells.
Describe the process of Humoral immunity
- The humoral response is best at fighting pathogens which are free in the bodily fluids
- Free antigen binds to a complementary B cell receptor, activating the B cell (clonal selection)
- The pathogen is endocytosed, and the antigen presented on the plasma membrane
- T helper cell binds to the presented antigen and stimulates the B cell to divide by mitosis (clonal expansion)
- The B cell differentiates to plasma and memory cells
Comment on the Primary and secondary immune resposnse and the difference in their speed / vigour
- The primary immune response is when a pathogen infects the body for the first time the initial immune response is slow.
- The secondary immune response is a more rapid and vigorous response caused by a second or subsequent infection by the same pathogens. This is due to the presence of memory cells
Comment on a graph of primary and secondary immune response and what is happening at each stage
What are vaccinations and how do they work
- Vaccination is the introduction into the body of a vaccine containing disease antigens, by injection or mouth, in order to induce artificial immunity
- Vaccines work by injecting weakened/dead pathogens into the body to stimulate an immune response, to form memory cells against the specific antigen, which destroy the pathogen quickly upon infection.
What is herd immunity
Herd immunity is when the vaccination of a significant proportion of the population provides protection for individuals who have not developed immunity
What happens to the efficiency of a vaccine if a pathogen mutates
Pathogen may mutate so that its antigens change suddenly (antigenic variability) So the vaccine is now ineffective to the new antigens.
What are some ethical consideration of vaccinations
- side effects
- financial cost
- right to choose
- animal testing of vaccines
- human trials
What is the difference between active and passive immunity
- Active immunity occurs when specific antibodies are produced by the individual’s own immune system
- Passive immunity occurs when specific antibodies are introduced to the individual from an outside source.
Give an example of natural active immunity
Direct contact with pathogen
Give an example of natural passive immunity
Antibodies through breastmilk
Give an example of artificial active immunity
Vaccinations
Give an example of artificial passive immunity
Injection of antibodies
Antibiotics prevent the growth of (1).
1 - bacteria
Why are antibiotics effective
They are effective because they show specificity in killing bacteria without harming human cells.
What can happen as a result of overuse of antibiotics
However, overuse has led to the spread of resistance in bacteria e.g. MRSA
How can we reduce the risk of spreading antibiotic resistant bacteria
To reduce spread prescription of antibiotics is controlled, patients must finish their course and prevent spread by control measures
How can DNA sequencing be used to develop new medicines
New medicines can be discovered from plant compounds using DNA sequencing to screen plants and organisms for potential medical compounds. DNA sequencing can also be used to develop a specific drug suited to persons genome.
List some human primary defences (5)
- The skin acting as a barrier
- Blood clotting and skin repair
- Mucous membranes
- Coughing and sneezing
- inflammation
List some plant passive defences (5)
- Cellulose barrier
- Lignin
- Waxy cuticle
- Bark
- Callose blocking flow in sieve tubes
list some plant active defences (6)
- Deposit callose
- Close stomata
- Add cellulose
- Induce cell necrosis
- Increase the number of oxidative bursts
- Produce chemical defences
What is the action of phenols
Antibiotic and antifungal proteins. One example is the tannins present in tree bark
What is the action of alkloids
Compounds containing nitrogen (e.g. caffeine, nicotine, cocaine and morphine) are bitter to stop herbivores feeding on them and affect enzyme action.
What is the action of defensins
These cysteine-rich, defensive proteins have anti-microbial activity. They appear to affect the functioning of ion transport channels in the plasma membrane.
What is the action of hydrolytic enzymes
Present in the spaces between cells, they can have a variety of effects. Chitinases break down the chitin in fungal cell walls, glucanases hydrolyse the glycosidic bonds in glucans, and lysozymes destroy bacterial cell walls.
