M4 C12: communicable diseases Flashcards
what is a disease?
a condition that impairs the normal function of an organism
What is a pathogen?
a microorganism that can cause disease
what are some types of pathogens?
bacteria, viruses, fungi, protoctista
what is a communicable disease?
disease that can be spread from person to person by a pathogen
what is tuberculosis?
bacterial disease can affect animals human/cattle
what is bacterial menigitis?
bacterial disease affects humans
what is ring rot?
bacterial disease affecting tomatoes/ potatoes
what is HIV/AIDS?
a virus affecting humans
What is influenza?
virus affecting animals/humans
what is tobacco mosaic virus?
virus affecting plants
what is black sigatoka?
fungus affecting banana plants
what is ringworm?
fungus affects cattle
what is athletes foot?
fungus affects humans
what is potato/tomato late blight?
a protoctist affecting potato and tomato plants
what is malaria?
a protoctist affecting animals including humans
what is direct transmission of diseases?
when disease is transmitted directly from one organism to another
what is indirect transmission of diseases?
via a intermediate such as air, water, food, vector
what is an example of a direct transmission of disease?
droplets in the air, intercourse, touching an organism. eg athletes foot or HIV
what is an example of indirect transmission of disease?
malaria is transmitted via mosquitoes
potato late blight is transmitted by spores between plants
what are 3 factors affecting transmission?
living conditions
social factors
climate
how does living condition affect transmission of diseases?
overcrowding increases disease as people are closer together eg TB stays in the air for a long time so confined space = increased risk
how does social factors affect transmission of diseases?
income, occupation and area increases risk for example increase risk of HIV when people have limited access to anti-HIV drugs or no education about how to stop HIV
how does climate affect transmission of disease?
affects the spread of disease. for example wet summers increases potato blight as spores need water to spread. malaria need tropical climates to reproduce to spread malaria
why do organisms need defences against pathogens?
pathogens need to enter an organism to cause disease. animals and plants have evolved defences to protect themselves against pathogens.
how is skin a defence against pathogens?
blocks against pathogens as a physical barrier. also secretes antimicrobial chemicals which destroy or slow growth of microorganisms e.g. lysosomes
how are mucous membranes a defence against pathogens?
protect the body openings that are exposed to the environment e.g. nose, mouth etc. some membranes secrete mucus to trap pathogens e.g. mucus lining the lung epithelium which traps pathogens.
how is blood clotting a defence against pathogens?
a mesh of protein fibres that plug wounds to prevent pathogen entry and blood loss. They are formed by chemical reactions in the body that take place when platelets are exposed to damaged blood vessels.
how is inflammation a defence against pathogens?
-the damaged tissue releases molecules to increase the permeability of the blood vessels, so they leak fluid into the surrounding areas. This causes swelling and isolates any pathogens that may have entered the damaged tissue.
- vasodilation increases blood flow to the affected area. This makes the area hot and brings white blood cells to the area to fight off any pathogens.
how is wound repair a defence against pathogens?
Skin is able to repair itself in the event of an injury and re-form a barrier against pathogen entry. The surface is repaired by the outer layer of skin cells dividing and migrating to the edges of the wound. The tissue below the wound then contracts to bring the edges of the wound closer together. It is repaired using collagen fibres.
how are expulsive reflexes a defence against pathogens
cough stems from irritation in the respiratory tract. Both coughing and sneezing are an attempt to expel foreign objects, including pathogen when they become irritated.
what are the physical defences of a plant?
waxy cuticle
cell wall
Callose gets deposited between plant cell walls and plasma membranes
what are some chemical defences of a plants?
Plants produce antimicrobial chemical which kill pathogens or inhibit their growth. Other chemicals secreted by plants are toxic to insects to prevent diseases spread by vectors
what is the immune response?
the body’s reaction to foreign antigens
what is an antigen?
molecules on surface of a cell
what happens when antigens are identified in the body?
activates the immune response
what is a non specific immune response?
same response for all microorganisms
what is a specific immune response?
antigen specific involves white blood cells and T an B lymphocytes
what is stage 1 of the immune response?
phagocytosis
what is phagocytosis?
phagocytes engulf pathogens.
phagocytes are a type of white blood cell and are found in the blood and tissues and carry out a non specific response
what happens in phagocytosis?
-phagocyte recognizes the antigen o0n the pathogen
-phagocyte cytoplasm then surrounds pathogens
-lysosomes then fuses with the phagosome to break down the pathogen
-phagocyte then sticks the pathogens antigens on its surface to activate other immune system cells.
what makes phagocytosis easier?
opsonins that are molecules in the blood that attach the foreign antigens
what is a phagocyte called when it places the pathogens antigens on its surface?
antigen-presenting cell (APC)
what are neutrophils?
a type of phagocyte (white blood cell) that move towards a wound in response to signals from cytokines that are released at the site of a wound
what is the 2nd stage of the immune response?
t lymphocyte activation
what is a t lymphocyte?
another type of white blood cell that has a surface covered in with receptors
what do the t lymphocyte receptors bind to?
antigens presented by APC’s (phagosomes)
how are t lymphocytes a specific immune response?
each receptor has different shapes complementary to different antigens
what happens after the t lymphocyte receptor binds with the antigen?
it becomes activated called ‘clonal selection’ and once activated it clones ‘clonal expansion’
what are the 3 types of t lymphocytes?
t helper
t killer
t regulatory
what are t helper cells?
release substances to activate b lymphocytes and t killer cells
what are t killer cells?
kills cells infected with a virus
what are t regulatory cells?
suppress immune system cells from attacking the hosts cells. some are also memory cells
what is the 3rd stage of the immune response?
b lymphocyte activation and plasma cells production
what are b lymphocytes?
a type of white blood cell. they are covered with antibodies that bind to antigens to form and antigen-antibody complex
how are b lymphocytes a specific immune response?
each have different shaped antibodies on its membrane to bind to different antigens
what happens after a antibody on a b lymphocyte binds to a antigen?
once binded t helper cells activate the b lymphocyte. another example of clonal selection
what happens once the b lymphocyte is activated?
divides by mitosis into plasma cells and memory cells
how are antibodies produced?
plamsa cells secrete antibodies specific to the particular antigen into the blood
what do the antigen-antibody complexes signal to the immune system?
signal for the immune system to attach and destroy the pathogen
what is cell signaling?
how cells communicate e.g. releasing a substance that binds to receptors on another cell causing a response in some kind in the other cells
why is cell signaling important for the immune response?
helps active all the types of blood cells that are needed
how will white blood cell look like in a blood smear?
lymphovyte-nucleus takes up most of cell
neutrophil- grainy cytoplams
what is the structure of an antibody?
glycoproteins with 4 polypeptide chains, 2 heavy, 2 light
what does each chain of a antibody have?
a constant and variable region
what is the variable region?
antigen binding sites, which are complementary shape to the antigen
what does the constant region do on antibodies?
binding to receptors on immune system cells
how do antibodies agglutinating pathogens?
can bind to 2 antigens at once which makes pathogens become clumped together.phagocytes then bind to the antibodies and phagocytose them
how do antigens neutralize pathogens?
toxins have different shapes that bind to complementary antibodies. they prevent toxins from affecting human cells. this then becomes phagocytosed
how do antibodies prevent pathogens binding to human cells?
they block the cells surface receptors that pathogens need to bind to host cells so pathogens cant attach or infect host cells
what is the primary immune response?
*when a pathogen enters the body the antigens on its surface activate the immune system.
*this is slow because there aren’t many b lymphocytes that can make the antibody needed to bind to the pathogen.
what happens after exposure?
Memory T lymphocytes remember the specific antigen and will recognize it a second time around.
what is autoimmune disease?
when the immune system stops recognizing self cells and attacks healthy body tissue
what are vaccines?
Vaccines containssubstancesthat cause your body to produce memory cells against aparticular pathogen, without the pathogen causing disease. so you become immune
what substances are in vaccines?
antigens, which could be free or attached to a dead or attenuated (weakened) pathogen or other molecules, such as mRNA designed to code for antigens found on a pathogen.
how does vaccines work?
the mRNA enters the body cells, its provides the instructions needed for cells to produce these antigens, which triggers memory cells to be made.
what is herd immunity?
people who have not been vaccinated are unlikely to get the disease, because there is no one to catch it from.
why do some vaccine programs have to change?
some pathogens can change their surface antigens such as the influenza virus
what do antibiotics do?
kill or inhibit the growth of bacteria
what infections do antibiotics treat?
bacterial infections
what was the first antibiotic discovered?
penicillin by alexander fleming
what are the risks to using antibiotics?
side effects such as allergic reactions
antibiotic resistance
what is antibiotic resistance?
when there is a genetic variation in a population in bacteria eg from genetic mutations. this then makes the bacteria easier to survive and reproduce multiple times
what is the problem with antibiotic resistance?
cant get rid of the bacteria easily, superbugs that are resistant to antibiotics are becoming more common which are harder to treat
What are some exampleds of antibiotic resistant bacteria?
MRSA- causes serious wounds infections. resistant to methicillin + others
c-difficile- infects digestive system causing problems in people who have already been treated with antibiotics such as diarrhoea
how do we prevent antibiotic resistance?
reduce use of antibiotics/ overprescribing
not prescribe them to prevent infections
take full course of antibiotics to make sure infection is cleared
what are many medicines sourced from?
natural compunds in plants, animals or microorganisms
where is penicillin obtained from?
fungus
Why is protecting biodiversity important to medicine?
only a small proportion of organisms have been investigated so far meaning its possible some exist that may contain compounds ton cure currently incurable diseases.
what are personalized medicines?
medicines tailored to an individuals DNA as that determines how your body reacts to certain drugs, this can be used to predict how you will respond to certain medicines so you are prescribed the right ones
what is synthetic biology?
using technology to design and make things like artificial proteins and call. e.g. engineering bacteria to destroy cancer cells
