module 4.1 Flashcards
what are the 4 types of pathogen
- virus
- fungi
3.bacteria
4.protist (protozoan)
state points about bacteria
-smaller than eukaryotic cells, can reproduce rapidly
-once in the host, they can multiply rapidly, they cause disease by damaging cells or by releasing waste products/toxins that are toxic to the host
-in plants bacteria live in vascular tissue and cause blackening and death
state points about fungi
-cause a variety of diseases in plants and animals
-often found in the skin of animals + vascular tissue of plants
- hyphae (reproductive fungal cells) produce mycelium which grows under the skin surface.
-hyphae then grows to the surface of skin to release spores, this causes redness and irritation
state points about viruses
-cause diseases in plants and animals
-viruses invade cells and take over the genetic machinery and other organelles of the cell.
-they then cause the cell to manufacture more copies of the virus. The cell eventually bursts, releasing any new viruses which will infect healthy cells.
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state points about protists (protoctista)
-animal like cells that typically invade other cells for nutrients
-caused by animal like protists
-these organisms usually cause harm by entering host cells and feeding on the contents as they grow.
order of size, bacteria, virus, fungi?
smallest=virus
largest=fungi
what is a pathogen
an organism that causes disease- a disease caused by a pathogen is a communicable disease.
what are the two ways pathogens can spread
via direct transmission
via indirect transmission
what does direct transmission require and what are the 3 examples
-requires either contact or that go from host to host.
1. Droplets: moisture is emitted by sneezing, talking and coughing.
2. Contact: any exchange of body fluid e.g. sexual, touching contaminated surfaces, blood exchange.
3. Faecal- oral: infected excrement re-entering via contaminated water + food.
what is indirect transmission and what is 1 example
-these pass through other organisms
1. Vector: transmission via an intermediary organism
host->vector->host
what are zoonotic infections
animal infection that jumps to humans
-e.g. Ebola
-e.g. coronavirus from bats
what is malaria caused by
plasmodium (a mosquito carries plasmodium)
how dos malaria occur in humans
from the mosquito, the parasite first goes to liver cells where they replicate. the liver cells burst with asexual parasites that infect red blood cells and reproduce causing them to burst, this causes the symptoms of malaria ( anaemia and fever), some parasites then change role and are taken up by a mosquito, after a few days the mosquito becomes infectious and able to infect people they bite.
summary, + & - of insecticide treated bed nets
fine nets that mosquitos cant pass through, they have insecticides kill them.
+very cheap
+easy to use
+very effective
-limited space covered
-have to sleep under the net- people are not sleeping during peak mosquito biting
-insecticide resistance is developing
summary, + & - of indoor residual spraying
spreading insecticide inside homes, interior walls. DDT often used
+effective at killing mosquitos
+only 1 intervention per year
+simple to execute relatively cheap
-ecosystems disrupted, DDT= toxic, ecological damage
- not every mosquito likes to live inside, only effective for indoor mosquitos
examples of plant pathogens
-rose black spot
-aphids
-potato blight
-tobacco mosaic virus
-ring rot
plant pathogens: describe rose black spot
fungi
causes splodges of black on plants
spread in soil and compost
plant pathogens: describe aphids
parasite
(greenfly)
suck out nutrients from phloem
plant pathogens: describe tobacco mosaic virus
virus
browned and yellowed patches
spread in soil and compost
plant pathogens: describe potato blight
bacterial
rots tubers
potato= black inside
plant pathogens: describe ring rot
bacterial
ring of decay in vascular tuber of potato or tomato
what do many plants produce in response to insect vectors of disease or to kill invading pathogens and give an example (simply what does this example do)
-plants produce chemicals
-e.g cyanide->stops respiration from happening
what are the 4 subsections of plant defenses
-passive physical
-active physical
-passive chemical
-active chemical
state the 6 passive physical defenses
- cellulose cell wall
- lignin thickening of cell walls- lignin= indigestible & waterproof
3.waxy cuticle-prevent water from collecting on cell surfaces
4.stomatal closure- guard cells close the stomata when pathogenic organisms are collected - TYLOSE formation-balloon like swelling that fills the xylem so it can no longer carry water, tylose also contains high concs of chemicals toxic to pathogens
6.CALLOSE- a large polysaccharide that is deposited around the sieve plates and blocks the flow in the sieve tube- can prevent the pathogen from spreading around the plant
passive chemical plant defenses?
chemicals are produced when a plant detects an infection as not all chemicals are present befor an infection
active physical plant defenses (there are 4)
-the plant responds by fortifying the defenses already present
-cellulose cell walls become thickened and strengthened with additional cellulose
-cellulose is deposited between plant cell wall and cell membrane near the invading pathogen- blocks the plasmodesmata
-necrosis= deliberate cell suicide, few cells sacrificed to save plant- limits pathogens access to h2o and nutrients. brought about by an intracellular enzyme that’s activated by injury
canker- a sunken necrotic lesion on stem or branch, causes death of cambium tissue
active chemical plant defenses 5
defensins-small cysteine rich proteins with broad antimicrobial action. act on molecules in plasma membrane of molecules
alkaloids- N- containing compounds e.g caffeine. gives a bitter taste to inhibit herbivore eating and inhibit/ activate enzyme action
phenols- antibiotic/antifungals- tannis is an e.g of this bitter antiseptic. deactivate salivary proteins and digestive proteins.. insects that ingest high vols of tannis will die thus reducing transmission of pathogens
hydrolytic enzymes- in spaces between cells
terpenoid- essential oils that have antibacterial/ antifungal properties
whats the order of the 3 defenses?
primary defense
\/
non-specific immune response
\/
-specific immune response
whats the order of the 3 defenses?
primary defense
\/
non-specific immune response (secondary defense)
\/
specific immune response (secondary defense)
def of primary defense
-physical barrier or responses to prevent entry of pathogens
def. of non-specific immune response
generic and apply to any pathogen
def. of specific immune response
tailored response that is different to each pathogen
def. of secondary defenses
cellular/antibody responses to infection in tissue
4 examples of primary defenses
-skin
-mucus & membranes
-clotting
-coughing and sneezing
talk about the primary defense: skin
- the outer layer of epidermis is a layer of dead cells which contains the fibrous protein keratin
-these cells are produced in a process called keratinization- the cells dry out and the cytoplasm is replaced with keratin.
-this layer of cells acts as a barrier
-the basal cell layer has stem cells present
talk about the primary defense :mucus and membranes
mucus is secreted by the epithelial linings of airways, digestive systems and reproductive systems.
-in the airways ciliated cells move mucus up to the mouths where it can be swallowed.
-in the stomach, hcl kills most pathogens we ingest.
talk about the primary defense: clotting
-platelets release clotting factors that cause an enzyme cascade that forms a clot and eventually a scab (Ca2+ is involved)
talk about the primary defense: coughing and sneezing
many infected areas can be sensitive to foreign invasion. They respond to the irritation caused by their microbes or their toxins by attempting to expel them
talk about the 3 steps of the innate immune response: inflammation
- Damaged cells release chemicals that trigger MAST cells.
- mast cells release histamine
- histamine causes:
-blood vessels to dilate (vasodilation)
-tissue fluid floods area (oedema)
- causes swelling + redness + heat
-neutrophils are recruited to area
state general things about neutrophils
-short lived
-most abundant type of white blood cell
-travel in bloodstream
-respond to inflammatory mediators in seconds
-neutrophils are phagocytes
what are the symptoms relived by the drug antihistamine
-swelling, redness and heat by preventing vasodilation and oedema
describe the innate immune response- phagocytosis
- phagocyte identifies antigens and bind to opsonin attached to the antigen of the pathogen- the phagocyte detects a foreign body
- Phagocyte extends pseudopodia around pathogen to engulf it. The pathogen is trapped in a phagosome
- lysosomes bind to the phagosome to form a phagolysosome
- enzymes destroy the pathogen
- MACROPHAGES ONLY: antigens are presented to T cells
state stuff abt macrophages / monocytes
-longer lived ( than neutrophils)
-most are embedded in tissues (macrophage) although a small percentage are found circulating ( monocytes)
-additional role in presenting antigens to T- cells and triggering the specific immune response
state stuff abt the innate immune response- opsonins
-OPSONINS are non-specific protein antibodies.
-they bind to antigens (they’re markers on cell surface membranes on pathogens)
-role is to increase the ability of phagocytes to bind and engulf invading pathogens.
why are opsonins non specific
they can attach to a variety of pathogenic cells and help the process of phagocytosis.
how are neutrophils specialised for their role
-plasma membrane contains receptors for opsonins.
-well developed cytoskeleton for phagocytosis.
-many mitochondria for respiration
-many ribosomes to make enzymes
what are examples of the innate (non-specific) immune response
inflammation, phagocytes and macrophages
what are the 2 types of specific specific responses and describe them
Cellular Response:
-Cytotoxic T-cells identify infected cells and kill them- requires T cells
Humoral Response:
-specific antibodies are produced that stop pathogens from functioning- requires B cells
whats a lymphocyte
a white blood cell found in lymph nodes- includes all T and B cells
if its not a phagocyte, its a….
lymphocyte
white blood cells that reside in the lymph nodes are called lymphocytes- what are the two families?
T cells and B cells
state general stuff about T cells
- enter lymph via thymus gland ( hence T cell)
-responsible for coordination of the immune response by releasing cytokines
-some are also responsible for killing infected cells
state general stuff about B cells
enter lymph via bone marrow (hence B cell)
-responsible for producing antibodies or remaining dormant to activate at a reinfection.
what are the 4 types of T cells
T killer, T helper, T REG, T memory
what is T killer
cytotoxic + trigger infected cells to self- destruct
what is T helper
release cytokines + interleukins to coordinate other cells (incl. B cells)
what is T REG
release cytokines to limit immune response
what is T memory
long lived T cells that can reactivate future infections
what are the 2 types of B cells
B memory, PLASMA
What is B memory
long lived B cells that can reactivate in future infections
what does plasma do ( B cell)
release antibodies
what do memory cells do
they circulate in the blood after the pathogen has been removed. if stimulated, they divide and rapidly produce a secondary immune response
state how the non- specific immune response and the specific immune response interacts
-macrophage identifies pathogen, phagocytosis occurs.
-antigen presentation occurs in lymph node.» specific»_space;
-clonal selection occurs- T/B cells are presented with antigen and role is determined.
- clonal expansion occurs-selected cell undergoes mitosis to produce many selected cells. ( cytokines + interleukins control selection and differentiation).
Differentiation of T/B cells occurs.
T Lymphocyte, B-Lymphocyte or both: form part of the immune system
both
T Lymphocyte, B-Lymphocyte or both: matured in thymus
T
T Lymphocyte, B-Lymphocyte or both: secrete substances which kill infected cells
T
T Lymphocyte, B-Lymphocyte or both: manufacture antibodies
B-cells
T Lymphocyte, B-Lymphocyte or both: undergo clonal expansion
both
T Lymphocyte, B-Lymphocyte or both: activate other lympocytes
T
what are vaccinations
injections that promote the development of antibodies and confer immunity
attenuated definition
a live vaccine which has its virulence reduced (e.g. measles)
inactivated definition
a dead pathogen (e.g. polio vaccine)
subunit definition
injections of antigens only (e.g HEP B)
vaccines can also be…
-whole live organisms of a simmilar less harmful microorganism ( cowpox used as a vaccine for smallpox)
-a toxoid, harmless version of a toxin
vaccination application; HERD VACCINATION DEF
-vaccinating all or most people at risk
-with enough people vaccinated, disease is unable to spread.
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vaccination application; HERD VACCINATION DEF
-vaccinating all or most people at risk
-with enough people vaccinated, disease is unable to spread.
- high numbers needed, depends on disease 95% needed
vaccination application; RING VACCINATION DEF
-used when a new case of disease is reported - vaccinating all people within immediate vicinity of new case.
-used in livestock disease worldwide.
epidemic
localised outbreak
endemic
common everywhere at all times
pandemic
global epidemic-can spread across multiple countries
4 types of immunity
active natural, passive natural, active artificial, passive artificial
active natural
getting ill- white blood cells fight infection and you become immune
passive natural
through the placenta and breastfeeding
active artificial
vaccines
passive artificial
infection of antibodies
what is active immunity;
any type where antibodies are MADE by the immune system
what is passive immunity:
any type where antibodies are introduced but NOT MADE
