Immunity (4) Flashcards
what do phagocytes do after phagocytosis
They produce cytokines; which act as cell-signalling molecules, informing other phagocytes of the infection; stimulates them to site of inflammation/infection.
name two viral pathogens + two bacterial pathogens in animals
virus: HIV and INFLUENZA
bacterial: TUBERCULOSIS and BACTERIAL MENINGITIS
what occurs when the skin is cut
((two parts))
Blood clots rapidly to seal a wound and prevent entry of pathogens. POSITIVE FEEDBACK: clotting cascade.
The clot dries out forming a hard scab.
what is an autoimmune disease
+ 5 examples
When the body’s own cells become antigens (self-antigens). Tf the body’s immune system attacks its own cells.
- Rheumatoid arthritis- synovial fluid + membranes of joints attacked*
- Multiple sclerosis- myelin sheath of nerve axons attacked*
- Lupus- many tissues attacked*
- Diabetes Type 1*
- Eczema*
A graft of tissue, such as skin, from a different person is usually rejected by the body. Which immune system cells cause this
The graft is rejected by T-lymphocytes because they circulate in the blood and can gather at the graft site.
why is the is the second exposure to an antigen much larger than during a vaccination/first exposure
The vaccination/first exposure is the primary exposure, which takes time because the immune system goes through clonal selection, clonal expansion/proliferation and differentiation.
The second exposure already has long-lasting memory cells from the first infection, meaning there is a more rapid and larger response as the memory cells act as cell-signalling molecules.
function of immunoglobulins?
Identify and neutralise foreign material, eg. b**acteria & viruses.
how are ringworm + athlete’s foot transmitted and what are their symptoms
DIRECT (AF: skin to skin, R: housing and bedding) & INDIRECT
AF: itchiness, R: inflammation, scaly patches, itchiness
how is a new vaccine created against a new strain of influenza virus
WHO + CDC laboratories collect samples of different strains, and test the effectiveness of different influenza vaccines against them. Each year the most effective is chosen, so governments/health authorities implement a programme of vaccination.
Some people can be given a vaccine to prevent the strain causing an epidemic in another country & spreading globally.
The antigen is either inactive/dead/attenuated.
describe the second exposure to an antigen/pathogen
- Memory cells replicate rapidly on encountering the antigen
- Response is much greater- more rapid elimination of Ag/Pg
how do phagocytes (macrophages, neutrophils + dendritic cells) pass from the blood into the tissue fluid
- Lobed/narrow nucleus
- They can squeeze between pores/gaps/fenestrations in the capillary walls/endothelium
- Cells can change shape
- Histamines from mast cells make the capillary walls/endothelium leaky
how do the following actively defend plants from pathogens:
- Hypersensitivity*
- Systemic Acquired Resistance*
- General toxins*
Hypersensitivity- immediate death of tissues surrounding the site of infection by a pathogen
SAR: signalling molecule travels to uninfected areas + gives protection.
Toxins- plant produces chemicals that when broken down, produce a toxic product eg. cyanide
what are immunoglobulins secreted from and where are they secreted into
By B lymphocytes (B cells) into the blood.
why are personalised medicines necessary?
Genes determine how the body responds to certain drugs- making them more or less effective for different people.
Personalised drugs are tailored to an individual’s DNA; genetic information is used to predict how a person will respond; the most effective drug will be prescribed.
how is black sigatoka transmitted + its symptoms?
INDIRECT transmission eg. wind, rain, water, irrigation
large brown patches
how are HIV & influenza transmitted and what are their symptoms
HIV = direct transmission eg. bodily fluids
depressed immune system, AIDS
influenza = indirect transmission by droplet infection
runny nose, fever, coughing, sneezing
name the 5 passive physical barriers present in plants all the time
+ what is the difference between animal/plant disease defence
-waxy cuticle
-bark
-cellulose cell walls
-casparian strip
-closing stomata
Plants do not heal diseased tissue, they seal it off & discard it.
which ROUTINE VACCINES are offered to everybody in the UK
MMR- measles, mumps, rubella- attenuated virus given
Meningitis C- bacterial
what is IMMUNITY (3 marks)
The ability of an organism to resist a particular infection or toxin by the action of specific antibodies and sensitised white blood cells. Either:
NATURAL- produced by own antibodies or from antibodies mother-foetus/newborn
ARTIFICIAL- administrated medically
Define autoimmune disease (2 marks)
A disease in which the body produces antibodies that attack its own tissues, leading to the deterioration and sometimes destruction of such tissue.
how is bacterial meningitis transmitted and what are the symptoms
DIRECT + INDIRECT transmission eg. kissing, coughing, sneezing, (respiratory secretions)
Symptons = fever, headache, neck stiffness, light sensitivity
what is the specific/adaptive immune response
A pathogen and antigen-specific immune response with both cell-mediated and humoral components. Characterised by immunological memory.
name the parasite that causes malaria + the vector for the malarial parasite
Plasmodium is the parasite eg. Plasmodium vivax**, Plasmodium malariae etc.
female Anopheles is the vector
how is tobacco mosaic virus transmitted and what are the symptoms
- DIRECT transmission: contact between plants*
- INDIRECT transmission: farm machinery, tobacco products*
Yellow streaking, stunted growth.
name a bacterial pathogen in plants + what are the symptoms
(bacterial plant infection)
RINGROT in potatoes
discolouration, oozing, wilting leaves
define an OPSONIN
Any substance that binds to foreign microorganisms or cells, making them more susceptible to phagocytosis.
They act as cell-signalling molecules.
why do some vaccines have to be changed every year?
The antigens on the CSM change regularly eg. the influenza virus, forming new strains.
Therefore the memory cells from one vaccination with one strain will not recognise the new strain with different antigens; strains are immunologically different.
why is there a HINGE REGION on an immunoglobulin
to allow movement of variable regions, therefore increasing antigen-binding potential
which cells carry out PHAGOCYTOSIS
Specialised phagocytic white cells i.e. phagocytes- neutrophils, macrophages + dendritic cells.
differences between types of immunity- active + passive
Exposure?
Time/how rapid?
How long protection will last?
Memory cells produced?
ACTIVE
REQUIRES EXPOSURE TO ANTIGEN
TAKES A WHILE FOR PROTECTION TO DEVELOP
LONG-TERM
M CELLS PRODUCED
- passive*
- no exposure to antigen*
- protection is immediate*
- short-term*
- m cells are not produced*
what happens in an inflammatory response after the mast cell histamines make capillary walls leaky
Fluid, platelets & antimicrobial proteins enter tissue from the capillary. Clotting begins.
Further cytokines secreted by mutliple cells- attract phagocytes from blood.
Phagocytosis by neutrophils + macrophages of pathogens and cell debris at the site.
why does the government aim to vaccinate a large % of the population
Herd immunity- helps to prevent epidemics i.e. mass outbreaks of disease.
-Those not vaccinated are unlikely to become infected because they will not come into contact with anyone who has the disease.
what is the SPECIFIC immune reponse
- Recognises & targets a specific antigen only
- Involves lymphocytes (specialised leucocytes), which are produced in the bone marrow and differentiate in the bone marrow; B lymphocytes + thymus: T lymphocytes
- Interleukins/cytokines.
- Humoral + Cell-mediated parts.
what are the types of transmission & the 5 factors affecting transmission of communicable disease in plants
DIRECT transmission - eg. touching
INDIRECT TRANSMISSION - wind, water, soil, animals, humans
- poor _____ nutrition
- susceptibility to disease
- over-crowding
- abiotic conditions
- climate change
what is ACTIVE immunity
An organism’s own memory cells are produced and antibodies are obtained from organism’s own B cells.
i.e. the immune system has been stimulated by an antigen
what is the inflammatory reponse
A localised response to pathogens/irittants/damage resulting in inflammation at the site of the wound i.e. heat, pain, swelling/oedema, redness.
The heat prevents pathogens reproducing.
what is the difference between a primary and secondary immune response?
PR: The response of the immune system the first time it is exposed to an antigen.
SR: The response of the immune system the second and subsequent times it is exposed to an antigen.
How do antibodies act as ANTI-TOXINS
They combine with toxins secreted by bacteria to render them harmless
eg. Tetanus + Diphtheria toxins
what kind of protein is an immunoglobulin
how many antigens can an antibody bind to
- Y-shaped GLOBULAR protein*
- two antigen molecules per antibody*
explain how production of callose, tyloses + phtoalexins help actively defend the plant from pathogens
CALLOSE- Closes plasmodesmata, blocking passage between cytoplasms to inhibit pathogen entry. Deposited in sieve pores to block transport of phloem sap to entire plant.
TYLOSES- ingrowths in xylem vessels. (blocks xylem lumen)
PHYTOALEXINS- cell-signalling molecules produced as a response to breakdown products of cellulose by bacteria + fungal cellulases. They stimulate production of chitinase enzymes to digest fungi cell wall. Disrupt cell membrane & delay reproduction of bacteria.
in which natural compounds are many medicinal drugs found?
give 3 examples
Plants, animals, microorganisms (only a small proportion have been investigated)
- Penicillin obtained from fungus*
- Some cancer drugs made using soil bacteria*
- Alzheimer’s disease drugs produced from daffodils*
what is natural active immunity
EXPOSURE TO A DISEASE: immune system makes its own antibodies + memory cells
what is immunisation and vaccination
A programme that can involve both artificial active immunity & artificial passive immunity
Artificial active immunity only.
what is immunological memory
The ability of the immune system to respond rapidly in the future to antigens encountered in the past.
name the human cells in which the malaria parasite reproduces
Hepatocytes + erythrocytes
WHAT ARE ANTIBIOTICS FOR
Chemicals that kill or inhibit the growth of bacteria.
Used in drugs to treat bacterial infections- do not harm human body cells or viral cells because they do not have a cell wall, unlike bacteria (peptidoglycan).
The antigen is either inactive/dead/attenuated.
What causes the measles vaccine to be less effective in children from less economically developed countries?
Their diet it protein deficient
what happens in the first exposure to a pathogen
CLONAL SELECTION
Clones of lymphocytes that are complementary bind to antigens, all other lymphocytes are blind
CLONAL EXPANSION/PROLIFERATION
Those that are complementary increase in number- plasma cells.
CLONAL DIFFERENTIATION
Some clones differentiate into memory cells.
what is artificial active immunity
Immune system produces own antibodies and memory cells after exposure to a vaccine.
what is natural passive immunity
Antibodies are provided by natural means, i.e. from the placenta or breast milk.
from mother to baby
what are interleukins
A group of cytokines (cell-signalling proteins + other signal molecules) secreted by leucocytes and regulate proliferation, differentiation & activation of the cells of the specific immune system.
name two potential problems with antibiotics
Side effects/severe allergic reactions in some people.
Antibiotic resistance.
name a protoctista + a fungal pathogen in plants
PROCTISTA = blight (in tomatoes, potatoes etc.)
FUNGAL = black sigatoka eg. in bananas
how is malaria transmitted + what are the symptoms
by a vector i.e. Plasmodium, in a mosquito
tiredness, fever, decreased O2, death
Outline ANTIBIOTIC RESISTANCE
- genetic resistance in a population
- natural resistance
- antibiotic kills all
- resistant survive
- lack of competition = thrive
- allele passed for resistance passed on (artificial selection)
- resistant spreads, (frequency)
- ‘superbugs’ antibiotic redundant
why are booster vaccines given
to make sure memory cells are produced (after several years)
what is clonal selection
A model for how B and T cells are selected to target specific antigens invading the host.
Define PHARMING + Nanotechnology in synthesis of medicines
Using animals to mass-grow drugs/make many copies.
Particles** used to **deliver drugs** to **pathogens or tumours.
give 5 examples of primary physical+chemical defences
- Nasal cavity- hairs & mucus trap microorganisms, the mucus is wafted away or digested. Other MUCOUS MEMBRANES- urethra, lungs, vagina, alimentary canal
- Tear glands- clean eyes with tear solution containing lysozyme
- Skin- Impervious unless broken, friendly bacteria outcompete, sebum + fatty acid secretions kill many bacteria
- Stomach- Acidic juices kill many bacteria
- Large intestine- bacteria outcompete pathogenic bacteria
name 2 ways in which the body forcibly removes pathogens
EXPULSIVE REFLEXES
Coughing + sneezing.
Caused by pathogens in the linings of the airways eg. in the mucus in the upper respiratory tract.
what is cell-mediated immunity
An immune response involving the activation of macrophages, specific T cells + cytokines against antigens.
Describe the structure of an antibody
4 polypeptide chains: two heavy two light
The heavy chains are held at a HINGE REGION by INTERCHAIN DISULFIDE BONDS
The phagocyte binds to the constant region, whilst the variable region binds to the specific complementary antigens on a pathogen via the antigen-binding site.
what is an ANTIGEN
An identifying chemical on the surface of a cell or macromolecule that induces an immune response.
eg. allergens, pathogens & foreign bodies i.e. non-self antigens.
name two fungal pathogen + a protoctista pathogen in animals
ATHLETE’s FOOT and RINGWORM
MALARIA from PLASMODIUM
explain how antibodies act as AGGLUTININS
Antibodies bind to two identical antigens or two or more pathogens, causing them to CLUMP together
-tf difficult for them to spread/easy for phagocytes to engulf them
what is the difference between Innate and Acquired immunity
INNATE immunity: non-specific rapid response to a range of pathogens
primary defences- prevent entry of pathogen into body
secondary defences- internal, killing pathogen when it has entered system
ACQUIRED immunity: specific immune response, targeted at one particular pathogen
briefly describe the SPECIFIC/ADAPTIVE immune response
humoral
B cells activated by T cells
B cells secrete antibodies into the blood plasma, they bind to antigens.
cell-mediated
Helper T cells bind to an APC eg. macrophage, and are activated
Helper T cells divide/proliferate
Helper T cells activate B cells, cytotoxic T cells & produce T memory cells
Cytotoxic T cells destroy infected body cells
name 6 active defence mechanisms in plants
- HYPERSENSITIVITY (immediate death of tissues)
- production of CALLOSE (closes plasmodesmata)
- production of TYLOSES (xylem vessel blockages)
- production of PHYTOALEXINS cell-signalling molecules
- Systemic Acquired Resistance cell-signalling molecules
- General toxins
how does the skin/wound heal after a scab has formed
Epithelial cells below the scab start to grow, sealing the wound permanently. damaged capillaries regrow
Collagen fibres are deposited to give new tissue strength.
Scab falls off once epidermis normal and wound is healed.
Describe the stages of the clotting mechanism
Platelets gather near the wound and release clotting factors, stimulating the conversion of prothrombin to thrombin, which splits fibrinogen to form fibrin.
FIBRIN FIBRES form a mesh over the wound, trapping RBCs + platelets- stopping the bleeding.
Clot hardens-scab- new cells grow for repair- enzyme plasmin released to dissolve clot.
name the 5 PASSIVE chemical defence mechanisms in plants
- secretion of toxins
- secretion of enzyme inhibitors
- sticky resin in bark
- secretion of growth substance, promoting growth of microorganisms that compete with the pathogen
- receptors on cell surface detecting pathogen, activate plant defences
explain how antibodies act as OPSONINS
The antibodies cover the pathogen(s) to facilitate phagocytosis bc the phagocytes can bind to their constant regions (receptors).
By attaching to bacteria, they mark the pathogen for phagocytes.
If binding to viruses, they prevent the virus binding to a host.
what is tobacco mosaic virus
A viral pathogen in plants.
what is the function of a vaccine
They contain antigens (free or attached to a dead or weakened pathogen) so that the body produces memory cells against a particular pathogen- without the pathogen causing disease/symptons of it.
Vaccination causes immunisation, i.e. the process by which you develop immunity.
PASSIVE immunity?
Antibodies are not produced by organism’s own B cells, but obtained otherwise.
Memory cells not produced.
how is tuberculosis transmitted and what are the symptoms
INDIRECT transmission by droplet infection
-causes a respiratory disorder
Describe the process by which a pathogen is destroyed once recognised
PHAGOCYTOSIS of pathogen/foreign cell
- Endocytosis of pathogen, enabled by cytoskeleton, forming pseudopodia.
- This forms a phagosome, which is a vacuole containing bacteria.
- Phagosome fuses with a lysosome, which contains hydrolytic enzymes, forming a phagolysosome.
- These begin to hydrolyse the pathogen into monomers eg. amino acids, fatty acids.
- The antigens of the pathogen are presented on the surface of the phagocyte- becomes an APC.
- Waste products released by exocytosis.
After CLONAL SELECTION, what happens to the clones and what are their roles
expansion/proliferation
they differentiate into PLASMA CELLS; carry out cell function, secreting antibodies
and MEMORY CELLS; they have a long life-span, replicate occassionally and induce a rapid second immune response and the proliferation of many plasma cells
how is synthetic biology used in antibiotic production
- Technology is used to design/produce artificial proteins, cells + microorganisms
- eg. engineering bacteria to destroy cancer cells while leaving healthy body cells intact
what are the 3 types of T cell + their functions
T helper cell : receptors on surface membrane bind to APC. T cells produce interleukins that stimulate proliferation of B cells & all T cells.
T killer/cytotoxic cell
T regulator
what is the function of MACROPHAGES + MAST CELLS when the body is wounded eg. skin broken
MACROPHAGES RELEASE CYTOKINES - cell-signalling molecules- alerting other phagocytes to the pathogen(s) in the site of infection.
MAST CELLS RELEASE HISTAMINES - type of cytokine- making nearby capillary walls leaky (for phagocytes).
what is artificial PASSIVE immunity
Antibodies injected into bloodstream
how is blight transmitted and what are the symptoms
INDIRECT transmission eg. spores in the wind
rotting flesh, foul smelling
what are the factors that increase the chance of infection of tuberculosis
- not vaccinated against TB
- weakened immune system
- overcrowding
- poor ventilation of housing
- homelessness
- lifestyle- poor diet/ lack of protein/ malnourished/smoking/alcoholism
- close/prolonged contact with infected individuals
- close contact with people from/visiting, area where TB is common
- consumption of milk/beef from infected cattle/in developing countries
