chapter 12 - communicable diseases Flashcards
define disease
a condition that impairs the normal functioning of an organism. both plants an animals can get diseases
define pathogen
a (micro)organism that causes a disease - often called a microbe
what are communicable diseases
diseases that spread between organisms
what are the 4 types of pathogen
fungi, bacteria, protoctista (protista) and viruses
how do fungi cause disease
some fungi are parasitic so they feed off of living plants and animals. (saprophytic digestion)
produce millions of spores allowing them to spread rapidly throughout crop plants.
stop plants from photosynthesising
some fungi produce toxins which effect host cells
how do viruses cause disease
- virus attaches to cell
- viral DNA injected into cell
- viral components assembled, viral nucleic acid is replicated and proteins are synthesised
4.viruses released, death/ bursting of cell
how do bacteria cause disease
bacteria produce toxins that poison or damage host cells
either destroying cell membranes, cell walls or genetic information so the host cell cannot reproduce
what is the name for the collection of hyphae on fungi
mycelium
tuberculosis
organism effected:
pathogen type:
animals
bacterial
bacterial meningitis
organisms effected:
pathogen type:
humans
bacterial
ring rot
organism effected
pathogen type
potatoes and tomatoes
bacterial
HIV/AIDS
organism effected
pathogen type
humans
viral
influenza
organism effected
pathogen type
animals
viral
malaria
organism effected
pathogen type
animals
protoctist
late blight
organism effected
pathogen type
potatoes and tomatoes
protoctist
black sigatoka
organism effected
pathogen type
banana plants
fungal
ring worm
organism effected
pathogen type
cattle
fungal
athletes foot
organism effected
pathogen type
humans
fungal
what are examples of direct spread of disease
droplet infection (coughing or sneezing)
sexual intercourse
touching
what are examples of indirect spread of disease
intermediate eg. air, water, food, surfaces or another organism (vector)
what factors can effect the spread of disease
social :
overcrowding, poor health and nutrition
poor education of health , culture and infrastructure - some countries traditional medical practices can increase transmission
climate:
potato/tomato blight is most common in WET SUMMERS
malaria most common in TROPICAL COUNTRIES
how does climate change effect the spread of disease
results in changing environments which can lead to new vectors and disease in different areas
what are some physical plant defences
thick waxy cuticle: physical barrier + waterproof
cell wall - physical barrier + contains chemicals
callose - polysaccharide deposited between cell walls and membranes when plant is infected
prevents pathogens entering cells - blocks phloem sieve plates - stop spread of pathogen
what are some chemical plant defences
produce antimicrobial chemicals which kill or inhibit the growth of pathogens
e.g. saponins destroy the membranes of fungi
produce chemicals that are toxic to insect pests eg. vectors
what is the function of saponins in plants
destroy the membranes of fungi
define primary non-specific defence in animals
prevent initial entry of ANY TYPE of pathogen into an organism
what are some primary non-specific defences in animals
skin - physical barrier + secretes antimicrobial chemicals
nose hairs, eyelashes + tears - physical barrier
mucus - traps pathogens
wound repair - mitosis and migration of epidermal skin cells repair open wounds
blood clotting - platelets stop pathogens from entering + prevent blood loss
swelling - more tissue fluid drains into the lymphatic system
describe the primary non-specific defence of swelling in animals
histamines make the blood vessels dilate and more leaky more tissue fluid drains into the lymphatic system and heat raises
raised heat helps prevent pathogens reproducing
cytokines attract white blood cells to the site
define secondary non-specific defence in animals
once ANY TYPE of pathogen is already in an organism
why is the specific immune response quicker than the non-specific response in animals?
because the immune cells have to identify the specific pathogens that enter an organism
why is the secondary specific immune response faster than the primary?
because the secondary immune response already has memory cells which, when they come across the pathogen for the second time, are able to rapidly divide and form a large number of clones
what are helpful chemicals in non-specific defence
cytokines - act as cell signalling molecules informing other phagocytes that the body is under attack
can also increase body temperature and stimulate the specific immune system
opsonins - bind to pathogens and tag them so they can be more easily recognised by the phagocytes
what is an antigen?
a protein or glycoprotein that has a specific shape for organisms to recognise self-antigens and foreign antigens
what two responses do foreign antibodies trigger?
phagocytosis (secondary non-specific)
or
production of antibodies (specific)
what are antibodies
y shaped glycoproteins called immunoglobulins
bind to a specific antigen on the pathogen or toxin
describe the structure of antibodies
y shaped
two heavy peptide chains on the inside
connected by disulfide bridges
two light peptide chains on the upper outside
antigen binding site on the top of each side
the hinge region between the upper half of the two heavy peptides - provides flexibility for binding to two separate antigens - one at each binding site
how do antibodies defend the body
- antibody of the antigen-antibody complex acts as an opsonin so the complex is easily engulfed and digested by phagocytes
- most pathogens can no longer effectively invade host cells once they are in a complex
- antibodies act as agglutinins causing pathogens carrying antigen-antibody complexes to clump together - helps prevent spread and easier identification
- antibodies can act as anti-toxins, binding to toxins produced by bacteria
describe how the structure of antibodies are related to their function
variable regions - form antigen binding sites - complimentary
hinge region - allows flexibility
constant region - allows binding to immune cells
what are the main types of T lymphocytes
t helper cells
t killer cells
t memory cells
t regulator cells
where do T lymphocytes mature
in the thymus gland
where do B lymphocytes mature
in the bone marrow
what are the main types of B lymphocytes
plasma cells
b effector cells
b memory cells
what cells form antibodies
b plasma cells
what is clonal selection and expansion
the selection of the correct T cells for the immune response and they divide by mitosis to produce masses of identical clones
what is the function of T helper cells
release “interleukins” (type of cytokine - chemical messenger)
stimulate:
B cells to differentiate
the production of clonal selection and expansion of other T cells
macrophages to ingest pathogens
what is the function of T killer cells
attack and destroy infected body cells using the chemical called “perforin” to pierce the cell membrane and then secrete cytotoxins into the cell
what is the function of t regulator cells
shut down immune response after pathogen is removed. prevent auto immunity
what is the function of T memory cells
involved in the immunological memory - remain in the body for years after infection and become active in secondary response to make more T cells fast - before showing any symptoms
what is the function of B plasma cells
manufacture and release antibodies very quickly
what is the function of B memory cells
remain in the body for years and act as immunological memory
respond quickly to secondary response to make more plasma cells - do not produce antibodies
what is the size difference between plasma cells and b lymphocytes
plasma cells - lots more organelles - 6-8 um
b lymphocytes - fewer organelles - 4um
define autoimmunity
what are some auto immune diseases
when your immune system does not recognise self antigens
Rheumatoid arthritis (joints)
lupus (connective tissue)
MS - multiple sclerosis (myelin sheath surrounding neurons)
what are the 3 main types of antibodies
agglutinins
opsonins
antitoxins
what is the function of the antibody agglutinins
stick pathogens together (via antigens)
hampers mobility of pathogens, allows phagocytes to engulf a larger number of pathogens
what is the function of the antibody opsonins
bind to antigens via the antigen binding site
bind to the phagocyte via the constant region
makes it easier for phagocytes to find and engulf pathogens
what is the function of the antibody antitoxins
bind to toxins produced by bacteria, and other pathogens, and make them harmless
what are the features of lymphocytes and what do they differentiate into
large, round nucleus
6-8um (smaller than phagocytes)
no granules in cytoplasm
B cells - produced in bone marrow - mature in bone marrow then distributed into the lymphatic system
T cells - produced in bone marrow - mature in thymus - then distributed in the blood and lymphatic system
what is an antigen presenting cell
cells that are attacked by pathogens will display antigens on their surface - attracting T&B cells
increasing the chances that the correct T and B lymphocytes will locate the antigens
describe the process of inflammation in animals
localised response to a pathogen
hormone “histamine” is released which dilates the blood vessels
leading to increased local temperatures (vasodilation) - slows reproduction of pathogens
vessel dilation also leads to leakier capillaries - more blood leaves capillaries and forms tissue fluid in the lymphatic system
as tissue fluid goes into the lymphatic system - it takes pathogens with it
where white blood cells (and lymphocytes) act on pathogens
describe the features and function of neutrophils
multi-lobed nucleus, made in bone marrow - allows cell to change shape - squeeze through gaps in capillaries
granular cytoplasm - lots of lysosomes
larger than R.B.C.s
short lived - undertake phagocytosis
describe the features and functions of macrophages
larger than neutrophils, made in bone marrow
travel through the blood as monocytes
undertake phagocytosis
display antigens from pathogens on their surface - antigen presenting cell - help initiate an immune response
describe the process of phagocytosis
- phagocyte recognises antigens (foreign protein) on surface of pathogens
- phagocyte engulfs the pathogen, folding its membrane in
- a phagosome is formed
- lysosomes fuse with phagosome - phagolysosome
- lysosomes release enzymes (lysins) to digest the pathogen
- harmless products absorbed
- macrophages then display the antigens on the plasma membrane
what are the 4 types of immunity
active
passive
natural
artificial
define active immunity
immune system is activated and you make antibodies and memory cells
define passive immunity
is provided by antibodies NOT made in your system
could be provided across placenta or breastmilk
define natural immunity
is gained “normally” or with no help, usually as a result of an infection (active)
antibodies provided from a mother in breast milk/ across placenta is also natural (passive)
define artificial immunity
is gained by deliberate exposure to antigens or antibodies (active or passive) eg. vaccination
define vaccination
a deliberate exposure to antigenic material which activates the immune system to make an immune response and provide immunity as memory cells
what is herd immunity/ vaccination
when 90% of the population is vaccinated, it covers everybody as the disease cannot spread - limits chance of transmission and protects those unable to receive the vaccination
why do vaccinations change frequently - boosters etc.
pathogens reproduce rapidly and therefore DNA is replicated frequently - binary fission in bacteria
mutations are more common and can change - when pathogens mutate their antigens change
what is the function of antibiotics
drugs that only kill bacteria
what is the function of antiviral drugs
what are the disadvantages
drugs that kill viruses - difficult to develop and often have side effects
what is the function of antiseptics
kill pathogens but used for surfaces - not ingested
what is the function of painkillers
treat symptoms of a disease - don’t actually kill the pathogen
how are drugs traditionally made
extracted from plants and microorganisms
what is digitalis and what is it made from
heart drug
made from foxgloves
what is aspirin and what is it made from
painkiller from willow
who discovered penicillin and what is it made from
by alexander flemming
from penicillium mould
explain how phagocytes are able to pass from the blood to the tissue fluid
phagocytes have a multi-lobed nucleus and a flexible membrane. therefore they can change shape and pass through small gaps in capillaries
histamine causes the capillaries to become leakier
describe the process by which a pathogen is destroyed after it has become attached to the surface of a phagocyte (non-specific)
- after the pathogen is attached, the membrane of the phagocyte folds around the pathogen engulfing it - phagocytosis/ endocytosis
- a phagosome is formed
- lysosomes fuse with the phagosome and release digestive enzymes (lysozymes) which break down/ digest pathogens into amino acids/ glucose/ fatty acids
- harmless products are absorbed and harmful products are drained into the lymphatic system to be disposed of
Why are low income countries more likely to develop/spread infections
Houses may be overcrowded
Lack of trained Healthcare professionals
Culture - traditional medical practices
Name the type of cell that produces antibodies
B plasma cell
describe the role of memory cells on secondary infections
Recognize virus/antigen/pathogen
Produce clones
Can change to plasma cells on infection
Plasma cells produce antibodies against antigen
Responsible for secondary response
Destroy virus before symptoms appear
Can change into named t-cell
how and why do plasma cells differ from b lymphocytes
larger : More organelles
More RER : More protein synthesis
Larger nucleus : More transcription
More golgi : More protein synthesis
More mitochondria: More aerobic respiration for protein synthesis
define autoimmune disease
a disease which is caused by the body’s immune cells, mistaking your body cells for foreign cells/ pathogens
suggest why antibodies specific to nuclear proteins are not normally made
nuclear proteins are normally hidden in the nucleus/ not exposed to tissue fluids
