chap 6- responding to antigens Flashcards
(77 cards)
1
Q
what are microbes
A
small cellular organisms that can only be seen with a microscope
2
Q
what is an example of a protist
A
bacteria
3
Q
example of protozoans
A
malaria
4
Q
example of fungi
A
yeast or athletes foot
5
Q
example of a virus
A
covid-19
6
Q
example of prions
A
mad cow disease
7
Q
how can pathogens be transmitted
A
person-person contact
airborne droplets
contact with contaminated objects, food or blood
injection of contaminated food or water
vectors that carry pathogenic agents and spread them to people
8
Q
what is the pathway for disease to occur
A
1- gain entry to the organism
2- reach target cells
3- overcome body’s defense systems
4- become established at one or more sites
5- multiply rapidly
6- cause harm to the host and produce the symptoms of disease
9
Q
what does the first line of defence do
A
stops pathogens from causing damage
10
Q
is the first line of defense innate and non specific
A
yes
11
Q
what does innate mean
A
from birth
12
Q
what does non-specific mean
A
works on any pathogen
13
Q
what do physical barriers do
A
act to stop pathogenic material from gaining entry into the body
14
Q
example of physical barriers in animals
A
intact skin, mucus- membranes, sneezing/coughing/vomiting
15
Q
example of physical barriers in plants
A
thick bark, wax coatings, cellulose cell wall
16
Q
what do chemical barriers in animals do
A
chemicals attack pathogenic material
17
Q
examples of chemical barriers in animals
A
stomach acid (contains HCl)
sweat/tears/saliva (contains lysozyme
fluid in lungs (contains surfactants)
18
Q
examples of chemical barriers in plants
A
caffeine (is toxic to insects and fungi)
tannins (toxic to insects)
citronella (repels insects)
19
Q
what do microbiota barriers do
A
act to prevent colonization of microorganisms that may be pathogenic.
20
Q
when do be acquire normal microbiota
A
from birth
21
Q
is the second line of defense innate and non-specific
A
yes
22
Q
when does the second line of defence kick in
A
after microbes pass 1st line of defence
23
Q
where does second line of defense mainly occur
A
at sight of infection
24
Q
what does second line of defence react against
A
microbes
25
what is inflammation
the accumulation of fluid, plasma proteins and leukocytes that occurs when tissue is damaged/infected
26
what is inflammation characterized by
pain, redness, heat and swelling
27
what triggers the inflammatory response
the interaction between leukocytes and pathogens triggers the inflammatory response that results from the production, activation or release of substances such as complement proteins and cytokines.
28
what are leukocytes
all cells in the immune system are WBC (leukocytes). derived from pluripotent stem cells in bone marrow
29
what are phagocytes
WBC that engulfs foreign matter (endocytosis). they arrive at sight of infection first
30
what are the phagocytes
macrophages, neutrophils and dendritic cells
31
what are granulocytes
leukocytes with granules that have enzymes that are released during infections, allergic reactions and asthma
32
can leukocytes be phagocytes and granulocytes
yes
33
what are the granulocytes
neutrophils, eosinophils, mast cells and basophils.
34
what is an antigen
any substance that triggers an immune response in the body
35
what are antigen presenting cells
phagocytes that digest foreign material containing an antigen and display a fragment of this antigen on the surface of their membrane where it can be recognized by the adaptive immune response
36
what are cytokines
small protein signalling molecules released by body cells in response to cell damage or presence of a pathogen. they trigger innate responses associated with the 2nd line of defense such as inducing inflammation and fever along with activating macrophages.
37
what are macrophages
large phagocytes that tend to be located close to pathogen entry points. they engulf microbes, digest them and display a fragment on their surface. also release cytokines to initiate inflammatory response
38
what are neutrophils
exist in bloodstream. engulf microbes and kill them with toxic chemicals. contain granules with antimicrobial compounds. also release cytokines to attract other immune cells to site of infection and cause inflammation
39
what are dendritic cells
reside in tissues that have contact with the outside environment (skin, linings of nose), are phagocytic and APC's, move through the body via lymphatic vessels to lymph glands where they act as APC's to the adaptive immunity cells. secrete antiviral cytokines.
40
what are eosinophils
release cytotoxic chemicals from granules onto the surface of their targets. also release cytokines to attract other immune cells to site of inflammation. key in defense against larger parasites. phagocytic.
41
what are natural killer cells
contain granules that are filled with cytotoxic chemicals like perforin which punch holes in cell membranes and trigger apoptosis. recognize and attack cells that don't contain self markers.
42
what are mast cells
found in connective tissues close to the external environment and known as "border guards". raise the alarm that a pathogen has entered the body. contain granules containing histamine and other active molecules which are released during inflammation. involved in early recognition of pathogens and releases chemical signals that attract other immune cells to the infection site
43
what are complement proteins
a group of proteins dissolved in plasma of blood that helps phagocytes recognise foreign antigens. circulate the body in inactive form until they are activated by an antigen or a signal from an immune cell. once activated they adhere to the invading microorganism making it more readily identifiable as foreign so phagocytes will be attracted to site of infection (opsonisation). "complement" the function of immune cells through a series of biochemical reactions
44
what are interferons
a type of cytokine that is released by cells infected with viruses to signal other nearby cells to heighten their antiviral defences, interferons attract natural killer cells to the site to release cytotoxins to kill the infected cell and activate macrophages to clean up the cell debris after lysis of infected cell.
45
what is an antigen
a pathogen is an organism that can cause sickness or disease in another organism. it is a unique molecule/part of a molecule that is recognised by the immune system and can initiate an immune response.
46
what are antigens made of
protein based and are composed of one or more polypeptide chain. however some can be composed of carbohydrates, lipids or nucleic acids
47
what are self antigens/self markers
antigens expressed by cells belonging to an organism (have originated from that organism)
48
what are non-self antigens
antigens that have not originated from an organism and therefore do not belong to that organism
49
where are MHC I markers found
on surfaces of all nucleated cells of your body (all exept RBC)
50
where are MHC II markers found
only on the cell surfaces of special white blood cells known as professional antigen presenting cells- macrophages, dendritic cells and B cells.
51
what does MHC proteins stand for
Major Histocompatibility complex proteins
52
what is the process of phagocytosis
1- phagocyte activated by chemicals the microbe gives off
2- adherence of pathogens antigen to phagocyte induces membrane protrusions to extend around microbe
3- microbe fully enclosed in a membrane results in phagosome
4- as phagosome moves into cell interior, lysosomes bind with phagosome to form phagolysosome
5- enzymes, like lysozyme, break down and digest microbe
6- formation of residual body with undigested material
7- discharge of undigested material by exocytosis
53
what do APCs do
display fragments of digested antigens from foreign. non/self substance on their MHC II markers, on the surface if their plasma membranes. signal to the third line of defense
54
what are cellular pathogens
pathogens that have a cellular structure and are capable of reproducing without the use of a host cell
55
what are the cellular pathogens
parasites, protozoa, fungi and prokaryotes
56
what is an example of a parasite
tapeworm
57
what is non-cellular pathogens
dont have a cellular structure and need a host cell in order to reproduce
58
what are the non-cellular pathogens
viruses and prions
59
where are endotoxins derived from
the outer membrane of gram negative bacteria which are only released when hese bacteria doe and their outer membrane breaks down
60
what are symptoms of bacteria cellular pathogens
chills, fevers, weakness
61
how are exotoxins produced
by living bacteria when they metabolise they are released into their surroundings
62
what are exotoxins
highly toxic soluble proteins
63
what does bacteria have for protection
external capsule
64
how does bacteria replicate
binary fission
65
how do protists reproduce
binary fission
66
symptoms of protists pathogens
headaches, muscle aches, tiredness
67
how does fungi reproduce
spore formation
68
can parasites live without a host
no
69
what are anthropods
multilcellular invertebrates with exoskeleton.
reproduce asexually with stages of life. e.g. lice
70
what are comycetes
unicellular. penetrate living cells and release molecules that suppress hosts innate immune response. e.g. cinnamon fungus
71
what are viruses called outside of a host
virion/ viral particle
72
can viruses metabolise their own energy
no and they cannot reproduce without a host cell
73
how does a virus invade a cell
1- virus enters cell
2- substances in the cell begin to strip off the viruses outer coat of protein
3- nucleic acid in center of virus is released
4- nucleic acid gets into the cells chemical manufacturing system
5- cell 'ignores' its own chemical needs and switches to making new viruses.
6- the cell is sometimes destroyed in the process. many of the new viruses are released to infect other cells.
74
when are prions produced
when a normal cellular protein is converted to an infectious, harmful form due to incorrect folding
75
what are virioids composed of
short, circular strands of RNA.
76
what is an allergen
any antigen that elicits an allergic response.
77
what is an allergic reaction
an immune response in which immune system overreacts to a normally harmless substance.
