Lesson 12a - Lymphoid and Immune System Flashcards
(276 cards)
1
Q
pathogens
A
agents capable of producing disease, including viruses, bacteria, fungi, and other microbes
2
Q
three lines of defenses: first line of defense
A
skin and mucous membranes, which serve as barriers
3
Q
three lines of defenses: second line of defense
A
protects against pathogens that break the skin and mucous membrane barriers
4
Q
the second line of defense includes (7)
A
- leukocytes
- macrophages
- antimicrobial proteins
- natural killer cells
- fever
- inflammation
5
Q
three lines of defenses: third line of defense
A
adaptive immunity, mechanisms that defeat a specific pathogen and leave the body with a memory of it
6
Q
immune system
A
widely distributed population of cells, diverse chemicals, physical barriers, and physiological responses
7
Q
two broad forms of defense
A
- innate immunity
- adaptive immunity
8
Q
innate immunity
A
defenses we are born with that protect us from broad spectrum of disease agents
9
Q
innate immunity has…(3)
A
- local effect
- non-specific
- lacks memory
10
Q
innate immunity: local effect
A
defends at point of invasion, but there are exceptions like fever
11
Q
innate immunity: non-specific
A
defenses are against a broad spectrum of disease agents, rather than on particular pathogen
12
Q
innate immunity: lacks memory
A
does not ‘remember’ exposure to a specific pathogen
13
Q
adaptive immunity
A
defenses against specific pathogens, developed only upon exposure (adaptive) and maintains immune memory
14
Q
peptides in the skin that kill microbes (3)
A
- dermcidin
- defensins
- cathelicidins
15
Q
protective features of skin (4)
A
- toughness of keratin, difficult to penetrate
- too dry/nutrient-poor to support microbial growth
- skin is continually shed so microbes ‘don’t stick’
- presence of an acid mantle
16
Q
acid mantle
A
thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth
17
Q
digestive, respiratory, urinary, and reproductive tracts are open to the exterior and protected by _____ _____
A
mucous membranes
18
Q
protective features of mucous membranes (2)
A
- sticky mucous physically traps microbes
- presence of lysozyme
19
Q
lysozyme
A
enzyme that destroys bacterial cell walls
20
Q
protective features of subepithelial areolar tissue of skin and mucous membranes
A
contain a viscous barrier of hyaluronic acid in ground substance
21
Q
pathogens can release _____
A
hyaluronidase
22
Q
hyaluronidase
A
an enzyme to make hyaluronic acid less viscous
23
Q
phagocytes
A
cells that engulf foreign matter
24
Q
five types of leukocytes
A
- neutrophils
- eosinophils
- basophils
- monocytes
- lymphocytes
25
where are neutrophils found?
wander in connective tissue and functions to kill bacteria
26
neutrophils can ensnare bacteria by releasing...
a neutrophil extracellular trap (NET)
27
neutrophil extracellular trap
web of nuclear chromatin and proteins
28
neutrophils can kill by... (2)
- phagocytizing and digesting microbe
- releasing bacterial chemicals to create a killing zone
29
where are eosinophils found?
especially in mucous membranes
30
what do eosinophils guard against?
large parasites like tapeworms, and roundworms
31
eosinophils also participate in...(2)
- participate in inflammation
- react to allergens and participate in allergic reactions
32
basophils
secrete chemicals that aid mobility and action of other leukocytes
33
leukotrienes
activate and attract neutrophils and eosinophils
34
histamine
a vasodilator; increases blood flow and speeds delivery of leukocytes to the area
35
heprin
inhibits clot formation that would impede leukocyte mobility
36
mast cells
also secrete these substances; similar to basophils but found in connective tissues
37
lymphocytes include...
T and B cells, and also Natural Killer cells
38
T and B cells are part of innate/adaptive immunity?
adaptive
39
Natural killer (NK) cells are part of the innate/adaptive immunity?
innate
40
monocytes
emigrate from the blood into connective tissues and transform into macrophages
41
macrophage system
all the body's avidly phagocytic cells, expect leukocytes
- includes monocytes, macrophages, dendritic cells, and others
42
specialized macrophages in the CNS, lungs, and liver
- microglia: CNS
- alveolar macrophages: lungs
- stellate macrophages: liver
43
interferons
proteins secreted by virally infected cells and immune cells to serve as an alarm to nearby cells
44
what do interferons do? (2)
- bind to receptors on nearby cells, stimulating their synthesis of defensive antiviral proteins to prevent their infection
- activate NK cells and macrophages to better destroy infected cells/cancer cells
45
complement system
group of 30 or more globular proteins that contribute to both innate and adaptive immunity
46
what synthesizes most of the complement system?
the liver
47
T/F the complement system circulated in the blood in an inactive form
true
48
what complement contributes to inflammation
C3a
49
what complement contributes to immune clearance, phagocytosis, and cytolysis?
C3b
50
three complement pathways
1. classical
2. alternative
3. lectin
51
classical pathway
requires antibody binding to microbe, which changes the antibody's shape and exposes complement-binding sites on the antibody
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complement fixation
binding of the complement C1 to the antibody sets of a reaction cascade
53
alternative pathway
complement Cb3 binds to microbe surface, activating reaction cascade
54
lectin pathway
use lectins to trigger the pathwaysl
55
lectins
plasma proteins that bind to carbohydrates on the pathogen's surface, activating reaction cascade
56
four outcomes of complement activation
1. inflammation
2. immune clearance
3. phagocytosis
4. cytolysis
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outcomes of complement activation: phagocytosis
C3b coats microbial cells and serves as binding sites for phagocyte attachment
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opsonization
proteins coat microbial cells that serve as binding sites for phagocyte attachment
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outcomes of complement activation: inflammation
C3a stimulates mast cells and basophils to secrete histamine and other inflammatory chemicals which activates and attracts neutrophils and macrophages
60
outcomes of complement activation: immune clearance
C3b binds the antigen-antibody complexes to red blood cells that then circulate to the liver and spleen where macrophages strip off and destroy the Ag-Ab complexes leaving the RBCs unharmed
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outcomes of complement activation: cytolysis
- complement C3b initiated formation of C5b
- C5b aggregates with other complement proteins within plasma membrane of microbe which forms the membrane attack complex (MAC)
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membrane attack complex (MAC)
forms a hole in the target cell membrane, made of complement proteins
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process of a MAC on its target cell
electrolytes leak out, water flows rapidly in, and the target cell ruptures (cytolysis)
64
immunological surveillance
natural killer (NK) cells continually patrol the body looking for pathogens and diseased host cells
65
NK cells attack and destroy...(4)
- microbes
- transplanted cells
- cells infected with viruses
- cancer cells
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NK cells recognize an infected cell and bind to it, releasing proteins called _____
perforins
67
perforins
polymerize to form a ring to create a hole in the target's plasma membrane
68
granzymes
a group of protein-degrading enzymes
69
process of granzymes
enzymes enter through the pore created by perforins and degrade intracellular enzymes and induce apoptosis
70
cancer cells may exhibit _____-_____ antigens
tumor-specific
71
where are tumor specific antigens found?
cell's plasma membrane
72
T/F tumor-specific antigens are identified as abnormal by NK cells
true
73
immunological escape
some cancer cells avoid NK cells
- either destroy NK cells that detect them or avoid detection by not displaying tumor specific antigens or masking them
74
cells infected with viruses present...
abnormal proteins on their plasma membranes, allowing NK cells to identify and destroy them
75
fever (pyrexia)
an abnormal elevation of body temperature
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fever results from...(5)
- trauma
- infections
- drug reactions
- brain tumors
- other causes
77
a fever is a defense mechanism that, in moderation, does more good than harm by...(3)
| promotes...elevates...inhibits...
- promotes interferon activity
- elevates metabolic rate and accelerates tissue repair
- inhibits reproduction of bacteria viruses
78
antipyretics
fever-reducing medications
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stages of fever (3)
onset, stadium, defervescence
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the body's thermostat is located in the _____
hypothalamus
81
Reye syndrome
serious disorder in children younger than 15 following an acute viral infection like chickenpox or influenza
82
what can Reye syndrome be triggered by?
the use of aspirin, so do not give to children with chickenpox or flu-like symptoms
83
Reye syndrome symptoms (3)
- swelling of the brain neurons
- pressure of the swelling leads to nausea, vomiting, disorientation, seizures, and coma
- fatty infiltration of liver and other viscera
TLDR; swelling of the liver and brain
84
inflammation
local defensive response to tissue injury, including trauma and infection
85
general purposes of inflammation (2)
- limit spread of pathogens and destroys them
- remove debris from damaged tissue and initiate tissue repair
86
four cardinal signs/symptoms
redness, swelling, heat, pain
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cytokines
small proteins that function in chemical communication between cells
88
what do cytokines do?
alter physiology of receiving cells
89
cytokines include...(4)
- interferon
- interleukins
- tumor necrosis factor
- chemotactic factors
etc.
90
what is the most immediate requirement after tissue injury?
to get defensive leukocytes to the site quickly
91
getting leukocytes to tissue injury sites is achieved by...
local hyperemia (increasing blood flow)
92
what does hyperemia wash away from injury sites faster? (2)
toxins and metabolic wastes
93
vasoactive chemicals (2)
- histamine
- leukotrienes
94
vasoactive chemicals stimulate...(2)
(1) endothelial cells to contract, (2) widening the gaps between them to increase capillary permeability
95
cell-adhesion molecules aid in..
recruitment of leukocytes
96
margination
cell-adhesion molecules make membranes sticky, so leukocytes adhere to the vessel wall
97
diapedesis
emigration
- leukocytes crawl through gasps in the endothelial cells and enter tissue fluid
98
extravasated
term for cells and chemicals that have left the bloodstream
99
four cardinal signs of inflammation: heat results from...
hyperemia
100
four cardinal signs of inflammation: redness results from (2)
hyperemia and extravasated RBCs in tissue
101
four cardinal signs of inflammation: swelling results from
an increased fluid filtration from the capillaries
102
four cardinal signs of inflammation: pain results from...(5)
- direct injury to the nerves
- pressure on nerves from edema
- stimulation of pain receptors by prostaglandins
- bacterial toxins
- bradykinin
103
another priority of inflammation is to prevent _____ from spreading throughout the body
pathogens
104
_____ filters into tissue fluid and clots to form a sticky mesh that walls off microbes
fibrinogen
105
_____ prevents clotting at the site of injury
heparin
106
after leaving the bloodstream, neutrophils exhibit chemotaxis, meaning...
they exhibit attraction to chemicals that guide them to the injury site
107
respiratory burst
neutrophils absorb O2 to form H2O and release hypochlorite - al highly toxic and creates a killing zone around the cell
108
neutrophils secrete cytokines for recruitment of _____ and additional _____
macrophages, neutrophils
109
macrophages and T cells secrete _____-_____ factor to stimulate _____
colony-stimulation, leukopoiesis
110
neutrophilia
5,000cells/uL to 25,000 cells/uL in bacterial infection
111
eosinophilia
elevated eosinophil count in allergy or parasitic infection
112
tissue cleanup and repair primarily involves _____
monocytes
113
when do monocytes arrive to tissue injurys?
8-12 hours
114
how does edema contribute to tissue cleanup? (2)
- swelling compresses veins and reduces venous drainage
- forces open valves of lymphatic capillaries, promoting lymphatic drainage of bacteria, dead cells, and debris
115
pus
yellow accumulation of dead neutrophils, bacteria, cellular debris, and tissue fluid
116
abscess
accumulation of pus in a tissue cavity
117
platelet-derived growth factor
stimulates fibroblasts to multiply and synthesize collagen
118
this is secreted by blood platelets and endothelial cells in injured areas
platelet-derived growth factor
119
_____ clot forms a scaffold for tissue reconstruction
firbrin
120
what does pain cause us to do with injuries?
makes us limit the use of a body part so it has a chance to rest and heal
121
increased heart rate increases...(2)
- metabolic rate
- speeds up mitosis and tissue repair
122
third line of defense is...
adaptive immunity
123
three characteristics of adaptive immunity
1. it has a systemic effect
2. it exhibits specificity
3. it has memory
124
three characteristics of adaptive immunity: systemic effect
act throughout the whole body
125
three characteristics of adaptive immunity: specificity
generates protection and immunity to specific pathogens on an individual basis
126
three characteristics of adaptive immunity: memory
when re-exposed to the same pathogen, the body reacts so quickly that there is no noticeable illness
127
two types of adaptive immunity
1. cellular (cell-mediated)
2. humoral (antibody-mediated)
128
cellular (cell-mediated) immunity (2)
- T cells directly attack and destroy foreign cells or diseased cells
- rids body of pathogens that reside inside human cells where they are inaccessible to antibodies
129
humoral (antibody-mediated) immunity
- B cells become plasma cells that release antibodies that do not directly destroy a pathogen but tag it for destruction
130
humoral immunity is effective against...(5)
- viruses
- bacteria
- yeasts
- protozoans
- molecular disease agents like toxins, venoms, allergens
131
natural active immunity
production of one's own antibodies or T cells as a result of infection or natural exposure to antigen
132
artificial active immunity
production of one's own antibodies or T cells as a result of vaccination against disease
133
vaccine
consists of dead or attenuated (weakened) pathogens that stimulate the immune response without causing the disease
134
_____ _____ may be given to re-stimulate immune memory to maintain a high level of protection
booster shots
135
natural passive immunity
temporary immunity that results from antibodies produced by another person (mother to fetus)
136
how to a fetus and a baby acquire antibodies from their mother? (2)
- fetus is through the placenta
- baby is through breast-feeding
137
artificial passive immunity
temporary immunity that results from the injection of immune serum (antibodies) from another person or animal
138
what is the emergency treatment for things like snake bites, botulism, tetanus, and rabies?
artificial passive immunity- injection of immune serum (antibodies) from another person or animal
139
antigen (Ag)
any molecule that can bind an antibody
140
most antigens have _____ molecular weight
large, over 10,000 amu
141
antigens include...(4)
proteins, polysaccharides, glycoproteins, glycolipids
142
characteristics of antigens (Ag) enable the body to do what?
distinguish self from non-self
143
epitopes (antigenic determinants)
certain regions of an antigen molecule that stimulate immune responses
144
haptens (incomplete antigens)
too small to be antigenic in themselves
145
how may haptens trigger an immune response?
combining with a host molecule creating a complex that the body recognizes as foreign
146
examples of epitopes (6)
- cosmetics
- detergents
- industrial chemicals
- poison ivy
- animal dander
- penicillin
147
antibodies (Abs)/immunoglobulins (Igs)
defensive proteins that play a variety of defensive roles
148
about how many antibodies is the human immune system capable of creating?
roughly 1 trillion different antibodies
149
where are some antibodies/immunoglobulins found?
membranes of immune cells
150
soluble antibodes
antibodies dissolved in blood plasma, tissue fluids, lymph, mucus, saliva, intestinal secretions, tears, and breast milk
151
antibody monomer
basic structural unit of an antibody
152
antibody structure
four polypeptide chains linked by disulfide bonds
153
all four chains of an antibody have a _____ region that gives the antibody its uniqueness
variable (V)
154
antibodies have two larger _____ chains and two _____ chains about half as long
heavy, light
155
antigen-binding site (2)
(1) formed from the V regions of the heavy and light chains of each arm, (2) attaches to the epitope of an antigen molecule
156
constant (C) region
has the same amino acid sequence within a given antibody and determines mechanism of antibody action
157
five antibody classes
1. IgA
2. IgD
3. IgE
4. IgG
5. IgM
158
which Ig forms a dimer in places like mucus, saliva, tears, breast milk, and intestinal secretions?
IgA
159
which Ig is found as a pentamer in plasma and lymph?
IgM
160
which Ig is a B cell transmembrane anitgen receptor?
IgD
161
which Ig is bound to receptors on basophils and mast cells?
IgE
162
which Ig constitutes 80% of circulating antibodies?
IgG
163
IgA (2)
- prevents pathogen adherence to epithelia and penetrating underlying tissue
- provides passive immunity to newborns
164
IgD
functions in B cell activation by antigens
165
IgE (2)
- stimulates release of histamine and other chemical mediators of inflammation and allergy
- stimulates eosinophil defensive actions against parasites
166
IgG (2)
- predominant antibody in secondary immune response
- capable of complement fixation, can cross placenta to fetus
167
IgM (2)
- predominant antibody in primary immune response
- strong agglutinating and complement-fixing abilities
168
what are the lymphocytes of the innate immune system?
natural killer cells (NK)
169
what are the lymphocytes of the adaptive immune system?
T and B cells
170
where are T cells produced? where do they migrate?
bone marrow and migrate to the thymus to mature
171
what happens to T cells in the thymus?
they are tested
172
positive selection
cortical epithelial cells test developing T cells to ensure they have the proper receptors (no self antigens)
173
what happens to T cells if they do not have the proper receptors? (aka they react to a self antigen)
they DIE
174
the immune system is self-tolerant, meaning...
it will not attack one's own tissue
175
anergy
self-reactive T cells remain but are unresponsive
176
with proper receptors, T cell are now _____
immunocompetent
177
immunocompetent
capable of recognizing antigens presented to them
178
immunocompetent, unactivated T cells are part of the....
naive lymphocyte pool
179
where do B cells develop?
bone marrow
180
B cells that react to self-antigens under either _____ or _____ _____, same as T cell selection
anergy, clonal deletion (death)
181
when B cells leave the bone marrow, what do they do?
they colonize the same lymphoid tissues and organs as T cells
182
Self-tolerant B cells do what? (2)
- synthesize antigen surface receptors
- divide rapidly to produce immunocompetent clones
183
T cells can only recognize antigens presented by...
antigen-presenting cells (APCs)
184
APCs include (3)
dendritic cells, macrophages, and B cells
185
the function of APCs depends on...(2)
(1) MHC proteins (2) encoded by major histocompatibility (MHC) complex genes
186
MHC molecules act as..
identification tags that label every cell of your body as belonging to you
187
MHC molecules are unique for each individual except for...
identical twins
188
where are MHC molecules displayed? and with what?
surface of APCs along with a fragment of presented antigen
189
antigen processing (5)
(1) APC encounters antigen, (2) internalizes it by endocytosis, (3) digests it into fragments, (4) and attaches it to the MHC protein (5) and display it on the plasma membrane
190
what happens if a T cell encounters an APC with self antigens presented?
it ignores it
191
what happens when a T cell encounters an APC with a non-self antigen presented?
the appropriate T cell will initiate an immune response against the source of that antigen
192
APCs and lymphocytes communicate with cytokines called...
interleukins
193
three classes of T cells
1. cytotoxic
2. helper
3. memory
194
cytotoxic T cells
carry out attack
195
helper T cells
promote activities of other immune cells
196
memory T cells
responsible for memory in cellular immunity
197
what happens after an APC encounters an antigen? (3)
it (1) processes it, (2) migrates to the nearest lymph node, (3) and displays it to the T cells
198
T cells respond to two classes of MHC proteins
MHC-I and MHC-II
199
where do MHC-I proteins occur?
on all nucleated cells
200
what kind of peptides do MHC-I molecules present?
internal peptides including virus infected cells, and cancer cells
201
where do MHC-II proteins occur?
only on antigen-presenting cells
202
what kind of peptides do MHC-II molecules present?
external (phagocytosed, foreign) antigens
203
MHC restriction (2)
(1) cytotoxic T cells respond only to MHC-I proteins and (2) helper T cells only respond to MHC-II proteins
204
when does Tc and Th cell activation begin?
when they bind an MHC protein displaying an epitope that the cell is programmed to recognize
205
costimulation
additional signaling process required for T cell activation
206
in addition to MHC and antigen binding, T cells must also bind..
signaling proteins on surface of APCs in damaged, infected tissues
207
what does costimulation help ensure?
the immune system does not launch an attack in the absence of an enemy or else it would turn against one's own body and injure our tissues (autoimmune disorders)
208
successful costimulation will trigger _____ _____
clonal selection
209
clonal selection (3)
(1) activated T cells undergo repeated mitosis to (2) produce identical clones programmed against the same epitope that (3) become either cytotoxic, memory, or helper T cells
210
Immune memory follows the _____ response in cellular immunity
primary
211
T cell recall response
since memory cells are long-lived, more numerous than naive T cells, and have fewer steps to be activated, so they respond more rapidly
212
helper T cells play a central role in coordinating...(2)
both cellular and humoral immunity
213
when helper T cells recognize the Ag-MHC (MHC-II) complex, what happens?
it secretes interleukins that exert effects
214
three effects of the interleukins secreted by activated helper T cells (4)
- attract neutrophils, NK cells, and macrophages
- stimulate their phagocytic activity
- inhibit them from leaving the area
- stimulate T and B cell mitosis and maturation
215
what are the only cells that directly attack other cells?
cytotoxic T cells
216
when a Tc cell recognizes a complex of Ag-MHC protein on a diseased or foreign cell, it ___ on that cell
docks
217
what happens after a Tc cell docks onto a diseased cell?
it delivers a lethal hit of chemicals
218
the cytotoxic T cell lethal hit includes...(4)
perforins, granzymes, interferons, and tumor necrosis factor (TNF)
219
lethal hit: perforin and granzymes
kills cells in the same manner as NK cells
220
lethal hit: interferons (2)
inhibit viral replication, recruit and activate macrophages
221
lethal hit: tumor necrosis factor (TNF)
aids macrophage activation and kills cancer cells
222
after the lethal hit, what do cytotoxic T cells do?
goes off in search of another enemy cell while the chemicals do their work
223
immunocompetent B cells have _____ of surface receptors for _____ antigen
thousands, one
224
what happens when antigens bind to B cell receptors?
(1) it binds several of these receptors, (2) links them together, and (3) then the B cell takes it into itself by receptor-mediated endocytosis
225
after a B cell endocytosis an antigen, what happens?
processes the antigen and displays fragments onto MHC-II on its surface
226
helper T cells bind to displayed _____ on B cells and secretes _____ that activate the B cell
antigen-MHC, interleukins
227
B cell clonal selection gives rise to...
clones of identical B cells programmed against the same antigen
228
most B cells differentiate into...
plasma cells
229
some B cells become...
memory B cells (they remember the antigen)
230
antibodies travel through the body in...(2)
(1) blood and (2) other body fluids
231
first exposure to an antigen triggers production of what Igs? and how?
(1) IgM and a (2) slower production of IgG
232
later exposure to an already known antigen produces what Ig?
IgG much more rapidly than the first exposure
233
antibodies assist in the immune response in four ways
1. neutralization
2. complement fixation
3. agglutination
4. precipitation
234
antibodies: neutralization
masking active regions of an antigen (toxin, virus, microbial cells)
235
antibodies: complement fixation
activating complement by the classical pathway
236
antibodies: agglutinaiton
clumping of enemy cells, immobilizing them; having the clump cleared by phagocytosis
237
antibodies: precipitation
antigen molecules (no whole cells) are clumped by antibodies; clumps cleared by phagocytes
238
primary response
immune reaction brought about by the first exposure to an antigen
239
why is the appearance of protective antibodies delayed for 3-6 days?
naive B cells multiple and differentiate into plasma cells
240
as plasma cells produce antibodies, the _____ _____ rises
antibody titer
241
antibody titer
level of antibodies in blood plasma
242
when do IgM levels peak in a primary response?
10 days, soon decline
243
when does the IgG titer drop to low levels from a primary response?
within a month
244
secondary (anamnestic) response
immune response when re-exposed to the same antigen
245
during an anamnestic response, how quickly do memory B cells become plasma cells?
within hours of re-exposure
246
describe the IgG titer during a secondary response
rises sharply and peaks in a few days
247
during an anamnestic response, low levels of Ig__ are also secreted and then quickly decline
M
248
after a secondary response, IgG levels remain elevated for...?
weeks to years; conferring long lasting protection
249
memory does not last as long in ____ immunity as in _____ immunity
humoral, cellular
250
autoimmune diseases
failures of self-tolerance; immune system does not correctly distinguish self-antigens from foreign ones and produces auto- antibodies that attack body's own tissue
251
auto-antibodies
attack one's own body tissues
252
three reasons for failure of self-tolerance
1. cross-reactivity
2. abnormal exposure of self-antigens in the blood
3. changes in structure of self-antigens
253
failures of self-tolerance: cross-reactivity
some antibodies against foreign antigens react to similar self-antigens
254
example of cross-reactivity
Rheumatic fever - streptococcus antibodies also attack heart valves
255
failures of self-tolerance: abnormal exposure of self-antigens to the blood
some of our native antigens are not normally exposed to blood
256
failures of self-tolerance: changes in structure of self-antigens
viruses and drugs may change the structure of self-antigens or cause the immune system to perceive them as foreign
257
severe combined immunodeficiency disease (SCID)
hereditary lack of T and B cells; vulnerability to opportunistic infection and must live in protective enclosures
258
acquired immunodeficiency syndrome (AIDS)
non-hereditary diseases contracted after birth
259
AIDS is caused by
human immunodeficiency virus (HIV)
260
HIV invades...(3)
helper T cells, macrophages, and dendritic cells
261
how does HIV invade cells?
'tricking' them to internalize viruses by receptor-mediated endocytosis
262
HIV is a retrovirus, meaning...
it sues the viral enzyme reverse transcriptase to convert its viral RNA genome into DNA which can be inserted into the host genome
263
how does HIV cripple the entire immune response? (2)
by (1) taking out helper T cells and (2) causing them to be vulnerable to opportunistic infections
264
early signs of AIDS
flu-like symptoms of chills and fever
265
progressive symptoms of AIDS (4)
night sweats, fatigue, headache, extreme weight loss, lymphadenitis
266
AIDS helper T cell count
200 cells/uL compared to 600-1200 cells/uL
267
opportunistic infections include (5)
- toxoplasma
- pneumocystis
- herpes simplex virus
- cytomegalovirus
- tuberculosis
268
how is HIV transmitted? (5)
- blood
- semen
- vaginal secretions
- breast milk
- across the placenta
269
therapy for aids
antiretroviral therapy (ART) maintains near-normal life expectancy
270
COVID-19 (coronavirus disease of 2019)
global pandemic of 2020-2021
271
COVID-19 is caused by...
SARS-CoV-2
272
viral structure of SARS-CoV-2 (4)
(1) single strand RNA stabilized by (2) RNA-binding nucleocapsid (N) protein and surrounded by (3) outer lipid envelope studded with (4) projecting spike proteins
273
SARS-CoV-2 infection cycle (2)
- virus in inhaled and invades great (type II) alveolar cells by binding to ACE2 receptors
- virus replicated in host cells, and new ones are releases to infect new cells
274
mechanisms of disease - SARS-CoV-2 (3)
- body cells with ACE2 receptors are infected (heart, kidneys, digestive tract, blood vessels, brain)
- cytokines released by immune cells activate inflammation
- potential cytokine storm produces hyperinflammatory response
275
COVID-19 symptoms (4)
- flu-like symptoms
- loss of taste and smell
- possible breathing difficulty
- low blood oxygen
276
what is the most effective way to prevent critical illness and halt the spread of COVID-19?
VACCINATION
