Chapter 21 - The Immune System - Innate and Adaptive Body Defenses Flashcards
The immune system’s two intrinsic systems are:
- Innate (nonspecific) defense system
2. Adaptive (specific) defense system
The immune system is a ____ system rather than ____ system.
functional; organ
Innate and adaptive defenses of the immune system are ____.
intertwined
Both innate and adaptive defenses release and recognise many of the same
defensive molecules
How do innate defenses differ from adaptive?
- innate defenses have specific pathways for certain substances
- innate responses release proteins that alert cells of adaptive system to foreign molecules
Innate defense system has two lines of defense–first and second. The first is composed of:
external body membranes (skin and mucosae)
Innate defense system has two lines of defense–first and second. The second is composed of:
antimicrobial proteins, phagocytes, and other cells
The second innate line of defense does what?
- inhibits the spread of invaders
2. has inflammation as its most important mechanism
The adaptive defense system’s third line of defense does what?
It attacks particular foreign substances.
How does the adaptive line of defense differ from the innate line of defense?
Takes longer to react than innate system.
Innate defenses have ____ to ward off invading pathogens.
surface barriers
The surface barriers of innate defenses are in the most general context:
skin, mucous membranes, and their secretions
What are the characteristics of surface barriers of the innate defense system?
- they are a physical barrier to most microorganisms
- they are keratin resistant to weak acids and bases, bacterial enzymes, and toxins
- mucosae provide similar mechanical barriers
Surface barriers of the innate defense system have protective chemicals that inhibit or destroy microorganisms. What are they?
- the acidity of skin and secretions–acid mantle
- enzymes
- defensins
- other chemicals
The acidity of skin and secretions in the innate defense system does what to microorganisms?
inhibits growth
What are the enzymes that inhibit microorganisms in the innate defense system?
- lysozome of saliva
- respiratory mucus
- lacrimal fluid
What do the enzymes of the innate defense system do?
kill many microorganisms
Defensins of the innate defense system are what? What do they do to microorganisms?
antimicrobial peptides; inhibit growth
Other chemicals of the innate defense system are what? What effect do they have on microorganisms?
lipids in sebum, dermcidin in sweat; toxic
Respiratory system modifications (surface barriers) of the innate defense system are:
- mucus-coated hairs in nose
- cilia of upper respiratory tract that sweep dust
- bacteria-laden mucus toward mouth
Surface barriers of the innate immune system can be breached by nicks or cuts. What happens then?
second line of defense must protect deeper tissues
If microorganisms invade deeper tissues, internal defenses of cells and chemicals are necessary. What are they?
- phagocytes
- natural killer (NK) cells
- antimicrobial proteins
- fever
- inflammatory response
What is an example of antimicrobial proteins that protect deeper tissues upon invasion?
interferons and complement proteins
What partakes in the inflammatory response to protect deeper tissues upon invasion?
- macrophages
- mast cells
- WBCs
- inflammatory chemicals
The phagocytes that participate in internal defenses are:
- neutrophils
- macrophages
These are the most abundant phagocytes but die fighting.
neutrophils
_____ become phagocytic on exposure to infectious material.
neutrophils
____ develop from monocytes.
macrophages
The chief phagocytic cells are:
macrophages
____ macrophages wander through tissue spaces, e.g. alveolar macrophages.
free
___ macrophages are permanent residents of some organs, e.g. Kupffer cells (liver) and microglia (brain).
fixed
In order for phagocytosis to take place, the phagocyte must
adhere to particle
Some microorganisms evade phagocytic adherence with ____.
capsule
____ marks pathogens—coating by complement proteins or antibodies.
opsonisation
In phagocytosis, cytoplasmic extensions bind to and engulf the particle in a vesicle called ____.
phagosome
In phagocytosis, the phagosome fuses with lysosome, which creates ____.
phagolysosome
Pathogens are killed during phagocytosis due to acidifying and digesting with _____.
lysosomal enzymes
If lysosomal enzymes are unable to kill pathogens, helper T cells cause a release of enzymes of _____, which kill pathogens.
respiratory burst
What are the three ways that helper T cells kill pathogens that are resistant to lysosomal enzymes?
- release cell-killing free radicals
- produce oxidising chemicals (e.g. H2O2)
- increase pH and osmolarity of phagolysosome
In phagocytosis, defensins in neutrophils pierce ____.
membrane
nonphagocytic large granular lymphocytes
natural killer (NK) cells
NK cells attack cells that lack
“self” cell-surface receptors
NK cells induce ___ in cancer cells and virus-infected cells.
apoptosis
NK cells secrete potent chemicals that enhance:
inflammatory response
This is triggered whenever body tissues are injured.
inflammatory response
This prevents the spread of damaging agents.
inflammation
The cardinal signs of acute inflammation are:
- redness
- swelling
- heat
- pain
- sometimes impairment of function
When inflammation is triggered, it disposes of what?
cell debris and pathogens
When inflammation is triggered, it alerts which system?
adaptive immune system
When inflammation is triggered, it sets the stage for what?
repair
The inflammatory response begins with chemicals released into _____ by injured tissues, immune cells, blood proteins.
ECF
Macrophages and epithelial cells of boundary tissues have ____ receptors.
Toll-like (TLR)
11 types of toll-like receptors (TLR) recognise specific classes of:
infecting microbes
Activated TLRs trigger release of _____ that promote inflammation.
cytokines
The three inflammatory mediators are:
- kinins
- prostaglandins
- complement
Inflammatory mediators dilate _____.
local arterioles
When inflammatory mediators dilate local arterioles, this is known as:
hyperemia
When inflammatory mediators dilate local arterioles, this causes:
redness and heat of inflamed region
Inflammatory mediators make capillaries ____.
leaky
Inflammatory mediators attract ____ to area.
leukocytes
Does edema increase capillary permeability or decrease it? What does this cause?
increase; exudate goes to tissues
Exudate is fluid containing ___ and ___.
clotting factors; antibodies
Exudate causes:
local swelling (edema)
When swelling occurs, it pushes on nerve endings which causes:
pain
Pain can also occur from:
- bacterial toxins
- prostaglandins
- kinins
Exudate moves foreign material into ____.
lymphatic vessels
Exudate delivers ____ and ____ to area of inflammation.
clotting proteins; complement
The clotting factors that exudate delivers to area of inflammation form _____.
fibrin mesh
The fibrin mesh formed by clotting factors at areas of inflammation is the scaffold for ____.
repair
The fibrin mesh formed by clotting factors at areas of inflammation isolates the injured area so that:
invaders can’t spread
In phagocyte mobilisation, ___ lead, and ___ follow.
neutrophils; macrophages
As phagocyte attack continues, ___ arrive.
monocytes
12 hours after leaving bloodstream, monocytes become ____. These are called ___.
macrophages; “late-arrivers”
“Late-arrivers” replace ____ and remain for ____.
dying neutrophils; clean up prior to repair
If inflammation is due to pathogens, ____ is activated and ____ arrive.
complement; adaptive immunity elements
The steps for phagocyte mobilisation are:
- leukocytosis
- margination
- diapedesis of neutropils
- chemotaxis
the release of neutrophils from bone marrow in response to ____-inducing factors from injured cells
leukocytosis
neutrophils cling to walls of capillaries in inflamed area in response to CAMs
margination
inflammatory chemicals promote positive ___ of neutrophils
chemotaxis
inflammatory chemicals that promote chemotaxis are known as
chemotactic agents
Two different antimicrobial proteins are:
- interferons (IFNs)
- complement proteins
Antimicrobial proteins attack microorganisms directly or indirectly?
directly
Antimicrobial proteins hinder the microorganisms’ ability to ____.
reproduce
The family of immune-modulating proteins are known as:
interferons
Viral-infected cells secrete interferons to:
warn neighbouring cells
After viral-infected cells secrete IFNs, they enter neighbouring cells and cause the cell to do what?
produce proteins that block viral reproduction and degrade viral RNA
IFN alpha and beta also activate ____.
NK cells
IFN ____ is secreted by lymphocytes.
gamma (immune interferon)
IFN gamma activates ____.
macrophages
IFN gamma has widespread ____ effects.
immune-mobilising
Since IFN activates NK cells and macrophages, it indirectly fights ____.
cancer
Artificial IFNs are used to treat:
- hepatitis C
- genital warts
- MS
- hairy cell leukaemia
The complementary system is composed of ~20 blood proteins that circulate in ___ form.
inactive
The complement system includes which blood proteins?
- C1-C9
- factors B, D, and P
- other regulatory proteins
Complement is the major mechanism for destroying:
foreign substances
Our cells contain complement activation ____.
inhibitors
Complement unleashes inflammatory chemicals that:
amplify all aspects of inflammatory response
Complement kills bacteria and certain other cell types by ____.
cell lysis
Complement enhances which defense?
both innate and adaptive
There are three pathways to complement activation, which are:
- classical pathway
- lectin pathway
- alternative pathway
In the classical pathway, antibodies bind to ____ and ____. This is called _____.
invading organisms; complement components; complement fixation
The classical pathway is the ___ step in complement activation.
first
____ are produced by the innate system to recognise foreign invaders.
lectins
When lectins are bound to foreign invaders they can also bind and activate ____.
complement
Complement pathway that is triggered when activated C3, B, D, and P interact on the surface of microorganisms.
alternative pathway
Each complement pathway involves activation of ___ and in an orderly sequence.
proteins
In complement activation, each step ___ the next.
catalyses
Each complement pathway converges on ___, which cleaves into __ and ___.
C3; C3a; C3b
In complement activation, there is a common terminal pathway initiated that does three things, which are:
- enhances inflammation
- promotes phagocytosis
- causes cell lysis
Cell lysis begins when:
C3b binds to target cell
After C3b binds to target cell, what happens?
insertion of complement proteins called [membrane attack complex (MAC)] into cell’s membrane
After MAC is inserted into cell’s membrane, what happens?
MAC forms and stabilises a hole in the membrane surface
After MAC forms a hole in the membrane surface, what happens?
Influx of water –> lysis of cell
C3b also causes ____.
opsonisation
C3a and other cleavage products amplify ___.
inflammation
C3a stimulates mast cells and basophils to release ___.
histamine
C3a attracts ___ and ____.
neutrophils; other inflammatory cells
Fever is a systemic response to:
invading microorganisms
Leukocytes and macrophages exposed to foreign substances secrete ___.
pyrogens
Pyrogens act on:
body’s thermostat in the hypothalamus, raising body temperature
The benefits of moderate fever are:
- causing the liver and spleen to sequester zinc and iron (needed by microorganisms)
- increasing metabolic rate –> faster repair
this system must be primed by initial exposure to a specific foreign substance
adaptive (specific defense) immune system
The adaptive immune system activates ___.
complement
The adaptive immune system amplifies ____.
inflammatory response
The adaptive immune system protects against ___ and ___.
infectious agents; abnormal body cells
part of the adaptive immune system that recognises and targets specific antigens
specific
part of the adaptive immune system that is not restricted to initial site
systemic
the adaptive immune system has ____, which leads to stronger attacks to known anitgens
memory
The two separate, overlapping arms of adaptive immune system are:
- humoral (antibody-mediated) immunity
- cellular (cell-mediated) immunity
humoral immunity is composed of ___, produced by lymphocytes, circulating freely in body fluids
antibodies
in humoral immunity, antibodies bind temporarily to the target cell and do two things:
- temporarily inactivate target cell
- mark the target cell for destruction by phagocytes or complement
in cellular immunity ___ act against target cell.
lymphocytes
lymphocytes that act against target cell act directly by
killing infected cells
lymphocytes that act against target cell act indirectly by
releasing chemicals that enhance inflammatory response or activating other lymphocytes or macrophages
substances that can mobilise adaptive defenses and provoke an immune response
antigens
antigens are the targets of all ___ immune responses
adaptive
Most antigens are large, complex molecules not normally found in
body (nonself)
The two important functional properties of complete antigens are:
- immunogenicity
- reactivity
Examples of complete antigens are:
- foreign protein
- polysaccharides
- lipids
- nucleic acids
ability to stimulate proliferation of specific lymphocytes
immunogenicity
ability to react with activated lymphocytes and antibodies released by immunogenic reactions
reactivity
incomplete antigens are known as
haptens
incomplete antigens are not ___ by themselves
immunogenic
Example of haptens:
- peptides
- nucleotides
- some hormones
haptens may be immunogenic if attached to ____ and combination is marked foreign
body proteins
haptens cause the immune system to mount
harmful attack
Examples of mounted harmful attack as a result of haptens:
- poison ivy
- animal dander
- detergents
- cosmetics
antigenic determinants are also known as
epitopes
Only certain parts (epitopes) of entire antigen are ___
immunogenic
Antibodies and lymphocyte receptors bind to epitopes as enzyme binds ___.
substrate
Most naturally occurring antigens have numerous antigenic determinants that
- mobilise several different lymphocyte populations
- form different kinds of antibodies against it
Large, chemically simple molecules (e.g. plastics) have little or no ___.
immunogenicity
self-antigens are also known as
MHC proteins
self-antigens are
protein molecules on the surface of cells that are not antigenic to self but antigenic to others in transfusions or grafts
Example of self-antigens:
MHC glycoproteins
MHC glycoproteins are coded by genes of ____ and are unique to the individual.
major histocompatibility complex
MHC glycoproteins have a groove holding ___ or ___.
self-antigen; foreign antigen
Lymphocytes only bind ___ on MHC proteins.
antigens
The three types of cells of the adaptive immune system are:
- B lymphocytes
- T lymphocytes
- Antigen-presenting cells (APCs)
B lymphocytes participate in ___ immunity.
humoral
T lymphocytes participate in ___ immunity.
cell-mediated
these do not respond to specific antigens and play essential auxiliary roles in immunity
antigen-presenting cells (APCs)
The five steps of lymphocyte development, maturation, and activation are:
- origin (all originate in red bone marrow)
- maturation
- seeding secondary lymphoid organs and circulation
- antigen encounter and activation
- proliferation and differentiation
Lymphocytes are educated as they mature, and become B cells in ___ or T cells in ___.
bone marrow; thymus
a lymphocyte can recognise one specific antigen by binding to it is known as
immunocompetence
lymphocytes unresponsive to own antigens is known as
self-tolerance
Thanks to immunocompetence, B or T cells display a unique receptor on their surface when they achieve maturity, so they can bind
only one antigen
T cells mature in the thymus under ___ and ___ pressures.
- positive selection
- negative selection
selects T cells capable of regonising self-MHC proteins; failures are destroyed by apoptosis
positive selection
T cells capable of recognising self-MHC proteins is known as
MHC restriction
prompts apoptosis of T cells that bind to self-antigens displayed by self-MHC; ensures self tolerance
negative selection
B cells are positively selected if they successfully make
antigen receptors
B cells that are self-reactive are handled by
elimination by apoptosis (clonal deletion)
Immunocompetent B and T cells that are not yet exposed to antigen are called
naive
Naive B/T cells are exported from ____ to ____.
primary lymphoid organs; “seed” secondary lymphoid organs
Exportation of naive B/T cells increases the chance of:
encounter with antigen
examples of primary lymphoid organs
- bone marrow
- thymus
examples of secondary lymphoid organs
- lymph nodes
- spleen
naive lymphocyte’s first encounter with antigen leads to selection for further development. this is known as
clonal selection
If the correct signals are present in clonal selection,
lymphocyte will complete its differentiation
An activated lymphocyte ____.
proliferates
Due to lymphocyte proliferation, this leads to
exact clones
Most lymphocyte clones become
effector cells that fight infections
Few lymphocyte clones remain as
memory cells
Memory cells are able to respond to the same antigen
more quickly the second time
B and T memory cells and effector T cells circulate ___.
continuously
____ determine which foreign substances the immune system will recognise.
genes (not antigens)
