Immune System Flashcards
1st line of defence (innate defence)
Surface barriers such as skin and mucous membranes
2nd line of defence (innate defence) is composed of internal defences such as
Internal defences such as phagocytes, natural killer cells, inflammation, anti microbial proteins, fever
Combined 3rd line of defence (adaptive defences)
Humoral immunity such as B cells
Cellular immunity such as T cells
Skin as an (almost) impenetrable barrier- what is it
Heavily keratinised epithelial barrier, immune cells in its layers
Skin barrier- what does it secret on surface
Antimicrobial secretions
Skin barrier- why is the Keratin important
Keratin is a fibrous protein which is acid, alkali and enzyme resistant
Mucosal membranes line which parts of the body
Entry and exit points such as eyes, nose, mouth, lungs, gut, etc
What do mucosal membranes do
They physically trap microorganisms with sticky mucous
In nose how is mucous pushed towards the mouth to be swallowed
By cillia
Mucin dissolves to do what
Dissolves in water to form sticky mucous traps
Defensins are
Skin and mucous membranes
Immune cell mobilisation step 1
Leukocytosis- Neutrophils enters blood from bone marrow
Immune cell mobilisation step 2
Margination- Neutrophils cling to capillary walls
Immune cell mobilisation step 3
Diapedesis- Neutrophils flatten and squeeze out of capillaries
Immune cell mobilisation step 4
Chemotaxis- Neutrophils follow chemical trail
Which immune response are lymphocytes a part of?
The adaptive immune response. Make up 25% of WBCs
Which immune cell recognised foreign antigens
Lymphocytes
B-cells develop in
Bone marrow. There is a plasma cell and memory cell
T-cells develop in the ??? And there are 3 types
Thymus. There are T-helper cells, cytotoxic T cells and suppressor T cells
Natural Killer cells develop in
Bone marrow and other immune tissues
What don’t Natural Killer cells have?
No classical Antigen receptor
No memory capacity
What is the third subclass of lymphocyte called
Natural killer cells
What is the function of Natural Killer cells
Recognise abnormalities in infected cells or tumour cells as well as some microorganisms and destroy
How do NK cells work/ how do they kill!
By signalling apoptosis (eg virus infected cells)
Causing pore formation via perforin
Firing proteases at cells
Antimicrobial proteins- what are Interferons (IFNs)
Small proteins released by virus infected cells that interfere with protein synthesis in other cells
Antimicrobial proteins- what are the three types of IFNs (think Greek alphabet)
Alpha, beta, gamma
Which IFNs inhibit viral replication and activate NK cells?
Alpha and beta
Which IFNs mobilises the immune system ?
Gamma from lymphocytes
What is the function of the complement system in Antimicrobial proteins? (Think immune defence types)
Enhances both the innate and adaptive immune defences
~20 different proteins in the blood produced by the liver which when activated form
Protein pores called membrane attack complexes- lysis
Coat pathogens in opsonins so phagocytes can bind
What can the complement system do to inflammation?
Enhance inflammation
the classical pathway is made of ??? that activates the ??? system
Antibodies (classical pathway) that activate the complement system
True or false, the complement system is a reactive cascade
True, each enzyme activated the next
How is the complement system restricted?
By both short activation times and specific inhibitors
Fever is what type of response
An innate
What is a fever caused by
WBCs and macrophages releasing pyrogens in response to foreign substances
Where and why do pyrogens cause thermostat
In hypothalamus to raise body temperature
What is the function of fever
Inhibit microbe growth, sequester iron and zinc within liver and spleen (less available for bacteria)
Increase metabolic rate of tissues to speed repair
What is febrile seizure
A common neurological disorder in infants and young children which alarmist always resolve spontaneously and almost never cause long term harm
What is cellular senescence
Ageing cells losing their ability to divide permanently
True or false: senescent cells are harmless
False. They release toxic and inflammatory byproducts
What is the 3rd line of defence against infection know as
Specific immunity or acquired immunity
Acquired immunity features three main response things (S.S.M)
Specific to a pathogen or foreign substance
Systemic: happens everywhere in body
Memory: for future encounters
Adaptive immune system: humoral immunity is what
Antibody mediated immunity created by B-lymphocytes
Which fluids does humoral immunity work through?
Through blood and lymphatic system
What does humoral immunity specialise in
Bacteria, toxins and some viruses
Adaptive immune system: cellular immunity what is it
Cell mediated immunity with T-lymphocytes
What does cellular immunity specialise in
Infected cells, parasites and cancer cells
An antigen is
Anything that can trigger an immune response. Most are large complex molecules with multiple possible binding sites
Antigens are immunogenic and stimulate ??? Multiplication
They stimulate lymphocytes to multiply
Antigens are reactive and react with activated ???
They react with activated lymphocytes. Small molecules that only cause reactions called Haptogens or incomplete antigens eg RAT tests for covid
Humoral immune system: Blood groups are determined by
By which Antigenic receptors on your RBCs and
by which antibodies against those receptors are in your plasma
Lymphocyte life cycle: B and T lymphocyte precursors originate in
Red bone marrow
Lymphocyte life cycle: precursors destined to be T cells migrate to
The thymus and mature there
Lymphocyte life cycle: precursors destined to be B cells mature in
Bone marrow.
Self tolerance of lymphocytes means what
Each lymphocyte must not attack self antigens. Failures of self tolerance can cause the body to attack itself
Immunocompetence of lymphocytes means what in terms of binding and recognising antigens?
Each lymphocyte must be able to recognise and bind to one antigen. It dies if it can’t. Many copies of this antigen receptor are in the surface of each lymphocyte
Clonal deletion occurs when
Cells responding to self antigens are told to apoptose
Antigen sequestering is what
Some self antigens are simply not exposed to the immune system
Privilege Tissue status is when some body tissues
Apoptose immune cells that would activate against them
Suppression by regulatory T-cells is when
Activated cells are suppressed throughout their life.
Clonal anergy is when
Cells are inactivated
Receptor editing is when B cells are given a second chance to
B cells are given a second chance to change receptor if stimulated by self antigens
B cells differentiate into
Memory B cells or
Plasma cells
IgM is a class of antibody that is
1st to be produced, clinically indicates current infection.
What are IgM antibodies good at
Agglutination and activating complement. They are pentameric but also exist as a monomer bound to B cells
What are IgA antibodies
Mostly secreted in saliva, sweat, intestines, breast milk.
They stop attachment of microbes to epithelium. Are dimeric but some monomer in blood
What are IgD antibodies bound to and act as
Bound to B cells surface, acts as antigen receptor
What are IgG antibodies
Most abundant type in blood, main antibody of late primary and secondary responses.
What are IgG antibodies good at
Fixing and activating complement. Have passive immunity via crossing placenta, shows past infections
IgE antibodies are secreted by
Secreted by plasma cells in skin and mucosa
IgE antibodies work against
Parasites
In allergies, IgE antibodies bind to
Mast cells and basophils tissue cause histamine and inflammatory chemical release
Primary antibody production from first exposure is small and slow or big and quick?
Small and slow
Secondary antibody production is
Faster and stronger due to memory cells already available
Active humoral antibody immunity is either ??? Acquired or ??? Acquired
Naturally acquired through contact with pathogen or
artificially acquired though vaccine
Passive humoral antibody immunity is acquired through either
Naturally acquired through mother to fetus or
Artificially acquired via injection of exogenous antibodies
Types of vaccines
- inactivated pathogen
Live but attenuated - Parts of a pathogen
- Toxoid
- Viral vector
- mRNA
True or false: t lymphocytes can turn into effector or memory T cells
True
Memory T cells assist in
The quick response to secondary infections
Three types of effector T cells
Helper T cells
Cytotoxic T cells
Regulatory T cells
Helper T cells help activate and control
Activate B cells and other T cells and macrophages
Control and direct the adaptive immune response
Cytotoxic T cells are specific killers that directly
Destroy virus infected cells, fast multiplying bacteria, old cells and cancer forming cells. Similar to NKs but act against specific targets
Regulatory T cells help suppress
T cell activity once no longer needed
How do cytotoxic T cells know what cells to kill?
Via MHCs as all cells constantly display bits of their innards on their membrane like a passport for immune cells to survey
How does displaying MHCs cause cytotoxic T cells to attack
Potentially the cells have antigens in them, so it warns cytotoxic T cells if that cell is infected
MHC type 2 receptors are ??? and release ??? which ??? other immune cells
all immune cells. MHC class 2 releases signals to attack, activating other immune cells
second line of defence initial response is
inflammation
??? called lectins, also known as the ??? pathway is one of three ways to activate the ??? system
Proteins called lectins (Lectin pathway)
complement system
the complement system can be activated spontaneously by lack of ??? known as the ??? pathway
Spontaneously by lack of inhibitors (alternate pathway)
which immune cell type phagocytoses microbes to produce antigens on their cell surface and then present these antigens to lymphocytes to initiate adaptive immune response?
Dendritic cells
which immune cell type is an Antigen Presenting Cell?
Dendritic cells
opsonins are what type of protein?
complement protein aka antibody
Natural killer cells recognise when there is a lack of ??? Surface proteins and destroy these cells
Major histocompatibility complex
Signalling of cells for apoptosis is seen by ??? Cells which then destroy the cell
Natural Killer cells
How do interferons help by interfering with protein synthesis in other cells? By inducing the synthesis…
They induce the synthesis of protective proteins in the cell they have entered to protect against the virus.
What interferes with the replication of virus mRNA in neighbouring cells when released by infected cell?
Interferons- small proteins
Alpha and Beta interferons inhibit ??? Replication and activate NK cells
Viral replication
Gamma interferons mobilise the ??? System
Immune system
Membrane attack complexes are ??? That are produced by liver and are in the blood
Proteins
TRUE or FALSE: membrane attack complexes come together to form protein pores in the membrane of target cells and enhance inflammation
True
Each enzyme activated the next enzyme and thus restricted by both short activation times and specific inhibitors- what immune system is this?
The complement system
TRUE OR FALSE: Fever is a type of adaptive defence
False it is an innate defence
White blood cells and macrophages release ??? To induce fever
Pyrogens
interferons are small ??? released by infected cells
small proteins
what type of immunity is known as specific or acquired immunity, adaptive or innate?
adaptive immune
which immunity type works through blood and lymphatic system? humoral or cellular?
humoral
immunogenic antigens stimulate ??? to multiply
lymphocytes
antigens can react with activated ???
lymphocytes
TRUE or FALSE: antigens are usually large complex molecules with multiple binding sites known as antigenic determinants
TRUE
immunogenic antigen response is when ??? are stimulated to multiply by the presence of ???
lymphocytes, antigens
blood groups contain antigenic ??? and antibodies in plasma against particular receptors
receptors
autoimmune disorders occur when b-cells fail to recognise ???
self
TRUE or FALSE: in humoral immunity, Clonal Deletion is when B-cells responding to self antigens are ‘told’ to apoptose
TRUE
lymphocytes (B and T cells) are born in which immune tissue?
bone marrow
what does P.L.A.N stand for with the work of antibodies?
P: precipitation
L: lysis from complement system
A: agglutination
N: neutralisation
passive humoral antibody immunity is when antibodies are
antibodies are passed from mother to child
active humoral antibody immunity is when antibodies are acquired
acquired from contact with pathogen resulting in memory cells
artificial active humoral antibody immunity is from dead ???
dead or attenuated pathogens
artificial passive humoral antibody immunity is passed through what type of vaccine injection?
injection of exogenous antibodies
what cells display class 1 major histocompatibility complexes?
all cells that become infected except for red blood cells
Type 1 major histocompatibility complexes are recognised by
cytotoxic T cells and naive CD8 cells
Class/type 2 major histocompatibility complexes are displayed by which cells
antigen presenting cells such as dendritic cells, macrophages and B-cells
Class 2 MHCs are recognised by what cell
Helper T-cells
deficiency in responding to an attack can be genetic (primary) and ??? (secondary) immunodeficiency
acquired (secondary)
acute (immediate) hypersensitivity is mediated by which antibody? (MADGE)
antibody IgE
TRUE or FALSE: acute hypersensitivity occurs by IgE causing degranulation of mast cells & basophils
True
which two types of hypersensitivity is caused by antibodies
type 2 and 3
