Immune System Flashcards
Self cells
Cells, Tissues, and molecules comprising ones own body
Non Self Cells (Antigen)
Molecule that stimulate your immune system to mount an immune response
Example of Self Marker Cells
A,B,O Antigens (Blood Types)
MHC
Major Histocompatibility Complex
Antigen
A unique molecule or part of a molecule initiating an immune response
Self Antigen
From within the body
Tolerated by the immune system
Non Self Antigen
From external environment
Identified as invaders and attacked by the immune system
Auto immune disorder
When the immune system mistakenly attacks own body tissue
MHC I Markers
found on almost all body cells
alert the immune system if a cell gets infected
MCH II Markers
Found on certain white blood cells
Dendritic Cells, Macrophages, and B Cells
What do MHC Markers Do?
Activate other parts of the immune system if an infection is detected within the body
Pathogens
Agents that cause disease or illness in their host
Two Types:
Cellular Pathogens
Non cellular Pathogens
Types of Cellular Pathogens
Bacteria
Fungi
Worms
Protozoa
Bacteria
Bacteria can cause disease if they enter the host, by reproducing inside the host, causing harm
Some bacteria cause disease by directly damaging tissue
Others secrete enzymes that digest material that holds the cell together
Fungi
Most fungal infections affect the exzternal surface layers of the body
Feed on dead outer layers of skin
(Tinnea, Ringworm)
Worms
Multicellular Invertebrate Parasites
(Tapeworm)
Protozoa
Single cell eukaryotes that can live free or parasitic
Many different mechanisms of action
(Malaria)
Types of Non Cellular Pathogens
Prions
Viruses
Prions
Abnormal and infectious proteins causin Neurodegenerative disease (diseases within the nervous system)
Convert normal proteins into neurodegenerative ones through contact
Mis-shaped proteins that cause disease by aggregating to form plaques in the Central Nervous System, Disrupting normal tissue, causing formation of holes
(Mad Cow Disease)
Viruses
Obligate intracellular parasites - They MUST infect the host to reproduce
Consist of DNA or RNA inside a protein coat, lack the machinery required to produce their own proteins
Viruses use RIBOSOMES or ENZYMES of their host to express the gene
Viruses are NOT considered living organisms, as they cannot independantly reproduce
Physical barriers in plants (1st LoD)
Bark
Waxy Intact Cuticle
Cellulose Cell wall
Thorns
Chemical Barriers in plants (1st LoD)
Peppermint oil - acts as antibacterial chemical
Citronella oil - Protects against fungi and bacteria
Physical Barriers in Animals (1st LoD)
Intact Skin
Mucous Membrane
Mechanical Barriers (reflexes) (1st LoD)
Sneezing
Coughing
Vomiting
Diarrhoeia
Flushing Tears
Flushing Urine
Chemical Barriers (1st LoD)
Hydrochloric Acid in Stomach
Lysozyme in Tears
Microbiota barriers (1st LoD)
‘Microbes’ in the gut
exist in mutualistic relationship with person
prevent growth of colonies of other bacteria by outcompeting for nutrients, adhesion sights and secreting antimicrobial chemicals preventing growth of pathogenic bacteria
In return, the immune system tolerates their presence
Innate Immunity
Non Specific Immunity
1st and 2nd Line of Defence
Same for all infections
No ‘Memory’
Adaptive Immunity
Specific immunity
3rd Line of defence
Specific to particular infections
Long Term ‘Memory’
1st Line of Defence
Prevents entry of foreign mateial using physical and chemical barriers
Located on body’s surface
Lymph Nodes
a small
secondary lymphoid tissue
found throughout the body where
antigen-presenting cells activate
the adaptive immune system
Lymphocytes
White blood cells in Lymph Nodes
All lymphocytes formed formed in bone marrow of long bone
T - Lymphocytes then leave bone marrow and mature in thymus gland
Second Line of Defence
Non specific cellular and molecular responses to pathogens
Mast Cells
Leucocytes that embed in connective tissues
When mast cells detect damage, they release histamines, invoking inflammatory response
Inflammatory Response
- Vasodilation
- Increased Permeability of blood cells
- Attraction of Phagocytes
Phagocytes
Leucocytes that engulf non-self cells by endocytosis
digesting them using lysosomes
Types of Phagocytes
- Neutrophils - most common Phagocyte
- Monocytes - largest Phagocyte
- Macrophages
- Dendritic Cells
Large Granular Lymphocytes
Releases a death ligand; a signalling molecule causing cell to die
eg. Apoptosis
Eosinophils
- Granulocytes with many vesicles containing chemicals involved in the innate immune response
- Effective against multicellular parasites
- When activated, release cytotoxic cationic granular proteins which are toxic to many tissue
Granulocytes
A type of immune cell that has granules (small particles) with enzymes that are released during infections, allergic reactions, and asthma
Interferons (INFs)
Signalling molecules released from virus infected host cells
- Cause nearby cells to heighten antivirus defence
- Cells stimulated by INFs prouce various enzymes to inhibit protein synthesis
Complement System
Suite of small proteins synthesized by the liver, circulating in the blood in an inactive state
- attract chemoattractants
- opsonise bacteria
- form cell destroying membrane attack complex (MAC)
Second Line of Defence
When first LoD fails, second line is available
- both cellular and chemical responses
- range of respnses that occur regardless of nature of infection
Amoeba
White blood cell - like
Specialise in finding and ingesting bacteria, viruses and dead/injured cells
Macrophages
Engulf bacteria
use cytokines to signal other Phagocutes to attack bacteria
Neutrophils
Respond to cytokines
Use phagocytosis to engulf bacteria
Main producer of pus
Mast Cells
Cause vasodilation - making cells bigger
Monocytes
Largest white blood cells
Become macrophages when leaving blood stream
Dendritic Cells
Produce antigen material and present it on cell surface to other cells in the immune system
Act as messengers between innate and adaptive immune systems
Natural Killer Cells
Lymphocytes that kill virus infected body cells or tumour cells
Release toxic granules into abnormal cells to kill them
Cytotoxic (Cell Killing)
Complement Proteins
Made in liver, circulate bloodstream inactively
When activated:
- Attract Phagocytes
- Mark bacteria for destruction (Phagocytes)
- Form cell destroying Membrane Attack Complex (MAC)
Cytokines
Signalling molecules, coordinate immune response
Induce growth, movement, differentiation, or death of cells
Inflammation
Physical condition
Reddened, swollen, hot painful reaction to injury/infection
Inflammation followed by discharge of pus
Fever
In addition to local inflammation, more extensive infection can trigger fever
symptoms:
- Elevated body temp
- Increased rate of Phagocytosis
- Acceleratees actions of protein defences
Antigen Presenting Cells
Activated T Helper Cells initiate both humoral or cell mediated immune response
Two parts are:
- Cell mediated immunity
- T Cells
Humoral Immunity
Form of adaptive immunity
Antibodies, produced by Plasma Cells, protect host from infection in 3 ways:
- Neutralization
- Opsonization
- Complement Activation
Neutralization
Binding to pathogen to inhibit toxic effects
Opsonization
Coating pathogen and facilitating their uptake and Phagocytes
Complement Activation
activating complement cascade
Humoral Imunity Summary
- Complementary pathogen interacts with B Cell
- T Helper selected with same antigen is activated and secretes cytokines, causing B cell to undergo Clonal Expansion
- Differentiation of selected B Cells occurs resulting in B memory and Plasma Cells
- Plasma cells produce large numbers of antibodies, specific to pathogen to initiate a response
Cell Mediated Immune Response
Antigen presentation to T Helper Cells
- Adaptive immune response initiated by presentation of antigen with MHC II markers, by Antigen Presenter Cells, to T Helper Cells
- Activated T Helper Cells clone themselves
Activation of Cytotoxic T Cells
Cytotoxic T Cells are also stimulated to clone themselves
This is initiated by recieving a cytokine from a T Helper cell
Antibody
Large receptor on surface of B - Lymphocyte
M Memory Cell
Long living clone of B - Lymphocyte
Plasma Cell
Clone of B - Lymphocyte that produces and secretes antibodies
Allergy Reaction
- IgE produced by plasma cells
- IgE stick in Mast Cells around the body in connective tissue
- IgE makes Mast Cells sensitive to larger parasites such as worms or amoeba
- If a person has too many IgE. Mast Cells can be stimulated to release histamines as a reaction to something otherwise harmless
Lymphatic System as a transport network
- Plasma leaks out of capillaries into intercellular space, forming tissue fluid which bathes cells
- Lymphatic system is a network of blind-ended vessels that collect tissue fluid and drain it back into the circulatory system
- Lympth flows through lymph vessels, as a result of muscle movement, preventing lymph from flowing backwards
Plasma
‘watery’ component of blood
Tissue fluid
Fluid between cells, supplies oxygen and nutrients to cells
Primary Lymphoid Tissue
- Those in which lymphocytes form and mature
- includes bone marrow and thymus gland
Secondary Lymphoid Tissue
Act as fil;ter for lymph flowing back toward the heart
In lymph nodes, lymphocytes are highly concentrated
- Lymph Nodes, Tonsils, Spleen, Peyer’s patches in small intestine and mucosal surfaces such as lining of nose lymph nodes.
Tonsils
Have specialised antigen capture cells called Microfold cells (M Cells)
M Cells take up antigens and present them to B-Lymphocytes, Macrophages and Dendritic Cells
Antigen Presenting Cells
- Macrophages - 2nd LoD
- Dendritic Cells - 2nd LoD
- B Cells - 3rd LoD
Artificial Immunity
Artificial is acquired from medical technology to purposely give immunity
Natural Immunity
Results from unintentional exposure to antigen by interaction with other biological entities
Active Immunity
When a persons own immune system produces their antibodies
Passive Immunity
When someone has antibodies produced by someone else’s immune system
Natural Passive Immunity Example
Breastfeeding, Placenta
Artificial Passive Immunity Example
Injection of Antibodies
Natural Active Immunity Example
Resistance to Common Cold
Artificial Active Immunity Example
Vaccination
Inactivated Vaccine
Whole Pathogen Vaccine
Contains whole bacteria or virus which has been killed so it CANNOT reproduce
Live attenuated Vaccine
Whole Pathogen Vaccine
Contains whole bacteria or virus weakened through genetic modification or other means
- Can reproduce (unless virus)
Recombinant Protein Vaccine
Subunit Vaccine
Vaccine made by genetically modifying harmless yeast or bacteria to produce a surface protein of the bacteria
Toxoid Vaccine
Subunit Vaccine
Some bacteria cause disease by releasing toxins.
A toxoid is an inactivated version of a toxin
Virus Like Particles (VLPs)
Subunit Vaccine
Molecules that closely resemble viruses but are non-infectious because they contain no genetic material
Outer Membrane Vesicles
Subunit Vaccine
Naturally produced by bacteria, essentially a bleb or bacterial outer cell membrane
RNA Vaccine
Nucleic Acid Vaccine
Use RNA in a lipid membrane.
The RNA, once inside a cell, enters the ribosome, where it is ranslated to make the protein
DNA Vaccine
Nucleic Acid Vaccine
Currently No DNA vaccines Licensed for use
Viral Vector Vaccines
Nucleic Acid Vaccines
Contain a recombinant harmless virus that retains the ability to reproduce, but contains the genetic instructions to mkae antigens from a different virus
Inoculation
Deliberately introducing foreign antigens into the body
Whole Pathogen Vaccine
Vaccine containing a whole weakened or killed vaccine
Subunit Vaccine
Contain one or more antigens from a pathogen
Nucleic Acid Vaccine
Dont supply protein antigen into the immune system
Instead they provide genetic instructions for making the antigen
DNA/RNA is taken up by vells through Phagocytosis, then the host cell uses nucleic acid to produce protein antigens
Primary Immune Response
Much faster, it is the antibody response, following first exposure to an antigen
Secondary Immune Response
More immediate, it is the antibody response following a subsequent exposure to an antigen
Herd Immunity
Resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals
B Cells
Found concentrated in the spleen, tonsils and lymph nodes
Once activated, B Cells differentiate to become PLasma cells which produce antibodies and B Memory Cells
Attack outside the cell
Clonal Selection
Only cell with specific receptor that binds to antigen present will be selected to produce clones
Clonal Expansion
Rapid cloning following clonal selection
Triggered by helper T Cells
Differentiation
Cells produced by clonal expansion then differentiate into different roles of plasma cells
Imobilization
Antibodies can restrict movement of Pathogens around the body through formation of large antigen antibody complexes
Agglutination
Antibodies can bind together with antigens on 2 seperate pathogens
Makes it easier for Phagocytes to recognise pathogens and destroy them
ICONA
Imoblization
Complement Activation
Opsonization (MAC)
Neutralization
Agglutination
T Cells
- White blood cells derived stem cells in bone marrow, which travel through blood to organ called the THYMUS to mature
- T Cells Multiply and Differentiate in Thymus
- Sent to peripheral tissues or to circulate in the blood or lymphatic system
Attack inside the cell
Cell Mediated Immunity
- Antigen Presenting Cells concurrenlty initiate selection of T Helper and Naive T Cells
- Naive T Cells stimulated by cytokines (from Th) and undergo clonal expansion and differentiation
- Clones differentiate into either Tc or Tm
- Upon contact with infected cell, T Cell binds to antigen MHC I complex
- This induces secretion of cytotoxic chemicals to induce Apoptosis
T Cell Receptor
T Cells can be distinguished from other lymphocytes by presence of T Cell Receptor on surface
Cytotoxic T Cell Activation
- Naive blood cells circulate in blood
- When a cell becomes infected, it will present antigens on it’s MHC I Markers to indicate this
- Cytotoxic T Cells specific for this particular antigen will bind to Antigen MHC I complex and become activated
- Helper T Cells aid in activation of cytotoxic T Cells
- Activated Cytotoxic T Cells will begin dividing and differentiating into effector cytotoxic T Cells and Memory Cytotoxic T Cells
Naive Cells
Cells not yet activated
