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