Immunology 1 Flashcards
What does the immune system identify and eliminate?
Microorganisms
Pathogens
Abnormal cancer cells
How does the immune system identify and eliminate harmful substances?
Distinguishing self and non-self molecules
Identifying danger signals
A combination of the two
What must be kept balanced for an optimal immune system?
Protection from pathogens
Rejection of donor tissues
What are the two types of an immune over-reaction and what are they called?
Reaction to self - autoimmunity
Reaction to innocuous substances - allergy
What is the result of an immune under-reaction?
Recurrent infections
What are the two types of immunity?
Innate
Adaptive/acquired
What is innate immunity?
Defence mechanism present from birth and is generally non-specific
What is acquired immunity?
Induced by the presence of foreign material and is usually specific to the substance or pathogen that induced the response
What are examples of innate immunity?
Physical barriers
Some soluble factors
Some immune cells
What are examples of acquired immunity?
Some soluble factors
Some immune cells
What are examples of soluble factors that are part of innate immunity?
Cytokines
Acute phase proteins
Inflammatory mediators
Compliment proteins
What are examples of soluble factors that are part of acquired immunity?
Cytokines
Antibodies
What are examples of immune cells that are part of innate immunity?
Macrophages
Mast cells
NK cells
Neutrophils
What are examples of immune cells that are part of acquired immunity?
B and T cells
What are pathogens’ points of entry to the body?
Digestive system
Respiratory system
Urogenital system
Skin damage
What are pathogens’ routes of attack in the body?
Circulatory system
Lymphatic system
What factors of skin make it a barrier to infection?
Physical barrier
Physiological factors
Sebaceous glands
What makes the skin an effective physical barrier?
Constantly undergoing renewal and replacement
Composed of tightly packed, highly keratinised, multilayered cells
What physiological factors of skin protect against infection?
Low pH of 5.5
Low oxygen tension
What do sebaceous glands of the skin produce that protect against infection?
Secrete hydrophobic oils
Lysozyme
Ammonia
Antimicrobial proteins
In what way does secreted mucus protect against infection?
Mucus lines all body cavities that come into contact with the environment and traps bacteria which are removed by cilia
What methods of eliminating pathogens does the body have?
Coughing
Sneezing
Urination
Diarrhoea
What areas of the body have a pH that is unfavourable to pathogens?
Stomach acid
Sweat
Saliva
Urine
Where are lysozyme enzymes found and what do they do to protect against pathogens?
Tears, sweat
Digest bacterial cell walls
What is the response time in innate immunity and acquired immunity?
Innate - rapid (mins - hrs)
Acquired - slow (days)
What do macrophages do?
Phagocytosis Bacterial killing mechanisms Antigen prevention Wound healing/tissue repair Self and non-self recognition
What do mast cells do?
Pro-inflammatory
Parasitic killing mechanisms
Self and non-self recognition
What are examples of tissue-resident innate immune cells
Macrophage
Mast cell
What are examples of phagocytic cells?
Macrophages
Dendritic cells
What are the modes of ingestion used by macrophages?
Pinocytosis
Receptor-mediated endocytosis
Phagocytosis
What is pinocytosis?
Ingestion of fluid surrounding cells
What is receptor-mediated endocytosis?
Receptor proteins on the cell surface are used to capture a specific target molecule
What is phagocytosis?
Intact particles are internalised whole
What are modes of ingestion used by phagocytes facilitated by?
Opsonisation
What is the process of phagocytosis? (7)
Macrophages express a set of PRRs
Receptor binding to PAMPs signals the formation of a phagocytic cup
The cup extends around the target and pinches off, forming a phagosome
This fuses with lysosomes to form a phagolysosome where the killing of pathogens and degradation of contents occurs
Debris is released into the extracellular fluid
Pathogen-derived peptides are expressed on special cell surface receptors
Pro-inflammatory mediators are released
What do macrophages engulf in phagocytosis?
Solid matter, including apoptotic cells and microbial pathogens
What does PRR stand for?
Pattern Recognising Receptor
What does PAMP stand for?
Pathogen Associated Molecular Pattern
What is opsonisation?
The coating of pathogens by soluble factors to enhance phagocytosis
What are examples of opsonins?
C3b
C-reactive protein
IgG/IgM
What two methods do mast cells use to protect against pathogens?
Degranulation
Gene expression
What is degranulation?
Release of pre-formed pro-inflammatory substances by mast cells after binding to a pathogen
What is gene expression?
Production of new pro-inflammatory substances by mast cells after binding to a pathogen
What are examples of pro-inflammatory mediators?
Nitric oxide
Prostaglandins
Histamines
Pro-inflammatory cytokines (TNF alpha)
What are the local physiological signs of acute inflammation?
Vasodilation of small blood vessels
Increased permeability of post-capillary venules
Stimulation of nerve endings
Swelling/pain
What are the symptoms of vasodilation of capillaries?
Redness
Heat
What is the symptom of increased permeability of post-capillary venules?
Swelling
What is the symptom of stimulation of nerve endings?
Pain
What does vasodilation of blood vessels cause?
Increased blood flow
> Cell accumulation
> Increased cell metabolism
What does permeability of post-capillary venules cause?
Fluid accumulates in extravascular space
