Foundations in Immunology Flashcards
Whats a pathogen?
Any microorganism that causes harm
What are physical barriers to pathogens?
Skin
Reproduction, respiratory and digestive tracks
Describe the innate immune system…
Non-specific
First to come into play
Will produce the same response time and again – no memory
Describe the adaptive immune system…
Highly specific
Involves antibody Production
Has immunological memory
Give an example of an innate response.
Splinter enters foot
Area around splinter gets red and swollen
Macrophages flood area
Where Do Macrophages Come From?
Bone Marrow
Monocytes differentiate into them
How to macrophages work?
Mø give off chemicals that restrict blood flow away from site of injury (redness)
Contraction of endothelial cells (swelling)
Produce Cytokines to alert other cells to the ‘danger’ and induce them to travel to the site of injury
What is the main role of the immune system and what does it employ?
Bodies 1st line of defense
Uses physical barriers - tight junctions between epithelum and mucous membranes
Uses phagocytic cells like macrophages and neutrophils
Uses soluble factors
- Growth and Enzyme inhibitors
- Lysins
- Complement proteins
Describe phagocytosis…
Phagocytosis is triggered when the phagocyte recognises a foreign cell.
It is the internalization of foreign matter by cells into cytoplasmic vesicles. Once inside, the matter is digested by lysosomes, which contain enzymes
This also kills the phagocytic cell that did the ingesting.
What are the 3 activation pathways of the complement system?
Classical
Alternative
Lectin
Briefly describe the complement system.
The complement system consists of about 20 individual proteins which act together in an enzyme cascade to form a membrane attack complex
This makes a hole in the pathogen (bacterium) which disrupts the ability of the pathogen to maintain homeostasis and it dies.
What do all 3 pathways always end up with?
C5 convertase
What two pathways are effector mechanisms of the innate immune system?
Alternative and Lectin
What pathway is an effector mechanism of the adaptive immune system?
Classical
What happens with the C5 convertase?
It cleaves C5, which goes on to comine with C6, C7, C8 and C9 to form a MAC.
C5-8 forms the stalk and C9 forms the pore which causes cell cysis - poking hole in the cell.
What does the complement system achieve?
Opsonisation of invaders
C3a and C5a (bits that were cleaved) act as chemoattractants
Functions of the complement system?
Lysis of microbes
Promotes phagocytosis of microbes
Stimulates inflammation - activating mast cells and neutrophils
Also stimulate activation of B Cells and Ab production
What stops NK cells targeting our own cells?
Our cells have MHC class 1 proteins which signal to it that its our cells
Whats a cytokine?
Chemicals used by cells to communicate with other cells
Function of the lymphatic system?
Drainage of tissue
Absorption and transport of fatty acids
Immunity
Differences between lymphatic and blood vessels?
Lymphatic vessels are blind ended cells
Lymph vessels only carry fluid away from tissues unlike blood
What are the 3 phases of immune defence?
Recognition of danger
Production of specific weapons
Transport of weapons to site of attack
Where are blood cells produced and what type of organs are they?
Bone marrow and thymus
Primary lymphoid organs
What is hematopoiesis?
Formation and activation of blood cells
Function of the thymus?
T-cell education
Function of secondary lymphoid organs?
Site of lymphocyte activation by antigens
What 2 areas is the spleen divided into?
Red and white pulp
Function of spleen?
Filtration of blood
What separates red and white pulp?
Marginal zone
What is a high endothelial venule?
Simple columnar cells line venules,
They are slightly looser than normal venules, which allows fluid and lymphocytes to leak out of the blood vessels.