immune system Flashcards
(47 cards)
The function of the immune system is to…
- prevent infections
- eradicate established infections
- detect and eliminate tumours as well as tolerate self
Congenital (primary) immune deficiencies
e.g. patients who completely lack key cells and molecules of the immune system
Acquired (secondary) immune deficiencies
e.g. HIV infection that leads to the eradication of key immune cells
The immune system is integrated with other systems…
gastrointestinal, cardiovascular, respiratory, nervous, endocrine, skin
Molecules of the immune system can act in a … matter
Autocrine
paracrine, or
endocrine (when secreted)
The cells and molecules of the immune system access most organ systems in the body by travelling via:
blood vessels
lymphatic vessels
Immune cells originate from…
bone marrow stem cells
central sites
often used to refer to lymphoid tissues or lymphoid organs
Primary lymphoid organs:
bone marrow, thymus
Secondary lymphoid organs:
spleen, lymph nodes, mucosal & cutaneous associated lymphoid tissues
Peripheral sites
all other tissues and systems
skin, liver, gut, heart, brain, CNS, muscle, lungs etc
Innate
Neutrophil
Basophil
Eosinophil
Monocyte
Adaptive
Lymphocyte
Hallmarks of the Innate Immune System
Speed - Early, rapid
Duration - short-lived
Repetitive - responds the same way each time a microbe is encountered
Interactive - with other cells of the innate immune system and with cells of the adaptive immune system
Non-reactive to the host
Lymphocytes
express receptors that specifically recognise a wider variety of molecules produced by microbes as well as noninfectious substances
lymphocytes expand and differentiate into…
Effector cells
Memory cells
how does innate immune system tell the difference between self and non-self?
Different Microbes express different “patterns”
Our own cells do not express these microbial patterns
Epithelial, Endothelial and Resident Immune Cells express receptors on their surface that allow them to sense danger
Phagocytes
neutrophils & macrophages
scavengers that ingest microbes
Exocytes
eosinophils, mast cells, basophils
release active mediators from granules
Tissue Resident Mast Cells
- reside in peripheral tissues exposed to the environment
- have receptors on their surface that allow them to sense danger - 1st responders
- perform antibacterial functions
- degranulate the contents of their cytoplasm - granules contain histamine & other soluble factors increases vascular permeability & promotes inflammation
What are Cytokines
Proteins that are produced & secreted by many different cell types
* modulate inflammatory and immune reactions
* are a principal mediator of communication between cells
Cytokines can target cells in an
- autocrine manner (acting on the cell that produced the cytokine)
- paracrine manner (acting on neighbouring cells)
- endocrine manner (acting on distant cells or systemically)
When danger is detected a few things happen:
- Release of histamine & inflammatory cytokines
- Dilated blood vessels allow for more blood flow to the area (redness) and fluid to come in (swelling)
- Induces the expression of adhesion molecules on endothelial cells lining the blood vessels which attracts innate immune cells
Chemokines
- Set up in a gradient: more chemokines closer to source
- Helps neutrophils know where to move