Immunology Flashcards
PAMPS
Pathogen Associated Molecular Pattern Molecules - recognised by innate immune system
Neutrophil
The most abundant immune cell circulating the blood - attracted to area by a signal from infected tissue. Engulfs and destroys pathogens (phagocyte)
Macrophage
“Big Eaters” - Can migrate or reside permanently in organs and tissues - phagocytose pathogens
Dendritic cells
Populate tissues that contact the environment (skin) and stimulate adaptive immunity
Traditional Role of Immune system
mechanism to protect us from infectious diseases through recognition and elimination
Innate Barrier defenses
Solid barrier first step in preventing invasion - easy and cost effective
Mucous Membranes
Line nose, respiratory tract, reproductive tract - cannot just have a wall as we need to have transport (for nutrients and gasses)
Where are cilia and how do they assist in innate barrier defences
Line mucus membranes and beat in one direction to keep things moving and prevent colonisation.
Skin as a barrier
Covered by dead skin cells (Keratinocytes) that form waxy impenetrable layer, and a low pH - making it inhospitable.
Mucus
Thick goopy, can bind up pathogens which can be coughed up or swallowed AND creates distance between microbes and the skin layer
Lysozyme
Enzyme that digests peptidoglycan in cell walls, therefore killing cell walls and preventing infection
Where is lysozyme found
Mothers milk, tears, saliva
How does the stomach prevent infection
low pH (1.0) therefore killing many pathogens
How is the barrier defence breached
- Cut, problems with tight junctions, change in pH or temperature, loss of normal flora
Immune cells must (5 things)
- Sense Danger
- React
- Move
- Self renew
- Be everywhere
Approach to immunity that all animals shares (4)
- Barriers to prevent infection
- Barriers that also enable limited passage
- Hostile measures to eliminate the enemy
- Layered immune system
Immune system at PEACE
Low cost, easy to maintain BUT able to react quickly
Immune System at War
High energy demand, expensive to maintain, potential for damage BUT essential for survival.
5 signs of inflammation
- redness
- heat
- swelling
- pain
- loss of function
What mediates physiological changes of inflammation
Most are cause by change in blood flow - vasodilation of blood cells = hottness and redness. Blood vessels become more permeable, so fluid can leak into surrounding tissue = swelling.
Benefit of pain/loss of function
Recognise we are at war so do not use/touch injured site
How is the immune system designed to fulfil its function
- Composed of cells that move around, react to specific things, lie dormant in peace, in war they expand and take over and are very expensive
What does immunity mean in regards to an infectious disease?
Recognition of danger and WHAT TYPE of danger - different receptors drive different types of response. Virus vs bacteria vs lungs vs skin
What is the cost of immunity
Expensive - cells which change their metabolism and react QUICKLY. Reason why we get tired when you’re sick - all energy and resources are devoted to the immune system.
What are the first defences against infection?
Barrier = cheap, effective, inhospitable wall.
How does innate immune system recognise non self
Rely on traits common to groups of pathogens, known as PAMPS
How do innate cells recognise PAMPS
Highly specific receptors - such as toll-like receptors (found in most animals). Each cell has multiple identical receptors, and each cell recognises something unique.
Function of TLR
Recognise PAMPS and activate innate immune cells
what is RAG
Recombination activating Gene
What can RAG do
give the cell that expresses it the ability to rearrange its DNA under certain conditions - allowing innate cells to create unique receptors.