Immune System Flashcards
What is the immune system?
A personal army of cells that protects the body from threats like germs, injuries, and foreign particles.
What are the two main parts of the immune system?
Innate immunity and adaptive immunity.
What is innate immunity?
The body’s first natural, non-specific defense that prevents or kills intruders without differentiating between pathogens.
What are examples of physical barriers in innate immunity?
Skin and mucous linings of organs.
What are examples of chemical barriers in innate immunity?
Lysozyme in eyes and stomach acid.
What is the role of inflammation in immunity?
It brings leukocytes to infection sites using histamine signals released by mast cells.
What causes allergic reactions?
Immune responses to harmless substances like dust.
What are leukocytes?
White blood cells that act as soldiers of the immune system.
What are neutrophils?
Most abundant phagocytes that patrol the body and die after killing pathogens, forming pus.
What are macrophages?
Large cells that engulf up to 100 pathogens and detect rogue cells like cancer.
What are Natural Killer Cells (NKCs)?
Cells that detect abnormal cells lacking MHC and destroy them.
Where are dendritic cells found?
In areas exposed to the environment like the nose and lungs.
What do dendritic cells do?
They link innate and adaptive immunity by carrying antigens to T-cells.
What are antigens?
Molecules on pathogens that can be recognized by the adaptive immune system.
What are the main components of the adaptive immune system?
T lymphocytes and B lymphocytes.
What is the function of T-cells?
They mediate cell-based immunity and act when infection is present.
What is the function of B-cells?
They produce antibodies in the humoral response before disease occurs.
What do helper T-cells do?
They activate other immune cells and form memory T-cells.
What do cytotoxic T-cells do?
They kill heavily infected or damaged cells.
What do B-cells produce?
Antibodies that tag pathogens for destruction by macrophages.
What are memory cells?
T- and B-cells that store information about past infections for faster future response.
How is innate immunity different from adaptive immunity?
Innate is fast and non-specific; adaptive is slower but specific and creates memory.
What threats does the immune system protect us from?
Mechanical injuries, germs (bacteria, viruses), and foreign particles like dust.
Why don’t we fall sick every day despite encountering pathogens?
Because our immune system is constantly working to destroy harmful invaders.
