7 immune system Flashcards
🧼 What are neutrophils and what do they do?
🧼 Neutrophils are the most common granulocytes. They’re phagocytic and key players in the 🛡️ innate immune response.
Found at sites of 🔥 acute inflammation.
🪱 What are eosinophils best known for?
Eosinophils fight parasitic infections 🦠 and are involved in allergic reactions like 🌬️ asthma. Their granules stain with eosin and contain basic proteins.
🧪 What do basophils do and what’s in their granules?
Basophils are rare granulocytes. They contain histamine, leukotrienes, and 🩸 vasoactive mediators. Their granules stain with basic dyes (they have acidic proteins).
🗑️ What role do macrophages play in the immune system?
🗑️Macrophages are major phagocytic cells, part of innate immunity, and found in all body tissues. They originate from blood monocytes 🩸 that migrate into tissues.
🔄 What happens to B-cells when activated?
B-cells become 🧪 plasma cells that secrete antibodies. They are part of the 🎯 specific immune response.
⚔️ What are the two main types of T-cells and what do they do?
Cytotoxic T-cells: Kill virus-infected cells ☠️
Helper T-cells: Activate B-cells & macrophages 💬
🕵️ What do Natural Killer (NK) cells do?
NK cells are large granular lymphocytes that kill virus-infected cells ⚡ despite lacking antigen-specific receptors. Part of the innate response.
🎈 What are mast cells and their role?
🎈Mast cells are found near blood vessels and release histamine & heparin upon activation. 🧪 They’re key in allergy and mucosal defence 🛡️.
🧬 Where do immune cells originate and mature?
All immune cells come from haematopoietic stem cells in the 🦴 bone marrow. B-cells mature there, while T-cells go to the thymus.
🧠 What are the two primary lymphoid organs?
Bone marrow 🦴 and thymus 💗 (also called central lymphoid organs).
🧪 What happens in the thymus?
T-cells mature and undergo ✅ positive and ❌ negative selection. Only ~5% survive and enter the bloodstream 💉.
⚖️ What is the purpose of MHC molecules in the thymus?
MHC-I and MHC-II present antigens. T-cells must recognise these to survive. Those that react to self antigens are eliminated 🚫.
🧭 What are secondary lymphoid tissues?
Places where mature lymphocytes encounter antigen:
Lymph nodes 🫘
Spleen 🩸
MALT (e.g. tonsils, Peyer’s patches, appendix) 🧻
🌊 What is lymph?
Fluid drained from tissues by lymph vessels, containing cells and antigens. It enters nodes via afferent vessels and exits via efferent ones 🚰.
🧬 What’s the structure of a lymph node?
Cortex: B-cell follicles 🎯
Paracortex: T-cells 🧠
Medulla: Exit point
Entry via HEVs 🚪
💉 What does the spleen do?
Filters blood 🩸, removes old red cells 🔴, and presents blood-borne antigen to lymphocytes.
🔴Red pulp: RBC removal
⚪️White pulp: Like a lymph node (PALS = T-cells, corona = B-cells)
🧻Where is MALT found?
🧻Beneath epithelium in the respiratory, gastrointestinal, and genitourinary tracts.
🍽️ What is GALT and what does it include?
GALT = Gut-Associated Lymphoid Tissue.
Includes:
Tonsils & adenoids 👅
Peyer’s patches 📍
Appendix 🌀
😷 Why do tonsils swell during infection?
Activated immune cells divide rapidly 📈 when they detect antigen in lymphatics, causing swelling.
📍 What are Peyer’s patches and where are they found?
Specialised lymphoid tissue in the ileum. They sample antigens from the gut and contain B- and T-cell zones under M-cells 🧫.
🌀 What is the immune function of the appendix?
Like the tonsils, it contains crypts and lymphoid follicles. It can present antigens and initiate immune responses.
🦴What is the primary function of the bone marrow in the immune system?
🦴The bone marrow 🦴 produces all immune cells (including red blood cells and platelets) 🩸 from haematopoietic stem cells. It is the site of haematopoiesis, especially in the axial skeleton as you age 👵.
🫁How does the thymus contribute to T-cell maturation?
🫁The thymus 🫁 plays a critical role in T-cell maturation and selection, ensuring T-cells can recognize foreign antigens 🦠 while avoiding self-antigens 🧬. It shrinks after puberty but remains important for immune function 💪.
What is the role of MHC molecules in the thymus?
MHC molecules 🧬 present antigens to developing T-cells 👾 in the thymus. T-cells that can recognize MHC and foreign peptides survive ✅, while those that react to self-antigens undergo apoptosis (cell death) 💀.
How do lymphocytes migrate to secondary lymphoid tissues?
Lymphocytes 🦠 migrate through High Endothelial Venules (HEVs) 🚪 into secondary lymphoid tissues, like lymph nodes 🏥. This migration is highly specific 🔍 and involves adhesion molecules on the HEVs.
What is the function of lymph nodes in the immune system?
Lymph nodes 🏥 filter lymph 🧴, trapping antigens 🦠 and presenting them to lymphocytes 🧑⚕️. This process helps activate the immune response 💥 by exposing lymphocytes to pathogens 🦠.
