Immunology Flashcards
(28 cards)
What are the three main functions of the lymphatic system?
What are the three main functions of the lymphatic system?
What are the primary lymphatic organs?
Bone marrow and thymus
What happens to lymph as it travels through lymph nodes
It is filtered and encounters immune cells like T and B lymphocytes
What are three features of innate immunity?
Non-specific, rapid response (minutes–hours), no memory
Name two types of cells involved in innate immunity
NK cells and macrophages
How do NK cells kill infected cells?
Release perforin to create pores, then granzymes to induce apoptosis
What do macrophages do during phagocytosis?
Engulf pathogens to form a phagosome
Lysosome creates a phagolysosome Enzymatic digestion and exocytosis
What are examples of chemical barriers in innate immunity?
Acidic pH (skin, stomach), enzymes (saliva, bile), complement proteins.
What are the key features of acquired immunity?
Antigen-specific, slower onset, has memory.
What are the two arms of acquired immunity
Humoral (B cells/antibodies) and cell-mediated (T cells)
What activates B cells in a T cell-dependent manner
Antigen presented on MHC II and cytokines from helper T cells.
How do B cells aid in the immune response
Differentiate to form plasma cells, which secrete antibodies specific to the antigen
What is the function of memory B cells?
Provide long-term immunity by remembering the antigen
What do cytotoxic T cells (CD8+) do?
Kill infected cells using perforin and granzymes.
What do helper T cells (CD4+) do?
Release cytokines to activate B cells and cytotoxic T cells.
What is MHC I and where is it found?
Found on all nucleated cells, interacts with CD8+ T cells.
What is MHC II and where is it found?
Found on antigen-presenting cells, interacts with CD4+ T cells.
How does the immune system respond to an allogeneic transplant?
The immune system recognizes non-self MHC (HLA) antigens on the donor tissue, causing immune rejection.
1. APCs present these antigens to T cells, triggering their activation
2. CD8+ cytotoxic T cells kill donor cells directly.
3. CD4+ helper T cells release cytokines, triggering B cell and macrophage activation.
4. B cells may produce antibodies against donor HLA, leading to complement activation and inflammation.
Why are tissue transplants often rejected?
Because T cells recognize non-self MHC (HLA) antigens as foreign.
What is histocompatibility?
The compatibility between donor and recipient tissues based on HLA similarity.
What is an autograft?
A graft from the same individual
Why is a corneal implant less likely to be rejected?
It lacks blood supply and has reduced immune surveillance.
What is a cross-match test?
A test to detect donor-specific antibodies in recipient serum. Recipient serum added to donor lymphocytes along with complement proteins.
Describe the four phases of wound healing?
- Haemostasis: Vasoconstriction and platelet activation causes a blood clot to form.
- Inflammation: Neutrophil and monocyte migration to the wound site. Differentiation into M1 macrophages which undergo phagocytosis to remove the foreign object.
- Proliferation: Replacing the blood clot with scar tissue involves rapid ECM production and angiogenesis, macrophages to remove debris.
- Remodelling: M2 macrophages, replace scar tissue with organised tissue growth. Involves MMPs and TIMPs to control ECM.
