BIOL 273 - Unit 6.1 +6.2 Flashcards
What are key features of the immune system
- Lymphoid tissues and immune cells
- Chemicals that coordinate and execute function
What are the three major functions of the immune system
- Protecting the body
- Remvoes dead/damaged tissue and cells
- Tries to recognize and remove abnormal cells
Pathologies when the immune system does not perform normally
Incorrect response (autoimmunity)
Overreactive response (allergies)
Lack of response (Immunodeficiency)
What are pathogens and the types of pathogens
disease causing agents
- Bacteria 🧫
- Viruses 🦠
Bacteria 🧫
- Can be intracellular or extracellular
- surrounded by a cell membrane and cell wall
- survive and reproduce outside host
- most can be killed by drugs (antibiotics)
Viruses 🦠
- Intracellular pathogens
- not cells - cannot produce alone
- some have envelope derived from host cell membrane
- cannot be killed by antibiotics (instead antiviral drugs)
- new viral particles can either rupture host cell or bud off from host cell
Immune system organs are called what and why
lymphoid organs because they have lymphocytes (subset of leukocytes)
lymphoid organs are connected by blood vessels and the lymph vessels
Lymph
conduit for immunologically active cells to travel through
Regions of the body outside lymphoid organs
periphery
Primary lymphoid organs
Organs where lymphocytes develop
- Bone marrow - B lymphocytes mature
- Thymus - T lymphocytes mature
Secondary lymphoid organs
Organs where lymphocytes interact and initiate responses
Spleen, lymph nodes, tonsils and Gut Associated Lymphoid tissue (GALT)
Filters blood and lymph for pathogens and pathogen containing lymphocytes
Describe the two structures of the secondary lymphoid organs
Afferent lymph vessel: brings in lymphocytes from periphery (towards secondary lymphatic organ)
Efferent lymph vessel: allows them to keep circulating (exiting secondary lymphatic organ)
What is it called when there is a fibrous connective wall on secondary lymphoid organs
Encapsulated (fibrous wall) ex. Spleen and lymph nodes
Diffuse (no wall) ex. Tonsils and GALT
What are the six main types of leukocytes cells
- Eosinophils
- Basophils (Mast cells)
- Neutrophils
- Monocytes (Macrophages)
- Lymphocytes
- Dendritic cells
What are Granulocytes (leukocytes)
cells that have prominent cytoplasmic granules
Eosinophils, basophils, neutrophils
What are phagocytes (leukocytes)
can engulf and ingest pathogens
Neutrophils, macrophages, dendritic cells
Lysosomal enzymes digest pathogen
What are cytotoxic cells (leukocytes)
(killer T-cells)
kill other cells, even self-cells
Eosinophils and some lymphocytes
ex. Tc lymphocytes, natural killer cells
What are antigen presenting cells (APC’s) (leukocytes)
Display fragments or pathogens on cell surface
Some lymphocytes, dendritic cells and macrophages
Antigens (Ag)
antibody generator - substances that are recognized by an antibody and induces an immune response
Antibodies (ab)
proteins that bind specifically to Ag’s and target pathogens for destruction
Eosinophils (primary role and where is it found)
cytotoxic granulocytes with bright pink staining granules
Role in defence against parasites and function in allergic response (degranulate)
Found in digestive tract lungs, genital tract, and skin
How do eosinophils respond to antigens and during allergic responses
respond by binding to an antibody-coated parasite and degranulate - spew granule contents
Granule contents ; damage and kill parasites - cytotoxic
Also degranulate in allergic responses
basophils
granulocytes involved in allergic responses
have large dark blue staining granules (granulocyte)
Basophils in blood (rare in numbers), mast cells in tissue - found in digestive tract, lungs and skin
Granules contain histamine. heparin, cytokines
How do basophils respond to allergic responses
degranulate
Neutrophils
granulocytes that are phagocytic
Most abundant
leaves circulatory system to attack pathogens in tissues
Granules contain cytokines that cause fever and start other inflammatory responses
Monocytes
precurser cells of tissue macrophages
move into tissues to become macrophages
function as scavengers and phagocytose bacteria
Have a role in adaptive immune response - phagocytosed pathogens are digested, and fragments are placed on the cell surface (APCs)
Lymphocytes
key player in adaptive immune response
dont last long in circulation and mostly found in lymphoid tissues
Dendritic cells
phagocytic antigen presenting cells (APCs) (like macrophages)
have long thin process
found in skin and organs
recognize and engulf pathogens (pathogens are digested and placed on cell surface)
Activated cells than migrate to secondary lymphoid organs to present the antigens to lymphocytes
Describe the steps to the development of red blood
produced in bone marrow
derived from pluripotent haematopoietic stem cells
give rise to uncommitted stem cells
give rise to progenitor cells (that develop in each cell type)
B lymphocytes
produced in the bone marrow
Produces antibodies - which can be found on the cell surface as receptors (which can then interact with antigens)
Why are B lymphocytes called B lymphocytes
leaves the bone marrow to mature in the Bursa of fabricius
T lymphocytes
produced in bone marrow but migrates to the thymus to mature
Use contact dependent signalling via T-cell receptor on T cell membrane via MHC antigen complexes
CANNOT bind to free antigens
Why are T lymphocytes called T lymphocytes
because they mature in the thymus
MHC
Major Histocompatibility complex
- proteins expressed on surface cells that display “self antigens” and “non self antigens” to T cells
Two classes of MHC that interact with T cells and where are they located
Class I - on all nucleated cells
Class II - on APCs
T cell subtype: Cytotoxic T cells / killer T cells
Recognizes Antigen presented on Class I MHC
Kills cell that expresses appropriate antigen
T cell subtype: Helper T cells
Recognize antigen presented on Class II MHC
Promote differentiation of B cels and T cells and can activate macrophages
T cell subtype: Regulatory T cells (Tregs)
recognize antigen presented on Class II MHC
Suppress other immune cells to prevent excessive immune responses
