Lymphatic system Flashcards
Does the immune system consist of organs or tissues? what does it consist of?
Does not contain organs or tissues - consists of cells and proteins located in blood and tissue of systems
What is the lymphatic system composed of?
Groups of organs and tissues
-lymphatic vessels- blind ended tubes
-lymphatic tissues and organs - clusters of lymphoid follicles
-carries excess fluids to bloodstream and filters pathogens from blood
What is lymph and what is accumulation of this called?
-Interstitial fluid once it has entered the lymphatic system
-lymhedema
What are lymphatic capillaries in the GI system called and what do they do?
Lacteals - transport dietary lipids and lipid-soluble vitanmins to bloodstream
What does the thoracic duct begin as?
Cisterna chyli
Where do immune cells arise from?
Hemopoietic stem cells in the bone marrow
What are B cells?
The express B cell receptors that bind antigens on pathogens
-differentiate into plasma cells that secrete antibodies
What are T cells?
Do not secrete antibodies
-Secrete soluble factors that communicate w other cells or destroy cells infected w pathogens
What are Natural Killer cells?
Contains cytotoxic granules in cytoplasm
-defence against viruses and cancer
Examples of primary lymphoid organs?
Bone marrow - B cells mature here
Thymus gland - T cells leave bone marrow and mature here
Examples of secondary lymphoid organs?
-Lymph node, spleen, mucosa-associated lymphoid tissue - MALT
–sites were lymphocytes mount an immune response
Structure of thymus gland
2 lobes - connective tissue sepaeates lobes and forms a capsule
-Each lobe has outer cortex (immature T cells) and inner medulla
Structure of lymph nodes
-Small, bean shaped
-External CT capsule
-Cortex - lymphoid follicles divides by inwards extensions of capsule (TRABECULAE)
-Inner medulla
How are pathogens eliminated from lymph nodes?
Via leukocytes and dendritic cells
What are germinal centers?
Dividing B cells surrounded by T cells
Purpose of MALT
Mucosa-Associated Lymphatic Tissue
-Protect mucous membranes exposed to large no of pathogens
-Oral and nasal cavities, git, respiratory passages,
What are Peyers patches
Aggregated lymphoid nodules - ileum - in small intestine
What are the 3 main tonsils and what are the indents in the epithelium?
-Pharyngeal (adenoids)
-Palatine
-Lingual
Indents - tonsillar crypts (traps bacteria and debris)
What do M cells do?
Specialised endothelial cells
-Sample material from intestinal lumen, transport to follicles, mount adaptive immune response
Examples of non specific immune systemß
- Physical barriers
- Phagocytes
- Natural Killer cells
- Interferons
- Complement
- Inflammation
What do NK cells do?
Recognise and destroy abnormal cells
-Induce apoptosis in cells infected w intracellular bacteria and viruses
What are interferons and what do they do?
-Chemicals released by lymphocytes, macrophages and viral infected cells
-Cells infecxted w viruses secrete interferons - travel to adjacent cell - induce them to make antiviral proteins
-Defend against viral infection
What is complement?
-Binds to pathogen memnbrane, activates it, labelling for phagocytosis
-Acts as chemotactic agents to attract phagocytic cells to inflammation
-Form damaging pores in plasma membrane of pathogen
What do mast cells release when tissue is damaged and what does this do?
Release histamine - increased blood flow, dilation of vessels, increased vessel permeability
What is the specific immune response divided into?
Antibody mediated
Cell mediated
What happens in antigen mediated immunity?
-Binding of antigen to a B cell induces the cell to differentiate into plasma cells and memory cells
-Plasma cell produvces antibodies - help eliminate invading pathogens
-Memory cells deal w subsequent exposure to same antigen
How does an antigen presenting cell present an antigen? What are the types of this?
Via its major histocompatability complex
-MHC I - Intracellular antigens (virus replicated inside cell)
-MHC II - Extracellular antigens (bacteria from outside cell)
What happens in cell mediated immunity?
-Antigen presented to mature T cell by APC -T cell processes this antigen w MHC molecule
-Express CD4 or CD8 marker - cell adhesion molecules- keep T cell in close contact w APC
-CD4 - bearing T cells - helper T cells
-CD8- bearing T cells - Cytotoxic T cells
-rapid division
-Cytotoxic T cells induce apoptosis of infected cells
