Lymphatic system Flashcards
How is the lymphatic system closely associated with the cardiovascular system?
Lymphatic system includes a network of vessels that assist in circulating body fluids
Why do lymph enter lymph nodes?
Purifies and remove toxins in lymph so these aren’t present in interstitial fluid when returned back to cardiovascular system
What cations are found in the body fluid?
Na+, K+, Ca2+, Mg2+
What anions are present in the body fluid?
Cl-, HCO3-, HPO4^2-, SO4^2-
Main cation and anion found in ECF?
Na+
Cl-
Main cation and anion in ICF?
K+
HPO4^2-
What makes up ECF?
Plasma
Interstitial fluid
What makes up ICF?
Intracellular fluid
What do lymphatic vessels transport?
Excess interstitial fluid in most tissues and return it to blood system
What are lymphatic capillaries called?
Lacteals
Where are lacteals found?
Lining of small intestine at centre of each villus
What do lacteals in the small intestine do?
Absorb fats
Transport fats to venous circulation
What allows movement of fluid in/out of lacteal capillary
Fenestrations in endothelial cells of lacteal
How is lymph moved?
Smooth muscle action
Valves
Compression due to skeletal muscle contraction
Arterial pulsation
What are special about lymphatic capillaries?
They have valves
Abundance of leukocytes (most abundant to least abundant)
Neutrophils Lymphocytes Monocytes Eosinophils Basophils
What releases pro-inflammatory cytokines?
Macrophages
T helper cells
Components of the innate immune system
Inflammation
interferon
Complement system
Natural Killer cells
What activates acute phase proteins in the innate response?
Cytokines released by macrophages- IL-6
What stimulates natural killer cells?
Type 1 Interferons- IFN alpha and IFN beta
IL-12 released by macrophages
Why is it good that MHC genes are polymorphic?
Able to identify a range of genes
What do lymphocytes originate from?
Progenitor lymphoid stem cell in the bone marrow
During B cell development what are the B cell surface markers called?
Clusters of differentiation (CD)
What are clusters of differentiation (CD)?
Most= proteins
Include cell surface receptors, cell signalling and adhesion molecules
range from CD1-371
Useful in identifyting types of leukocytes
CD number tells us what stage of maturation B/T cell is at
Where are CD3 found on?
T cells
Where are CD19 found on?
B cells
How do CDs show us stage of development of B/T cells
CD1 found on thymocytes(immune cell in thymus before It becomes a T cell) but not on mature T cells
Where are CD22 found on?
Mature B cells
What happens when B cell binds to antigen?
B cell engulfs and phagocytoses pathogen (process of phagocytosis) Pathogen is chooped up by phagolysosomes Antigens are loaded onto MHC II in the phagolysosome Activates CD4+ T helper cells
WHere is CD10 found?
Germinal centre of lymph node
CD38
plasma cells
CD4
T helper cells
CD8
Cytotoxic T cells
CD16, CD56
Natural killer cells
Antigen route in lymph node
APC and antigen enter lymph node through afferent vessel
Dendritic cell in paracrotex processes antigen in paracortex
Dendritic cell APC activate antigen specific T helper cells
T helper cell activates B cells
B cells proliferate
T and B cells migrate to primary follicle in cortex and interact with follicular dendritic cells
In secondary follicle- germinal centre= b cell proliferates and produces antibody making plasma cells
What does the white pulp of the spleen consist of?
Primary follicle
Marginal zone
PALS
What is the marginal zone?
Edge of PALS
has B cells and primary follicles
Antigen route in spleen
Antigen enters spleen via splenic artery
Antigen captured by dendritic cell in marginal zone
Dendritic cell APC moves to PALS where T cells are
Dendritic APC cell activates T cell (costimulation=B7,CD28, Cytokines)
Activated T helper cell activates B cell
Activated B and T cells move to primary follicle in marginal zone
Secondary follicle made= germinal centre
What happens in medulla of thymus?
VDJ recombo (somatic recombination) of TCR T cell develops CDs (cell surface markers (CD4+ and CD8+)
What is central immune tolerance?
Key role of thymus (and bone marrow)
In thymus if T cell recognises self antigen= apoptosis of these cells= clonal deletion to prevent automminuty
In thymus cortex T cells with non functional TCR= removed and cells with functional TCR= selected and moved into thymic medulla (become mature naive T (CD4+/CD8+) cells
Order of T cell
Progenitor lymphoid cell to progenitor T cell in bone marrow
In thymus= mature naive CD4+/CD8+ T cell (gain TCR via VDJ and CD cell surface markers)
In lymph node= activated CD4+ T hlper cell (when it meets non-infected phagocyte MHC II)
Activated CD8+ T cytotoxic cell (When meets infected phagocyte MHC I)
