6.2 Flashcards
Why is immune system organs called lymphoid organs and how is the lymphoid organs connected
they are called lymphoid organs because lymphocytes are found there
lymphoid organs are connected by blood vessels and the lymph vessels
what is lymph
clear fluid
essenntuially extracellular fluid that has left capillaries and filter through tissue
lymph is conduit for immunologicallly active cells to travel through
whare are lymphe nodes located
at strategic positions , knee, grouin , elbow, shourder and neck
what are the regions of the body ourside lymphoid organs
perifery
what er the two types of lymphoid organs
primary and seccondary
primary lymphoid organs
wha originate and mature here
organs where lymphocytes develop
- bone marrow - all blood cells originate here
b lymmphocytes mature here
thymus - T lymphocites (cells) mature here)
what is secondary lymphoid organs
organs where lymphocytes interact and initiate responses
filter blood and lymph - for pathogens and pathogen containing lymphocytes
what does the structure of secondary lymphoid organs reflect
thier function
what does afferent lymph vessel bring
bring in lymphocytes from periphery
what does efferent lymph vessels do
allows them to keep circulating
what does the pulp inside the lymph node do
allows mixing od lymphocytes and other leukocytes
what do arterues and veins do
supply nutrients and O2, plus non-lymphocytic leukocytes
what are spleen and lymph nodes surrounded by fibrous wall
encapsulated
what are tonsils and GALT
secondary lymphoid organstonsils and GALT are unencapsulated tissues - diffuse
what is the main player in the immune system and talk size and where and how it could be
leukocytes
Larger in size than RBC and less numerous
able to leave the blood stream and function extravascularly (in the tissue)
life span of leukocytes
variuos lifespans
6 main types of leukocytes cells
- esinophils
- Basophils (mast cells)
- nuetrophils
- monocytes (macrophages)
- Lymphocytes
- dendritic cells
in what ways can leukocytes be subdevided by function and or morphology
- granulocytes
- phagocytes
- cytotoxic cells
- antigen precenting cells
granulocytes
- have prominent cytoplasmic granues
- eosinophils, basophils and nuetrophils
phagocytes
- can engulf and ingest pathogens
- neutrophils, macrophagesm dentritic cells
cytotoxic cells
- kill other cells, even self-cells
- eosinophils and some lymphocytes
antigen precenting cells
- display fragments of pathogens on cell surface
- some lymphocytes, dendritic cells and macrophages
antigen
substances tahat are recognized by an antibody and induces an immune respoce
what are anitibodys
proteins that bind specifically to Ag’s and targe pathogens for destruction
structure and function of esinophils
cytotoxic granulocytes with bright pink staining granules
role in defence against parasites and function in allergic response
where are esinophils found and how ling they live
few in perifery circulation, only live for 6-12 hours
- found in digestive tract, lungs, genital ract, and skin
how does eosinophils respond
by binding to an antibody-coated parasite and degranulate - spew granule contents
granule contets damage and kill parasites - cytotoxic
what happes to eosinophils in allergic responses
they degranulate
basophil looks and function
granulocytes involved in allergic responses
have large dark blue staining granules (granulocyte)
where basophils found
blood (rare in numbers), mast cells in tissue-found in digestive tract, lungs and skin
what do granules in basophils contain
histamine, heparin, cytokines
in allergic responses cells what do basophils do
they degranulate
what is granulocytes that are phagocytic and most abundant leukocyte
nuetrophils
how long can nuetrophils live and how many manny bacteria can in injest
1-2 days
5-20 bacteria
what does nuetrophils do and how it do
can leave circulotory system to attack pathogens in tissues
granules contain cytokines that cause fever and start other inflamotory responses
what are monocytes and what are they precursors of
they are precursor cells of tissue macrophages and are uncommon in blood
how long do monocytes be in blood and what they do after
they in blood for 8 hours and then move into tissues to become macrophages
what are macrophages
large ameoboid cells and function as scavengers by phagocytosing old red blood cells and dead nuetrophils
can phagocytose up to 100 bacteria
what do macrophages have a role in
adaptive immune response - phagocytosed pathogens are digested, and fragments are placed on the cell surface (APCs)
what are lymphocytes
key players in the adaptive immune response
make up 20-30% of all leukocytes
where are lymphocyes found
5% in ciruclation
most are found in lymphoid tissues
10^12 per individual at any given time
what are dendritic cells and structure
phagocytic antigen presenting cells (APCs)
have long thin processes
where are dendritic cells found
skin and other organs
how do dentritic cells function
they recognise and engulf pathogens
pathogens are digested and placed on cell surface
activated cells then migrate to secondary lymphoid organs to present the antigen to lyphocytes
explain haematopoiesis
all blood cells are produced in the bone marrow
derived from pluripotent haematopoietic stem cells
give rise to commited progenitor cells - develop into each cell type
the path takes is guided by cytokines
what are teh two types of lymphocytes
B lymphocytes ( B cells)
T lymphocytes (T cells)
wehre are B lymphocytes produced
bone marrow
what do B lymphocytes do, and where they found
produce antibodies - can be found on the cell surface as receptors or secreted AB’s in the plasma
where T lymphocytes produced and where they mature
produced in the bone marrow and develop in the thymus
What and what T cells bind to
use contact-depending signalling (cell-cell comuniatoion) via T-cell receptors expresed on the T cell membrane - can only bind to MHC-antigen complexes
T-cell recceptor cannot bind to free Ag (anitgens)
what is an MHC
protiens expressed on the surface of cells that display “self-antigens” and “non-self- anitigens” to T cells
what are the two claasses of MHC that interact with T cells and where they found
class I (all nucleated cells)
class II (cytotoxic Tcells)
what are teh subtypes of T cells:
cytotoxic T cells or killer T cells
helper T cells
Regulatory T cells
cytotoxic T cells or killer T cells
- recognizes Ag presented on class I MHC
Kills cell that expresses appropriate Ag
Helper T cells (Th)
recognizes Ag presented on class II MHC
Promote differentiation of B cells and Tc Cells (cytotoxic T cells) and can activate macrophages
regulatory T cells
recognize Ag presented on class II MHC
supress other immune cells to preent excessve immune responses
