E-learning 5 immune system Flashcards
what is the most predominant type of granulocyte in the blood
neutrophil
what type of cells are neutrophils
phagocytic cells
what cells are found at the sites of acute inflammation
neutrophils
what type of cell is an eosinophil
granulocyte
what are eosinophils important for
defense against parasitic infections
eosinophils are involved in atopic reactions such as
asthma
what granulocyte is found in relatively low numbers in normal blood
basophil
what do granules contain
histamine, leukotrines, vasoactive mediators and platelet activating factor
what are the major phagocytic cells which play a critical part in innate immunity
macrophage
what cell differentiates into a macrophage upon migration into the tissues
a monocyte
what are the different forms of lymphocytes
B cells
T cells
NK cells
Mast cells
what do B cells differentiate into as part of the specific immune response
antibody secreting plasma cells
where do T cells mature
the thymus
what are the 2 types of T cells
Helper T cells
Cytotoxic T cells
what do helper T cells do
activate other cells such as B cells and macrophages
what do cytotoxic T cells do
kill virus infected cells
Natural killer cells are part of which immune response
innate
they can detect and attack some virus infected cells
mast cells release substances from their granules that affect what?
vascular permeability
what do the granules of mast cells contain
histamine and heparin
all immune cells are produced from which stem cells
haematopoietic
what are primary lymphoid tissues
tissues where lymphocytes develop and mature to a stage where they can recognise antigens
what do primary lymphoid tissues consist of
bone marrow and the thymus
what are the two types of marrow
red and yellow
which marrow is involved in haematopoiesis
red
what is yellow marrow made up of
adipocytes
where does haematopoiesis take place at birth
in all medullary cavities of the bone
what do lymphocytes descend from
a common lymphoid progenitor
where do B cells mature
in the bone marrow
the T cells leave the bone marrow as immature progenitors and travel to the ______ via the blood to complete maturation
thymus
where does the thymus sit
within the thorax, specifically the superior and anterior mediastinum. it is positioned anterior/superficial to the heart and pericardium but posterior to the sternum
why do most developing T cells die in the thymus
as they fail to produce a T cell receptor
Pro T cells travel to the thymus and enter the
cortex
positive selection selects only those T cells capable of recognising
self MHC
cortical epithelial cells present antigens to the T cells on
MHC-I and MHC-II
cells which recognise MHC-I become what?
cytotoxic T cells
cells which recognise MHC-II become what?
helper T cells
surviving T cells advance to what region
medullary region
negative selection eliminates those T cells which
recognise self peptide too much and therefore be dangerous
in the medulla what cells present self antigen on MHC-I and II
dendritic cells
secondary lymphoid tissues are found in sites where mature lymphocytes are exposed to and stimulated by what
antigens
these tissues are
lymph vessel
lymph nodes
spleen
mucosa associated lymphoid tissue (MALT)
what do lymphocytes enter to migrate to the secondary lymphoid tissues
high endothelial venules (HEVs) which express adhesion molecules on their endothelium to which lymphocytes bind
adhesion leads to the lymphocyte squeezing through the endothelium into the lymph node
what do lymph vessels drain tissue fluid from
connective tissue
what do the lymph vessels empty by
the thoracic duct to the left venous angle
what are lymph nodes
highly organised, bean shaped structures at junctions between lymph vessels
where are lymph nodes found
they are aggregated in particular sites around the body such as the neck and groins.
what is the function of lymph nodes
to filter lymph from tissues
antigen is trapped in the lymph node and taken up by
antigen presenting cells and it is then presented to lymphocytes passing through the node
Afferent lymphatics enter the node in the ______, then pass through the _________ and exit via the efferent lymphatic in the _______.
cortex
paracortex
medulla
High Endothelial Venules (HEVs) enter the lymph node in the
paracortex.
where are B cells located in the lymph nodes
in the primary and secondary follicles in the cortex
where are t cells located in the lymph nodes
in the paracortex region
the spleen is associated posteriorly with the
left ribs 9 to 11
what do the spleen do
collects antigen from the blood presenting it to lymphocytes
there are two distinct components of the spleen
- red pulp is a well perfused-tissue responsible for the filtration role of the spleen, removing ageing and damaged RBCs from the circulation
- white pulp has many similarities to a lymph node. it is packed with T cells, B cells and dendritic cells and sifts antigen from the blood instead of the lymph
T cells are located in the
periarteriolar lymphoid sheath
B cells are located beyond the sheath in a
corona around a germinal centre
MALT are found under the epithelium of the following
respiratory tract
gastrointestinal tract
genitourinary tract
gut associated lymphoid tissues (GALT) include
- tonsils and adenoids
- peyers patches
- appendix
there are different types of the tonsil
- palatine tonsils (located at the back of the oral cavity)
- tubal tonsils (these are located in the nasopharynx near the opening to the inner ear internally)
- lingual tonsil (this sits at the base of the tongue)
the adenoids are a type of tonsil which is located high in the
nasopharynx behind the nasal cavity and soft palate
these four different tonsils create a ring around the openings of the nasal and oral cavities. this provides a line of defence against pathogens which may enter into these openings. this is known as
waldeyers ring
peyers patches are located in the mucosa throughout the
small intestine, particularly in the ileum
they collect antigen present in the
GI tract
the appendix is part of the
large intestine
