Defence Systems 2 - University of Western Australia
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Transcript Defence Systems 2 - University of Western Australia
Immune-Lymphatic System – 2
Lymphatic Organs
ANHB 2212 – 2008
Avinash Bharadwaj
Recognition of Antigens
The Antigen Presenting Cell (APC)
Macrophage
Phagocytosis
Fragmentation of foreign material
Attachment to cell surface molecules (MHC)
Other APCs
Many sites, many types
Example : Langerhans cells in the epidermis.
Lymphocytes
Two major types – T and B lymphocytes
Not distinguished by LM
Two types of immune responses
Cell mediated – direct attack by cells
Humoral – antibodies as the medium
(Humor : fluid. Antibodies are transported by
the blood and also present in certain
secretions)
Cellular and Humoral Immunity
“Cell mediated” immunity.
Cytotoxic T cells – Perforin, Lympotoxin, TNF
Helper T cells
Suppressor T cells
Memory
Humoral immunity
B lymphocytes plasma cells (abundant rER)
Memory B cells
Helper T cells
Exposure and Barriers
External surface – skin
The “open” systems
The epithelial barrier
Digestive and Respiratory systems – most exposed
Urogenital (to a lesser extent)
Integrity of epithelium
Intra-epithelial defence cells
Antibodies
“Local” infections and non-specific defence
Beyond the barrier…
Blood, Tissue Fluid and Lymph
Blood capillaries
“Extravasation” of fluid
Tissue fluid and exchange
Not all the fluid returns to blood vessels.
Lymph flows through lymphatic vessels before
returning to larger veins.
Lymphoid (Lymphatic) Tissues
Scattered lymphocytes and other cells
Lymphatic nodule – structural organisation
Lymphocytes, macrophages, plasma cells, other
leucocytes
Outer zone (corona) and germinal centre
Aggregates of lymphatic nodules
Mucosa of GI Tract, respiratory system and other sites
Larger aggregates – Peyer’s patches (ileum), tonsillar
tissue.
Organised, encapsulated structures
Lymph nodes
Spleen – special functions
Thymus – the academy
Lymphatic Nodule
“Non-capsulated”
Single or aggregated
Independent
OR
parts of other lymphoid
organs
Outer dark zone
(Corona or cap)
Germinal centre
Lymphocyte Training – Thymus
Lymphoid organ
Anterior Mediastinum
Foetal life Childhood Puberty
Involution in adult life
Thymus
Hassal’s
Corpuscles
Capsule
Lobules
Cortex
Medulla
Regions and Cells
Capsule
Cortex
Epithelial
reticular cells
Lymphocytes
Stages of
maturation
Medulla
Blood vessels
Barrier
Lymphocyte
Training
CFU-L
Recognise antigen –
pass/fail
Recognise self/non-self
– pass/fail
Cytotoxic / Helper T
cells
B Lymphocytes
Bursa of Fabricius
Lymphoid organ in birds
Bursa equivalent structures
Bone marrow
Gut and other mucosa-associated
structures
Tonsil
A group of lymphoid
structures
Around the pharynx
(GIT and RS)
Lingual, “palatine”,
tubal,
nasopharyngeal
Structurally similar
Palatine Tonsil
•
•
•
•
Epithelium of the
pharynx
“Crypts”
Lymphatic nodules
Connective tissue and
pharyngeal muscle.
Peyer’s Patches
Ileum – “antimesenteric border”
Lamina propria submucosa
Lymph Node
Capsulated
Afferent lymphatics “subcapsular sinus”
Hilum – blood vessels, efferent lymphatic
Cortex and medulla
Cortex
Lymphatic nodules, germinal centres
“Paracortex”
Medulla
Medullary cords and sinusoids
C
M
Lymph Node
Lymphatics
Afferent
Efferent
Blood vessels
A
A
A
E
Lymphocytes
Cortex
A
Nodules (B)
Deep cortex (T zone)
sinuses)
Medulla (Cords,
Function
Antigens etc
APCs
Nodule : B
High Endothelial Vv
Medulla : Plasma
cells etc
Spleen
Lymphatic function
– lymph nodules
(white pulp)
around arterioles.
Red pulp
Sinusoids
Last Slide