Immune System Flashcards
primary lymphoid organs
thymus
bone marrow
secondary lymphoid organs
lymph nodes
spleen
various lymphoid mucosal tissues
superficial lymph nodes
cervical
axillary
inguinal
deep lymph nodes
tracheal
aortic
innate defences
physical barriers
phagocytes
immune surveillance
interferons
complement
inflammation
fever
immune cell development in red bone marrow
hemocytoblasts: immune stem cells
series of differentiation and migration
formation of mature NK cells and B cells
formation of T cell stem cells
immune cell development in the thymus
stem cells from bone marrow differentiate in response to thymic hormones
forms T cells
which immune cells are granulocytes vs agranulocytes
granulocytes: neutrophils, eosinophils, basophils
agranulocytes: lymphocytes, monocytes
neutrophils
nucleus
granules
proportion of immune cells
lifespan
role
nucleus: 3-5 lobes
granules: faint/light pink
proportion of immune cells: 50-70%
lifespan: 1-4 days
role: kill and phagocytose bacteria
eosinophils
nucleus
granules
proportion of immune cells
lifespan
role
nucleus: bilobed
granules: red/dark pink
proportion of immune cells: 1-4%
lifespan: several months
role: kill parasites and modulate local inflammation
basophils
nucleus
granules
proportion of immune cells
lifespan
role
nucleus: bilobed or S-shaped
granules: dark blue/purple
proportion of immune cells: 1%
lifespan: several months
role: modulate inflammation, histamine during allergy
lymphocytes
nucleus
granules
proportion of immune cells
lifespan
role
nucleus: large and spherical
granules: none
proportion of immune cells: 20-40%
lifespan: hours to many years
role: adaptive immunity
monocytes
nucleus
granules
proportion of immune cells
lifespan
role
nucleus: C (kidney) shaped
granules: none
proportion of immune cells: 2-8%
lifespan: hours to years
role: precursors of macrophages and mononuclear phagocytic cells
roles of IL1-6
IL-1: Fever
IL-2: T-cell stimulator
IL-3: Marrow stimulator
IL-4: IgE stimulator
IL-5: Class switching to IgA
IL-6: Stimulates acute phase protein
Proinflammatory
Potentially drives COVID-19
symptoms
why does the type of infection causing pneumonia change the colour of lung histology
due to different immune cells present
can be used to identify the source of pneumonia by biopsy histology
why do fungi remain in the lung
cells are large and hard to remove
pitting oedema
causes
treatment
palpation leaves imprint, often in extremities
caused by heart failure (causing fluid build up in legs) and impaired kidney function (causing fluid retention)
NOT related to lymphatics
treated with frusemide - diuretic
lymphoedema
causes
primary vs secondary
treatment
non-pitting oedema due to blocking of lymph channels
chronic accumulation of fluid in soft tissues
primary: inherited mutation alters lymphatic development
secondary: result of obstruction or damage
treatment: skincare, exercise, elevation, compression, decongestive therapy, surgery
MHC class I
cells
structure
role
cells: all nucleated cells
structure: alpha subunit and B2 microglobulin
role: present self antigens to NK cells
tumour and virus-infected cells lack MHC I
recognised by CD8 cells
MHC class II
cells
structure
role
cells: macrophages, dendritic cells and B cells
structure: two alpha subunits
role: recognised by CD4 cells leading
leads to clones, CD8 and B cell activation
stroma of the thymus
epithelial cells in crypts - maturation site of T cells
provide physical and chemical environment for T-cell maturation
involution of the thymus
atrophy with age leading to reduction of immunity
starts after puberty
regions of the thymus and their roles
cortex: where lymphocytes originate
medulla: where selective clonal deletion occurs
outer capsule
Di George syndrome
thymic aplasia (incomplete or absent development)
causes susceptibility to viruses and fungi
HIV
primary infection with acute HIV syndrome and wide dissemination of virus
seeding of lymphoid organs
long period of clinical latency with decreasing CD4 count
constitutional symptoms and opportunistic diseases eventually lead to AIDS
causes encephalitis and global atrophy of the brain
lymph nodes role
what cell types are each region
filter lymph and help activate immune cells
site of T and B cell clonal expansion and maturation
lymphocytes in cortex
macrophages in medulla
B cell generation in lymph nodes
subcapsular space
generated from follicles
Spleen capsule
fibrous
has trabeculae that extend inward
white pulp of spleen
role
composed of lymphocytes around central arteries
small branches of splenic artery
where blood borne antigens are presented to immune cells
red pulp of spleen
where worn out RBCs and bloodborne pathogens are destroyed by macrophages
consists of splenic cords and splenic sinusoids
functions of the spleen
production of immune response
removal of particulate matter and aged blood cells
recycling iron to bone marrow
haematopoiesis in the foetus
key structural differences between spleen and lymph nodes
periarteriolar sheath
lymph nodes have no capsule or trabeculae
contents of the red pulp of the spleen and their function
stave cells: remove effete RBCs
cords of Billroth: rich in macrophages and lymphocytes
splenomegaly causes
massive splenomegaly causes
congestion, haematological infection, neoplasm, autoimmune
malaria myelofibrosis, chronic myeloid leukaemia
what is MALT
mucous associated lymphoid tissues
set of lymphoid tissues distributed in the mucous membranes
provide a variety of immune cells that have memory for trapped pathogens
germinal centres with no capsule
tonsils
palatine, lingual, pharyngeal
not capsulated epithelium with invaginations known as crypts
examples of MALTS
tonsils
Adenoids
Peyer’s patches
lymphoid aggregates of intestines
bone marrow cords
framework of vascular sinusoids lined by endothelial cells and intervening spaces
cells in bone marrow
megakaryocytes: next to sinusoids so that platelets can be release
erythroblastic islands: direct RBCs into sinusoids
granulocytes: site away from sinusoids, motile cells then migrate
