Immunology overview Flashcards
Physical and chemical barriers to infection
Skin Mucosa Respiratory tract (with cilia) Gastrointestinal tract Genital tract and urinary system Chemical barriers Hydrochloric acid (stomach) Lysozyme (sweat and tears)
draw out the initial response to pathogen invading tissue
Complement system activation by pathogen
Membrane Attack Complex destroys pathogen
C3b is an opsonin
C5a attracts cells (neutrophils, monocytes and eosinophils)
C3a, C4a and C5a activate mast cell degranulation.
C3a and C5a activate eosinophil degranulation.
Macrophages recognise pathogen and activate the innate immune system
Dendritic cells pick up antigens and head off to activate the specific immune system
innate immune system
Macrophages recognise pathogen and are activated
Start phagocytosis
Release cytokines
Release interferons
Interferons inhibit viral entry and replication within cells
Cytokines recruit help
Monocytes are recruited and become macrophages
More macrophages are activated
Neutrophils are recruited
Cytokines initiate an Inflammatory Response
Vasodilation
Increased vascular permeability
Localised endothelial cell activation
Cytokines activate other systems
Mast-cell degranulation
Clotting system activation
Kinin system
Inflammation leads to an acute phase response, which is where macrophages and neutrophils secrete more cytokines, notably interleukins
IL-1 causes fever, lethargy and anorexia
IL-6 simulates the liver to produce acute phase proteins (opsonins)
IL-8 recruits and activates neutrophils
IL-2 and IL-12 activate natural killer cells
Tumour necrosis factor alpha (TNF-α) also does all of the above
Natural Killer Cells are recruited to the tissues
Kill virally infected cells (and tumour cells)
Produce interferon-gamma (IFN-γ) that further stimulates macrophages
specific immune system
Dendritic cells present antigens to CD4 cells
CD4 cells become T helper cells
T helper cells
Activate CD8 cells to become cytotoxic T cells
Activate B cells
Activate macrophages
Cytotoxic T cells help destroy infected cells via
Cytokines
Activating Fas molecule
B cells when activated either:
Differentiate and multiply into plasma cells
Secrete antibodies
Become memory B cells
Wait to be activated during a subsequent infection
prefix/suffixes in immunology
Baso: foundation Blasts: immature cells Cyte: cell Eosin: red coloured Haemo: blood Karyo: nucleus Kine: motion Lympho: lymphatic system Lysis: broken down Macro: large Mega: large Mono: single Myelo: bone marrow Neutro: neutral Phage: eat Phil: attraction Pluri: multiple Poietic: creative Potent: potential Pro: moving forward Reticulo: net like
pluripotent haematopoietic stem cells
undifferentiated cells that have the potential to become a variety of blood cells:
myeloid stem cells
lymphoid stem cells
dendritic cells
myeloid cells
- Megakaryocytes = platelets
- Reticulocytes = Red Blood Cells (RBCs)
- Promyelocytes=
Monocytes – Macrophages
Neutrophils
Eosinophils
Mast Cells
Basophils
lymphoid cells
travel to the thymus gland and differentiate into
- B lymphocytes (B cells) which mature in the bone marrow and differentiate into
a) plasma cells
b) memory b cells - t lymphocytes (mature int eh thymus) and differentiate into
a) cd4 cells (t helper)
b) cd8 cells (cytotoxic cells)
c) natural killer cells
megakaryocytes
Large cells
Big lobulated nucleus
Produce platelets
Platelets are essential for blood clotting
reticulocytes
Immature red blood cells
Remnant RNA material called reticulum in cytoplasm
Released from bone marrow
Normally 1% of red blood cells are reticulocytes
Higher percentage indicates rapid turnover of blood, such as in:
Acute blood loss
Haemolysis
Loose their reticulum after a few days – becoming RBC
what is bone marrow?
found inside long bones
the shaft of long bones have three layers- periosteum, compact bone and inner medullary cavity lined by endosteum and contains bone marrow
bone marrow is the ORIGIN of ALL immune cells. most cells also develop here (e.g. b lymphocytes)
what is the thymus?
this is an organ with two lobes which is located behind the sternum within the mediastinum
the lymphocytes develop into T cells
outer area is called the cortex, which is where T cells proliferate and start to develop into specialised cells
inner area is called the medulla, which is where the mature T cells are found before they enter the blood, and it also contains the waste products of defective T cells
lymphatic system
network of lymphatic vessels similar to blood vessels. no pump (e.g. heart) so circulation relieso n muscles and there are valves to direct flow
drains into circulation via:
1) thoracic duct
2) right lymphatic duct
what is lymph?
This is interstitial fluid that have drained from the intersitial space
High concentration of lymphocytes and dendritic cells
Low protein content
No red blood cells or other leukocytes
lymph nodes
- structures which occur intermittently along the course of lymphatic vessels
- shaped like a kidney
- surrounded by a capsule
- have their own blood supply
afferent (away into lymph nodes)
efferent (exist- lymph nodes)
roles:
hold cells of the immune systems (lymphocytes)
filter pathogens and abnormal cells
