Lecture 5- microbes, immunity and disease Flashcards
what causes the symptoms of a febrile infant (fever, lethargy, drowsiness, muscle aches, joint tenderness, back pain, hyperalgesia)
infection is partly causal but the inflammatory response often causes these
external biochemical defense protection
lysozyme in most secretions.
sebaceous gland secretions
commensal organisms in gut and vagina
spermine in semen
biophysical external protection
mucus
cilia lining respiratory tract
acid in stomach
skin
Innate (non specific) internal protection
resistance not improved by repeated infection.
- lysozyme, complement, acute phase proteins, interferon
- phagocytes, natural Killer (NK) cells
Adaptive (specific) internal protection
resistance improved by repeated infection
- antibodies, complement, cytokines
- lymphocytes, monocytes, antigen-presenting cells
Blood phagocytes include…
granulocytes (mostly neutrophils-short lived) and blood monocytes (longer lived).
Bacterial infections especially can also stimulate inflammation and promote phagocytosis by activating a cascade called the… explain this.
Compliment system.
eg. staphylococus Aureus-infected hair follicle.
common cell wall components on tap. aureus bind with first compliment components.
this activates other compliment components.
these causes chemotaxis, opsonisation and increased vascular permeability.
What do neutrophils recognise?
common bacterial cell wall components.
C3b complement component (component mediated opsonisation).
Fc region of antibodies (immune complex mediated opsonisation).
What is opsonisation
process of enhancing phagocytosis by coating the thing to with molecules which the phagocyte is able to bind to with high affinity.
Phagocytes of the Reticuloendothelial System (RES)
strategically placed macrophage like cell all derived from bone marrow stem cells to meet foreign material. eg. alveolar macrophage.
Role of the lymphatic system
fluid from blood leaks into capillaries due to hydrostatic pressure.
acute inflammation enhances fluid movement from blood into tissues.
body needs a mechanism to collect this fluid and return to blood.
fluid is pumped through lymph vessels by muscle activity which squeezes or dilated lymphatic vessels pushing fluid up the tree.
a series of one way leaf valves inside these vesels direct the flow in one direction.
Function of lymph nodes
they are called secondary lymphoid organs. serve as organs that filter material from the fluid and expose the immune system to that fluid.
Afferent lymphatic vessels drain…
interstitial fluid from tissues into lymph nodes, dotted along the lymphatic tree.
Efferent lymphatic vessels drain…
out of the lymph nodes and connect up with other lymphatic vessels eventually connecting one large vessel called the thoracic duct. this empties back into the blood stream.
Secondary lymphoid organ
organs which the mature lymphocytes formed in the primary organs migrate. organs which filter foreign matter out of the body fluids and are places where immune responses to foreign antigens usually take place. spleen, lymph nodes, tonsils, adenoids, peers patches, skin.
