INTRO TO NON-SPECIFIC IMMUNITY Flashcards
what are the functions of the lymphatic system?
Draining excess interstitial fluid (Extracellular fluid) from the tissue spaces
Transporting dietary lipids and lipid soluble vitamins around the body
Defence against disease or Immunity
how is lymph formed?
formed from blood plasma that filters from the blood capillaries into the interstitial space
Excess interstitial fluid passes through the endothelium of the lymphatic vessels and enters the lymphatic capillaries. This fluid resembles blood plasma, but lacks the larger plasma proteins
what are the 2 groups lymphatic organs and tissues can be classified into?
the primary lymphatic organs
the secondary lymphatic organs and tissues
what are the primary lymphatic organs?
provide an environment in which mature white blood cells called the B and T lymphocytes can develop and mature
give examples of primary lymphatic organs
red bone marrow, and the thymus gland.
what are the secondary lymphatic organs and tissues?
majority of the immune response occurs
give examples of the secondary lymphatic organs and tissues
lymph nodes, the spleen and the lymphatic nodules
what is a pathogen?
the infectious agent
what is a host?
the organism that is infected
what are the 2 types of immune systems?
Innate (Non-specific)
Adaptive (Specific)
what is the innate immune system?
Recognises molecules commonly associated with pathogens
Represents the most of immunity
when does the innate immune system respond?
Is able to respond immediately to presence of pathogen, the first line of defence
does the response of the innate immune system change if the same pathogen is encountered?
Response is effectively identical each time the same pathogen is encountered
what is the adaptive immune system?
Is specific for an antigen
Only found in vertebrates
how is the adaptive immune system acquired?
by experience
what does the adaptive immune system do on the first exposure to the pathogen?
pathogen takes a number of days to respond, subsequent responses are greater in amplitude and more rapid: memory
what is the function of barriers?
Many barriers prevent pathogens from crossing epithelia and colonizing tissues or destroy them without distinguishing types
what is haemopoiesis?
h
what are haemopoetic stem cells?
h
what is the non-specific immune response?
mechanisms that protect from foreign substances in a non-specific way
what is the function of the non specific immune system?
Prevention of entry into the body
Destruction of foreign materials once they have entered the body by internal non-specific defences
give examples of non-specific defences
Antimicrobial proteins
Natural killer cells and phagocytes
Inflammation
what are the different antimicrobial proteins?
Interferons (IFNs)
Compliment
Transferrins
what are IFNs produced by?
lymphocytes, macrophages and fibroblasts that have been infected by viruses.
what is the function of IFNs?
act as chemical messengers instructing neighbouring cells to produce antiviral proteins that interfere with viral replication
what are the 3 types of IFNs?
the alpha, beta and gamma interferons
what are compliment?
a protein normally found in an inactive state in the blood plasma and on plasma memb, where it forms the complement system
what happens when compliment becomes activated?
enhance specific inflammatory reactions
what are transferrins?
iron binding proteins that inhibit the growth of certain bacteria by reducing available iron
what are natural killer cells?
specialized granular lymphocytes
why are NK cells important?
Crucial for defense against tumor and virally infected cells
what do NK cells detect?
Don’t tend to recognise pathogen directly, detect affects of the pathogen on the host cell
detect the lack of host proteins or the induction of stress proteins
what cell membrane proteins do natural killer cells attack?
histocompatibility complex (MHC) antigens
what happens when the natural killer cells attack?
NK cells destroy their targets by releasing perforins or by binding and inflicting damage directly
what are phagocytes?
engulfing cells
what do phagocytes recognise?
microbes through specific receptors
what are neutrophils found?
Short-lived found normally in blood
what are neutrophils?
Highly phagocytic granulocyte
Migrates during inflammation
what do neutrophils produce?
vast repertoire of antimicrobial factors
where are dendritic cells found?
throughout the body, sentinels of the immune system
what are dendritic cells?
Phagocytic
Crucial link between innate and adaptive immune response
where are macrophages found?
in most, if not all tissues
what are macrophages?
Highly phagocytic and antimicrobial
what do macrophages direct?
both innate and adaptive through secretion of cytokines and antigen presentation
what are macrophages important for?
for non-inflammatory clearance of apoptotic cells
what is inflammation?
Describes defence response to damage or infection associated with symptoms such as redness, pain, heat and swelling
what is the function of inflammation?
traps invading micro-organisms and allows the region to be perfused with phagocytes and NK rich tissue fluids
what pass does inflammation follow os the damage is different?
the process is non-specific, and will follow the same path regardless what the source of damage is
what are the 3 phases of inflammation?
vasodilatation and increased permeability of BV, this is followed by phagocyte migration and then tissue repair
what is the inflammation process aided by?
histamine, kinins, prostoglandins, leukotriens and complement
what are histamines released by?
by mast cells in CT, and by basophils and platelets in response to injury
what do histamines attract?
neutrophils and macrophages to the injury and also induces vasodilatation and an increased permeability of BV
what are kinins formed from?
inactive precursor molecules (kininogens)
and induces vasodilation, increased permeability to blood and promotes chemotaxis by phagocytes
what are prostaglandins?
are lipids that are released by damaged cells
what do prostaglandins intensify?
the effects of histamine and the kinins, and also the migration of phagocytes through capillary walls
what is the function of leukotrienes?
act as a guidance cue for phagocytes, increase permeability of BV and also function in the adherence of phagocytes to pathogens
what are leukotrienes released by?
by basophils and mast cells
what does complement consist of?
of a no. of components that are associated with the release of histamine, attraction of neutrophils, the promotion of phagocytosis, and also the direct destruction of some bacteria
what happens following an injury?
arteries dilate and become more permeable resulting in localised edema, erythema, and increased temp
how is a scab formed?
Leakage of blood clotting
what happens an hour after the injury?
the migration of neutrophils and monocytes are attracted to the wound site
what is diapedesis?
neutrophils and monocytes migrate from the bloodstream into the tissue
what goes into the wound site?
neutrophils first then the monocytes a few hours later, which then transform into wondering phagocytic macrophages
what happens to the phagocytic macrophages in the wound site?
they die and forms the pus
how long does pus formation last?
until the infection has been destroyed, and dispersed by drainage, or absorption
what happens if pus doesn’t drain away?
it results in an abscess or inflamed spot, or if the superficial inflamed tissue sloughs away leaving an open running sore, an ulcer.
what is ulceration?
a feature common in the extremities of individuals with a poor blood circulation
what are static ulcers?
ulcers indiabetics with atherosclerosis
what is a fever?
the increase in body temp associated with the inflammatory response
why does fever arise?
because many bacterial toxins can elevate body temp by stimulating the release of cytokines and interleukin –1
what does fever result in?
results in the hypothalamic thermoregulatory set point being elevated
what does increased temp enhance?
can enhance the activity of inerferons and increase the activity of macrophages
what does increased temp inhibit?
the replication of bacterial cells
what does increased temp increase?
biochemical reactions and activity of enzymes associated with repair
what is the function of macrophages?
Role in homeostasis and tissue remodelling
what do macrophages do?
ingest and process foreign material, dead cells and debris
what do phagocytes express?
many receptors on the surfaces that detect signals that are not normally present in healthy tissues
surface molecules which are commonly used in research
what is the function of scavenger receptors?
for recognition of apoptotic and necrotic cells, opsonised pathogens, cell debris
what is the function of toll-like receptors?
for recognition of pathogens
what is the function of pattern recognition receptors?
detect “non-self” or damage
what are the different macrophage subsets?
M1 macrophages
M2 macrophages
Regulatory macrophages
TAMs
what are Classically activated macrophages (M1 macrophages)?
defend against bacteria, protozoa, viruses;
Anti-tumour activity
what are Alternatively activated macrophages (M2 macrophages)?
anti-inflammatory action;
Regulate wound healing
what are regulatory macrophages?
secrete large amounts of IL-10
what are Myeloid derived suppressor cells / tumor associated macrophages (TAMs)?
suppress anti-tumor immunity
