1/35
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Blood components
Plasma - water and dissolved substances (55%)
White blood cells + platelets
Red blood cells (45%)
Cellular components of blood
Red blood cells
White blood cells
Platelets
Red Blood Cells
are cells that carry oxygen
White blood cells
are cells that fight infection
Neutrophils
lymphocytes ( B + T cells)
monocytes
Immune system
differentiate between self and non-self
seek and destroy non-self, pathogens + bacteria
Pathology
the study of diseases and how they progress
Pathogen
something that causes a disease, for example bacteria or virus
Immune system
a system of defences to stop invading pathogens
Immunogenic
something which induces an immune response in the body, this can be a humoral (antibody) and/or cell-mediated immune response
Antigen
a molecule which induces an immune response via a lymphocyte. Pathogens have many antigens on their surface
Antibody
a molecular component of the immune system that recognises and binds (interacts with) antigens
Innate immunity
Always deployed
Ready to be quickly deployed
First and second line of defense
Adaptive immunity
Activated by exposure to specific pathogens
Third line of defense—internal adaptive defense s
Consists of lymphocytes B cell and T cells
Antibodies
The lymphatic system is involved in…
internal innate immunity and adaptive immunity, lymph nodes
External innate defences
Barrier defences
Skin
Mucous and mucous membranes
bodily secretions
All pathogens must get around these barriers to gain access to body
Internal innate defences
Second line of defense
Phagocytic cells engulf pathogens
Vasodilation + increased permeability of blood vessels
Blood cells leave blood vessels + enter injury site causing redness, heat, swelling
Natural killer cell recognition + killing of virus infected
Clean up and repair
Not pathogens specific, immune cell based responses
Inflammation
Tissue injury; release of chemical signals such as histamine (dilate blood vessels)
Dilation and increased leakiness of local blood; migration of phagocytic cells to the area from blood vessels, blood clots and swelling
Phagocytic cells engulf bacteria and cell debris; tissue heals
Phagocytosis
Performed by phagocytes e.g. neutrophils, monocytes/macrophages
What happens first when injured?
Tissues cells damaged by the wound
Damaged cells release chemicals - histamines
Histamine makes the nearby blood vessels get leaky - fluid enters nearby tissues causing swelling
Fluid includes factors to assist with healing and clotting
Phagocytic cells are activated, recognise and engulf bacteria
Internal adaptive defenses
Third line of defence
Lymphocytes - B and T cells
This immune response is generated in the lymphatic system and carried out all over the body
Lymphocyte B cell produces antibodies
B cells
Develop and specialise in the bone marrow
Makes antibodies
T cells
Develop in bone marrow and mature in the thymus
How are B and T cells activated?
Activated by exposure to specific pathogens
Specific shapes of receptors detect specific pathogens ‘lock and key’
Born with a massive repertoire of B and T lymphocytes — high variety means more likely to be able to recognise several varieties of pathogens
Each lymphocyte represents a different antigen
Specificity randomly produced by rearrangement of genes coding for the B cell and T cell antigen receptors
Antigens have 2 important characteristics:
Immunogenicity
Reactivity
Immunogenicity
The ability to provoke an immune response by stimulating the production of antibodies of T cells
Reactivity
The ability of the antigen to react specifically with the antibodies or cells it provoked
Most antigens have several…
Epitopes that are recognised by antibodies or T cells
Antigen recognition activates lymphocytes to undergo…
‘clonal expansion’ that mediate adaptive immunity
What provides basis for infection induces immunity and vaccination?
Memory B (and T) cells can live for decades in lymph node
Activated if the body is exposed a scone time to same pathogen
Secondary response much faster, stronger, lasts longer than first
What happens if immediate response doesn’t deal with all bacteria?
Bacteria grows rapidly, 20m doubles—infection spread
Phagocytes that engulfed bacteria during innate system will ‘advertise’ antigen
T cells can recognise antigen amd ‘help’ B cells - amplify response, clone and pump antibodies binding to bacteria
B-cells will clone themselves, produce antibodies, and save a copy of themslevs for future infections (memory B cells)
Antibodies are important markers of _______ + ______
previous infection + immunity
_______ and ___/___ are the ______ antigens and most commonly used in serology
Nucleocapsid, Spike/RBD, immunodominant
Applications of antibody assays
Detect historical infections
Estimate prevalence
Understand persistence and protection
Neutralising antibodies
RBD (receptor binding domain) of spike protein binds to ACE2 receptor to infect human cells
Nabs (neutralising antibodies) bind to the RBD and block tehre interaction (with ACE2) - virus is now unable to enter cells
Serology for indiviudal
Antibody test provides data on a single persons’ infection or vaccine history
Serology for population (serosurvey)
The collection and testing of blood from a defined population population to estimate the prevalence of antibodies against an infectious pathogen as an indicator or exposure