final exam Flashcards
what does MHC-1 present?
Presents endogenous (intracellular) antigen and is expressed on all nucleated cells
What does MHC-II present?
presents exogenous (extracellular) antigen and is expressed on only antigen presenting cells.
explain MHC-I antigen processing
antigenic proteins degraded into peptides in cytoplasm
peptides imported into ER
Peptide loading of MHC-I takes place in the ER
Explain MHC-II antigen processing
antigenic proteins are degraded in an acidic phagolysososme
peptide loading of the MHC-II takes place in the phagolysosome.
what are peptides?
fragments of protein antigen that are displayed by MHC-I and MHC-II on cells
Explain the development of t cells
immature T cells are found in the bone marrow where they then travel through the blood to the thymus where they become mature (naieve) T cells which all express unique anitgen receptors (t cell receptors are rearranged in the thymus)
what do T cell receptors recognise?
peptide and MHC
what type of receptors do MHC-II have?
CD4 receptors which help T cells dock
what type of receptors do MHC-I have?
CD8 receptors which also assist with docking
what are the functions of the CD4 T helper cell?
help the CD8 T cell become cytotoxic and help b cell make antibodies
function of CD8 T cell
recognise MHC-1
develops into cytotoxic T lymphocyte (cytotoxic T cell)
Describe memory T cells
the activation of a T cell= a memtory T cell
memory CD4 or CD8 T cells live in the body for long periods of time
they become effector cells much quicker than naieve cells.
what are the 3 functions of antibody in the immune system
1) neutralisation- knocking out toxins with anitbodies- antibody stops the virus from binding to our cells
2) opsonisation- make the pathogens tasty to phagocytes. receptor can bind to antibody and drag in the antibody with the microbe into the cell so that they can be phagocytosed
3) complement activation- complement forms membrane attack complex, this puts holes in the pathogen so that the microbe will explode. IgG and IgM are good at activating complement
what is the role of IgG
most abundant class in the blood
opsonises and neutralises
the only IG class that crosses the placenta for ‘passive immunity’
targets virus and bacteria
role of IgA
present in secretions, tears, saliva, mucus and breast milk
monomeric form in the blood
defence of the mucous membranes
present in breast milk- passing on antibodies to babies
targets virus bacteria
role of IgM
first ig class produced after the intial exposure to antigen.
expressed on niaeve B cells
very effective in activating ocmplement
targets extracellular bacteria
acts as an antigen receptor as it is able to sense when antigen bacteria is present in the body
role of IgE
present in the blood at low concentrations
immunity to muticellular parasites
allergic reactions to harmless antigens eg pollen or penicillin
role of IgD
expressed on naieve B cells
Together with LgM they act as an antigent receptor
their specific function is unknown
primary immune response vs secondary immune response
primary- 7-14 days to produce enough antibody to eliminate the pathogen. there is a low amount of antibody produced and its mainly IgM
secondary- (sucess of vaccination)
relies on memory B cells
works in 2-3 days, there is enough antibody produced to eliminate the pathogen
maining IgG, additional class switching to IgA and IgE.
posterior pituitary hormones?
Made, stored and faciliatated
made the neurons with their cell bodies in the hypothalamus
travel down the axon to be stored in the axon terminals until required.
released into the main bloodstream when an action potential depolarises the axom terminal
anterior pituitary hormones
how are they connected and released?
hypothalamic neurons secrete ‘releasing’ or ‘inhibiting’ hormones, they travel by a blood portal system to the anterior pituitary and bind to membrane receptors on anterior pituitary cells. causing them to release an anterior pituitary hormone
what are the anterior pituitary hormones?
growth hormone
thyroid stimulating hormone
adrenocorticotropin hormone
what makes a thyroid hormone
cells that line follicles.
thyroglobulin a protein containing tyrosine.
T3- 1 tyrosine, 3 iodine
T4- 1 tyrosine, 4 iodine
they are lipid soluble hormones
what does thyroid hormone increase?
and what how does it increase this?
basal metabolic rate
they increase it through
thermogenesis
oxygen consumption and ATP production and use
Fat and protein breakdown
when are growth hormone concentrations highest during the day and your lifetime
highest during sleep
highest during puberty then decline with age
what is an indirect effect of growth hormone being released and what impact does it have?
Indirect effect- liver secretes insulin like growth factor released when growth hormone is released.
this promotes the growth of bones, muscles and other tissues
direct effects of growth hormone
liver- stimulates glucose synthesis
muscle-inhibits cellular glucose uptake, stimulated protein synthesis
fat -increases fat breakdown
how is fuel mobilised into the blood during the reisstance phase
cortisol
glucagon
adrenaline
growth hormone
how does blood pressure increase during the resistance phase
coristol
antidirectic hormone
aldosterone
how does antidiretic hormone increase blood pressure
stimulates vasoconstriction of the blood vessels
also stimulates the kidneys to reabsorb more water into the plasma
how does aldosterone increase blood pressure
stimulates the kidneys to reabsorb more Na+ into plasma. This means with the higher presence of ions there will be more water that enters the blood stream which increases blood pressure.
what activates the alarm phase
sudden stress triggers the hypothalamus to activate the sympathetic nervous system.
(dialated pupils, saliva production, increased breathing rate)
these sympathetic nerves stimulate the adrenal gland.
the adrenal medulla released adrenaline
adrenaline amplifies cellular response helping to deal with stress
fast response time- seconds to minutes
affects of catacholamines
increased oxygen uptake and delivery to blood cells (lungs, heart, blood vessels)
increased fuel released into blood for cells to use
(liver, skeletal muscle, fat )
what complement fragments are associated with labelling (opsonisaton)
C3b
what do the C3a and the C5a complement fragments contribute to?
the recruitment outcome
inflammation and recruitment of phagocytes