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
what occurs at the destroy outcome of complement and what complement fragment is associated with it?
the membrane attack complex forms pores in the microbe causing their interior to fall out.
C9
what do pamps do?
signal through receptors on the phagocytes and regulate gene transcription
what receptors do the cytotoxic t lymphocytes have and what do they recognise?
They have T cell receptors and they recognise MHC-1
what receptors do CD4 t cells have and what do they recognise?
they have T cell receptors that recognise MHC-II
what pathway of complement activation represents cooperation between innate and adaptive immunity?
classical- it relies on molecules that are produced by B cells
what are on the surface of B cells that are responsible for antigen recognition?
membrane anchored antibodies (B cell receptors)
what is the Ig class that is first produced in an initial immune response?
IgM & some IgD
what is the main Ig class for the secondary immune response?
IgG with class switching to IgA and IgE at low levels
what do skin and mucousal surfaces have in common?
they both are constantly renewed.
what muscles bring the knee into flexion?
hamstrings and gastrocnemius
what muscles bring the knee into extension?
quadriceps
what is severe combined immunodefficieny
x chromosome linked disease, more common in males. lack functional T and B cells
what does HIV do to the body?
targets and kills CD4 t cells, unable to help CD8 t cells become cytotoxic.
impacts microbe and cancer immunity
what is autoimmune disease?
it is where T and B cells attack self tissue
immune tolerance
this is a critial process to avoid autoimmunity
the thymus deletes autoreactive T cells
what is the allergic effector response
DC cells present peptide from allergen to helper T cells
helper t cells activate b cells to secrete IgE
IgE binds to mast cell receptors (FCR)
the allergin protein binding to the FCR on the mast cells causes them to degranulate and release histamine and other inflammatories.
what is clonal selection
the selective expansion of lympocytes that ineract with antigen.
B&T cells specific to the antigen undergoes the extensive cell divison
what are the functions of antibody?
1) neutralise
2) opsonise
3) activate complement
what cells are the thyroid hormone made in?
the follicular cells in the thyroid gland
what effector does glucagon not work on?
muscles
if the confidence interval contains 0 what can we conclude?
that there is no difference between the two groups
what can we conclude if the confidence interval is either side of 0
that there is evidence of a difference between the two groups
absolute refractory period
2nd AP cannot be generated
Na+ channels are already open or are inactivated
relative refractory period
2nd AP can be generated only if the stimulus is much larger than normal
occurs when some Na+ channels shift from inactive to closed state
what happens when an action potential arrives at the axon terminals. what type of channels and what is the process that occurs
at the axon terminals there are voltage gated calcium channels. when these become depolarised calcium moves into the axon terminal
this causes the mobilisation of vesicles containing the neurotransmitter acetylcholine.
the vesicles release this into the synaptic cleft where it diffuses across
the acetylcholine binds to the chemically gated ion channels on the post synaptic cell
whats GABA an example of?
an inhibitory neurotransmitter
what happens to acetylcholine after binding to a chemically gated ion channel?
it is broken down by acetylcholinesterase into choline and acettate.
only choline is recycled and used again
features of NMJ
it is a cholingeric synapse, always excitory
summation isnt typically required
only uses acetycholine
what are the two rami communicans and what do they do?
only for sympathetic and only at T1-L2.
dorsal ramus- effertent to back, afferent from back
ventral ramus- efferent to ventral, afferent from ventral
what is the somatic efferent system made up of
is is voluntary movement. Upper motor neuron cell body in brain axon in spinal cord.
Lower motor neuron cell body in spinal cord axon into PNS.
only acetylcholine and both axons are myelinated
in the sympathetic nervous system where is the cell body of the second neuron?
In the sympathetic ganglion
temporal summation
repeating firing of one pre synaptic nerve to meet threshold
spatial summation
multiple pre synaptic nerves firing to collectively reach threshold
briefly describe action potential propigation
initial segment to threshold an action potential propigates
when inital segment depolarises to 30mV the Na+ ions disperse causing the second segment to be brought to threshold. this develops an action potential
what is sensory transduction?
the conversion of a sensory stimulus into an action potential
basal nuclei role
modifying movement
assists with posture and muscle tone
refines movement, selecting what to allow and what to inhibit
alters sensitivity of neurons that project into corticospinal pathway
cerebellum role
stores the motor programmes to learn movements. monitors and compares the sensory input. compares the actual movement in comparison to the planned movement.
what is somatic sensation?
detected by the receptors in the skin, muscle and joints
what is visceral sensation
detected by receptors in the internal organs
what section of the spinal cavity does the spinal cord finish?
at the L1 but the spinal cavity goes all the way to the conus medularis- the attatchment point for the filum terminale which anchors the spinal cord.
what type of cells is MHC - I presented on
all nucleated cells
what type of cells is MHC-II presented on
only antigen presenting cells
what class of antibody most effectively removes multicellular parasites is?
IgE
B cells recognise _____ via their ___
T cells recognise _____ through ____
B cells regonise native antigent through their b cell receptors
T cells recognise peptides through MHC
what do adjuvants do?
immune stimulants added to vaccines to enhance the activation of antigen presenting cells
tendons
connect muscle to bone, lest elastin than ligaments. facilitate and control movements
ligaments
connect bone to bone
have collagen and elastin so they resist tension and allow for a little stretch and recoil
restrict movements away from themselves
muscle fibres
slow vs fast
slow- small diametre, large blood supply, large mitochondrial supply, red in colour, high fatigue resistance and slow until peak tension
Fast- large diametre, small blood and mitochondrial supply, white in colour, have a low fatigue resistance and a short time until peak resistance
a single action potential pulse is called a ____
Many action potentials fired in rapid sequence for a sustained period of contraction is _____
maximum signalling and contraction capability is called ______
twitch
summation
tetanus
whole muscle structure form cellular level upwards
Actin and myosin make up myofilaments
make up sacromeres
make up myofibrils
make up fibres
make up fasciles
make up muscles
what are the two things that muscle tension relies on?
1) recruitment- number of muscle fibres recruited
2) frequency- rate at which muscle is stimulated
what determines the function of a muscle
1) length of muscle
2) number of muscle fibres- cross sectional area big= big tension
3)arrangement of muscle fibres
isometric muscle action
muscle is active- develops tension
tension doesnt outweigh load
muscle length doesnt change
no change in joint position
holding a joint still
stabilisers=always isometric
what is the knee doing during the late stance (toe off stage)
in extension due to body positioning
hamstrings and gastrocnemius are contracting ready for the next movement
