Exam 3 Flashcards
What binds to start signal transduction by RTKs?
a protein with SH2 domain to a tyrosine on the receptor
What is the Ras family composed of?
small G-protiens
What drives over 30% of all human cancers?
Ras genes
How do signals pass from activated Ras?
Ras to Raf to MEK to MAPK
What regulates the activity of many transcription factors that control early response genes?
MAP kinase (MAPK)
In unstimulated cells, where is PKB?
cytosol
In unstimulated cells, what inhibits PKB activity?
catalytic kinase domain bound to pH domain of PKB
What leads to the activation of PI-2 kinase & PKB?
hormone stimulation
Disrupted JAK/STAT signaling can lead to what diseases?
skin conditions, cancer, immune system disorders
What are cytokines important in?
cell signaling
Examples of cytokines?
chemokines
interferons
interleukins
lymphokines
tumor necrosis factors
transforming growth factor
How can the same signal induce different responses in different cells?
different types of cells have different collections of proteins that lead to different cellular events
ex. epinephrine simulates liver for breakdown of glycogen but stimulates heart to contract faster
What causes termination of the cell signal?
- concentration of signal decreases
- G-protein hydrolyzes
- cAMP to AMP
- phosphorylated kinases inactivated
- GRK desensitizes receptors
4 phases of the cell cycle
- G1 (gap stage 1)
- S (synthesis)
- G2 (gap stage 2)
- M (mitosis)
What drives cell cycle progression and initiates centrosome splitting?
CDK
What drives CDK activity?
positive & negative feedback loops
What guarantees each cell cycle step is completed correctly before going to the next step?
checkpoint pathway surveillance mechanisms
How do cells reproduce?
cell division
How do cells produced from mitosis look?
identical to their parent
How do cells produced from meiosis look?
have half the genetic content of the parent
3 main features of cell cycle
- cell growth & DNA replication
- chromosome segregation
- cell division
What cells lack the ability to divide?
nerve, muscle & red blood cells
What cells have a high level of mitotic activity?
stem cells
What cells can be induced to begin DNA synthesis?
liver cells & lymphocytes
Which cell cycle phase is the shortest?
mitotic
What is cytokinesis & when does it happen?
formation of 2 daughter cells; in M phase
What is the interphase?
period between M phases
includes G1 & G2 and S-phase
What are G0 cells & where do they exist?
cells with no ability to receive signals to initiate division; G1 stage
G1 phase
first stage within interphase
runs from M phase until the beginning of DNA synthesis
S phase
second stage within interphase
DNA synthesis & chromosome/centrosome replication
G2 phase
third stage within interphase
lasts until cell enters mitosis
M phase
duplicated chromosomes separate into 2 nuclei, cytokinesis happens
What is a centrosome?
move to opposite ends of the cells during division
work with microtubules to assemble a spindle
What are kinetochores?
near the centromere of the chromosome, where the spindle attaches
What aligns sister chromatid pairs in the spindle?
kinetochore-associated tension-sensing mechanism
What are the stages of mitosis
interphase
prophase
prometaphase
metaphase
anaphase
telophase
cytokinesis
What happens during interphase?
chromosome/centrosome duplication & cohesion
What happens during prophase?
chromosomes condense, nuclear envelope breaks down, formation of mitotic spindle apparatus, kinetochore assembles
What happens during prometaphase?
spindle microtubules attache to kinetochores and center the sister chromatid pairs
What happens during metaphase?
chromosomes align at the metaphase plate
What happens during anaphase?
spindle microtubules shorten, sister chromatids pulled towards opposite sides
What happens during telophase?
each daughter cell reassembles a nuclear membrane
What happens during cytokinesis?
cells fully separate
contractile ring forms cleavage furrow to split the cell
3 classes of microtubules
- astral (project towards cortex/outside)
- kinetochore (connected to chromosomes)
- polar (project towards center)
What are the model organisms for studying cell cycle?
saccharomyces cervisiae
schizosaccharomyces pombe
xenopus laevis
drosophila melanogaster
Where are the major checkpoints?
- G1 checkpoint
- G2 checkpoint
- mitotic checkpoint
What are the checkpoint proteins?
CDK
protein phosphatases
ubiquitin-protein ligases
What does the activity of CDK depend on?
cyclins
What cyclin-CDK complexes promote entry into cell cycle?
G1 cyclin-CDK
G1/S phase cyclin-CDK
What cyclin-CDK complex triggers S phase
S phase cyclin-CDK
What cyclin-CDK complex initiates mitosis?
mitotic cyclin-CDK
How can you regulate CDKs?
- cyclin binding
- CDK phosphorylation
- CDK inhibitors
- controlled proteolysis
- sub cellular localization
What cyclins can CDK1 act on?
cyclins A & B
for mitosis
What cyclins can CDK2 act on?
cyclins E & A
for entry into cell cycle & S phase
What cyclin can CDK4 act on?
cyclin D
for G1 entry into cell cycle
What cyclin can CDK6 act on?
cyclin D
for G1 entry into cell cycle
What dephosphorylates CDK1?
Cdc25
What phosphorylates CDK1?
Wee1
What inhibits the S phase CDK complex & prevents the cell from entering the S phase?
Sic1
In order for the cell to enter the next phase what must be done?
everything must be done correctly & the cyclin that blocks it must be degraded
5 basic steps of genome replication
- recognition of replicate origins
- assembling replication initiation factors
- recruitment of helicase cofactors
- activation of helicase
- DNA polymerase copies each strand
What CDKs get phosphorylated to then phosphorylate MCM helicases to make them active?
S phase CDKs
What glue sister chromatids together?
cohesive molecules
What do aurora proteins do?
stop mitotic process until the correct tension is formed
What does chromosome condensation result in?
dramatic reduction in chromosome length
What is sister chromatid resolution & what is is mediated by?
untangling of sister chromatids; topoisomerase II
What triggers chromosome condensation?
CDK1
What inhibits separase?
binding of securin or by phosphorylation
What are some steps checked at each checkpoint?
damage to chromosomal DNA
incomplete DNA replication
incomplete chromosomal alignment
What are the 2 categories of surveillance genes?
genes promoting cell proliferation genes (encode of proteins that promote division)
anti proliferation genes (encode for checkpoint proteins)
Daughter cells for mitosis
2 that are diploid (genetically identical)
Daughter cells for meiosis
4 that are haploid (genetically different)
Which cells does mitosis happen in?
somatic cells
Which cells does meiosis happen in?
germline cells
What hormone stimulates red blood cell formation?
erythropoietin (Epo)
When & where is erythropoietin synthesized?
synthesized in the liver & kidney in response to low OXYGEN levels
What transcription factor coordinates many cellular responses to low O2?
Hif-1alpha
When is Hif-1alpha protein present?
only at low O2 levels
(gets degraded at high O2 levels)
Defime chronobiology
the study of the biology of circadian rhythms
What organisms exhibit circadian rhythms?
all eukaryotes & some prokaryotes
What is the most powerful external cue for the circadian rhythm?
dark-light cycle
What are other cues that impact circadian rhythms?
medication
temp
social interactions
exercise
eating / drinking
weather
In mammals, what functions as the master clock or pacemaker for circadian rhythms?
suprachiasmatic nucleus (SCN)
Melatonin production is inhibited by what?
light
Melatonin production is stimulated by what?
darkness
What secretes melatonin?
pineal gland
When is cortisol hormone the highest?
during daytime
What is the primary disease of circadian rhythms?
narcolepsy
What are some other diseases accompanied by alterations to circadian rhythms?
alzheimers & autism spectrum
Cells respond to tension across what?
intercellular adherents junctions
What modulates cell growth & differentiation?
hippo pathway
How does hippo signaling & YAP-TAZ look when there are actin stress fibers?
hippo signaling is off
YAP-TAZ is ACTIVE in nucleus
How does hippo signaling & YAP-TAZ look when there are NO actin stress fibers?
hippo signaling is on
YAP-TAZ is INACTIVE in cytosol
What is required for YAP nuclear localization?
actin stress fibers
Where is YAP-TAZ in the outer cells of morula?
in nucleus because cells are dividing (hippo pathway is off)
Where is YAP-TAZ in the inner cells of morula?
in cytoplasm because cells are not dividing
What 2 systems make up the nervous system?
central & peripheral nervous system
(CNS & PNS)
What 4 areas make up the CNS?
spinal cord, brain stem, cerebellum, cerebrum
What does the spinal cord do?
relays sensory & motor info
What does the brainstem do?
controls basic functions such as breathing & HR
What does the cerebellum do?
coordinates movements
What does the cerebrum do?
controls higher functions like language, learning, memory, & emotion
What do glial cells do?
provide support to nerve cells
theres more of them than neurons in the brain
How much of the total body energy does the brain consume?
20%
What 4 lobes make up the cerebrum (brain)?
frontal, temporal, parietal, occipital
What does the frontal lobe do?
involved in analytical stuff such as problem solving, language, & impulse-control
What does the temporal lobe do?
involved in auditory processing, memory, & emotion
What does the parietal lobe do?
involved in sensations such as touch, taste, temp, & movement
What does the occipital lobe do?
involved in vision
What does the PNS consist of?
somatic & autonomic systems
What does the somatic system do?
involved with the conscious control of the body
What does the autonomic system do?
controls body functions that happen without us thinking about it
What are the two types of the autonomic nervous system?
sympathetic & parasympathetic nervous system
What does the sympathetic nervous system do?
stimulates the fight or flight response
regulates HR, respiration rate, & pupillary response
What does the parasympathetic nervous system do?
stimulates the rest & digest response
Where is the sympathetic nervous system located?
near the thoracic & lumbar regions
Where is the parasympathetic nervous system located?
between the spinal cord & the medulla
What 2 cells make up the nervous system?
neurons & glia
Types of glial cells in CNS
astrocytes
oligodendrocytes
microglia
ependymal glial cells
Types of glial cells in PNS
Schwann cells
satellite cells
What glial cells produce myelin sheaths in CNS
oligodendrocytes
What glial cells produce myelin sheaths in PNS
Schwann cells
What are the 3 functional classes of neurons
sensory (afferent) neurons
interneurons
motor (efferent) neurons
Describe sensory (afferent) neurons
detect stimuli & conduct signals TOWARDS the CNS
Describe interneurons
lie within the CNS
receives signals & decides where it goes
What class are the majority of neurons?
interneurons
Describe motor (efferent) neurons
lead to muscle cells
sends signals from CNS to the muscle or gland
Describe multipolar neurons
have 1 axon & multiple dendrites
What is the most common type of neuron?
multipolar
Describe bipolar neurons
have 1 axon & 1 dendrite
Examples of bipolar neurons
olfactory cells
sensory neurons
retina neurons
Describe unipolar (pseudounipolar) neurons
have a SINGLE process leading away from the soma
gets divided into dendrites later
Describe anaxonic neurons
have NO axon but multiple dendrites
do NOT produce action potentials
Where are anoxic neurons found?
brain
retina
adrenal medulla
What cells secrete & circulate CSF in the CNS?
ependymal cells
What cells engulf things & destroy them in the CNS?
microglia
What cells provide nutrients to cells in the CNS?
astrocytes
What cells provide electrical insulation in the PNS?
satellite cells
What is the myelin sheath?
insulation around a nerve fiber that aids in fast movement of APs
What is the neurilemma of the Schwann cell?
the thick outermost coil (bulging body) that contains the nucleus of the Schwann cell
What is the endonceurium of the Schwann cell?
a basal lamia & a thin sleeve of fibrous connective tissue
What is a node of Ranvier?
gap between segments of the myelin sheath
What are internodes?
myelin covered segments of the nerve
What is the initial segment?
the short section of nerve between the axon hillock & the first glial cell
What makes up the trigger zone?
axon hillock & initial segment
What are unmyelinated fibers enveloped in in the PNS?
enveloped in Schwann cells
The speed that the signal travels along a nerve fiber depends on what 2 factors?
diameter of the fiber
presence or absence of myelin
Commands to the skeletal muscle or signals for vision & balance use what kind of fibers?
fast myelinated fibers
Dilating the pupil & secreting stomach acid use what kind of fibers?
slow unmyelinated fibers
What are diseases of the myelin sheath & what do they cause?
multiple sclerosis (MS) & tay-sachs disease
cause a disruption of nerve conduction
Describe multiple sclerosis (MS)
oligodendrocytes & myelin sheaths of the CNS deteriorate & are replaced by scare tissue
Describe tay-sachs disease
there is an abnormal accumulation of ganglioside in the myelin sheath
What does the blood brain barrier do?
prevents free flow of substances
is the sight of a lot of signal transduction
Brain tumors (gliomas) are composed of what?
a mass of glial cells
What does a tumor consist of?
a mass of rapidly dividing cells
What are the 3 main components of the cytoskeleton?
microtubules
intermediate filaments
microfilaments
Describe microtubules
longitudinal structures that give neuritis their structure
Describe intermediate filaments
strong structures that consist of long proteins
Describe microfilaments
thin structures that are important for motility
When Tau proteins over phosphorylate, what does it cause neurons to form?
NFTs (neuron fiber tangles)
Describe axoplasmic transport
transport along the INTERIOR of the axon
What direction is anterograde axonal transport
from cell body (soma) to nerve ends
What direction is retrograde axonal transport
from nerve ends to cell body (soma)
What proteins are involved in transport along neurons-tubules?
kinesin & dynein
Fast axonal transport occurs in what direction?
both anterograde & retrograde
What transport moves organelles, synaptic vesicles, & small molecules?
fast ANTEROGRADE transport
(soma to nerve ending)
What transport returns uses synaptic vesicles to the soma & is used by pathogens?
fast RETROGRADE transport
(nerve endings to soma)
Slow axonal transport occurs in what direction?
anterograde (soma to nerve ending)
What transport moves enzymes & cytoskeletal components & renews worn-out axoplasmic components?
slow axonal transport
What is a disorder of peripheral nerves?
tetanus
During a tetanus infection, what transmitters get blocked & what does that cause?
blocks GABA & glycine (muscle contraction inhibitors)
causes uncontrollable muscle contractions
What is risus sardonicus?
face has a fixed smile
early sign of tetanus
What is opisthotonus?
muscle spasms
What is tetany?
prolonged muscular action that causes painful contractions, fractures, & muscle tears
What happens during early nerve regeneration?
a regeneration tube forms
What happens during late nerve regeneration?
the regeneration tube guides the growing sprout back to the original target cells, reforming synaptic contact; soma shrinks & muscle fibers regrow
Nerve regeneration can only happen if what is still intact?
the soma (cell body)
What maintains intracellular Na+ & K+ concentrations?
Na/K pump (ATPase)
E1 conformation of Na/K ATPase
releases K+
high affinity for Na+
E2 conformation of Na/K ATPase
releases Na+
high affinity for K+
How does Na/K ATPase go from E1 to E2 conformation?
conformational change
What does the K+ channel use to push K+ out?
the electrochemical gradient made from the Na/K pump
The Na/K pump sends how many Na+ out & brings how many K+ in?
3 Na+ out, 2 K+ in
What is the resting membrane potential?
-70 mV
What are the 4 properties of a local (graded) potential?
- graded: vary in magnitude bases on stimulus strength
- decremental: get weaker the further they travel
- reversible: returns to RMP when stimulus stops
- can be excitatory OR inhibitory
Excitatory local potentials do what?
depolarize the cell (more Na+ in) thus producing an action potential
ex. acetylcholine
Inhibitory local potentials do what?
hyperpolarize the cell (makes it more negative)
ex. glycine
What causes depolarization?
stimulus open Na+ channels allowing Na+ into the cell thus depolarizing it
Local potentials are produced by what?
LIGAND GATED channels
Action potentials are produced by what?
VOLTAGE GATED channels
Steps of an action potential
- local stimulus depolarizes membrane
- Voltage gated Na+ channels open at threshold (-55mV)
- Na+ enters cell, depolarizing it
- At 0 mV, Na+ channels close
- At +35 mV, K+ channels open
- K+ channels repolarize cell
- K+ channels remain open hyperpolarizing the cell
- RMP is restored
Characteristics of an action potential
- not graded: strong stimulus does not produce a stronger action potential
- non-decremental: do not get weaker with distance
- irreversible: once fired goes to completion
Why aren’t all nerve fibers large, myelinated, & fast?
it would make the nervous system very bulky & inefficient
A nerve signal is what?
a chain reaction of action potentials
Refractory membrane ensures what?
that the action potential travels in ONE direction
Unmyelinated nerve fibers have what kind of conduction?
continuous conduction
Myelinated nerve fibers have what kind of conduction?
saltatory conduction
signal “jumps” from node to node
On myelinated nerve fibers, where can action potentials occur?
only at nodes of Ranvier
this is what gives the appearance of the signal “jumping”
How does myelin speed up signal conduction?
by minimizing leakage of Na+ out of the cells & separating the inner positive ions from attraction of outside negative ions
What is a synapse?
where pre & post synaptic neurons meet
A presynaptic neuron can synapse with what 3 things?
dendrites
the soma of a postsynaptic neuron
the axon of a postsynaptic neuron
What are the types of synapses based by site of contact?
axodendritic synapse
axosomatic synapse
axoaxonic synapse
What are the types of synapses based by transmission mechanisms?
electrical & chemical synapses
What do electrical synapses have that chemical synapses do not?
gap junctions
Define electrical synapses
has gap junctions between pre & postsynaptic membranes that allow direct flow of current
Define chemical synapses
has no direct flow of current
rely on neurotransmitters
What is a synaptic cleft?
a gap between pre & post synaptic cells
How are neurotransmitters released into the cleft?
via exocytosis
Define neurotransmitters
molecules that are released when a signal reaches a synaptic cleft that binds to a receptor on another cell & alters its physiology
What are the major chemical categories of neurotransmitters?
acetylcholine
monoamines
amino acid neurotransmitters
purines
What do neuromodulators do?
modulate the activity to neuron groups in various ways
How can neuromodulators modulate the activity of neuron groups?
- increasing release by presynaptic neurons
- adjusting sensitivity of postsynaptic neurons
- altering rate of breakdown
What are 2 neuromodulators?
gases (nitric oxide)
neuropeptides (endorphins)
Who was awarded the Nobel prize in 1936?
Loewi & Dale
What does an excitatory cholinergic synapse use as its neurotransmitter?
acetylcholine
Describe the process of an excitatory cholinergic synapse
- signal arrives & opens voltage gated Ca2+ channels
- Ca2+ enders cell
- ACh released & binds to postsynaptic receptors
- Na+ & K+ diffuse into cell
- action potential generated
What proteins are involved in neurotransmitter release?
v-SNARE & t-SNARE (SNARE complex when bound together)
Influx of what triggers the release of neurotransmitters?
Ca2+
What prevents membrane fusion?
complexin protein & synaptotagmin without bound Ca2+ binding to the SNARE complex
What does an inhibitory GABA-ergic synapse use as its neurotransmitter?
game-aminobutyric acid
GABA receptors are what kind of channels?
chloride channels
An excitatory adrenergic synapse uses what as its neurotransmitter?
norepinephrine
acts through second messengers like cAMP
For an adrenergic synapse, what is the receptors?
GPCR
(G-protein coupled receptor)
Describe the process of an excitatory adrenergic synapse
- norepinephrine binds to G-protein
- G-protein dissociates & binds to adenylate cyclase
- cAMP is released
- ligand-gated channels open
- cell depolarizes
Define neural integration
the ability of neurons to process info, store & recall it, & make decisions
Define excitatory postsynaptic potential (EPSP)
any voltage change above resting membrane potential that makes a neuron more likely to fire
EPSPs usually result from what?
Na+ flowing INTO the cell
What excitatory brain neurotransmitters produce EPSPs?
glutamate & aspartate
Define inhibitory postsynaptic potential (IPSP)
when a neurotransmitters hyperpolarizes the postsynaptic cell & makes it less likely to fire
IPSPs usually result from what?
chloride flowing INTO the cell or K+ flowing OUT
What are inhibitory brain neurotransmitters that produce IPSPs?
glycine & GABA
Where does summation occur?
in the trigger zone
Describe summation
the process of adding up postsynaptic potentials & responding to their net effect
Describe temporal summation
a SINGLE synapse generates EPSPs so fast that the one before has not finished
Describe spatial summation
EPSPs from MULTIPLE synapses add up
Define neural coding
nervous system converts QUALITATIVE info to a meaningful pattern of APs
What is the most important mechanism for transmitting qualitative info?
labeled line code
(brain interprets based on the labeled neuron that the signal comes from)
In neural coding, qualitative info is..
where the stimulus is coming from
In neural coding, quantitative info is..
how strong the stimulus is
What are the 4 types of neural circuits
diverging
converging
reverberating
parallel after-discharge
Describe a diverging circuit
ONE neuron sends signals to multiple neurons
signals going OUT of the brain
Describe a converging circuit
signals from MULTIPLE neurons all come together at one point
signals coming back to the brain
Describe reverberating circuit
neurons stimulate each other in a linear sequence but some send signals back to neurons earlier in the path
is a loop (positive feedback) stopped by inhibitory signal
What neural circuit can play a role in seizures?
reverberating circuit
Describe parallel after-discharge circuit
ONE neuron stimulates several CHAINS
Describe mechanoreceptors
sensory structures that respond to touch, pain, & temp
are Na+/Ca2+ channels
What organism is used for research of mechanoreceptors?
C. elegans & heier MEC proteins
What receptor is used for salty & sour tastes?
channel proteins
What receptor is used for sweetness & bitterness?
GPCR
Describe the structure of an olfactory receptor neuron
have 1 dendrite that ends in a dendritic knob that has cilia extending into the nasal mucus
What catalyzes cAMP from ATP?
adenylyl cyclase
What hydrolyzes cAMP?
cAMP phosphodiesterase
Describe memory trace
memory pathway where new synapses form or existing synapses are modified
The ability of synapses to change is called what?
synaptic plasticity
Define immediate memory
ability to hold a memory in mind for a few seconds
What circuit is immediate memory based on?
reverberating
Define working memory
a form of short term memory that allows you to hold an idea long enough to perform an action
Define post-tetanic potentiation
memories lasting for a few hours
How long does short term memory last?
few seconds to a few hours
What taste can directly depolarize the membrane?
salt taste
What taste uses H+ to block K+ channels to depolarize the membrane?
sour taste
What tastes use GPCRs to elevate Ca2+ levels that open Na+ channels to depolarize the cell?
sweet, bitter, umami tastes
Describe the signal transduction from olfactory GPCRs
- odorant binds & releases active Galpha-GTP
- AC3 produces cAMP
- influx of Na+ & Ca2+
- cell depolarizes
What are the 2 forms of long term memory?
explicit & implicit
Describe explicit memory
retention of events that you can put into words
“physical memories”
Describe implicit memory
retention of emotions or motor skills
“emotional & procedural memories”
What is long term potentiation?
a process involving persistent strengthening of synapses
involves NMDA receptors
What blocks NMDA receptors?
magnesium ions
What is the model organism for studying synaptic plasticity & memory?
Aplysia californica
(sea slug)
Sensitization is accompanied by what?
the growth of new connections between the sensory & motor neurons
Habituation is accompanied by what?
a decrease in the number of connections between the sensory & motor neurons
What erases long term memories?
long term depression (LTD)
What is required for memory formation?
the hippocampus
How does long term depression affect receptors in the post synaptic?
decreases the number of receptors, decreasing the response
(long term potentiation does the opposite)
Mutation in FMRP (proteins) causes what mental disorder?
fragile X syndrome
Mutation in FMRI gene causes what?
autism
What are the 2 types of immunity?
innate & adaptive
Describe innate immunity
body recognizes any pathogen
dos not require previous exposure
Describe adaptive immunity
immune system specifically targets CERTAIN pathogens
has specific recognition of antigens
Describe plasma
blood without cells
Describe serum
blood without cells or proteins
What are platelets?
cell-like bodies that clump to prevent blood from leaking out when vessels are damaged
Describe erythrocytes
RBCs
have no nucleus & carry O2
All white blood cells (leukocytes) start as what & where?
start in bone marrow as stem cells
3 classes of leukocytes
granulocytes (neutrophils, eosinophils, basophils)
monocytes (macrophages, dendritic cells)
lymphocytes (B & T cells)
What is lymph?
fluid with WBCs that bathes tissues
What are the primary lymphoid organs?
bone marrow & thymus
What are the secondary lymphoid organs?
lymph nodes, spleen, MALT
What are the functions of the lymphatic system?
absorption of fat & excess fluid, immunity
Where do B cells mature?
in bone marrow
Where do T cells mature?
in thymus gland
What are lymph nodes & what do they do?
nodules in lymphatic veins
function to filter & purify lymph fluid
What is the function of the spleen?
to filter blood
What mediates innate immunity?
physical & chemical barriers
phagocytes
cytokines
Describe cell mediated immunity (CMI)
LYMPHOCYTES recognize specific antigens
Describe humoral immunity
ANTIBODIES recognize the antigen
What are the 2 types of cells involved in innate immunity?
- neutrophils
- monocytes & macrophages
How do neutrophils work for innate immunity?
they circulate through the blood & bone marrow & migrate to sites of infection causing an inflammatory response
How do monocytes & macrophages work for innate immunity?
monocytes circulate through the blood & lymph & have macrophages on their surface to present the antigen
What are PAMPs?
pathogen-associated molecular patterns
structural components on a particular PAHTOGEN
What are PRRs?
pattern recognition receptors
HOST proteins that interact with PAMPs on pathogens
What is an example of PRR?
TLR
During innate immunity, what are released by host cells in response to PRR binding to PAMP?
interferons which activate immune cells
How do macrophages & phagocytes take action during innate immunity?
- recognition & engulfment of pathogen
- produce antigen
- antigen presented on macrophage cell surface
- antigen presented to T & B cells
- immune response
How can phagocytes kill bacteria?
acid attack
phagocyte stimulation
toxic oxygen
How can pathogens fight against phagocytes?
production of anti-oxidants (to give resistance)
production of leucocidins (to kill phagocytes)
capsules (to block adherence of phagocyte)
What are the 3 fundamental characteristics of adaptive (specific) immune response?
specificity
memory
tolerance (protects host cells from immune response)
What do T-cells have that allow them to recognize a specific antigen?
antigen specific T cell receptors (TCRs)
What part of a TCR binds to the antigen?
variable region
What part of a TCR is integrated in the membrane & very specific?
constant region
What cells are responsible for producing antibodies?
B cells
What do antigens (from pathogens) interact with?
antibodies or TCRs
Antigens are what?
immumnogens
What are immunogens?
substances that induce an immune response
What are haptens?
antigens that bind to antibodies but cannot induce an immune response unless bound to a large carrier
What INTRINSIC factors affect the ability of an antigen to induce an immune response?
molecular size
complexity
form (more insoluble, better immunogen)
What EXTRINSIC factors affect the ability of an antigen to induce an immune response?
dose size
route of entry
foreign nature (more foreign better response)
What are ineffective immunogens?
small molecules
sugars
nucleic acids
What are effective immunogens?
proteins
What are epitopes?
the part of the antigen that directly binds to the antibody or TCR
What is a homologous antigen?
epitope that antibody recognizes to stimulate an immune response
What is a heterologous antigen?
epitope where the antibody ACCIDENTALLY binds
interaction is a cross reaction
What are the 2 kinds of adaptive immunity?
cell mediated
antibody mediated
What is cell mediated immunity?
pathogen infected host cells are immediately killed after recognized
What is antibody mediated immunity?
pathogen is recognized & antibodies are developed
effective against bacteria & extracellular pathogens
What cells process antigens?
antigen presenting cells
What do antigen presenting cells have to have on their surface to present the antigen?
major histocompatibility complex (MHC)
What do cytotoxic T cells (TC cells) do?
invade infected cells & destroy them
What do T helper cells (TH cells) do?
interact with the antigen & secrete cytokines that activate host defense OR stimulate B cells to produce antibodies
Antigen presentation requires what 2 things?
T cell receptors (TCRs)
MHC (on antigens)
What class of MHC proteins presents antigens to cytotoxic T cells?
class I
What class of MHC proteins presents antigens to helper T cells?
class II
Cytotoxic T cells have what kind of receptors?
CD8+
Helper T cells have what kind of receptors?
CD4+
What transporter delivers degraded pathogens to the interior of the ER to get loaded onto MHC protein?
TAP
Successful recognition of an antigenic peptide-MHC complex by a T cell receptor requires what?
a good fit among the receptor, antigen, & MHC molecule
What do class II MHC proteins have that prevent it from binding cellular peptides?
invariant chain
