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Physio ch. 6

QuestionAnswer
nervous system functions communication and homeostasis
communication can be either electrical or chemical
electrical communication happens through the...and chemical is between... axon...neurons and other types of cells like effectors
homeostasis controls...,...,... system coordination (turning on and off)...direct activity....regulating +/- feedback
neuron classes CNS and PNS
cns contains the brain and spinal cord
pns contains everything outside the cns including spinal nerves
axons are nerve fibers
nerves are bundle of axons in PNS
tracts are...also called... bundle of axons in CNS...columns
afferent pathway is for...reception and is the...part of the spinal... sensory...posterior...root
interneurons are in the..and used for... cns...integration
efferent pathway is the..spinal...and does... anterior..root...effector activation
membrane potential is key for neurons
resting potential is around -70 mV
resting potential is the..between.. electrical potential..inside and outside of the cell
inside the cell is k+, amino acids(-) and phosphates (-)
outside the cell na+, cl-
at the membrane: negative charges inside attracted to positive charges outside
when compared, the inside membrane is negative relative to the outside membrane
resting membrane potential: extracellular fluid is used for reference and is assigned a voltage of 0
resting membrane potential: intracellular fluid is compared...and voltage difference is... extracellular fluid...membrane potential
electrochemical gradient is a balance between electrical gradient (ion movement) and chemical gradient
electrical and chemical gradients influence movement of ions
key ions and their actions K+ leaks out and Na+ leaks in
which is the most important ion? K+
K+ follows... concentration gradient but agaisnt electrical gradient
Na+ follows.. concentration gradient and electrical gradient
ions get through the membrane via leak channels (diffusion)
P is higher for...because... K than Na+..there are more leak channels for it
why doesn't the concentration gradient disappear? overall distribution of ions and na+/k+atpase pump
na+/k+ atpase pump helps establish gradient
how many na+ are pumped out three
how many k+ are pumped in 2
leak channels...gradient increase
the fact that there are more K+ leak channels than na+ leak channels...on the outside augments the + charge
na+/k+ atpase pump...leak channels counteracts
variation in membrane potential includes resting potential, depolarizing, overshoot, hyperpolarizing
if the membrane potential is disrupted then na/k pump fixes it and uses atp
depolarizing takes the membrane potential towards...with means losing... zero...charge difference
overshoot is the membrane potential when it is...and the inside is...relative to the... above zero...+...outside
repolarizing from depolarizing back towards resting
hyperpolarizing means more negative than resting potential
graded potential involves ligand and mechanical, etc gated channels
graded potential DOES NOT involve voltage gated channels
graded potentials are localized meaning only a small area of the neuron is affected
the localized area of neuron that graded potentials affect are the cell bodies and dendrites
graded potentials have...channels, the charge flows...and it is not open ion...to surrounding area...propogated
graded feedback have no + feedback
graded potentials have a variable magnitude or strength
magnitude of depolarization for graded potential depends on strength, usually small
graded potentials can be summed
graded potentials can either be depolarized or hyperpolarized
depolarizing means that...open and they have an effect on na channels...internal charge (more +)
hyperpolarizing means that...open and the effect is that cl- channels...internal charge becomes more -
graded potentials can't go far because of decremental conduction (decrease magnitude over distance)
action potentials are not...and have the...principle localized...all or none
action potentials involve open...and they are... voltage gated ion channels...propagated
propagation means that the action potentials generate themselves
all or none magnitude requires a...which is usually a... stimulus...graded potential
enough change in the membrane reaches the threshold potential
action potentials involve three steps depolarization, repolarization and hyperpolarization
action potentials are non...meaning that the conduction is as... decremental conduction...strong at the end as at the beginning
voltage gated ion channels: voltage change triggers conformational change
voltage gated ion channels open in response to membrane depolarization
voltage gated ion channels are not leak channels
na+ channels respond...are closed until...open at...and are lastly quickly...until threshold...at threshold...inactivated
open na+ channels allow na+ to follow gradient
na channels remain open until equilibrium is almost met
k+ channels respond...then are...and then they... more slowly...closed to keep most k+ in the cell...open to allow k+ to follow gradient
3 positions of na+ channels closed, open and inactivated
2 positions of k+ channels closed, open
action potential mechanism 1: resting membrane potential =...only..are open..and the..is active -70 mV..leak channels..na+k+ atpase pump
mechanism 2: threshold potential =...and is usually... -55 mV...ligand gated
threshold potential is an... excitatory graded potential stimulus
how does the potential get to threshold? depolarization
mechanism 3: rapid depolarization voltage gated na+ channels open and reach overshoot
mechanism 4: near na+ equilibrium voltage gated na+ channels inactivate and voltage gated k+ channels open
mechanism 5: repolarization k+ moves out of the cells
mechanism 6: hyperpolarization na+ channels close, k+ channels still open
mechanism 7: resting membrane potential near k+ equilibrium, k+ channels close and potential returns to normal
na+ movement: ...until... positive feedback...na+ nears equilibrium (reinforcement)
after the na+ nears equilibrium the channels become inactivated
k+ movement: K+ channels can't open in -ly charged situations
k+ movement leads to neg feedback as membrane repolarizes
after cell is repolarized k+ channels close
all or none response subthreshold or threshold
subthreshold would be graded potentials or stimuli
threshold occur because of strong enough stimuli or all or none action potential
all or none action potential requires the opening of voltage gated na+ channels
all or none action potential: some anesthetics block na+ channels (novacain, lidocain, tetrodotoxin)
refractory periods limits # of action potentials
there is a ...of signals one way propagation of signals
absolute refractory period means no.. additional action potentials can occur because na+ channels open or inactivated
relative refractory period requires... stronger stimulus
relative refractory peiod allows neuron to carry potential in only one direction
during relative refractory period na channels close and k channels are still active
action potentials are generated via graded potentials
3 types of potentials that produce APs receptor potential, synaptic potential, pacemaker potential
afferent neurons produce receptor potentials
interneurons and efferent neurons produce synaptic potential (stimulus) and pacemaker potentials
pacemaker potentials are called...meaning they are...like in the... spontaneous...self generated by neuron or tissue...cardio, digestive systems
action potentials are initiated at initial segemtn by voltage gated Na+ channels
action potential propagation: initial segment: the...are opened by... voltage gated na channels...changed membrane potential
initial segment is...which...area depolarized...stimulates the adjacent
adjacent area: voltage gated na channels, depolarization, nondecremental, stimulation of adjacent area
previous area undergoes the...and produces a refractory period...one directional flow
rates of condution for action potential if it is a small unmyelinated neuron .5m/s
rate of conduction for ap on a large myelinated neuron 100m/s (instantaneous)
rate of conduction is affected by diameter and myelination
diameter: larger axons = less resistance
myelination provides insulance, less leakage
what types of cells produce lipid insulation? oligodendrocytes or schwann cells
lipid insulation has...and... poor conduction...less leak
oligodendrocytes or schwann cells have less...compared to graded potentials decrementation
nodes of ranvier have a high concentration of...and allow for... voltage gated na channels...saltatory conduction
saltatory conduction is...because it doesnt have to... faster...go entire length of axon
efficiency of myelin: saves...saves...and is...efficient time...space...metabolically (fewer ions to move back)
demyelination heavy metal poisoning, multiple sclerosis (difficulty moving bec impulses aren't sent) and active herpes
3 types of synapses convergent, divergent and reverberating
convergent synapses have info from...and mean autonomic and somatic...many presynaptic neurons come together to effect a single postsynaptic neuron
divergent synapses start with...-> a small number of neurons...synapse on many (one message/many receptors)
divergent means there are multiple motor units
reverberating synapses are...meaning... cyclic....rhythmic activities
examples of reverberating synapses breathing and staying awake (reticular)
synapses can either be...which both are excitatory or inhibitory...graded potentials
excitatory synapses lead to... EPSP and depolarization
EPSP tells what is happening to next cell
excitatory synapses do not guarantee an action potential to occur
inhibitory synapses create...and...the membrane IPSP...hyperpolarize
inhibitory synapses do not lead to action potentials
electrical synapses: neurons are connected via..which allows... gap junctions...direct transfer of action potential
electrical synapses are...meaning there is one... bidirectional...point of origin but two different directions for the action potential (just not backwards)
electrical synapses can be found in cardiac and smooth muscle
electrical synapses are extremely fast
chemical synapses contain presynaptic cell, synaptic cleft, post synaptic cell
chemical synapsdes...transfer action potentials via... indirectly...neurotransmitters that diffuse across the cleft
chemical synapses flow in...down the.. one direction..axon hillock
most of the nervous system is connected via chemical synapses
in the presynaptic cell during chemical synapsing there is the...which has.... axon terminal...active zone and voltage gated ca channels
active zone contains...that contain... docked synaptic vesicles...neurotransmitters
voltage gated ca channels are opened via...and causes depolarization...ca++ influx
ca++ influx allows...to... neurotransmitters...fuse with cell membrane and be diffused across the cleft
neurotransmitters undergo...and the amount at which this occurs depends on... exocytosis...amount of Ca++
synaptic cleft is where the neurot diffuses
postsynaptic cell contains the...which is a... postsynaptic density...dense collection of neurotransmitter receptors
postsynaptic acivity involves 2 steps neurotransmitter binding and removal
neurotransmitter binding opens ligan (chemical) gated channels
removal of neurotransmitter involes...or... reuptake by axon termical or diffusion away from cleft...chemically inactivated (enzymes change shape)
neurotransmitter binding and removal occur at the postsynaptic density
excitatory postsynaptic potential: ...allow...ions into the cell (usually...) ligand or chemical gated channels...+...(na)
the ligand is the neurotransmitter
the depolarization of the excitatory postsynaptic potential = graded potential
IPSP: ...allows...ions into cell (...) and...ions out of the cell (...) ligand or chemical gated channels...-...(cl-)...+...(k+)
IPSP...the cell membrane and cause a... hyperpolarize..graded potential
stabilization means...and makes it.. cell remains at resting membrane potential...harder for stimulus to cause E/IPSP
synaptic integration means that graded potentials can sum
temporal summation means that 1 presynaptic neuron sends multiple APs, neurotransmitters and graded potentials
temporal summation must be close enough together in time
spatial summation is different presynaptic neurons sending out at the same time
spatial summation must be close enough togehter in space
graded potentials can last longer than an AP
one epsp can result in multiple aps
presynaptic factors affecting synaptic strength includ intracellular ca, axo axonic synapses, other presynaptic factors, neurotransmitters, reuptake and breakdown
amount of intracellular ca++..to presynaptic cell promotes... influx...release of neurotramitters
amount of intracellular ca++ removed from presynaptic cell determines the amount of neurotransmitter released
axoaxonic synapses are responsible for...and they send neurotransmitter from... modifying instructions...other axon and presynaptic receptors
axoaxonic synapses are common for pain
axoaxonic synapses alter...and create neurotransmitter release...presynaptic inhibition or facilitation
other presynaptic receptors include reeptors to other chemicals (hormones) and autoreceptors
autoreceptors detect...and result in... neurotransmitter...neg feedback mechanism
postsynaptic factors affecting synaptic strength receptor variability
receptor variability includes altering...and also can be... # of receptors (up/down regulating), receptor activity (signal transduction and second messenger systems)...desensitized
second messenger systems produce...effect from altering... domino...one part of membrane to effect the next part
overall actions of drugs and diseases- they...with any step... interfere...in pathway of synaptic transmission and reception
agonists...and antagonists... promote...work against
clostridium tetani block..to..and result in.. neurotransmitter release...inhibitory neurons..severe muscle contractions
clostridium botulinum blocks..to..and ...muscle contractions neurotransmitters release...excitatory neurons...decrease
black widow spider venom...neurotransmitter relase to...and results in... increases...excitatory neurons...increase muscle contractions
curare is used in...and binds to...but doesn't...and results in... poison darts...ACh receptors...ion channels...decrease muscle action
nerve gas (sarin) inactivates...and the continued presence of...causes... acetylcholinesterase...ACh...continued depolarization of postsynaptic neuron and voltage gated na channels inactivated
nerve gas ultimately results in desensitization of ACh receptors
neuromodulators ...the synapse not... impact...drive
neuromodulates alter... action of synapse (presynaptic cell action and postsynaptic cell response)
neuromodulators have many...such as... sources...hormones, paracrine, immune system, presynaptic cell
neurotransmitters affect...of the... ion channels...postsynaptic cell
neurotransmitters can have an...or...effect excitatory or inhibitory
ACh is found in the...and is received by... somatic ns, para and symp...nicotinic receptors and muscarinic receptors
nicotinic receptors are refered to as...which causes ionotropic receptors...opening of both na and k channels
na electrochemical gradient is greater than k electrochemical gradient
which ion will have the greater movement in nicotinic receptors? will this result in depo or hypo? na+...depo (EPSP)
nicotinic receptors are found at...and also...and are responsible for... neuromuscular junctions...reward pathways in the brain (tobacco)...cognition, learning and memory
what disease is associated with a loss of ACh neurons alzheimers
muscarinic receptors function with...occur in the...and... g protines...brain and organs/glands
muscarinic receptors are considered...meaning they interfere with... metabotropic...metabolism
in the heart ACh muscarinic receptors... inhibit pacemaker (parasympathetic division)
antagonist to ACh muscarinic receptors that increases heart rate atropine
biogenic amines major cns neurotransmitters and modulators (some pns)
categories of biogenic amines catecholamines and serotonin
catecholamines include dopamine, NE, E and monoamine oxidase
catecholamines are the amine group attached to a...formed from the...and are... catechol ring...synthesis of tyrosine (amino acid)...metabotropic (funciton via g proteins)
dopamine is a precursor to...which is a precursor to... NE...E
dopamine in the...leads to... CNS...parkinson's (reduced motor control) and cocain addiction (blocks re-uptake)
NE is in the...and is considered... CNS and PNS...adrenergic neurons and receptors
adrenergic means neurons and receptors... release and respond to NE
E is in the...is also considered....and is most commonly produced as a... CNS & PNS...adrenergic neurons and receptors...hormone (adrenal medulla)
E=...and is also called...which is a... neurotransmitter...adrenaline...hormone
monoamine oxidase breaks down...in order to... catecholaimes in synaptic cleft...keep neurotransmitter in cleft
MAO inhibitors reduce...which is used as a treatment for...and there is an increased presence of rate of breakdown...depression...dopamine and norepinephrine
serotonin is a...and is formed from neuromodulator...synthesis from essential amino acid tryptophan
serotonin is...for...and...for... excitatory...muscle control..inhibitory...senses
increased activity of serotonergic neurons when awake
serotonin specific...treat...and leaves... reuptake blockers...depression...serotonin in synaptic cleft
Created by: handrzej