neuronal communication Flashcards
outline the ways in which the structure of a motor and sensory neurone are similar
both have 1 dendrite(s) ; 2 an axon ; 3 a cell body with a , nucleus / named organelle ; 4 myelin sheath / myelinated / (covered with) Schwann cell / nodes of Ranvier ; 5 voltage-gated channels / sodium-potassium (ion) pump ; QWC dendrite(s) axon(s) cell body(ies) myelin (or derived term) schwann
Why is the Pacinian corpuscle described as a transducer?
it converts energy (mechanical) into ,
another / different , form of energy (electrical)
Deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to Na+. Suggest why.
idea that deformation of membrane will allow more Na+
through because
1 (the increased pressure) causes
sodium (ion) channels to open ;
2 (temporary) gaps / holes / spaces , appear ,
between the phospholipids / in the bilayer ;
The generation of an action potential follows the ‘All-or-Nothing’ law.Explain what this means.
if the , stimulus is not strong enough /
threshold (value) is not reached /
depolarisation (of membrane) is insufficient ,
then , it / an action potential , is not ,
generated / AW ;
Describe how information about the strength and intensity of a stimulus is communicated to the brain.
1 idea that it is represented by the frequency of the
action potentials ;
2 high , frequency / rate (of generation) ,
of action potentials shows ,
a strong / an intense , stimulus ;
Suggest an explanation for the fact that action potentials are not generated constantly whilst wearing clothes.
action potentials not generated because 1 sodium (ion) channels (remain) open / resting potential not re-established ; 2 idea of ions being in the wrong place for correct ion movement (across membrane) ;
Outline the roles of synapses in the nervous system.
1 allows , neurones to communicate / cell signalling ;
2 ensure transmission (between neurones)
in one direction (only) ;
3 allows , convergence / impulses from more than one
neurone to be passed to a single neurone ;
4 allows , divergence / impulses from a single neurone
to be passed to more than one neurone ;
5 idea that filters (out) , ‘background’ / low level , stimuli
or
ensures that only stimulation that is strong enough
will be passed on ;
6 prevents fatigue / prevents over-stimulation ;
7 allows many low level stimuli to be amplified ;
8 idea that presence of inhibitory and stimulatory
synapses allows impulses to follow specific path ;
9 permits , memory / learning / decision making ;
Name one chemical that transfers a nerve impulse from one neurone to another.
acetylcholine
Suggest the part of the neurone where the plasma membrane has TRPA1 receptors.
either
post-synaptic membrane ;
(TRPA1) prevents attachment of (named) neurotransmitter
to its receptor ;
or
pre-synaptic membrane / (pre)synaptic knob /
axon terminal / bouton / synaptic bulb ;
(TRPA1) prevents , release of (named) neurotransmitter /
influx of calcium ions ;
Explain the difference in the speed of conduction of an action potential along the length of a myelinated neurone and a non-myelinated neurone.
in myelinated neurones
1 conduction faster in myelinated neurone ; ora
2 depolarisation / action potential , can only occur
where (voltage-gated / Na(+)) channels present ;
3 idea that myelinated neurones have long(er) sections
with no, (voltage-gated / Na(+)) channels present ;
4 ion , movement / transfer ,
can only take place at the gaps / nodes ; ora
5 longer local circuits / fewer local circuits ;
6 saltatory conduction /
action potential jumps from node to node ; ora
suggest, with reasons, the effects that botulinum toxin may have once it has entered a neurone.
1 vesicle cannot fuse with cell membrane
and acetylcholine not secreted ;
2 protease / enzyme / toxin / it ,
hydrolyses ,
VAMP / SNARE / protein / peptide bonds ;
3 (because of hydrolysis)
VAMP (protein) cannot bind to SNARE (complex) ;
4 microtubules broken down so vesicle cannot move
towards membrane ;
State one way in which the nervous system decreases the heart rate.
impulses along parasympathetic nerve /
impulses along vagus nerve /
nerve endings releasing acetycholine ;
Describe and explain how the resting potential is established and how it is maintained in a sensory neurone.
pumping / active 1 sodium-potassium pump , uses ATP / uses energy / by active transport / (pumps) actively ; 2 pumps / actively moves , sodium ions / Na+ , out of , cell / axon / neurone , and , potassium ions / K+ , in ; passive / diffusing 3 K+ , diffuse / move / flow / leak , (freely) back out (of cell) ; 4 membrane less permeable to Na+ / fewer Na+ channels open , so fewer Na+ , diffuse / move / flow / leak , back in ; ora 5 voltage-gated (Na+) , channels closed ; 6 AVP ; QWC sodium-potassium pump, ion(s), diffuse (or derived term), permeable, voltage-gated
What term is used to refer to the value of −50 mV
threshold (potential / value / voltage) ;
Comment on the relationship between the strength of a stimulus, and the resulting action potential,
1 idea that only stimuli , that reach / are greater than ,
threshold value / -50mV ,
produce an action potential ; ora
2 (when stimulated) action potential either occurs or
does not / all-or-nothing (law) ;
3 idea that the action potential is the same
(magnitude / size) ,
no matter how strong the stimulus /
even if strength of stimulus increases ;
4 idea that a strong stimulus produces
many action potentials (in rapid succession) ;
Suggest why this lactate is converted into pyruvate by the hepatocytes (liver cells) rather than by the respiring cells in which it is produced.
1 hepatocytes can tolerate , lactate / low pH
(which would otherwise be toxic) ;
2 hepatocytes have / (other) cells do not have ,
enzymes to ,
metabolise lactate / catalyse this reaction ;
3 (conversion of lactate) requires oxygen and ,
muscle cells do not have enough oxygen /
O2 is not available during anaerobic respiration /
O2 is sufficient in hepatocytes ;
Explain what might happen to a person if the liver did not break down insulin.
1 blood glucose (concentration) would fall ,
too low / below normal level ;
2 idea that
glucose would continue to be taken up by ,
cells / liver / muscle (results in low blood glucose)
or
idea that
glucose is continually converted into glycogen /
would store too much glucose as glycogen ;
3 (mitochondria eventually) cannot ,
release enough energy / generate enough ATP
(as less available glucose in blood) ;
4 coma / death ;
5 AVP ;
State the name given to this process of communication.
cell signalling ;
State the name given to the gap between the two neurones at this junction.
synaptic (cleft / space / gap) ;
Outline how the first neurone communicates with the second neurone across the gap.
1 (named) neurotransmitter / acetylcholine , released from
pre-synaptic / first , cell / membrane ;
2 diffuses across , gap / cleft / synaptic cleft
or
reaches second , neurone / cell / membrane , by diffusion ;
3 attaches to , receptors / binding sites of sodium channels ,
on post-synaptic membrane / membrane of second cell ;
4 neurotransmitter / acetylcholine , broken down (in cleft) ;
QWC
neurotransmitter, acetylcholine,
pre-synaptic / presynaptic, diffuse / diffusion,
synaptic cleft, receptor,
post-synaptic / postsynaptic
Outline the importance of the junctions between neurones in the functioning of the nervous system.
1 ensures movement of , impulse / action potential ,
in one direction (only) ;
2 integration
or
one neurone can ,
connect to / receive impulses from / transmit impulses to ,
many neurones ;
3 allows summation ;
4 idea that filters out , ‘background’ / low level , stimuli
or
ensures that only stimulation that is strong enough
will be passed on;
the structure of a motor neurone differs from that of a sensory neurone
the motor neurone - structure
the cell body is at (one) end of the , neurone / cell
or
the cell body is in , brain / spinal cord / CNS
or
dendrites connected (directly) to cell body
or
long(er) axon
or
no dendron
or
axon , connects to / ends at , effector / motor end plate ;
the function of a motor neurone differs from that of a sensory neurone.
the motor neurone - function
carries , impulse(s) / action potential(s) ,
from , brain / spinal cord / CNS / relay neurone
or
carries , impulse(s) / action potential(s) ,
to , effector / muscle / gland ;
Describe the function of myelin sheath
structure A / Schwann cell / it , produces myelin ;
(electrical) insulation / insulates ;
prevents movement of ions , into / out of , neurone / axon
or
prevents depolarisation ;
speeds up , conduction / transmission / passage , of ,
impulse / action potential ;
action potentials / local circuits / depolarisation /
only occur at , gaps / nodes (of Ranvier) ;
saltatory conduction / described ;
Name the process by which acetylcholine travels across the synaptic cleft.
diffusion
A feature of synapses is that they allow transmission in only one direction.State how this is achieved.
idea that only the presynaptic neurone ,
produces / releases / contains ,
acetylcholine / ACh / (neuro)transmitter ;
only the presynaptic membrane has ,
Ca(2+) / calcium (ion) , channels ;
idea that only the postsynaptic , membrane / neurone ,
has (ACh) receptors ;
ACh broken down at postsynaptic membrane ;
Atropine is a similar shape to acetylcholine. The presence of atropine prevents the initiation of an action potential in the post-synaptic neurone.Explain how the presence of atropine in the synapse will prevent the initiation of an action potential.
idea that atropine , binds to / occupies / competes for ,
(ACh) receptor on postsynaptic ,
membrane / neurone ;
idea that prevents ACh binding / blocks binding site /
blocks receptor ;
ion gates / ion channels / sodium channels /
protein channels , do not open / remain closed ;
Na+ cannot enter / K+ cannot leave ,
neurone / (nerve) cell ;
no / insufficient , depolarisation / postsynaptic potential /
excitatory postsynaptic potential / epsp /
generator potential ;
(so) does not reach threshold (value / potential) ;
Nerve gases have been used as chemical weapons. Some nerve gases act by inhibiting acetylcholinesterase, prolonging the effect of acetylcholine.Suggest how atropine could act as an antidote to nerve gas.
idea that will , bind to / occupy / compete for / block ,
(some of ACh) receptors ;
so acetylcholine / ACh , cannot bind / less likely to bind
(to receptor / to postsynaptic membrane) ;
prevents / reduces ,
constant stimulation / overstimulation /
constant depolarisation ,
of postsynaptic neurone
or
prevents / reduces ,
constant firing of action poten
Outline the hormonal and nervous mechanisms involved in the control of heart rate.
drenalin(e) increases ,
heart rate / stroke volume / cardiac output ;
cardiovascular centre in medulla oblongata ;
idea of nervous connection to , SAN / sino-atrial node ;
(which) controls frequency of waves of ,
excitation / depolarisation ;
vagus / parasympathetic , nerve decreases heart rate ;
accelerator / sympathetic , nerve increases heart rate ;
high blood pressure detected by ,
stretch receptors / baroreceptors ;
low blood pH / increased levels of blood CO2 ,
detected by chemoreceptors ;
(receptors) in , aorta / carotid sinus / carotid arteries ;
QWC
cardiovascular centre, medulla oblongata,
sino-atrial node, vagus or parasympathetic,
carotid, accelerator or sympathetic,
chemoreceptor
Suggest why MS is described as an auto-immune condition.
attacked by the body’s (own) immune system ;
(immune system) mistakes / treats / recognises ,
body cells / neurones / myelin ,
as , ‘foreign’ / non self ;
correct ref. to , antibodies / (named) phagocytes /
(named) B lymphocytes / (named) T lymphocytes ;
Explain why this damage leads to a loss of sensation.
(damage to) myelin / sheath / Schwann cell(s) ;
removes / has less , insulation ;
interferes with / slows / stops ,
conduction of , (nerve) impulse / action potential
or
slows / stops / prevents , saltatory conduction / described ;
occurs , in sensory neurones /
towards brain / towards CNS /
from sensory organ / from receptor ;
Describe the structure of the myelin sheath
myelin / myelinated / lipid / fatty (sheath) ;
(Schwann) cell, wrapped around / surrounds / AW, axon ;
except at nodes of Ranvier / (sheath) not continuous /
presence of gaps (in the sheath) ;
Suggest why an increase in temperature results in an increase in the speed of conduction.
increased kinetic energy / KE so, ions diffuse, across (axon) membrane / into neurone / into cell / between nodes / along neurone, more quickly or faster movement of (neurotransmitter) vesicles / exocytosis (of neurotransmitter) or neurotransmitter diffuses more quickly across, synapse / synaptic cleft or neurotransmitter (ACh) broken down by enzyme (acetylcholinesterase) more quickly ; faster diffusion of ions leads to, faster depolarisation or shorter duration of action potential or shorter refractory period or faster repolarisation ;
As the temperature continues to increase, it reaches a point at which the conduction of the impulse ceases. Suggest why.
ion, channels / pumps,
disrupted / denatured / no longer function ;
fluidity of, membrane / phospholipid / bilayer, disrupted ;
(named) synaptic enzymes denatured ;
Outline the events following the arrival of an action potential at the synaptic knob until the acetylcholine has been released into the synapse.
calcium channels open ;
Ca2+ / Ca++ / calcium ions , enter / diffuse into,
acetylcholine / ACh / neurotransmitter, in vesicle(s) ;
(synaptic) vesicles move towards presynaptic membrane ;
vesicles fuse with membrane ;
release acetylcholine, by exocytosis , into synaptic cleft
QWC
channel(s), vesicle(s),
neurotransmitter, presynaptic / pre-synaptic,
exocytosis, cleft,
Where, precisely, are acetylcholine receptors found?
postsynaptic membrane(s) (in , neurone / neuromuscular junction) ;
suggest and explain the effect that nicotine(similar shape as acetylcholine) has on the nervous system.
Effect Nicotine slows down rate of / stops, transmission of, action potentials / nervous impulses; Plus any 2 of the following: Explain binds to receptor; (nicotine) has the same response / opens Na+ channels / causes depolarisation ; nicotine remains in receptor for longer ; idea that receptor , remains in refractory stage for longer / unable to return to standby condition / cannot be reactivated ;
compare the structure and function of the dopamine synapse and the neuromuscular junction.
e structure mitochondria or vesicles or postsynaptic receptors ; NMJ membrane(s), wavy / AW * ora or receptors different (shape) or enzymes in different places ; function (neuro)transmitter, released / crosses gap or changes potential difference / AW ** or enzymes break down (neuro)transmitter ; different neurotransmitters / ACh vs. dopamine or muscle contraction vs. nerve impulse or different enzymes ;
Schizophrenia is a condition in which there is a higher than usual level of dopamine in certain areas of the brain.
Suggest why phenothiazine is used to treat schizophrenia
(drug) occupies / blocks / binds to, (dopamine) receptors ;
without causing, action potential / response ;
reduces effect of dopamine / is a dopamine antagonist ;
