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neuronal communication Flashcards

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1
Q

Peripheral nervous system (2)

A
  • Nerves that branch off the CNS and attach to muscles and tissues
  • Branches out into sensory division and motor division- autonomic and somatic
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2
Q

Central nervous system

A
  • The brain and the spinal cord, mainly responsible for processing information
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3
Q

Somatic NS (4)

A
  • Part of the motor division that allows voluntary movements especially in muscle contracts
  • contain heavily myelinated axons for fast impulses
  • contains single neurones from CNS to effector organs

Eg lifting a weight

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4
Q

Autonomic motor system (5)

A
  • actions that are involuntary: reflexes
  • divided into sympathetic and parasympathetic systems
  • neurotransmitter involved: acetylcholine
  • axons are lightly myelinated
  • impulses are carried to glands and smooth muscle cells in organs

Eg responsible for the heart beating and the digestion of food (peristalsis)

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5
Q

Sympathetic motor system

A
  • part of the autonomic system
  • actions that occur to increase activity
  • controls urgent situations like an increase in heart rate
  • neurotransmitter: noradrenaline
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6
Q

Sympathetic actions for the following:

  • Salivary glands
  • lungs
  • kidneys
  • stomach
  • small intestine
A

Sympathetic:

salivary glands: saliva reduced 
lung: bronchi relaxed
Kidney: less urine secreted 
Stomach: peristalsis reduced 
Small intestine: peristalsis reduced
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7
Q

Stimulus

A

Changes in the internal/ external environment

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8
Q

Describe the structure of a neurone

A
  • Cell body: contains main organelles for the cell: nucleus, RER, mitochondria, ribosome which produce neurotransmitters
  • Dendron: extend and divide into dendrites and carry impulses towards the cell body
  • Axon: single extension that carries impulses away from cell body
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9
Q

Sensory neurones

A
  • carry impulses from sensory receptor cells to a relay neurone, motor neurone or the brain.
  • Contains one dendron that carries impulses towards the cell body and an axon to carry the impulse away from the cell body.
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10
Q

Relay neurone

A
  • Transmits impulses between neurones

- have multiple short axons and neurones

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11
Q

Motor neurones

A
  • Carry impulses from a sensory or relay neurone to an effector cell- eg muscle
  • contain many dendrites: multipolar
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12
Q

Schwann cells

A
  • Peripheral glial cell that produces myelin sheath that wraps around axons for insulation
  • this allows quicker transmission of impulses
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13
Q

How does the myelin sheath contribute to the speed of impulses (3)

A
  • In peripheral nerves they have ‘nodes of Ranvier’ around the axon which are gaps between myelin sheath
  • the sheath acts as an electrical insulator which quickens impulses
  • the nodes allow a jump (saltatory conductivity) for the impulses which is quicker than a continuous transmission in non-myelinated axons
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14
Q

Sensory receptor (6)

A
  • Convert stimulus into a nerve impulse which is picked up by sensory neurones (transducer)
  • They are specific to a single type of stimulus
  • mechano: pressure and movement
  • chemo: chemicals
  • thermo: temperature
  • photo: light
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15
Q

Pacinian corpuscle

A
  • Sensory receptors that detect mechanical pressure in the skin
  • most prominent in finger tips and toes as well as joints
  • contain stretch mediated sodium channels
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16
Q

How does the pacinian corpuscle convert mechanical pressure into an impulse? (4)

A
  • Pacinian corpuscle detects pressure in the skin and changes shape
  • this also changes the shape surrounding membrane of neurones and stretch sodium pumps
  • this allows sodium ion channels to open so that Na can diffuse up to the point where the cell is depolarised
  • this causes an action potential which is created by the generator potential and sends impulse to the CNS
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17
Q

Olfactory receptor

A
  • Chemoreceptor that detects smell in the nose
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18
Q

Cone cells

A

Photoreceptor that detects light wavelengths in the eyes

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19
Q

Resting potential

A
  • When a neurone is not transmitting any impulses and the outside of the membrane is more positively charged than the inside
  • The polarised membrane usually has a voltage of -70 mV
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20
Q

Sodium- potassium pump

A
  • Helps maintain resting potential by actively transporting 2 potassium ions into the cell and 3 sodium ions out
  • This creates an electrochemical gradient where sodium diffuses into the axon and potassium diffuse out
  • Potassium ion gates are mainly opened which enables potential
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21
Q

Action potential (5)

A

When the charges of the axon are reversed from -70 mV to +40 mV- neurones are depolarised

Change in voltage of the membrane above around -55 cause sodium ion channels to open and cause them to diffuse into the axon

When the voltage reaches +40, voltage gates sodium pumps close which allow more K to diffuse into the now more permeable membrane

This causes a more negative axon where it goes into hyperpolarisation

Once Na ions move out of the cell via the sodium/ potassium pump, the resting potential is reached

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22
Q

Repolarisation

A

This happens after the voltage- gated sodium ion channel closes

Voltage gated Potassium ion channels open which causes potassium to diffuse out of the axon, down its electrochemical gradient.

Causes the inside of the axon to be more negative than outside

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23
Q

Hyperpolarisation (4)

A

When the axon is repolarising, initially a lot of Potassium ions diffuse out of the axon.

This makes the inside of the axon more negative than its usual resting potential.

This causes the voltage- gates potassium ion channels to close which prevents the inside of the axon to be too negative.

Now the sodium-potassium pump controls the K+ and Na+ ions until resting potential is achieved

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24
Q

Explain what saltatory conduction is and evaluate its effectiveness.

A

This is the method in which electrical impulses travel across the axon at the ‘Node of Ranvier’ in myelinated axons.

Here, sodium ions can only pass through the membrane proteins in the nodes. This creates a ‘localised’ circuit between nodes, which the action potential jumps between.

This is much quicker than a wave depolarisation down an axon, as there are less places for sodium to transport.

This is also more energy efficient as less ATP is needed for reploarisation when using the sodium ion channels.

25
Q

Describe how the first neurone communicates with the second neurone across the gap. (6)

A

An action potential travels along the presynaptic neurone which causes Ca2+ channels to open and allow calcium to diffuse in the knob.

This pushes vesicles containing neurotransmitters towards the membrane.

Vesicles fuse with meme range and releases neurotransmitters from vesicles via exocytosis.

The neurotransmitters diffuse across the synaptic cleft and binds to receptors in the post synaptic neurone.

This cusses Na+ channels to open and causes diffusion of Na+ into post-synaptic knob. This causes a depolarisation.

Enzymes are released (such as acetylcholinesterase) to break down neurotransmitters.

26
Q

How are neurones adapted to cell signalling

A

The pre-synaptic knob allows storage of vesicles filled with neurotransmitters.

The PS knob also provides a larger surface area to release more neurotransmitters.

Specialised proteins in the post synaptic membrane such as ligand gated sodium channels- specified response to molecules.

27
Q

Importance of synapses.

A

Allows the transmission of impulse in one direction as neurotransmitters can only be released from the Pre-S knob.

Allows acclimatisation: prevents continuous response to unimportant stimuli.

Allows summation: never impulses from more than one neurone combine to create the same response.

Inhibitory synapse prevent the formation of an action potential in postsynaptic neurone.

28
Q

The use of ATP at a cholinergic synapse.

A

Formation of acetylcholine: combines choline and ethanoic acid.

Exocytosis: release of acetylcholine from the pre-synaptic neurone.

Formation and movement of vesicles which store acetylcholine.

29
Q

Compare the structure of the sensory and motor neurone.

A
  • Motor neurone has a longer axon.
  • The cell body in the motor neurone is terminal whereas it’s in the middle for the sensory neurone.
  • Motor neurone contains no dendrons whereas sensory neurone contains long dendrons.
30
Q

outline the ways in which the structure of a motor and sensory neurone are similar

A 
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
31
Q

Why is the Pacinian corpuscle described as a transducer?

A

it converts energy (mechanical) into ,

another / different , form of energy (electrical)

32
Q

Deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to Na+. Suggest why.

A

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 ;

33
Q

The generation of an action potential follows the ‘All-or-Nothing’ law.Explain what this means.

A

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 ;

34
Q

Describe how information about the strength and intensity of a stimulus is communicated to the brain.

A

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 ;

35
Q

Suggest an explanation for the fact that action potentials are not generated constantly whilst wearing clothes.

A 
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) ;
36
Q

Outline the roles of synapses in the nervous system.

A

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 ;

37
Q

Name one chemical that transfers a nerve impulse from one neurone to another.

A

acetylcholine

38
Q

Suggest the part of the neurone where the plasma membrane has TRPA1 receptors.

A

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 ;

39
Q

Explain the difference in the speed of conduction of an action potential along the length of a myelinated neurone and a non-myelinated neurone.

A

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

40
Q

suggest, with reasons, the effects that botulinum toxin may have once it has entered a neurone.

A

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 ;

41
Q

State one way in which the nervous system decreases the heart rate.

A

impulses along parasympathetic nerve /
impulses along vagus nerve /
nerve endings releasing acetycholine ;

42
Q

Describe and explain how the resting potential is established and how it is maintained in a sensory neurone.

A

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 ;

43
Q

What term is used to refer to the value of −50 mV

A

threshold (potential / value / voltage) ;

44
Q

Comment on the relationship between the strength of a stimulus, and the resulting action potential,

A

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) ;

45
Q

Suggest why lactate is converted into pyruvate by the hepatocytes (liver cells) rather than by the respiring cells in which it is produced.

A

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

46
Q

Explain what might happen to a person if the liver did not break down insulin.

A

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 ;

47
Q

Outline how the first neurone communicates with the second neurone across the gap.

A

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)

48
Q

Outline the importance of the junctions between neurones in the functioning of the nervous system.

A

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;

49
Q

A feature of synapses is that they allow transmission in only one direction.State how this is achieved

A

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 ;

50
Q

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.

A

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) ;

51
Q

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.

A 
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 potentials /
tetanus / (muscle) spasm ;
52
Q

Outline the hormonal and nervous mechanisms involved in the control of heart rate.

A
  1. adrenalin(e) increases ,
    heart rate / stroke volume / cardiac output ;
  2. cardiovascular centre in medulla oblongata ;
  3. idea of nervous connection to , SAN / sino-atrial node ;
  4. (which) controls frequency of waves of ,
    excitation / depolarisation ;
  5. vagus / parasympathetic , nerve decreases heart rate ;
  6. accelerator / sympathetic , nerve increases heart rate ;
  7. high blood pressure detected by ,
    stretch receptors / baroreceptors ;
  8. low blood pH / increased levels of blood CO2 ,
    detected by chemoreceptors
    9.(receptors) in , aorta / carotid sinus / carotid arteries ;
53
Q

Suggest why MS is described as an auto-immune condition.

A

1
2
3
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 ;

54
Q

Explain why this damage leads to a loss of sensation.

A 
1
2
3
4
(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 ;
55
Q

Suggest why an increase in temperature results in an increase in the speed of conduction.

A 
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 ;
56
Q

As the temperature continues to increase, it reaches a point at which the conduction of the impulse ceases. Suggest why.

A

ion, channels / pumps,
disrupted / denatured / no longer function ;
fluidity of, membrane / phospholipid / bilayer, disrupted ;
(named) synaptic enzymes denatured ;

57
Q

Outline the events following the arrival of an action potential at the synaptic knob until the acetylcholine has been released into the synapse.

A

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 ;

58
Q

suggest and explain the effect that nicotine(similar shape as acetylcholine) has on the nervous system.

A 
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
59
Q

difference between motor and sensory neurone

A 
motor neurone: 
cell body in the CNS
cell body at the end of neurone
longer axon
no dendron
sensory neurone:
cell body in PNS
cell body in middle of neurone
shorter axon
dendron present

biology module 5 mine (9 decks)

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