Neuronal communication q's Flashcards
outline the ways in which the structures of a sensory neurone and a motor neurone are similar
both have:
- dendrites
- an axon
- a cell body w/ a nucleus
- mylein sheath
- voltage gated channels / sodium - potassium ion pump
explain the effect that this sweating will have on the body
- evaporation will have a cooling effect
- heat supplied by body is used for evaporation
- water has a high latent heat of vaporisation
suggest why shivering occurs during fever
- to incr body temp as it is lower than the ‘new’ set point even though body is hot
- as the new ‘ normal’ body temp is higher , the body is using shivering to raise the temp of the internal environment
explain why it is not a good idea to give alcohol to someone with hypothermia
- vasodilation results in more blood nearer to the skin surface
- will lose more heat
- organs will not be able to maintain function
- ref to lack of enzyme activity
why is the pacinian corpuscle described as a transducer
it converts energy into another form of energy
deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to Na+ - suggest why
the increased pressure causes the Na+ to open
gaps appear between phospholipids
the generation of an AP follows the ‘all of nothing’ law - explain what this means
if the stimulus is not strong enough, then an AP is not generated
describe how info about the strength + intensity of a stimulus is communicated to the brain
it is represented by the frequency of the AP
high frequency of AP shows a strong/ intense stimulus
suggest an explanation for the fact that AP are not generated constantly whilst wearing clothes
AP not generated bc :
- sodium ion channels remain open
- ions being in the wrong place for correct ion movement across membrane
outline the roles of the synapses
- allows cell signalling
- ensure transmission between neurones in one direction only
- allows impulses from more than one neurone to be passed to a single neurone
- allows impulses from a single neurone to more than one neurone
- ensures that only stimulation that is strong enough will be passed on
- prevents over stimulation
- allows many low lever stimuli to be amplified
- presence of inhibitory + stimulatory synapses allow impulses to follow specifc paths
- permits memory
name one chemical that transfer a nerve impulse from one neurone to another
- acetylcholine
suggest the part of the neurone where the plasma membrane has TRPA1 receptors
post synaptic membranes - TRPA1 prevents attachment of neurotransmitter to its receptor
pre synaptic membrane - TRPA1 prevents release of neurotransmitter
A - sinosoid
B - Branch of bile duct
C - Branch of hepatic portal vein
D - Branch of hepatic artery
E - Branch of central vein
suggest a reason for the accumulation of high conc of NAPQ1 in liver cells
- bc there is not enough glutathione to metabolise it
- enzymes catalysing glutathione reaction is in short supply
- the NAPQ1 cannot cross the cell surface membrane
name the liver cells that can lead to regeneration + type of cell division they carry out
hepatocytes
mitosis
A - cytoplams
B- cell surface membrane
C - nucleus
explain the diff in the speed of conduction of an AP along the length of a myelinated neurone + non myelinated neurone
in myelinated neurones
- conduction faster
- AP/ Depolarisation can only occur where Na+ channels present
- myelinated neurones have longer sections w/ no Na+ channels present
- ion movement can only take place at the nodes
- longer local circuits
- saltatory conduction / AP jumps from node to node
name the part of a neurone from which aCh is secreted
presynaptic membrane
suggest w/ reasoons the effects that toxin would have once it has entered a neurone
- vesicle cannot fuse w/ cell membrane + aCh not secreted
- toxin hydrolyses protein
- bc of hydrolysis no binding complec
- microtubulues broken down so vesicle cannot move towards membrane
process that causes glycogen to be broken down into glucose
glycogenolysis
2 hormones which increase the heart rate
adrenaline
noradrenaline
state a way in which the NS decreases the HR
- impulses along parasympathetic nerve
- impulses along vagus nerve
- nerve endings releasing acetlycholine
describe and explain how the resting potential is established and how it is maintained in a sensory neurone
pumping active
- sodium - potassium pump uses ATP
- The na/k pump activtely moves 3 Na+ out of + 2K+ into axon
passive/diffusing
- k+ diffuse freely back out of cell
- membrane less permeable to Na+ , so fewer Na+ diffuses back in
- voltage gated na+ channels closed
comment on the relationship between the strength of a stimulus + the resulting AP
- only stimulu that reach threshold value produce an AP
- when stimulated AP either occurs or does not
- AP is the same size no matter how strong the stimulus
- strong stimulus produces many AP
- (strong stimulus increases frequency but not magnitude of action potential )
outline how the first neurone communicates with the second neurone
acetylcholine released from membrane
diffuses across synaptic cleft
attaches to receptors on post synaptic membrane
acetlycholine broken down in cleft
outline the importance of the junctions between neurones in the functions of the nervous system
ensures movement of AP in one direction only
one neurone can transmit impulses to many neurones
allows summation
ensures that only stimulation that is strong enough will be passes on
permits memory
cell signalling
animals that are able to regulate + maintain their core body temp within narrow limits
endotherms
the incr in the diameter of the lumen of an arteriole to allow more blood flow to flow through
vasodilation
name a hormone that increases the metabloic rate + so generates heat
adrenaline
name the part of the brain where the thermoregulatory centre is located
hypothalamus
diff in the structure of motor+ sensory
m:
cell body at the end
no dendron
longer axon
cell body in CNS
dendrites connect directly to cell body
S:
cell body in middle
dendron present
shorter axon
cell body PNS
dendrites dont connect directly to cell body
describe the function of mylein sheath
- schwann cells produce myelin
- insulination
- prevents depolarisation
- speed up conduction of AP
- AP only occur at nodes of ranvier
- saltatory conduction impulses jumps from node to node
name the process by which acetly choline travels across the synaptic celft
diffusion
a feature fo synapses is that they allow transmission in only one direction . state how this is acheived
- Ach broken down at psot synaptic membrane
- only the presynaptic neurone contains ach
- only the postsynaptic neurone has Ach receptors
- atropine binds to receptors on post synaptic neurone
- blocks receptors
- ion channels remain closed
-Na+ cannot enter neurone - no depolarisation
- so doesnt reach threshold potential
- will block some of Ach receptors
- so Ach cannot bind to receptor
- prevents overstimulation
E , A AND F, D B
suggest why tetradotoxin is not toxic to the puffer fish
receptor is different
suggest why MS (mustiple sclerosis) is described as an autoimmune condition
attacked by bodyes immune systems
immune system recognises body cells as foreign
explain why this damage leads to loss of sensation (MS)
- damage to myelin/ schwann cell
- removes insulation
- prevent saltatory conduction
- occurs in sensory neruones
describe the structure of the feature of mylein sheath
- myelin sheath
- schwann and surrounds axon
- expect at nodes at ranvier
- myelination produces gretaer speeds
- unmyelinated needs larger diameter to produce same speed
- myleinated speed 25/30ms and unmyelinated speed 3/30 ms
axon diameter
- larger axon produces greater speeds
- 15 vs 3
- 1000 vs 30
sugegst why an increase in temp results in the speed of conduction
- increased kinetic energy so ions diffuese across memebrane more quickly
- incr Ek so neurotransmiiter diffuses more quickly across synaptic cleft
as the temp continues to increases, it reaches a point at which the conduction of the impulse ceases
- ion channels disrupted
- fluidity of phospholipid bilayer disrupts
- synaptic enzymes denatured
outline the events follwing the arrival of an action potenial at the synaptic knob until the acetylcholine has been released into the synapse
- Ca2+ channels open
- Ca2+ enter
- Ach in vesicle
- synaptic vesicles move towards presynaptic membrane
- vesicles fuse w/ membrane
- release Ach by exocytosis into synaptic cleft
desrcibe breifly one example of each of the following types of animal behaviour:
- habituation
- stimulus : touch
- sea anemone withdrawing tentacles
- responses stops over time
describe the componenst + events involved in a relfex arc
- AP in sensory neurone generated
- impulses slow down at synapses where a neurotransmitter is secreted to the post synaptic membrane of the relay neurone
- the impulse are further sent to the motor neurone which passes the nervous impulses to an effector
suggest one benefit to the quid relfex respose described above
mainatian balance
- kinetic energy converted to electrical energy
- movement of statolith moves sensory hairs
-membrane of sensory hairs depolarises
support is weak bc:
- classification based on pylogency
- statocysts could be an example of convergent evolution
- no AP in response to acid stimulus
- no voltage gated sodium channels open
- less depolarisation of receptor membrane/ fewer Na+ions moves in
explain how a pain receptor is an expmple of a transducer
converts chem energy to electrical energy
fucnction of mylein sheath
- saltatory conduction
- increase speed of AP transmission
- insulates axon
suggest how the immune system causes damage to the nervous system
- antigens on enurones
- antobodies against neurones
- phagocytes attack neurones
- fewer schwann cells
- less damaged mylein sheath
- no saltatory conduction
why is the transmission of action potenials along the axon slower in the absence of saltaotry conduction
- no nodes of ranvier
- shorter local current
- whole axon neeeds to be depolarised
dopamine neurone
- has a less -vce resting potential
- depolarisation shows less change
- AP peak is lower
- no clear refractory period
- AP duration is longer
- repolarisation is slower
resting potential set up by
- diff no/ of Na+/k+ pumps in neurone membrane
- diff no. of k+ ion channels
- steeper NA+ion grad in purkyne neurone
- more VG sodium + K+ ions in the purkyne neurone
- Na+ cannot enter , so no influx of Na+
- prevents depolarisation of membrane
-membrane remains at resting potential - prevents AP being generated
- impulse no conducted along axon
- so no release of neurotransmitter
explain how parlysisi of the diaphragm could lead to suffocation
diaphragm is paralysed so no change in vol of thorax( no increase), no change in pressssure in thorax (no decrease), no air drawn into lungs
- slow heart rate
- alows transmission of impulse from AVN to ventricles
- slows ventricular systole
- longer delay before ventricular systole begins
- incr time in relaxation
- conc of Ca2+ is prportational to the strength
- Ca2+ change from low to medium causes increase in membrane potential
- AP in presynaptic neurone leads to opening of Ca2+ channels
- Ca2+ causes release of neurotransmitter
- neurotransmitter cuases na+ channels to open in post synaptic neurone
- if threshold is exceeded this cuaes AP in postsynaptic neurone
conc may not be valid bc: - changes in Ca2+ conc may not be the cause of postsynaptic AP
- Ca2+ change from medium to high but no change in membrane potential