neuronal communication🧠 Flashcards
similarities between sensory and motor neurone structure
- cell body with nucleus
- axon
- dendrites
- myelin sheath
- voltage gated channels
which neurone transmits impulse from CNS
motor
why does shivering occur during fever
to increase body temp as it is lower than new set point
alcohol causes vasodilation why would it be bad to give to someone with hypothermia
- vasodilation results in more blood nearer to skin surface
- lose more heat
- lack of enzyme activity
why is the pacinian corpuscle described as a transducer
converts energy (mechanical) into a different form of energy (electrical)
why does deformation of plasma membrane at tip of neurone cause it to be more permeable to na+
causes Na+ ion channels to open
what is the all or nothing law of generating action potentials
- if stimulus is not strong enough then threshold not reached
- action potential not generated
how is info about strength of a stimulus communicated to brain
- represented by frequency of action potentials
- high frequency shows strong stimulus
why are action potentials not constantly generated when wearing clothes
sodium channels remain open
what are the roles of the synapses in the nervous system
- allow communication between neurones
- ensure transmission in one direction
- allow one neuron to connect to many neurones
- allows summation
- ensures only stimulation strong enough will be passed on
explain difference in speed of conduction between myelinated and non myelinated neurones
- myelinated has faster conduction
- depolarisation can only occur where Na+ channels present
- myelinated neurones have larger sections with no channels
- ion transfer can only take place at gaps
- saltatory conduction
name part of neurone where neurotransmitter is secreted
synaptic knob
what effect would a bacterial protease have in a neurone
neurone releases protein
- protease breaks down protein
- microtubules broken down so vesicle cannot move towards membrane
- vesicle cannot fuse with membrane and protein not secreted
what type of hormones are released into blood
endocrine
insulin is released from what region of pancreas
islets of langerhans
process that breaks glycogen down into glucose
glycogenolysis
state one way nervous system decreases heart rate
impulses along parasympathetic nerve
how is resting potential established and maintained in a sensory neurone
- sodium potassium pump uses ATP
- pumps 3 Na+ out of neurone and 2 K+ in
- K+ diffuse back out of cell
- membrane less permeable to Na+ so fewer diffuse back in
- voltage gated channels closed
process that makes voltage positive
depolarisation
process that makes voltage negative
repolarisation
process that makes voltage more negative than resting potential
-hyperpolarisation
minimum voltage for action potential is called
threshold potential
relationship between strength of stimulus and resulting action potential
- only stimuli that reach threshold produce action potential
- when stimulated action potential follows all or nothing law
- action potential is same size no matter how strong stimulus is
how do neurones communicate across synapse
- neurotransmitter released from pre synaptic membrane
- diffuses across synaptic cleft
- attaches to receptors on post synaptic membrane
- neurotransmitter broken down in cleft
differences between motor and sensory neurones
- sensory has dendron, motor does not have dendron
- sensory has short axon, motor has long axon
- sensory has cell body in the middle, motor has it at the end
- sensory dendrites at the end of dendron, motor has dendrites directly connected to cell body
action potentials all have the same
size
what happens to plasma membrane when neurone is stimulated
depolarisation
describe function of the cell that covers axon
- Schwann cell produces myelin
- insulation
- action potentials can only occur at nodes of ranvier
- saltatory conduction
how do synapses only allow transmission in one direction
only postsynaptic membrane has receptors
atropine has similar shape to acetylcholine, explain how the presence of atropine in the synapse prevents the initiation of an action potential
- atropine binds to receptors on post synaptic membrane
- prevents acetylcholine from binding
- sodium channels do not open
- Na+ cannot enter neurone
- no depolarisation
- does not reach threshold
when is the membrane most permeable to potassium ions
repolarisation
why does increase in temp increase speed of conduction
neurotransmitter diffuses across synapse faster
outline the events following the arrival of an action potential at synaptic knob until the acetylcholine has been released into the synapse
- calcium channels open
- ca2+ diffuse
- acetylcholine in vesicle
- vesicles move towards presynaptic membrane
- vesicles fuse with membrane
- release acetylcholine by exocytosis into synaptic cleft
specialised cells in retina of eye respond to..
intensity and wavelength of light
specialised cells in tongue and nose detect what type of stimuli
chemical
