5.1.3 Flashcards
What does the pacinian corpuscle do?
when pressure is applied
membrane surrounding neurone stretches
causes gaps/spaces to appear between phosopholipids
opens Na+ channels
Na+ rushes in a long electrochemical gradient generating an action potential
How is resting potential maintained and established?
3Na+ out and 2k+ actively transported
using the Na+ k+ pump some K+ leaks back out
membrane is more permeable to K+
sodium voltage gated channels are closed
What happens when pressure is applied to the pacinian corpuscle?
membrane surrounding neurone stretches
What does the membrane surrounding the neurone stretching cause?
gaps/spaces to appear between phospholipids
What happens when gaps / spaces appear between phospholipids?
Na+ channels open
What happens when Na+ channels open?
Na+ rush in along electrochemical gradient
What happens when Na+ rush in along the electrochemical gradient?
generates an action potential
How many volts is resting potential?
-70mV
What is the ratio for Na:K in the resting potential?
3Na out and 2K in
How are 3Na+ transported out and 2 K+ transported in?
active transport
using Na+/K+ pump
What happens to some K+ in the Na/K+ pump?
Some K+ leak out
Why do some K+ leak out of the Na+/K+ pump?
the membrane is more permeable to K+
What happens to the sodium voltage gated channels in resting potential?
CLOSED
What happens in depolarisation?
Na+ voltage gated channels open
Na+ rush into membrane along the electrochemical gradient
inc membrane potential
positive feedback
What channels open in depolarisation?
Na+ voltage gates channels
What ion rushes into the membrane along the electrochemical gradient in depolarisation?
Na+
What happens when Na+ voltage gated channels close?
repolarisation
What happens in repolarisation?
Na+ voltage gated channels closed
K+ voltage gated channels open
K+ rush out of membrane along electrochemical gradient
dec membrane potential
What channels open and close in repolarisation?
Na+ close
K+ open
What happens to K+ in repolarisation?
rush out of membrne along electrochemical gradient
What happens to membrane potential in depolarisation?
inc
What happens to membrane potential in repolarisation?
dec
What happens in the refractory period?
K+ voltage gated channels close but there is an overshoot of K+ ions
hyperpolarisation
What channels close in the refractory period?
K+ voltage gated channels close
What is beneficial about the refractory period?
allows action potential to move in 1 direction along the neurone
How does myelination help action potentials?
membrane is only depolarised at nodes of ranvier
creates a longer localised circut
inc rate of impulse transmission
Outline synaptic transmission?
Action potential trqavels down presynaptic membrane
Ca2+ channels open
Ca2+ rushes into presynaptic membrane along electrochemical gradient
rush of Ca2+ causes vesicles containing neurotransmitter to fuse with PSM
release neurotransmitter into the synaptic cleft by exocytosis
acetyl cholien diffuse across synaptic cleft
acetyl choline binds to receptors on Post synpatic membrane
receptors found on Na+ voltage gated channels
causing them to open
Na+ rush in and depolarise membrane trigger action potential
enzyme breaks acetyl choline
Na+ channels close
Acetyl choline diffuse back into the presynaptic membrane
What is temporal summation?
filters out background of low level stimuli
What is spatial stimuli?
allows convergence
impulses from more than 1 neurone to be passed to a single eurone
filters out background of low level stimuli
What is the role of the synapse?
allows neurones to COMM
ensures transmission in 1 direction
allows convergece
allows divergence
filters out backgroud of low level stimuli
Why does the synpase allow transmission in 1 direction?
Vesicles containing neurotransmitter ony fround in presynaptic knob
receptors on Na+ voltage gated channels can onl be found on post synaptic membrane
Calcium chanel only found on presynaptic membrane
What isa sensory neurone
dendron present and links to cell body
cell body centre of neurone
dendrites dont connect to cell body
axon shorter than motor
neurone connects t sensory receptor
What does a relay neurone look like?
short axon
dendrites present
found in CNS
What does a motor neurone look like?
no dendrons
cell body on end
dendrites connected to cell body
axon longer than sensory neurone
neurone endsat motor end plate
What travels down the presynaptic membrane?
action potential
What opens when the action potential travels down the presynaptic membrane?
Ca2+ channels open
What rushes in along the electrochemical gradient when Ca2+ channels open?
Ca2+
What does the rushing in of Ca2+ cause?
causes vesicles containing neurotransmitter to fuse with the presynaptic membrane
How is neurotransmitter released into the synpatic cleft?
exocytosis
What diffuse across synaptic cleft?
acetyl choline
What does acetyl choline do after diffusing across the synaptic cleft?
binds to receptors on post synaptic membrane
Where are the receptors on the post synaptic membrane found?
on Na+ voltage gated channels
What happens when acetyl choline binds to receptors on post synaptic membrane?
Na+ voltage gated channels open
What happens when Na+ voltage gated channels open?
Na+ rush in and depolarise the membrane
triggering action potential
What breaks acetyl choline down?
enzymes
What channels close when acetyl choline is broken down by enzymres?
Na+ voltage gated channels
What happens to acetyl choline when Na+ voltage gated channels c.lose?
diffuse back into presynaptic membrane
