Neuronal Communication (key points) Flashcards
most sensory nerve endings are transducers, what does this mean?
convert form of energy to another - electrical impulse)
pacinian corpuscle
pressure sensor on skin
series of concentric rings of connective tissue wrapped around nerve cell
pressure on skin changes and deforms the connective tissue so pushes against nerve ending
sodium potassium pump does what?
3 sodium out
2 potassium in
create potential gradient when channels closed
myelin sheath made from
Schwann cells
generator potential
a small depolarisation
what causes sodium channels to open?
they are voltage-gated so changes in p.d across the membrane causes it
self-perpetuating
once AP starts, carries on till end of neurone
all-or-nothing response?
all APs same magnitude at +40mV
same intensity
repolarisation
potassium ions out cell after AP so brings p.d back to negative inside
hyperpolarised
p.d overshoots slightly
refractory period
short time after AP, impossible for another because sodium and potassium in wrong places
local current
movement of charged particles along neurone from high conc. to low
AP can’t reverse directions because
of the the conc. gradient
saltatory conduction
AP jumps because sodium ions only diffuse at nodes of Ranvier, local currents elongated, jumping speeds transmission of AP up to 120m/s
determine intensity of stimulus by
frequency of APs arriving in sensory region of brain
