Z332 midterm 2 Flashcards
membrane permeability due to
number and type of channels that are open
gated channels
let specific ions through in respone to stimulus; change permeability to that ion, chages membrane potential
transduction
changing signal from one form to another ; converstion of a signal into a change of potential in a sensory neuron
exteroreceptors
at/near body surface, signals outside body
interoreceptors
signals inside body
proprioceptors
skeletal muscles, tendons, joints, ligaments, connective tissues
electromagnetic energy receptors
photoreceptors, electroreceptors, magnetoreceptors
rods and cons
photoreceptors
rods: gray scale
cones: red, gree, blue
transduction of specific color info…
activation of different receptor combinations which are then interpreted as the color in the visual association cortex of the cerebrum
photoreception elctromagnetic to chemical messenger
photon collides with cis retinal –> trans retinal
photoreception chemical signal –> change in membrane potential
trans retinal activates enzyme that effects membrane potential
rhodopsin
opsin + retinal
chemoreceptors
olfaction, gustatory, vomerolfaction
olfaction
odorant molecule binds to receptor portein that causes chemical cascade. causes change in membrane potential.
several chemical signlas transduced into change in potential
mechanoreceptors
hair cells (vestibular - acceleration, cochlear organs - sound waves)
mechanial energy transduction
acceleration imposed on hair cell, kinocilium shif causes mechanically gated ion channels to open and change in potential
proprioception
relative positon of body parts (mechanoreception)
muscle stretch transduced into
change in membrane potential
touch, vibration, pressure sensations of skin
meissner, merkel, hair root plexus, pacinian, ruffini
sensory receptor adaptation
reduction in amplitude of graded potentail of sensory receptor during maintained, constant stimulus
rapid adaptation
registers chaange in stimulus
meissner, hair root plexus, pacinian
slow adaptation
monitor stimulus, sustained response (pain, tension, chemical comp of blood)
merkel disc, ruffini
nociceptors
respond to noxious or painful stimuli, free nerve ending
chemical: cytokines released from damaged tissue
thermal: increaes frequency of nerve impulses in resposne to cold,
mechanical:
osmoreceptors
chemoreceptors that respond to osmotic pressure of body fluids (in hypothalamus)
baroreceptors
mechanical receptors that sense blood pressure
graded potential
localized, dendrites an cell bodies, decremental ,short lived, no refractory period
excitatory postsynaptic potential
results in depolarization
inhibitory postsynaptic potential
results in hyperpolarization
gradations
graded potentiall vary in amplitude
polarity (depolarization/hyperpolarization) depends on
which ions move (depends on receptor/channel)
Cl in and/or K out = hyperpolarization/inhibitory
Na and/or Ca in = depolarization/excitatory
intensity depends on
strenth of stimulus (# of open channels, time channels are open)
summation (spatail or temporal)
spatial summation
summing of postsynaptic potential that occur at different locations at same time
make bigger or cancle eachother out
temporal summation
summing of postsynaptic potential that occur at different times in same location
more time channels are open = greater stimulus strength
more ions come in, increase amp of signal synaptic transmission, increase probabilty another stimulus will occur
action potentail threshold
~-55mV
graded potentail last
~10-20 sec
3 states of voltage gated Na channels
closed, open, inactivated
states of K channels
closed or open
for replarization, voltage gated Na channels are
inactivated
most important info (vision, balance, motor) carries by
lare diameter myelinated axons
CIDP
chronic inflammatory demyelianting polyneuropathy
tingling and numbness, weakness of arms and legs, loss of deep tendon reflexes, abnormal sensations
chemical synapse steps
action potential arrives at terminal
voltage gated Ca channels open and Ca enters axon terminal
Ca entry causes synaptic vesicles to release NT
NT diffuses across synaptic cleft and binds to specific receptors on postsynaptic membrane
binding of NT opens ion channels resulting in membrane potential
NT effects termianted by reuptake, enzymatic degradation, or diffuse away
synaptic delay time
.3-.5ms
excitatory
increase likelihood of action potential
inhibitory
decrease likelihood of action potential
types of neurotransmitter receptors
channel linked (ionotropic)
G-protein linked (metabotropic)