Cell Functions-1st part NS

kms013's version from 2015-09-28 03:57


Question Answer
NervesThousands of Neurons; Billions of nerve cells all assisted by many more supporting cells called glial cells
NeuronMany billion nerve cells; functional unit of NS; One cell body supported by gliel cell; comes in shapes and sizes; cells that change rapidly which makes them excitable
Neuron vs NerveNeuron is singular, nerve is a collection of neurons
CNS vs PNSCNS is spinal cord and brain, PNC is cranial, spinal, preipheral nerves conducting impulses to and from the CNS and ganglia; sensory and motor nerves respectively
GangliaSmall groups of nerve cells outside the CNS
Cell BodyPerikaryon; typically changes shape in motor neuron, has cells organals and surves synantics center or tropic center for entire neuron; also has receptors (axosomatic); located in spinal cord; large neucli; chromatin finely dispercesed and contain nissl body
Dendritesnumerous enlongated processes extended from the cell body and specialized to recieve stemuli from other neurons from synapses
Axonsingle long process ending at synapsis specialized to generate and conduct nerve impulses to other cells (nerve, muscle and glad); also recieve information from other neurons that mainly modifys the transmisson of action potentials to those neurons
Axon Hillockarea between soma and axon
multipolarneuron has one axon and two or more dendrite; most are multipolar
bipolarneuronone dendrite and one axon; found in retina, olfactory mucosa, and the inner ear cochlear and vestibular ganglia
unipolar/pseudounipolar neuronhas single process that bifurcates close to the cell body will longer branch extending to peripheral ending and the other toward the CNS; found in spinal ganglia(the sensory ganglia found with the spinal nerves) and in most cranial ganglia
Initial segment of axon hillockarea of mathmatical stimulation and deciding what to do; go or no
terminal knobs tips of dendrites that hold synaptic end communication with other cells/neurons from place stimuli is recieved this spreads and causes are reversal in ion gradiant depolarization where there is an AP, increase calcium, vesicals of ACHL, synaptic cleft, recptor
sensory neurondorsal horn afferent and recieve stimuli from receptors throughout the body
motor neuronsventral horn efferent, sending impulses to effector organs such as mussle fibers and glands
somaticmotor nerves are under volentary control and typically intervate most skeletal muscle
autonomicmotor neurons control the involentary activities of glands, cardiac muscle and most smooth muscle
interneuronestablish relationships among other neurons forming complex functional networks or circuts; generally multipolar and include 99% of the neurons in the CNS
resting potentialdisequalibriam, -70 or -65, more IC than EC, more NA outside cell, more K inside, K can come and go whenever
graded potentialsummation of all local potentials
threshold volall or nothing
action potential travel along and axon, like a spark moves along and explosive fuse, initiated at axon hillock when threshold is met, produced by voltage gated NA/K channels; imidiately after AP depolarization, NA pumps close and K opens which restores membraine to resting potential
refractory periodthe time after the firing of and AP, where equalibriam is trying to be reached again
anterogradeorganelles moving soma of nerves cells along axon to synapic terminals; regulated by kinesin(ATP ace)
retrogradetransporting macromols from cell axons to cell bodies such as stuff like viruses and toxins brought in by endocytosis, regulated by dyenin(ATPase)
depolarization ligand binds to receptor on transport protine = open; NA floods in = change membrane potential; when it reaches threshold Na gates close K open via voltage change(threshold)
local potentialhappens on or in a specific area of dendrite or soma; graded, decramental, revericeable, +/-
action potential triggers own initiation is the axon hillock; cannot be stopped; no need for ligand anymore
repolarizationNa/K pumps start working again to get cell back RMP; Na close and K opens to restore -MP
exciatory post synaptic potentials small added steps that slowly bring us toward AP which results in depolarization
inhibitory post synaptic potential, brings us further away from firing AP; hyperpolerization; typically due to excess Ca; decremental-xif not enough signal, will run out