neurons and synapses

3 stages of information processing in nervous system

sensory input, integration, motor input

type of neuron that carries information from sensory receptors to the CNS

sensory neurons

type of neurons that analyze and interpret information in the CNS

interneurons

type of neuron that sends signals from CNS to muscles or glands

motor neurons

bundles of axons

nerves

functional (non-glial) cell type of the nervous system

neuron

part of neuron that receives incoming signals

dendrites

part of neuron that contains nucleus and major organelles

cell body (soma)

part that carries the action potential long distances

axon

where action potentials begin on the neuron

axon hillcock

ends of axons that release neurotransmitters

synaptic terminals

junction between neuron and another cell

synapse

role of glial cells

support, protext and assist neurons

which glial cells myelinate axons in CNS

oliododendrocytes

which glial cells myelinate axons in PNS

schwann cells

myelin

fatty insulating sheath around axons

function of myelin

speeds action potentials and saves energy

gaps in myelin sheath

nodes of ranvier

saltatory conduction

action potentials “jump” from node to node

how does axon diameter affect conduction speed

larger diameter=faster conduction

membrane potential

electrical charge difference across membrance

resting potential

membrance potential of a neuron not sending signals

ion higher inside the neuron

K+ (potassium)

ion higher outside the neuron at rest

Na+(sodium)

pump that maintains resting potential

sodium potassium pump

how many Na+ and K+ does the sodium potassium pump move per cycle

3 Na+ and 2 K+ in

voltage gates ion channels

channels that open in response to changes in membrane voltage

graded potential

small membrane potential shift; magnitude varies with stimulus

what must be reaches to trigger an action potential

threshold

what ion enters the neuron during depolarization

K+

hyperpolarization

membrane potential becomes more negative than resting level

are action potentials all of nothing

yes

does action potential speed depend on stimulus strength

no, frequency changes not speed

what triggers neurotransmitter release at the synapse

Ca 2+ entering the synaptic terminal

how do neurotransmitters cross the synapse

diffusion across the synaptic cleft

receptors that open ion channels directly

ionotropic receptors (ligand-gates)

receptors that use second messengers and GPCRs

metabolic receptors

EPSP

excitatory postsynaptic potential (depolarization)

IPSP

inhibitory postsynaptic potential(hyperpolarization)

temporal summation

multiple EPSPs from the same synapse in rapid succession

spatial summation

EPSPs from multiple synapses combine

neurotransmitters used in muscle movement

acetylcholine (ACh)

main exctitatory neurotransmitter in the brain

glutamate

main inhibitory transmitter in the brain

GABA

dopamine belongs to which neurotransmitter class

biogenic amines

neurotransmitters that affect pain perception

neuropeptides

gas that acts as a neurotransmitter and is made on demand

nitric oxide (NO)

two main ways neurotransmitters are cleared

reuptake and enzymatic breakdown

what does sarin do at the synapse

blocks ACh breakdpwn which leads to paralysis