Bio 2 Ch 48 Nervous System and Neural Signals

what is the structure for neural signaling

sensor, integration, effector

what is integration done by

central nervous system; brain and spinal cord

what is motor output done by

peripheral nervous system

what are neurons

nerve cells that transfer information throughout the body

long distance … and short distance …

electrical signals, chemical signals

what are dendrites

branch-like structures of neurons that receive signals from other neurons.

what are axons

long, slender projections of neurons that transmit electrical impulses away from the cell body to other neurons

what is a synapse

junction where each end of an axons transmits information to another cell

neurotransmitters

chemicals that pass info to receiving neuron

glial cells or glia

supporting cells that replenish certain groups of neurons and transmit info

sensory neurons

transmit info about external stimuli light light, touch, smell, or internal conditions

interneurons

analyze and interpret sensory input

motor neurons

transmit signals to muscle cells causing them to contract

central nervous system

organized neurons that carry out integration

peripheral nervous system

neurons that carry information out of the central nervous system

nerves

bundled axons that transmit signals

membrane potential

charge difference across plasma membrane with the inside of the cell being more negative

resting potential

the stable, negative charge of a neuron when it is not transmitting signals.

what concentration is higher inside of a neuron

potassium

what concentration is higher outside of a neuron

calcium

sodium potassium pump

used ATP to transport 3 sodium ions out and 2 potassium ions in

ion channels

pores formed by clusters of specialized proteins along the membrane that allows ions to diffuse back and forth

voltage-gated ion channels

ion channels that open or close in response to a shift in voltage across the neuron’s plasma membrane

hyperpolarization

makes the inside of the membrane more negative. Occurs through an outflow of positive ions or an inflow of negative ions

depolarization

reduction in the magnitude of the membrane potential. involves gated sodium channels. permeability to sodium increases and moves into the cell

action potential

massive change in membrane voltage and is spread along axons

threshold

certain level that membrane potential reaches, that opens voltage-gated sodium channels (positive feedback) sodium flows into the cell

what opens voltage-gated sodium channels

a stimulus

what is the first step of neural signaling

resting potential

what is resting potential in the process of neural signaling

most voltage-gated sodium and potassium channels are closed

what is the second step of neural signaling

stimulus depolarizes the membrane and voltage-gated sodium channels open allowing sodium into the cell

what is the third step of neural signaling

rising phase

what is the rising phase

the rapid increase in membrane potential as sodium ions flow into the neuron after the threshold has been crossed

what is the fourth step of neural signaling

falling phase

what is the falling phase

voltage gated sodium channels close and voltage-gated potassium channels open

what is the fifth step of neural signaling

undershoot

what is the undershoot

permeability to potassium increases more than at resting potential. Gated potassium channels eventually close moving back to resting potential

refractory period

downtime when a second action potential cannot be initiated

can action potentials occur partially

No, action potentials are all-or-nothing events.

how many action potentials can a neuron produce per second

100s

what indicated signals strength

frequencyof action potentials produced.

can action potentials travel backwards

no

what adaptation to axons conducts signals faster

widening

myelin sheath

electrical insulation that surrounds vertebrate axons

glia

oligodendrocytes in CNS and Schwann cells in PNS. They make myelin sheath and wrap axons in many layers of membrane

nodes of Ranvier

gaps in the myelin sheath that facilitate rapid conduction of nerve impulses.

saltatory conduction

A mode of nerve impulse transmission that occurs when action potentials jump from one node of Ranvier to another, increasing the speed of conduction.

what can synapses be

electrical or chemical

what are most synapses

chemical in nature, involving neurotransmitters to transmit signals between neurons.

what do electrical synapses contain

gap junctions that allow direct ion flow between connected neurons.

what to neurotransmitters do

carry information across synapses

what is the first step in neurotransmitter production/use

presynaptic neurons produce neurotransmitter at synaptic terminals and are stored in synaptic vesicles

what produces neurotransmitters

presynaptic neurons at synaptic terminals

where are neurotransmitters stored

synaptic vesicles

what is the second step of neurotransmitter production/use

calcium concentration causes synaptic vesicles to fuse with terminal membrane and release the neurotransmitter

what is the third step of neurotransmitter production/use

the neurotransmitter diffuses across the synaptic cleft

what is the fourth step of neurotransmitter production/use

neurotransmitter reaches postsynaptic membrane and binds to and activates a specific receptor (ligand-gated ion channels)

what are the classes of neurotransmitters

acetylcholine, biogenic amines, amino acids, neuropeptides, and gases

what does acetylcholine do

muscle stimulation/contraction, memory formation and learning. Inhibitory and slows heart rate

what are the biogenic amines

dopamine, serotonin, norepinephrine

what are biogenic amines synthesized from

amino acids

what does dopamine do

sleep, mood, attention, and learning

what does norepinephrine do

fight-or-flight response, attention, arousal, and mood. Excitatory NT in the ANS

what does serotonin do

mood, sleep, circadian rhythms, appetite and digestion, memory, learning, social behavior

what are neuropeptides

short chains of amino acids. They act slower over longer distances.

what are endorphins a class of

neuropeptide

what do endorphins do

decrease pain perception

what are the amino acids

glutamate and Gamma-aminobutyric acid (GABA)

what does glutamate do

common in central nervous system, excitatory signaling, learning and memory, sensory processing, and neurodevelopment

what does GABA do

inhibitory neurotransmitter. keeps neural activity calm, controlled, and balanced

what are the gases

nitric oxide and carbon monoxide

what does nitric oxide do

diffuses directly through membranes instead of being packaged into vesicles. neural communication, vasodilation, and immune responses

what does carbon monoxide do

regulates the release of hormones from the hypothalamus