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by marian


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nervous system
  • all the neural tissues in the body; like brain
  • two major divisions; central nervous system (CNS) and peripheral nervous system (PNS)
  • enables organisms to receive and respond to stimuli from their external and internal environments
  • responds to stimuli more rapidly than endocrine system
neurons
  • functional units of the nervous system
  • converts stimuli into electrochemical signals
  • structure is an elongated cell with several dendrites, a cell body, and a single axon
Dendrites
  • cytoplasmic extensions that receive information and transmit it toward the cell body
cell body (soma)
  • contains the nucleus and controls the metabolic activity of the neuron
axon
  • long cellular proces that transmits impulses away from teh cell body.
  • sheathed by insulating substance known as myelin
  • the ends of teh axon are synaptic terminals (terminal buttons)
myelin
  • allows the axons to conduct impulses faster
  • produced by cells known as glial cells
oligodendrocytes
  • produce myelin in the cenral nervous system
schwann cells
  • produce myelin in the peripheral nervous system
nodes of Ranvier
  • gaps between segments of myelin
neurotransmitters
  • released from these terminals into the synapse (snaptic cleft)which is teh gap between the axon terminals of one cell and the dendrites of the next cell
CNS; Central Nervous System
  • has four major types of cell
  • astrocytes
  • oligodendrocytes
  • microglia
  • ependymal cells
Astrocytes
  • maintain the integrity of the blood brain barrier
  • regulate nutrient and dissolved gas conc.
  • absorb and recycle neurotransmitters
Oligodendrocytes
  • myelinate CNS axons
  • provide sturctural framework for the CNS
Microglia
  • remove cellular debris and pathogens
Ependymal cells
  • line the brain ventricles and aid in the production, circulation, and monitoring of cerebral spinal fluid
PNS; Peripherial Nervous System
  • has two major types of cells
  • Satellite cells
  • Schwann Cells
Satellite cells
  • surround teh neuron cell bodies in the ganglia
Schwann Cells
  • enclose the axons in the PNS and aid in the myelination of some peripheral axons
Norepinephrine
  • neurotransmitters often found in the nervous system
  • when synthesized its immediate precursor is dopamine
  • in adrenal medulla its is transformed into epinephrine through process of methylation
acetylcholine
  • neurotransmitters often found in the nervous system
  • choline is combined with Acetyl-CoA to become acetylcholine
action potential
  • impulses travel the length of teh axon and invade the nerve terminal, causing the release of neurotransmitter into the synapse
resting potential
  • when a neuron is at rest the potential difference between teh extracelular space and the intracellular space is resting potential
  • is created cuz the neuron is selectively permeable to K+ so K+ diffuses down its conc. grad. leaving a net neg. charge inside
Na+ / K+ pump
  • K+ is higher inside the neuron than outside
  • Na+ is higher outside than inside
  • negative charged proteins are trapped inside of the cell
  • neurons are impermeable to Na+ so the cell remains polarized
  • uses ATP to transport 3NA+ out for every 2 K+ it transports into the cell
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