Toxicology

ToxicologyThe Nervous System

Nervous systemThe central nervous system (CNS) Brain cranial nerves spinal cordThe peripheral nervous system (PNS) Sensory (afferent) neurons Motor (efferent) neurons

skull

The BrainForebrain

Midbrain

Hindbrain

Midbrain

Cerebrum

Spinal cord

Cranial nerves

Neuroglial or glial cell

The Blood-Brain Barrier (BBB)The BBB is anatomical and physiological barrier between brain and circulation.Molecular size

Lipid solubility

Molecular charge

Concentration differences

Specialized transport mechanism

Neuron action potential and synaptic function

NeurotoxicityAluminumNeuropathy: degenerative changes in cortexArsenicNeuropathy : axonal degeneration in PNSMethanolNeuropathy : degeneration in ganglion cellsMethylmercuryNeuropathy : neural degenerationAcrylamideAxonopathy : axonal degeneration LeadNeuropathy : brain swelling, axonal lossCarbontetrachlorideNeuropathy NeurotoxicityMotor neurons: Muscle dysfunction, paralysisInterneurons: Memmory, learning coordinationSensory neurons: Dysfunction in vision,hearing, and senses,temperature,pressure,touch,taste,smell and pain.Chemicals that can produce neurotransmission-associated toxicitiesBlock the release of neurotransmitter (Botulinum) .Produce uncontrolled release of neurotransmittor.Block impulse conduction along axons (anesthesia).Activate synaptic function (nicotine) .Block synaptic function by interfering with normal calcium channel (lead, cobalt).Block reuptake or breakdown of neurotrasmittor resulting in receptor overstimulation (cocaine).