Nervous Tissue Ch 12

Function of the Nervous System sensory input motor input sensory receptor effector Function of the Nervous System integration

Anatomical Divisions of the Nervous System Central Nervous System (CNS) brain spinal cord Peripheral Nervous System (PNS) cranial nerves spinal nerves

Organization of the Nervous System

Organization of the Nervous System brain spinal cord CNS NS SNS (voluntary) PNS (spine & cranial nerves) Sympathetic Parasympathetic ANS (involuntary) Sensory (afferent) Motor (efferent)

CNS PNS brain cranial nerves spinal nerves spinal cord

Neuroglia

Typical Neuron dendrite cell body Myelin sheath Synapse axon

Myelin Sheath

Myelin Sheath Nodes of Ranvier Schwann Cells Axon

Types of Neurons unipolar bipolar multipolar eye, ear, & olfactory most abundant type in CNS Dorsal root ganglion cells

Neuron Interaction & Integration sensory neuron sensory receptors interneuron effector Interaction Between Neurons motor neuron

Resting Potential of an Axon

Resting Potential of an Axon

Depolarization of the Axon Membrane

Action Potential

Propagation of an Action Potential

Propagation of an Action Potential

Refractory Period

Saltatory Conduction

Synapses Ca2+ Presynaptic neuron Postsynaptic membrane Synaptic vesicles containing neurotransmitters

EPSP & IPSP

Synapses

Neurotransmitters Acetylcholine- slows heart rate; PNS Glutamate- most prevalent neurotransmitter in the brain Aspartate- in CNS GABA- inhibitory neurotransmitter Glycine- inhibitory neurotransmitter Norepinephrine- awakening from deep sleep Epinephrine- increase heart rate Dopamine- movement of skeletal muscles Seratonin- sensory perception, temp regulation, mood, sleep Nitric oxide- may play a role in memory and learning Enkephalin- inhibit pain impulses by suppressing release of substance P Substance P- enhances perception of pain tyrosine

Neurotransmitters

Types of Circuits in Neuronal Pools

Neuronal Circuits Converging circuit same source Pacinian corpuscles -- pressure different sources control of respiration Diverging Circuit permits broad distribution of a specific input types A.  amplification B.  divergence into multiple tracts

Neuronal Circuits Parallel after-charge circuit several neurons process same information at one time each chain has a different number of synapses, but eventually they all reconverge on a single output output neuron may go on firing for some time after input has ceased important in withdrawal reflexes longer-lasting output from small period of pain 

Neuronal Circuits Reverberating Circuit axons extend back toward the sources of an impulse and further stimulate the presynaptic neuron helps maintain consciousness, muscular coordination, normal breathing, short term memory... 

Neuron to Neuron Transmission synapses Afferent (sensory) Integration center Interaction Between Neurons Efferent (motor)

Nerve Damage & Repair in PNS Interaction Between Neurons chromatolysis Wallerian degeneration

Nerve Damage & Repair in PNS Myelin sheath axon cell body Shwann cell chromatolysis Shwann cell Interaction Between Neurons Wallerian degeneration Regeneration tube Regeneration