BIO 342: Ch1

• Neurons
• Glia

DNA in nucleus undergo transcription to be converted into mRNA which is then translated into protein

specialized for electrical signaling, communication with other cells

supporting cells

• Dendrites
• Synapses
• Myelinated axon
• Cell body
• Node of ranvier

• Arborized
• Info received via synapses on dendrites
• Primary location of post-synaptic specialization (many neurotransmitter receptors)

• Presynaptic terminal
• Synaptic cleft
• Post-synaptic specialization

• (aka synaptic ending)
• Versicles with neurotransmitter molecules or neurotransmitters

space between presynaptic terminal and post-synaptic specialization

• (aka post-synaptic cell)
• On dendrite or cell body

receive chemical signal and convert to an electrical

• specialized for electrical conduction
• Short = interneuron (local circuit)
• Long = projection neurons

• insulator
• increases speed of AP along axon

AP is initiated

• occasionally the site of synapses
• location of nucleus

• filled with ion channels
• AP propagation

• Maintain signal ability of neurons (maintain ionic environ)
• Modulate rate of nerve cell propagation (myelination)
• Modulate synaptic action (control uptake of neurotransmitters at synaptic cleft)
• Scaffolding for development
• Aid neurons in recovery

• Astrocyte
• Oligodendrocyte
• Microglia

• Maintain chem environ for neural signaling
• Stem cells

• Myelinate CNS neurons
• (equivalent in PNS is Schwann cell)

• Scavenge cellular debris after injury
• Moduilate inflammation and cell death

• composed of many neurons
• Afferent neurons
• Interneurons
• Efferent neurons

Carry info toward brain/spinal cord

Local aspects of circuit

Carry info away from brain or spinal cord

Myotatic spinal reflex

• 1) Tap stretches tendon, stretching sensory receptors in leg extensor muscle
• 2A) Sensory neuron excites motor neuron
• 2B) Sensory neuron excites spinal interneuron
• 2C) Interneuron inhibits motor neuron to flexor muscle
• 3A) Motor neuron conducts AP to synapses on extensor muscle fibers, causing contraction
• 3B) Flexor muscle relaxes, no activity
• 4) Leg extends

• Sensory interactions (organism and environ)
• Motor-organize and generate actions
• Link sensory and motor, produce higher order functions (cognition, emotion)

• Brain
• Spinal cord

More likely to fire AP

Less likely to fire AP

• Cranial nerves
• Spinal nerves

• Sensory pathways
• Motor pathways
• -Somatic nervous system
• -Autonomic nervous system (symphatic vs parasymphatic)

• cell bodies in ganglia
• axon are nerves
• myelinated by schwann cells

• Cell bodies are in gray matter
• Axons are in tracts (white matter)
• Myelinated by oligodendrocytes

Tracts containing axon crosses midline