neurophysiology 1.2 class notes

the nervous system is composed of two kinds of cells

• neurons

• glia

membrane

separates inside + outside of the cell

small uncharged molecules

move across membrane freely

• H20

• 02

• CO2

charged ions

pass through protein channels (small openings in membrane)

• Na

• K

• Ca

• Cl

four major structures that compose a neuron

• dendrites

• soma

• axon

• presynaptic terminals

dendrites

branching fibers; information receivers

soma

contains nucleus, ribosomes, mitochondria

*cell body

axon

thin fiber; information sender

presynaptic terminal

swelling at the tip of the axon; chemicals released here cross the synaptic gap to another neuron

*end bulbs

**think - before the synapse

types of axons

• afferent

• efferent

SAME

sensory

afferent

motor

efferent

afferent

brings info to a structure

*admission

efferent

sends info away from a structure

*exit

sensory neurons

send messages from skin + senses to brain + spinal cord

motor neurons

send messages from brain + spinal cord to muscles

interneurons

work in brain + spinal cord to help process + transmit info

nucleus

contains chromosomes

mitochondria

ribosomes

synthesize new protein molecules

endoplasmic reticulum

network thin tubes that synthesize new protein molecules

involved in isolation, modification, transport of proteins + other substances

myelin sheath

insulating material

nodes of ranvier

gap in myelin sheath

glia

• exchange chemicals w/ adjacent neurons

• support, protect, + nourish neurons

glia vs neurons: space edition

• glia are 1/10th the size of neurons

• glia are 10x more numerous in brain

• they take up same total space as neurons

types of glial cells

1. astrocyte

2. oligodendrocyte

3. schwann cells

4. radial glia

5. microglia

astrocyte

• helps synchronize the activity of axons, enabling them to send messages in waves

• removes waste material created when neurons die

*CNS

oligodendrocyte

• surrounds + insulates axons in brain + SPC

• builds myelin sheath around axons in brain + SPC

*CNS

schwann cell

• surrounds + insulates certain axons in periphery of the body

• builds myelin sheaths around axons in periphery of body

*PNS

radial glia

• type astrocyte that guides migration of neurons during embryonic development

• guides growth axons + dendrites during embryonic development

*CNS

microglia

• proliferate in areas of brain damage

• removes toxic waste materials

*CNS