Phase 1 + 2

Function of the soma (cell body)

contains nucleus & organelles; metabolic center of neuron.

Function of dendrites

receive incoming signal

Function of the Axon hillock

generates the action potential and decides if the neuron fires.

Axon

long projection that conducts action potential toward terminals.

Myelin

insulates axon to increase speed of conduction.

Nodes of Ranvier

gaps in myelin where action potential regenerates

Presynaptic terminal

releases neurotransmitter onto next cell

Postsynaptic terminal

receives neurotransmitter signal

Synapse

the communication site between two cells

What are neurons

excitable cells that send electrical and chemical signals

The function of astrocytes in the CNS

BBB, structure, support, nutrient uptake

Function of microglia in CNS

immune system, phagocytosis

Function of oligodendrocytes

myelinate CNS axons

Function of ependymal cells in CNS

line ventricles, produce cerebrospinal fluid

Schwann cells

myelinate PNS axons and help regeneration

Satellite cells

support PNS neurons, regulate enviroment

Central nervous system

brain + spinal cord

Peripheral Nervous system

nerves connecting CNS to body

Features than can cross the lipid bilayer easily

• small

• uncharged

• hydrophobic

• gases (o2, CO2)

• some small lipophilic molecules

Features that cannot cross the lipid bilayer

• ions

• charged molecules

• polar molecules

• most hydrophilic molecules

Major ions unevenly distributed across the cell membrane

Inside high: K⁺ , negatively-charged proteins

Outside high: Na⁺ , Cl⁻ , Ca²

Depolarization

membrane potential becomes less negative (moves toward zero; Na⁺ in)

Hyperpolarization:

membrane becomes more negative (K⁺ out or Cl⁻ in)

Describe the structure of gap junctions

formed by protein channels connecting cytoplasm of two cells

Compare and contrast electrical synapse and chemical synapses

Electrical synapses

• direct ion flow through gap junctions

• Fast

• Bidirectional

• no neurotransmitter required

Chemical synapses

• uses neurotransmitters

• slower

• mostly unidirectional

• requires presynaptic release

Describe the structure of SNARE complex

proteins that mediate presynaptic vesicle fusion with membrane during exocytosis

List mechanisms by which neurotransmitter function can be stopped

• reuptake

• enzymatic degradation

• diffusion away from synapse

Synaptic vesicle fusion at the plasma membrane is equivalent with

exocytosis

Synaptic vesicles fuse via

regulated secretion