Chapter 3

brain & spinal cord

• all the other nerves in the body - divided into somatic and autonomic (inside)

sensory, motor, & interneurons

• detect info from world - somatosensory provide info from skin and muscles

direct muscles to contract/relax

communicate within short circuits

dendrites, cell body, axon, and terminal buttons

short, branchlike appendages that detect chemical signals

• aka soma - collect & integrate info

• transmit signals • can be really long • covered in a myelin sheath

at the end of the axon

gap where chemical communication occurs between neurons

a semipermeable membrane that allows ions to travel through ion channels

inside a neuron is slightly more negative than outside, so it’s polarized

increases potassium & decreases sodium within cell to maintain resting potential

aka neural firing electrical signal that passes along the axon

excitatory (depolarize cell membrane by making inside more +) or inhibitory (increase polarization by making inside more -)

• sodium gates open–> sodium ions rush in and inside becomes + • potassium gates open–> K rushes out and inside becomes even more + • Na then K gates close, cell is even more - than normal • K-Na pump restores resting state

insulates axons and allows signals to travel faster made of glial cells

small gaps of exposed axon between the sheath

a neuron fires with the same potency each time or not at all

presynaptic sends and postsynaptic receives

• made in axon, stored in vesicles in terminal buttons - convey signals across synapses

specialized protein molecules located on receiving membrane that respond to a specific neurotransmitter and can open or close ion channels