Neuroanatomy

neuron doctrine

braincells are independent from one another structurally, metabolically, and functionally; information is transmitted from one neuron to the next across tiny gaps

dendrites

receives information from cells

many per neuron; tapes progressively toward end; no hillock-like region; no myelin sheath; often much shorter than axon

dendrites spines

receives input from a single axon at the synapse

cell body

maintain the cell and to keep the neuron functioning

axon hillock

controls the initiation of an electrical impulse based on the inputs from other neurons or the environment

axon

transmits electrical impulses

one per neuron; has many terminal branches; uniform until start of terminal branching; hillock-like region; present myelin sheath; ranges from practically nonexistent to several meters long

axon collaterals

develops so that one neuron can send information to several others

axon terminal

where electrical messages change to chemical signals using neurotransmitters to communicate with the next neuron

myelin sheath

wraps around axon and speeds up impulses

glial cells

protect, support, and assist neurons; participate in information processing 

what two glial cells wrap around the axon to provide fatty insulation (myelin)

oligodendrocytes and schwan cells

oligodendrocytes

provide myelin to neurons inside brain and spinal cord

schwan cells

provide myelin to neurons outside brain and spinal cord

nodes of ranvier

gaps between myelin where axon is exposed

astrocytes

start shaped cells that secrete chemicals; help from outer membrane around the brain

microglial cell

mobile cells that remove debris from injured or dead cells

what makes up the CNS?

brain and spinal cord

what makes up the PNS?

all nerves neurons surrounding the spinal cord

what two nerves are located in the PNS?

motor and sensory nerves

motor nerves

transmit information from the spinal cord and brain to muscles, organs, and glands 

sensory nerves

nerves that interconnect the brain and the major muscles and sensory systems of the body

somatic nervous system

controls voluntary muscles and transmits sensory information to the CNS

cranial nerves

innervate the head, neck, and visceral organs directly from the brain

automatic nervous system

controls involuntary functions

sympathetic nervous system

arouses body to expend energy

parasympathetic nervous system

calms body to conserve energy

gray matter

contain more cell bodies and dendrites which lack myelin

white matter

consists mostly of axons with white myelin sheath