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neuron

a nerve cell; an electrically excitable cell specialized for producing and transmitting action potentials and secreting chemicals that stimulate adjacent cells

afferent neuron

carries action potentials to the CNS

efferent neuron

carries action potentials away from the CNS

central nervous system

consists of the brain and spinal cord.

peripheral nervous system

consists of all nerves and and ganglia; all of the nervous system except the brain and spinal cord

gray matter

where the neuron cell bodies, dendrites, and synapses are found

white matter

white myelinated nervous tissue

somatic nervous system

a division of the nervous system that includes efferent fibers mainly from the skin, muscles, and skeleton and afferent fibers to the skeletal muscles

autonomic nervous system

a motor division of the nervous system that innervates glands, smooth muscle, and cardiac muscle; consists of sympathetic and parasympathetic divisions and functions largely without voluntary control

cranial nerves

any of the 12 pairs of nerves connected to the base of the brain and passing through the foramina of the cranium

spinal nerves

any of the 31 pairs of nerves that arise from the spinal cord and pass through the intervertebral foramina

sympathetic nervous system

a division of the autonomic nervous system that issues efferent fibers through the thoracic and lumbar nerves and usually exerts adrenergic effects on its target organs; includes a chain of paravertebral ganglia adjacent to the vertebral column, and the adrenal medulla

prosencephalon

develops into the forebrain and thalamus

mesencephalon

develops into the midbrain

metencephalon

develops into the hindbrain along with the myelincephelon

myelincephalon

deleops into the hindbrain along with the metencephalon

rhombincephalon

develops into the cerebellum and medulla oblongata

axon

a process of a neuron that transmits action potentials; also called a nerve fiber. There is only one axon to a neuron and it is usually much longer and less branched than the dendrites.

soma

the cell body of a neuron

perikaryon

another word for the cell body of a neuron

axon hillock

the mound on the side of the soma from where the axon originates

axon collateral

a branch of an axon

axon terminal

the end of the axon; has synaptic knobs that synapse with other cells

telodendria

an extensive complex of fine branches at the end of an axon; also called the terminal aborization

dendrites

processes of a neuron that receive information from other cells or environmental stimuli and conduct signals to the soma. Dendrites are usually shorter, more branched, and more numerous than the axon and are incapable of producing action potentials

Schwann cell

cells that envelop nerve fibers in the PNS. They produce a myelin sheath, and they also assist in the regeneration of damaged fibers

myelin

a lipid sheath around a nerve fiber, formed from closely spaced spiral layers of the plasma membrane of a Schwann cell or oligodendrocyte

Node of Ranvier

the space between Schwann cells that can conduct action potentials

neurilemma

the outermost coil of a Schwann cell, external to the myelin sheath

axolemma

the cell membrane of an axon

axoplasm

the cytoplasm of an axon

neuroglia

all cells of nervous tissue except neurons; cells that perform various supportive and protective roles for the neurons

oligodendrocyte

a type of glial cell that wraps around nerve fibers in the CNS and produces a myelin sheath around them

astrocyte

star shaped glial cells that form scar tissue to replace damaged nervous tissue

microglia

small macrophages that develop from monocytes, they phagocytize dead nervous tissue, microorganisms, and foreign matter. They concentrate in areas damaged by infection, trauma or stroke.

ganglion

a cluster of nerve cell bodies in the PNS

basal nuclei

deep masses of cerebral gray matter that play a role in the coordination of posture and movement

projection tract

a bundle of axons that communicates between two or more regions of the brain

association tract

a bundle of axons that communicates between subregions of the same area of the brain; from "primary" areas to "association" areas

ependyma

produce cerebrospinal fluid and line the cavities of brain and spinal cord

proprioception

the nonvisual perception, usually subconscious, of the position and movements of the body, resulting from input from proprioceptors and the vestibular apparatus

association neuron

a neuron that transmits action potentials from efferent neurons to afferent neurons

synapse

the junction between the synaptic knob of one neuron and some other part of another cell

action potential

a rapid voltage change in which a plasma membrane briefly reverses electrical polarity; has a self-propagating effect that produces a traveling wave of excitation in nerve and muscle cells

neurotransmitter

a chemical released at the distal end of an axon that stimulates an adjacent cell

lateral geniculate nucleus

relays visual information from the optic tracts to the visual cortex

medial geniculate nucleus

relays auditory information from the inferior colliculi to the auditory cortex

substancia nigra

is a primary producer of dopamine

superior colliculi

regulate reflexes of eyes and head to visual stimuli, and receives information from inferior colliculi about auditory stimuli

inferior colliculi

receives all info from the inner ear about sound, relays this info to the thalamus; also regulates reflexive movements of the head and trunk to auditory stimuli

olivary nucleus

relays info to and from the inner ear and to and from the cerebellum

nucleus gracilis

receives general sensory info from the lower half of the body

nucleus cuneatus

receives general sensory info from the upper half of the body

path of cerebrospinal fluid from the lateral ventricle to the superior sagittal blood sinus

lateral ventricle - interventricular foramen of Monro - 3rd ventricle - cerebral aqueduct of sylvius - 4th ventricle - foramina of Luschka OR foramen of Magendie - subarachnoid space - arachnoid villus - superior sagittal blood sinus

choroid plexus

made up of pia mater, nonciliated ependyma, capillaries. Secretes cerebrospinal fluid.

4 sources of blood supply to the brain

2 vertebral arteries and 2 internal carotids

parietal lobe

sensory reception

temporal lobe

hearing, smell, learning, memory, emotional behavior, visual recognition

limbic system

emotion and memory

frontal lobe

voluntary motor functions, personality, mood, emotion, judgment, aggression

pyramidal tracts

originates in the precentral gyrus, extends from the primary motor cortex down through the interal capsule, through the midbrain and the pons, into the medulla (where the decussate), and extending through the spinal cord as the corticospinal tracts

pairs of cervical spinal nerves

8

pairs of thoracic spinal nerves

12

pairs of lumbar spinal nerves

5

pairs of sacral spinal nerves

5

pairs of coccygeal spinal nerves

1

fasciculus gracilis

relays general sensory info from the lower half of the body to the nucleus gracilis

fasciculus cuneatus

relays general sensory info from the upper half of the body to the nucleus cuneatus

sympathetic nervous system

thoracolumbar subdivison

parasympathetic nervous system

craniosacral subdivision

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