Module 1 Definitions

Central nervous system (CNS)

the brain and spinal cord; the lecture also lists the brain, brainstem, spinal cord, and retina as CNS components

Peripheral nervous system (PNS)

structures other than the brain and spinal cord; includes nerves and ganglia

Sensory components

sensory receptors and sensory nerves that bring information from the internal and external environment

Motor components

the autonomic and somatic motor systems that carry output to effectors

Autonomic nervous system (ANS)

motor division controlling smooth muscle, cardiac muscle, and glands; includes sympathetic, parasympathetic, and enteric divisions

Somatic motor system

motor division controlling skeletal muscle

Neuron

the principal cell of the nervous system

Soma

the cell body of a neuron that contains the nucleus

Dendrites

typically shorter neuronal processes that receive information

Axon

a single long neuronal process with synaptic endings that allows the neuron to communicate

Schwann cell

a glial cell that provides myelin to protect peripheral axons

Node of Ranvier

gap between myelin segments along a myelinated axon

Nissl stain

stain that labels ribosomes on rough ER in neurons

Golgi stain

stain that can label the entire neuron

Cytoarchitecture

the number and arrangement of neurons and other cells in a particular region of the brain

Brodmann's areas

brain regions defined based on cytoarchitecture

Synapse

site where neurons make connections with other cells

Presynaptic cell

neuron that releases neurotransmitter at a synapse

Postsynaptic cell

cell that receives neurotransmitter at a synapse

Chemical synapse

synapse where a neurotransmitter is released into the synaptic cleft and binds a postsynaptic receptor

Synaptic cleft

space into which neurotransmitters are released at a chemical synapse

Neurotransmitter

chemical messenger released by a neuron that binds to a postsynaptic receptor and initiates a physiological change

Ligand-gated ion channel

receptor that directly allows charged ions through a channel when a neurotransmitter binds

G-protein-coupled receptor (GPCR)

receptor in which ligand binding activates a heterotrimeric G-protein, whose subunits act on an effector protein

Second messenger

small diffusible molecule produced by an effector protein that can produce intracellular effects such as activating an ion channel

Neurotransmitter clearance

removal of neurotransmitter from the synapse by enzymatic degradation or reuptake

Reuptake

removal of neurotransmitter from the synaptic cleft by specialized transporters

Enzymatic degradation

breakdown of neurotransmitter by enzymes in or near the synaptic cleft

Astrocyte

glial cell with various functions that is closely associated with synapses, wraps blood vessels, and helps form the blood-brain barrier

Oligodendrocyte

CNS glial cell that provides myelin around neuronal axons

Microglia

immune component of the nervous system with functions similar to macrophages

Satellite cell

glial cell found mainly around ganglion cells

Blood-brain barrier (BBB)

barrier that restricts what can pass from the circulation into the brain

Hypothalamus and BBB

the hypothalamus has a leakier blood-brain barrier than most of the brain

Dorsal

toward the back side; in human neuroanatomy, superior

Ventral

toward the belly side; in human neuroanatomy, inferior

Anterior

toward the front

Posterior

toward the back

Superior

above

Inferior

below

Horizontal/axial plane

plane parallel to the floor

Coronal/frontal plane

plane dividing the body into anterior and posterior portions

Sagittal plane

plane dividing the body into left and right portions

Midsagittal plane

sagittal plane through the midline

Parasagittal plane

sagittal plane parallel to but away from the midline

Nucleus

group of neuron cell bodies in the CNS

Ganglion

group of neuron cell bodies in the PNS

Tract

bundle of nerve fibers in the CNS

Nerve

bundle of nerve fibers in the PNS

Fasciculus

a bundle

Funiculus

a cord

Lemniscus

a ribbon

Commissure

bundle of fibers crossing the midline of the telencephalon or diencephalon

Ipsilateral

on the same side of the midline

Contralateral

on the opposite side of the midline

Decussation

point where a tract crosses the midline

Afferent

fibers that bring input to a structure

Efferent

fibers that carry output away from a structure

Nervous system development

embryological development in which neural vesicles give rise to different adult CNS structures

Prosencephalon

embryonic forebrain

Telencephalon

part of the prosencephalon that gives rise to the cerebral hemispheres, cerebral cortex, subcortical white matter, basal ganglia, and certain brain nuclei

Diencephalon

part of the prosencephalon that gives rise to the thalamus, hypothalamus, and epithalamus

Mesencephalon

embryonic midbrain

Rhombencephalon

embryonic hindbrain

Metencephalon

part of the rhombencephalon that gives rise to the pons and cerebellum

Myelencephalon

part of the rhombencephalon that gives rise to the medulla

Spinal cord

caudal portion of the developing nervous system that gives rise to the adult spinal cord

Optic nerve

develops from the diencephalon and is therefore associated with the CNS

Ventricle

space within the brain filled with CSF

Lateral ventricles

paired ventricles within the cerebral hemispheres

Third ventricle

ventricle located centrally in the diencephalon

Cerebral aqueduct

channel connecting the third and fourth ventricles

Fourth ventricle

ventricle located between the brainstem and cerebellum

Central canal

CSF-containing channel extending through the spinal cord

Cerebrospinal fluid (CSF)

fluid circulating through the brain and spinal cord that is ultimately absorbed into the venous/circulatory system

Venous system

system that carries blood back toward the heart

Anterior circulation

cerebral circulation supplied primarily by the carotid arteries

Posterior circulation

cerebral circulation supplied by the vertebral arteries

Carotid arteries

arteries supplying much of the brain's anterior circulation

Vertebral arteries

arteries supplying the brain's posterior circulation

Bilateral structure

structure organized into left and right sides

Longitudinal fissure

major fissure separating the left and right cerebral hemispheres

Gyrus

raised fold of the cerebral cortex that increases cortical surface area

Sulcus

groove between gyri

Cerebral cortex

convoluted outer layer of the brain

Brainstem

structure connecting the cerebrum with the spinal cord and containing many cranial nerve origins

Frontal lobe

cerebral lobe associated with anterior portions of the cerebral cortex

Parietal lobe

cerebral lobe located posterior to the frontal lobe

Temporal lobe

cerebral lobe located inferior to the frontal and parietal lobes

Occipital lobe

cerebral lobe at the posterior brain; associated with visual processing

Gray matter

nervous tissue rich in neuronal cell bodies

White matter

nervous tissue relatively poor in cell bodies and containing many nerve fibers

Cortical gray matter

gray matter forming the cerebral cortex

Basal ganglia

groups of nuclei located deep within the brain

Caudate nucleus

nucleus that is part of the basal ganglia

Putamen

nucleus that is part of the basal ganglia

Globus pallidus

nucleus that is part of the basal ganglia

Nucleus accumbens

nucleus located within the basal ganglia

Claustrum

deep brain structure shown alongside the basal ganglia in the lecture

Fornix

fiber tract shown in the midsagittal brain that is associated with the structures of the limbic region