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Neuroglia

cells that support and nourish neurons

Astrocytes

largest, most numerous glial cells; maintain blood-brain barrier to isolate CNS from general circulation; provide structural support for CNS; regulate ion and nutrient concentrations; perform repairs to stabilize tissue and prevent further injury

Astrocytes

Oligodendrocytes

wrap CNS axons in a myelin sheath

Oligodendrocytes

Ependymal cells

Type of neuroglial cell found in the ventricles, circulate cerebrospinal fluid

Ependymal cells

Microglia

Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system

Schwann cells

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

Schwann cells

Satellite cells

Type of glial cell, line the exterior surface of neurons in the peripheral nervous system. Satellite cells also surround neuron cell bodies within ganglia. They supply nutrients to the surrounding neurons and also have some structural function.

Satellite Cells

soma

cell body of a neuron

Nuclei

groups of nueron cell bodies in spinal cord gray matter

Neurofibrils

bundles of intermediate filaments (neurofilaments); maintain shape

Nissl Bodies

rough endoplasmic recticulum in neurons; important for protein production, i.e. NA/K protein channels

Nissl Bodies

Dendrites

branching extensions of neuron that receives messages from neighboring neurons

Axons

a part of a neuron that carries impulses away from the cell body

Input Zone (Dendrites, Cell Body)

The part of a neuron that receives information, from other neurons or from specialized sensory structures. Usually corresponds to the cell's dendrites.

Trigger Zone (Initial Segment of Axon)

nerve impulses arise most often at the junction of the axon hillock and initial segment

Conducting zone (Axon)

The zone where action potentials propagate along the axon

Output Zone (Axon Terminals)

swellings at the ends of the axon known as axon terminals that communicate the cell's acitivity to other cells

Collaterals

side branches from an axon

Collaterals

Axon Hillock

specialized region of the axon, which connects the inital segment of the axon to the cell body

Axon Hillock

Axon Terminals

bulb like structers at end of axon contain neuro transmitters that carry neuron message into synapse

Axon Terminals

Synaptic End Bulbs

found at end of axon terminal & contain synaptic vesicles that are filled with neurotransmitters

Synaptic End Bulbs

Neurotransmitters

chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

Neurotransmitters

Synaptic Vesicles

tiny oval-shaped sacs in a terminal of one neuron; assist in transferring mineral impulse from one neuron to another neuron by releasing specific neurotransmitters

Synaptic Vesicles

Synaptic Cleft

synaptic gap or synaptic space; tiny gap between the terminal of one neuron and the dendrites of another neuron (almost never touch); location of the transfer of an impulse from one neuron to the next

Synaptic Cleft

Membrane Receptors

cell communicaton via chemical signals-receptors specificity/ receptor activation produces a second messengr(chemical) inside of cell

Action Potential

a neural impulse; a brief electrical charge that travels down an axon. the action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane

Myelin

a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses

Neurilemma

thin membranous sheath around a nerve fiber

Neurilemma

Nodes of Ranvier

small gaps of exposed axon, between the segments of myelin sheath, where action potentials are transmitted

Nodes of Ranvier

Axolemma

The plasma membrane of the axon

Axoplasm

cytoplasm of the axon, contains numerous organelles

Unipolar Neuron

neuron with just one process extending from the cell body; are always sensory nerons

Unipolar Neuron

Bipolar Neuron

A neuron with a single axon and a single dendrite, often projecting from opposite sides of the cell body. Bipolar neurons are typically associated with sensory organs; an example is the bipolar neuron in the retina of the eye. - note that one axon may innervate many different muscles, or other things.

Bipolar Neuron

Multipolar Neuron

A nerve cell that has many dendrites and a single axon.

Multipolar Neuron

Sensory Neurons (Afferent)

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

Motor Neurons (efferent)

neurons that carry outgoing information from the central nervous system to the muscles and glands

Association Neurons (Interneurons)

Also called interneurons, located only in the brain or spinal cord, these neurons contact sensory neurons to motor neurons; the switch board of the nervous system.

Endoneurium

delicate connective tissue around individual nerve fibers in nerve

Endoneurium

Perineurium

connective tissue that covers a bundle of nerve fibers

Perineurium

Fascicle

a bundle of fibers (especially nerve fibers)

Epineurium

outermost layer of connective tissue on the spinal nerve; a dense network of collagen fibers

Epineurium

Dorsal Root

contains the axons of the sensory neurons in the dorsal root ganglion; each segment of the spinal cord is associated with a pair of these

Dorsal Root

Ventral Root

contains axons of somatic motor neurons and sometimes visceral motor neurons that control peripheral effectors; each segment of the spinal cord is associated with a pair of these

Ventral Root

MIxed Nerves

nerves composed of both sensory and motor fibers, nerves that contain both sensory and motor fibers and have the ability to send and receive messages

MIxed Nerves

Gray Matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.

White Matter

whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths

Plexus

large, interlacing network of nerves

Nuclei

clusters of cell bodies in the CNS

Ganglia

groups of nerve cell bodies that coordinate incoming and outgoing nerve signals

Nerve

any bundle of nerve fibers running to various organs and tissues of the body

Tract

a bundle of mylenated nerve fibers following a path through the brain

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