Chapter 13: Neural Tissue

Comprehensive vocabulary flashcards covering the structural and functional divisions of the nervous system, cellular anatomy of neurons, classification of neuroglia, nerve impulse propagation, synapses, and neuronal circuit pools from Chapter 13.

Central nervous system (CNS)

The division of the nervous system consisting of the brain and spinal cord in the dorsal cavity; acts as an integration center that processes sensory information and determines behavioral responses, covered by meninges and bathed in cerebrospinal fluid.

Peripheral nervous system (PNS)

The division of the nervous system consisting of nerves and ganglia that contain both sensory and motor neurons.

Afferent Division

The functional division of the PNS wherein sensory neurons send signals from sensory receptors toward the CNS.

Efferent Division

The functional division of the PNS wherein motor neurons send signals out of the CNS to effectors in the body.

Neurons

Amitotic, excitable cells that transmit impulses throughout the nervous system.

Perikaryon

The specialized cytoplasm surrounding the nucleus within the soma of a neuron.

Nissl bodies

Dark-staining ribosome clusters found in the soma of a neuron, named after Franz Nissl.

Dendritic spines

Small projections on dendritic branches that participate in receiving inputs and may account for 80-90% of a neuron's surface area.

Axoplasm

The unique cytoplasm found within the axon of a neuron.

Axolemma

The specialized cell membrane covering the axon of a neuron.

Collaterals

Side branches of an axon that allow a single neuron to communicate with multiple locations.

Telodendria

Branching terminal extensions at the end of an axon that terminate in synaptic terminals.

Axon hillock

The thickened region of the neuron cell body that connects the soma to the axon.

Anaxonic neuron

A small neuron where axons cannot be distinguished from dendrites; found only in the CNS and special sense organs.

Bipolar neuron

specialized nerve cells that feature two distinct extensions coming off the cell body (soma): a single dendrite that receives signals and a single axon that transmits them.

Pseudounipolar neuron

A neuron where several small dendrites converge onto one continuous axon bypassing the soma; constitutes the majority of sensory neurons in the PNS.

Multipolar neuron

A neuron featuring many dendrites extending directly from the soma and a single long axon; constitutes the majority of PNS motor neurons and CNS spinal interneurons.

Exteroceptors

Sensory receptors that monitor external stimuli such as touch, temperature, pressure, light, and chemicals.

Proprioceptors

Sensory receptors that monitor the position and movement of skeletal muscles and joints.

Interoceptors

Sensory receptors that monitor internal bodily systems, including the digestive, respiratory, and urinary systems.

Interneurons

The most abundant class of neurons, located entirely within the CNS, categorized functionally as either excitatory or inhibitory.

Somatic Division

The consciously controlled efferent division consisting of a single neuron with its soma in the CNS that targets skeletal muscle effectors.

Autonomic Division

The unconsciously controlled efferent division using two neurons (one soma in the CNS, the other in a peripheral ganglion) to target smooth muscle, cardiac muscle, or glands.

Astrocytes

Large, star-shaped CNS neuroglia with many cytoplasmic extensions; the most common glial cells, responsible for controlling interstitial environment, forming the CNS framework, repairing damaged neurons, guiding embryonic neurons, and creating the blood-brain barrier.

Oligodendrocytes

CNS neuroglia with few extensions that wrap around clusters of axons to form insulating myelin sheaths.

Microglia

The least common CNS neuroglia; derived from white blood cells, they phagocytize microbes, viruses, tumors, and cellular debris.

Ependymal cells

Cuboidal neuroglia with branched processes that line the hollow central cavities of the CNS (ependyma) and produce cerebrospinal fluid.

Satellite cells

PNS neuroglia that surround neuron somas in ganglia and regulate nutrient exchange between the cell body and the surrounding environment.

Schwann cells

PNS neuroglia named after Theodor Schwann that surround all peripheral axons; they enclose multiple unmyelinated axons in a single layer or wrap repeatedly around a single myelinated axon.

Action potential

A localized change in electrical charge across an axon's membrane resulting from the movement of ions through channels, triggering adjacent channels to open in succession.

White matter

Regions of the CNS that appear white on prepared slides due to the high presence of lipid-based myelin insulation around axons.

Gray matter

Regions of the CNS containing neuron somas and unmyelinated axons that lack the thick lipid layer and stain gray on slides.

Nodes of Ranvier

Unmyelinated gaps along an axon between Schwann cells or oligodendrocyte wrappings (named after Louis-Antoine Ranvier) where ion exchange occurs, allowing action potentials to jump and travel faster.

Synapse

A junction between two or more cells that allows for intercellular communication.

Presynaptic cell

The cell that delivers a signal across a synapse to another cell.

Postsynaptic cell

The cell that receives a signal transmitted across a synapse.

Electrical synapse

A type of synapse where cells are connected by gap junctions, allowing the direct exchange of charged ions, such as across intercalated disks in cardiac muscle.

Chemical synapse

A type of synapse where communication occurs via chemical messengers, termed neurotransmitters, released by one cell to bind to another.

Divergence

A neuronal pool circuit in which a single neuron branches to communicate with multiple neurons in the pool.

Serial processing

A neuronal pool circuit where one neuron communicates to another in a linear sequence or series.

Convergence

A neuronal pool circuit in which signals from many separate neurons come together to communicate with a single postsynaptic neuron.

Parallel processing

A neuronal pool circuit in which a single neuron sends an identical signal along multiple paths to many locations simultaneously.

Reverberation

A positive feedback neuronal circuit in which a neuron downstream in the pathway loops back to stimulate an earlier neuron.

Nuclei

Collections of somas working together within the CNS that possess distinct, clear anatomical boundaries.

Tracts

Bundles of axons running together within the central nervous system.

Ganglia

Collections or clusters of neuron somas located outside the CNS within the peripheral nervous system.

Nerves

Bundles of axons wrapped together in the peripheral nervous system.