HTHS 2111 Unit 11 Nervous System

Vocabulary practice flashcards covering structures, cell types, divisions, anatomical regions, and functional centers of the human nervous system based on HTHS 2111 Integrated Human Anatomy & Physiology II Unit 11.

Neurons

Nerve cells that receive, process, and transmit information by manipulating the flow of electric charge across their membranes.

Glia

Supporting cells of the nervous system that provide support, nutrition, and maintain the internal environment without manipulating information.

Central Nervous System

Division of the nervous system comprising the brain, spinal cord, and cranial nerves I and II.

Peripheral Nervous System

Division of the nervous system comprising somatosensory receptors, spinal nerves, ganglia, and cranial nerves III through XII.

Nucleus (Neuroanatomy)

A cluster of nerve cell bodies located within the central nervous system.

Ganglion

A cluster of nerve cell bodies located within the peripheral nervous system.

Tract

A cluster or bundle of nerve axons located within the central nervous system, typically named starting with its origin followed by its termination.

Nerve

A cluster or bundle of nerve axons located within the peripheral nervous system.

Afferent Information

Sensory information traveling into the central nervous system.

Efferent Information

Motor information traveling out of the central nervous system to effectors such as muscles or glands.

Sympathetic Nervous System

Division of the autonomic nervous system responsible for the 'fight or flight' (or freeze) response, activated throughout the body during danger.

Parasympathetic Nervous System

Division of the autonomic nervous system responsible for 'rest and digest' functions, activated on an organ-by-organ basis during quiet conditions.

Enteric Nervous System

An independent network of self-regulated neurons in the gut wall consisting of the myenteric and submucosal plexuses.

Dendrites

Neuronal processes that receive incoming input signals at synapses and process information.

Soma

The cell body of a neuron containing the nucleus, involved in receiving/processing inputs and providing metabolic support.

Axon

A neuronal process that conducts action potentials away from the soma toward axon terminals to transmit information.

Axon Hillock

The junction between the soma and the axon where the decision is made to initiate an action potential.

Nodes of Ranvier

Brief interruptions in the myelin sheath along an axon that allow propagation of action potentials.

Purkinje Cells

Large cerebellar neurons that gather information across a 2-dimensional slice of cerebellar cortex and send inhibitory output through a single large axon.

Unipolar Neurons

Neurons with a single process extending from the cell body, typically collecting somatosensory information from skin to the CNS.

Bipolar Neurons

Neurons with two processes extending from the cell body, found relaying information short distances in visual and auditory systems.

Multipolar Neurons

Neurons possessing multiple dendrites and a single axon extending from the cell body.

Myelin Sheath

An insulating layer composed of $80\%$ lipid and $20\%$ protein wrapping axons to increase impulse transmission speed and prevent signal leakage.

Gray Matter

Brain and spinal cord tissue consisting mainly of unmyelinated neuronal cell bodies and dendrites where information processing occurs.

White Matter

Brain and spinal cord tissue consisting primarily of myelinated axon bundles traveling from one area to another.

Astrocytes

Star-shaped CNS glial cells that maintain low extracellular $K^+$ and high $Na^+$, convert glutamate to glutamine, and form the blood-brain barrier.

Oligodendrocytes

Glial cells in the CNS that extend branches to wrap multiple neuronal axons with myelin sheaths.

Ependymal Cells

Ciliated glial cells lining the cerebral ventricles that produce cerebrospinal fluid (CSF) and assist in its circulation.

Microglia

Monocyte-derived glial cells that serve as the sole immune defense within the central nervous system.

Satellite Cells

Glial cells in PNS ganglia that provide functional support to neuronal cell bodies, serving a role analogous to astrocytes.

Schwann Cells

Glial cells in the PNS that wrap individual axons with myelin and permit or encourage axon regeneration.

Cauda Equina

The bundle of lumbar, sacral, and coccygeal nerve roots floating in CSF below the end of the spinal cord around vertebra L2.

Posterior Horn

Region of spinal cord gray matter responsible for processing incoming sensory information.

Anterior Horn

Region of spinal cord gray matter containing cell bodies of $\alpha$ motor neurons that send somatic motor signals to skeletal muscle.

Lateral Horn

Region of spinal cord gray matter present at T1-L2 levels containing cell bodies of neurons that send output to the autonomic nervous system.

Substantia Gelatinosa

Region in the posterior horn of the spinal cord where pain perception is processed, influenced by brainstem pathways, and acted upon by opioids.

Epineurium

Dense connective tissue layer surrounding an entire peripheral nerve.

Perineurium

Connective tissue sheath surrounding a fascicle (bundle of axons) within a peripheral nerve.

Endoneurium

Delicate connective tissue layer surrounding an individual axon inside a peripheral nerve fascicle.

Neural Tube

Embryonic tubular structure formed from the closure of neural folds that serves as the basis for all CNS structures.

Precentral Gyrus

Frontal lobe elevation (Brodmann area 4 / primary motor cortex) containing upper motor neurons organized as a motor homunculus.

Postcentral Gyrus

Parietal lobe elevation (Brodmann areas 3, 1, 2 / primary somatosensory cortex) organized as a sensory homunculus for conscious perception.

Corpus Callosum

A broad band of nerve fibers connecting the left and right cerebral hemispheres.

Insula

A folded-in cortical area concealed deep beneath the frontal, parietal, and temporal lobes involved in empathy, disgust, self-awareness, and grading pain.

Broca's Area

Cortical region located in Brodmann areas 44 and 45 of the frontal lobe responsible for symbolic language production.

Wernicke's Area

Cortical region located in parts of Brodmann areas 22, 39, and 40 responsible for decoding speech sounds and understanding language.

Primary Visual Cortex

Cortical area located along the calcarine sulcus in the occipital lobe (Brodmann area 17) containing a visuotopic map of visual space.

Primary Auditory Cortex

Cortical area located on the superior temporal gyrus (Brodmann areas 41 and 42) organized tonotopically for conscious perception of sound.

Dura Mater

The tough, fibrous outermost layer of the meninges tightly bound to the skull.

Arachnoid Mater

Spiderweb-like middle meningeal layer separated from the pia mater by the subarachnoid space containing CSF.

Pia Mater

Thin innermost meningeal layer composed of astrocyte end-feet adhering directly to the surface of the brain and spinal cord.

Blood-Brain Barrier

Protective seal formed by tight junctions between capillary endothelial cells and astrocyte end-feet that tightly regulates substance passage into brain ECF.

Circle of Willis

An arterial anastomosis at the base of the brain uniting the anterior (internal carotid) and posterior (vertebral/basilar) circulations.

Reticular Formation

A loosely connected network of neurons in the brainstem core that receives sensory inputs and regulates behavioral arousal and wakefulness.

Hippocampus

Structure within the limbic system crucial for consolidating short-term memory into long-term memory.

Amygdala

Limbic system structure responsible for processing emotional states, particularly anger and fear messages.