Neuroscience: Autonomic Nervous System, Cells of the CNS, and Neurogenesis

Vocabulary flashcards covering Autonomic Nervous System functions, CNS cellular anatomy, neuroglia, synaptic structures, and embryonic neurogenesis.

Autonomic Nervous System

The division of the nervous system that controls automatic and visceral body functions to maintain homeostasis, comprising the sympathetic, parasympathetic, and enteric systems.

Sympathetic Nervous System

The division of the autonomic nervous system responsible for the 'fight or flight' response, originating from the thoracolumbar outflow ($T1-L2/L3$).

Parasympathetic Nervous System

The division of the autonomic nervous system responsible for 'rest and recover' functions, originating from craniosacral outflow (cranial nerves III, VII, IX, X and spinal segments S2–S4).

Enteric Nervous System

A division of the autonomic nervous system dedicated to controlling the functions of the gastrointestinal system.

Dysautonomia

A general term for conditions or dysfunctions of the autonomic nervous system, categorized as primary (occurring insidiously) or secondary (resulting from another disease process).

Postural Orthostatic Tachycardia Syndrome (POTS)

A dysautonomia condition marked by excessive heart rate increase, dizziness, and blood pooling upon standing, diagnosed using a tilt table test.

Complex Regional Pain Syndrome (CRPS)

An autonomic-related condition caused by nerve hypersensitivity following limb injury, characterized by pain disproportionate to the original injury.

Autonomic Dysreflexia

A neurological emergency occurring in individuals with spinal cord injury at or above T6, triggered by noxious stimuli below the lesion level and causing severe hypertension and sweating above the injury level.

Sagittal Plane

An imaginary anatomical plane that divides a structure into left and right portions.

Coronal Plane

An imaginary anatomical plane (also called frontal plane) that divides a structure into anterior and posterior portions.

Horizontal Plane

An imaginary anatomical plane that divides a structure into superior and inferior portions.

Anatomical Planes Diagram

The three anatomical reference planes dividing the human body into sagittal, horizontal (transverse), and coronal (frontal) sections.

Nucleus (Neuroanatomy)

A group or collection of neuronal cell bodies located within the central nervous system (CNS).

Ganglion

A collection or group of neuronal cell bodies located outside the central nervous system in the peripheral nervous system (PNS).

Neuron

The basic structural and functional unit of the nervous system, highly specialized for encoding, conducting, and transmitting nerve impulses.

Perikaryon

The cytoplasm surrounding the nucleus within the cell body of a neuron.

Nissl Granules

Structures in the neuronal cell body consisting of rough endoplasmic reticulum and associated ribosomes involved in protein synthesis.

Neurofibrils

A complex network of structural proteins inside a neuron composed of neurofilaments.

Telodendria

The terminal branching processes of an axon that end as synaptic terminals.

Axoplasm

The specialized cytoplasm contained within an axon.

Axolemma

The surface cell membrane encasing an axon.

Nodes of Ranvier

Unmyelinated gaps along a myelinated axon containing high concentrations of voltage-gated sodium channels where action potentials are generated.

Saltatory Conduction

The rapid mode of nerve impulse propagation where action potentials jump from one node of Ranvier to the next along a myelinated axon.

Afferent Neurons

Nerve fibers that carry nerve impulses from peripheral receptors toward the central nervous system; termed sensory neurons if reaching consciousness.

Efferent Neurons

Nerve fibers that carry impulses away from the central nervous system toward effector organs; termed motor neurons when innervating muscles.

Interneurons

Tiny neurons located entirely within the central nervous system that integrate information between other neurons.

Pseudounipolar Neurons

Neurons featuring a single primary process extending from the soma that divides into an axon and dendrite, such as dorsal root ganglion cells.

Bipolar Neurons

Neurons possessing one axon and one dendrite extending from opposite ends of the cell body, such as retinal bipolar cells.

Multipolar Neurons

Neurons with multiple dendritic trees branching from the cell body and a single axon, such as pyramidal cells and Purkinje cells.

Neuroglia (Glial Cells)

Non-neuronal supporting cells of the nervous system that provide structural and biochemical support to neurons without conducting nerve impulses.

Schwann Cells

Glial cells in the peripheral nervous system responsible for synthesizing myelin sheaths around PNS axons and buffering excess extracellular $K^+$.

Oligodendrocytes

Glial cells in the central nervous system that form myelin sheaths around segments of multiple axons simultaneously.

Astrocytes

Star-shaped CNS glial cells that form the blood-brain barrier, transport nutrients from capillaries to neurons, buffer extracellular $K^+$, and assist in healing and debris removal.

Ependymal Cells

Ciliated columnar epithelial cells lining cerebral ventricles and the central canal of the spinal cord, forming a selective barrier and creating choroid plexus to produce CSF.

Microglia

Mesoderm-derived CNS glial cells that proliferate following injury and act as phagocytic scavengers to clear cellular debris.

Synapse

The specialized functional junction between two neurons, or a neuron and an effector cell, where nerve impulse transmission occurs electrically or chemically.

Synapse Classification Diagram

A comparison showing (a) chemical synapses utilizing neurotransmitters across a synaptic cleft and (b) electrical synapses passing ions directly through gap junction channels.

Neurogenesis

The process of nervous system development during embryonic and fetal growth, originating from the ectoderm.

Pre-embryonic Stage

The initial developmental stage in utero spanning from conception to day 14.

Embryonic Stage

The developmental stage in utero spanning from day 15 to the end of the 8th week, during which organogenesis occurs.

Fetal Stage

The developmental stage in utero extending from the end of the 8th week until birth, marked by full system growth and initial CNS myelination.

Neural Plate

A thickened, specialized portion of the ectoderm apparent by day 18 after conception that gives rise to the central nervous system.

Neural Groove

The central indentation formed on day 20 as the edges of the neural plate fold inward.

Neural Tube

The tubular structure formed on day 22 when the folds of the neural plate fuse in the cervical area, developing into the brain rostrally and spinal cord caudally.

Rostral Neuropore

The opening at the rostral (head) end of the developing neural tube that normally closes by day 24.

Caudal Neuropore

The opening at the caudal (tail) end of the developing neural tube that normally closes by day 26.

Anencephaly

A fatal severe neural tube defect resulting from failure of the rostral neuropore to close by day 24, characterized by absence of cerebral hemispheres, skull defects, and skin defects.

Hydroanencephaly

A neural tube defect caused by failure of rostral neuropore closure resulting in absent cerebral cortex without skull or skin defects.

Encephalocele

A neural tube defect characterized by herniation of brain tissue and meninges through a skull defect, most commonly occurring in the occipital region.

Myelomeningocele

A form of spina bifida resulting from failure of caudal neuropore closure, characterized by a vertebral defect and protrusion of meninges and spinal cord contents.

Neural Crest

Ectodermal cells remaining outside the neural tube that give rise to sensory ganglia (dorsal root ganglia) and sympathetic trunk ganglia.

Prosencephalon

The primary forebrain vesicle formed by day 28 of neural tube development, which subdivides into the telencephalon and diencephalon.

Mesencephalon

The primary midbrain vesicle formed by day 28 of neural tube development that develops into the adult midbrain.

Rhombencephalon

The primary hindbrain vesicle formed by day 28 of neural tube development, which subdivides into the metencephalon and myelencephalon.

Telencephalon

A secondary brain vesicle derived from the prosencephalon that develops into the cerebral hemispheres and basal ganglia.

Diencephalon

A secondary brain vesicle derived from the prosencephalon that develops into the thalamus, hypothalamus, optic nerves, and optic tracts.

Metencephalon

A secondary brain vesicle derived from the rhombencephalon that gives rise to the pons and cerebellum.

Myelencephalon

The most caudal secondary brain vesicle derived from the rhombencephalon that develops into the medulla.

Brain Vesicles Diagram

Diagram showing the developmental division of the neural tube into primary vesicles (prosencephalon, mesencephalon, rhombencephalon) and secondary vesicles (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon).

Cervical Flexure

The first embryonic brain flexure occurring between the hindbrain and the spinal cord in the cervical cord area.

Cephalic Flexure

An embryonic brain flexure occurring between the mesencephalon and rhombencephalon.

Hydrocephalus

An accumulation of excessive cerebrospinal fluid within the cerebral ventricles due to flow obstruction, causing ventricular enlargement and head expansion.

Arnold-Chiari Malformation

A congenital defect characterized by herniation of the posterior cerebellum and medulla downward through the foramen magnum, compressing lower brainstem structures.