Lecture 10: Introduction to the Nervous System

Vocabulary practice flashcards covering structural and functional divisions of the nervous system, neuron anatomy, glial cell types, nerve connective tissue coverings, and neurotransmitters.

Amyotrophic Lateral Sclerosis (ALS)

A neurodegenerative disease affecting motor neurons that govern voluntary movement via skeletal muscle, gradually resulting in loss of movement, eating, talking, and breathing.

Central Nervous System (CNS)

The structural division of the nervous system consisting of the brain and spinal cord, serving as the master control center ('boss') of the body.

Peripheral Nervous System (PNS)

All nervous tissue located outside the CNS, including cranial nerves, spinal nerves, and ganglia, which connects the body to the CNS.

Ganglia

Clusters of neuron cell bodies located outside the central nervous system in the PNS.

Nerve

A bundled cable of neuron axons situated within the peripheral nervous system.

Afferent

Sensory information 'arriving' at the CNS from receptors throughout the body via the PNS.

Efferent

Motor information 'exiting' the CNS and travelling via the PNS to effectors such as muscles or glands.

Somatic Sensory Division

The functional branch of the sensory nervous system that collects conscious sensory input from the skin, joints, skeletal muscles, and special senses (such as touch, pain, pressure, vibration, taste, and vision).

Visceral Sensory Division

The functional branch of the sensory nervous system that unconsciously detects input from internal organs and blood vessels, such as blood pressure and visceral distension.

Somatic Motor Division

The motor division responsible for initiating voluntary output to stimulate contraction of skeletal muscles.

Autonomic (Visceral) Motor Division

The motor division responsible for initiating involuntary output that regulates cardiac muscle, smooth muscle, and glandular secretion.

Neuron

The primary excitable cell and functional 'workhorse' of the nervous system (~85 billion in the brain alone) responsible for processing and transmitting electrical impulses.

Neuroglia

Supportive non-neuronal cells of the nervous system that nourish, protect, and insulate neurons; they occur in roughly equal numbers to neurons and retain the ability to divide by mitosis.

Dendrites

Branching extensions of a neuron that receive signals from other neurons and convey them inward toward the soma.

Soma

The cell body of a neuron that integrates incoming electrical input; contains the nucleus, abundant ribosomes, and typical organelles, lacks mitotic spindles (amitotic), and forms gray matter.

Axon

The long cytoplasmic projection of a neuron that transmits nerve impulses away from the cell body toward another neuron, muscle, or gland; typically wrapped in myelin to form white matter.

Synapse

The junction where a presynaptic neuron communicates chemically with a postsynaptic cell (another neuron, muscle fiber, or gland) across a synaptic cleft.

Synaptic Vesicles

Membrane-bound organelles located in the axon terminal of the presynaptic neuron that store neurotransmitters and release them via exocytosis upon stimulation.

Gray Matter

Nervous tissue in the CNS composed of neuron cell bodies, dendrites, and synapses, serving as the site of integration and information processing.

White Matter

Nervous tissue composed primarily of myelinated axons, specialized for rapid transmission and transport of electrical impulses.

Interneuron

Multipolar neurons located entirely within the CNS that integrate incoming sensory information and coordinate motor responses; they account for 99% of all neurons.

Astrocyte

The most abundant glial cell in the CNS; acts as the 'bouncer of the brain' using perivascular feet to maintain the blood-brain barrier by interacting with endothelial cells and tight junctions.

Oligodendrocyte

A CNS glial cell whose cytoplasmic processes wrap around and insulate multiple neighboring axons with a myelin sheath to speed impulse transmission; destroyed by the immune system in Multiple Sclerosis.

Microglial Cell

Small phagocytic immune cells of the CNS that clear waste, debris, and pathogens, multiplying in number during an infection.

Ependymal Cell

Ciliated glial cells lining the ventricles of the brain and the central canal of the spinal cord that produce, monitor, and circulate cerebrospinal fluid (CSF).

Satellite Cell

Glial cells of the PNS that surround sensory neuron cell bodies within ganglia to regulate nutrient, waste, and chemical exchange with the microenvironment.

Schwann Cell (Neurolemmocyte)

A glial cell of the PNS that wraps around an individual peripheral axon segment to produce the myelin sheath.

Glioma

A primary central nervous system tumor derived from mitotic glial cells, such as astrocytomas, ependymomas, or oligodendrogliomas.

Epineurium

The thick outer sheath of dense irregular connective tissue surrounding an entire peripheral nerve.

Perineurium

The dense irregular connective tissue layer that bundles groups of axons into distinct fascicles within a nerve.

Endoneurium

The delicate layer of areolar connective tissue that encloses each individual axon and its associated myelin sheath.

Peripheral Nerve Connective Tissue Sheaths

The organized protective layers enclosing peripheral nervous tissue: the epineurium encloses the whole nerve, the perineurium surrounds fascicles, and the endoneurium wraps individual axons.

Selective Serotonin Reuptake Inhibitor (SSRI)

A therapeutic class of drugs that increases serotonin availability within the synaptic cleft by inhibiting its transport back into the presynaptic neuron.

Acetylcholine (ACh)

A neurotransmitter responsible for initiating motor signals that trigger contraction in skeletal muscle tissue.

Dopamine

A neurotransmitter associated with reward processing, motivation, pleasure, and the control of body movements.

Norepinephrine

A primary neurotransmitter active in initiating the sympathetic 'fight or flight' response.

Glutamate

A major excitatory neurotransmitter primarily involved in learning, cognitive processing, and memory storage.