Introduction to the Nervous System

Astrocytes

Glial cells that support the blood-brain barrier.

Microglia

Modified monocytes that act as phagocytic cells in the central nervous system.

Ependymal cells

Ciliated cells that create cerebrospinal fluid (CSF).

Oligodendrocytes

Glial cells with multiple processes that form myelin in the central nervous system.

Schwann cells

Cells that are involved in myelin production and have single-cell involvement in the peripheral nervous system.

Dendrite

A part of a neuron that receives signals from other cells.

Axon Hillock

The part of the neuron where the axon begins and action potentials are initiated.

Myelin Sheath

A protective covering that surrounds an axon and increases the speed of nerve impulse transmission.

Synaptic knobs/boutons

The terminal ends of an axon that release neurotransmitters.

Multipolar neuron

A neuron with one axon and multiple dendrites.

Bipolar neuron

A neuron with two processes: one axon and one dendrite.

Unipolar neuron

A neuron with a single process that branches into two axonal processes.

Epineurium

The outermost layer of connective tissue surrounding a nerve.

Cerebrospinal fluid (CSF)

Fluid that cushions the brain and spinal cord, providing protection and nourishment.

Dura Mater

The tough outer layer of the meninges, protecting the brain and spinal cord.

Arachnoid Layer

The middle layer of the meninges that resembles a spider web.

Pia Mater

The delicate inner layer of the meninges that directly covers the brain and spinal cord.

Ventricles

Cavities within the brain filled with cerebrospinal fluid.

Cranial Nerve V (Trigeminal)

A major cranial nerve responsible for sensation in the face and motor functions such as biting and chewing.

Ascending Tracts

Nerve pathways that carry sensory information to the brain.

Descending Tracts

Nerve pathways that carry motor commands from the brain to the body.

Thalamus

A brain structure that relays sensory and motor signals to the cerebral cortex.

Hypothalamus

A region of the brain responsible for regulating vital functions such as temperature, hunger, and thirst.

Cerebral Cortex

The outer layer of the brain involved in complex functions such as thought, perception, and voluntary movement.

Hippocampus

A brain structure involved in memory formation and spatial navigation.

Cranial Nerve I (Olfactory)

Responsible for the sense of smell.

Cranial Nerve II (Optic)

Transmits visual information from the retina to the brain.

Cranial Nerve III (Oculomotor)

Controls eye movement and pupil size.

Cranial Nerve IV (Trochlear)

Innervates the superior oblique muscle, allowing for downward eye movement.

Cranial Nerve VI (Abducens)

Controls lateral eye movement.

Cranial Nerve VII (Facial)

Responsible for facial expressions, taste sensations, and some glands.

Cranial Nerve VIII (Vestibulocochlear)

Involved in hearing and balance.

Cranial Nerve IX (Glossopharyngeal)

Responsible for taste and some functions in the throat.

Cranial Nerve X (Vagus)

Controls the heart, lungs, and digestive tract; involved in autonomic functions.

Cranial Nerve XI (Accessory)

Controls shoulder and neck muscles.

Cranial Nerve XII (Hypoglossal)

Controls tongue movements.

Voltage-gated channels

Protein channels in the cell membrane that open or close in response to changes in membrane potential, allowing ions to flow in or out of the cell.

Ligand-gated channels

Protein channels that open in response to the binding of a specific chemical (ligand), allowing ions to pass through.

Synapse

The junction between two neurons where communication occurs, typically involving the release of neurotransmitters.

Pre-synaptic potential

The change in membrane potential in the neuron sending the signal before synaptic transmission.

Post-synaptic potential

The change in membrane potential in the neuron receiving the signal after synaptic transmission.

Synaptic vesicles

Small membrane-bound sacs in the pre-synaptic neuron that store neurotransmitters.

Epidural space

The space between the dura mater and the vertebral wall, containing fat and blood vessels.

Subdural space

The space between the dura mater and the arachnoid layer filled with interstitial fluid.

Subarachnoid space

The space between the arachnoid mater and the pia mater, filled with cerebrospinal fluid (CSF).

Choroid plexus

A network of blood vessels in the ventricles of the brain that produces cerebrospinal fluid (CSF).

Cervical enlargement

The region of the spinal cord that is thicker and responsible for innervating the upper limbs.

Lumbar enlargement

The region of the spinal cord that is thicker and responsible for innervating the lower limbs.

Cauda equina

A bundle of spinal nerves and nerve roots located at the lower end of the spinal cord.

Conus medullaris

The tapered end of the spinal cord located near the first lumbar vertebra.

Filum terminale

A fibrous extension from the conus medullaris that anchors the spinal cord to the coccyx.

Columns and fissures/sulci

The organized structures and grooves in the spinal cord that separate different regions and pathways.

Spinal nerve

A mixed nerve that carries both sensory and motor information; formed by the dorsal and ventral roots.

Dorsal primary ramus

The branch of a spinal nerve that supplies the muscles and skin of the back.

Ventral primary ramus

The branch of a spinal nerve that supplies the limbs and front part of the body.

31 pairs of spinal nerves

Total number of spinal nerves in the human body, which includes 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal pair.