Introduction to Neural Structure and the Nervous System

Comprehensive practice flashcards covering neural structure, glial cells, brain anatomy, spinal cord organization, and the peripheral nervous system based on lecture transcript notes.

Dendrites

Processes that branch out from the soma and serve as the main target for incoming signals received from other cells.

Spines

Small protrusions along the branches of the dendrites that are the sites of some synaptic contacts and increase surface area.

Cell Body (soma)

The part of the neuron that weighs incoming signals and performs "cellular arithmetic" to decide whether to send a "YES" or "NO" output.

Axon Hillock

The beginning of the axon located where the cell body transitions into the axon.

Plasticity

The ability of the nervous system to change, such as changes at the level of dendritic spines after exposure to drugs or stress.

Nerves

Bundles of several axons that travel together in the Peripheral Nervous System.

Myelin Sheath

A fatty substance that wraps around portions of the axon to increase signal conduction.

Nodes of Ranvier

Breaks between myelin segments that allow for saltatory conduction, increasing the conduction speed of signals.

Neurotransmitters

Endogenous chemicals released from the presynaptic terminal that allow neurons to communicate with each other.

Unipolar Neurons

Neurons that have one extension from the cell body that acts as both the receiving and sending end.

Bipolar Neurons

Neurons with one dendrite and one axon, found in human sensory systems like the eye or the pathway from the ear to the brain.

Multipolar Neurons

The most common neurons in the human nervous system, containing one axon and numerous dendrites.

Motor (efferent) neurons

Neurons that carry information away from the Central Nervous System (CNS) to the body.

Sensory (afferent) neurons

Neurons that obtain information from the outside world or internal environment and send it to the CNS.

Interneurons

A broad class of neurons that act as a relay between sensory or motor neurons and the CNS, or between each other.

Schwann cells

Glial cells in the PNS that provide a single section of myelin sheath and assist in the regeneration of injured axons.

Oligodendrocytes

Glial cells in the CNS able to myelinate up to $50$ segments of nearby axons to increase conduction speed.

Astrocytes

Star-shaped glial cells that maintain the Blood-Brain Barrier (BBB) and produce trophic factors to signal neuron survival.

Microglia

Cellular scavengers that make up $10-15\%$ of brain cells; they identify and destroy pathogens, dead cells, or protein clumps.

Ependymal cells

Ciliated cells found along the inside of the ventricles that produce cerebrospinal fluid (CSF).

Choroid plexus

A network of blood vessels and cells that form a boundary between the blood and the CSF.

Central Nervous System (CNS)

The division of the nervous system consisting of the brain and the spinal cord.

Somatic Nervous System

A branch of the efferent motor division involving conscious, voluntary control over muscle movement.

Autonomic Nervous System

The involuntary motor system that deals with the internal environment, including smooth muscle, cardiac muscle, and glands.

Sympathetic Nervous System

A branch of the autonomic system responsible for the "fight-or-flight" response.

Parasympathetic Nervous System

A branch of the autonomic system responsible for the "rest-and-digest" response.

Rostral

Anatomical terminology meaning toward the front of the brain or the top of the spinal cord.

Caudal

Anatomical terminology meaning toward the back of the brain or the bottom of the spinal cord.

Dorsal

Anatomical terminology meaning toward the top of the brain or the back of the body.

Ventral

Anatomical terminology meaning toward the bottom of the brain or the front of the body.

Frontal (coronal) plane

A plane that divides objects into front and back pieces in a medial-lateral direction.

Sagittal plane

A plane that divides objects into right and left regions in a rostral-caudal direction.

Proximal

A part of the body that is in close proximity to the CNS.

Ipsilateral

A term describing a part of the body that is on the same side as that half of the nervous system.

Gyri

Bumps or raised ridges on the outer surface of the brain.

Sulci

Grooved indentations on the surface of the brain.

Frontal Lobe

The largest lobe, located at the front of the brain, responsible for higher-level executive functions and planning movement.

Parietal Lobe

The brain region located behind the frontal lobe responsible for tactile properties, proprioception, and higher-level visual processing.

Primary motor cortex

Located in the precentral gyrus, this region is responsible for planning and executing movement.

Primary somatosensory cortex

Located in the postcentral gyrus, this region is responsible for the perception of touch and pain.

Temporal Lobe

Located on the side of the brain, it is involved in hearing, smell, taste, and memory (via the hippocampus).

Occipital Lobe

The smallest lobe, located at the back of the brain, primarily responsible for processing visual stimuli.

Thalamus

A sensory relay station in the brain through which almost every sensory modality passes information before the cortex.

Diencephalon

The region of the brain consisting of the thalamus and hypothalamus.

Cerebellum

A structure inferior to the occipital lobes involved in the regulation of body movement and emotional cognitive functions.

Brainstem

Located between the cerebrum and spinal cord, it regulates critical functions like heart rate, breathing, and sleep.

Tectum

The part of the midbrain consisting of the superior and inferior colliculi, important for vision and hearing.

Cervical region

The region of the spinal cord ($C1-C7$) where nerves innervate the muscles of the neck, shoulders, arms, and hands.

Dorsal root

A sensory (afferent) nerve root responsible for carrying information toward the CNS.

Ventral root

A motor (efferent) nerve root responsible for carrying information away from the CNS.

White matter

CNS pathways composed of axons, appearing pale due to the presence of myelin sheaths.

Gray matter

CNS regions dense with cell bodies, dendrites, and synapses.

Corpus callosum

The major communication tract between the left and right hemispheres of the brain.

Dermatome

A specific area of skin that carries information to the spinal cord through a particular pair of spinal nerves.

Circle of Willis

An anatomical redundancy of blood vessels that maintains cerebral blood flow even if one part of the arterial system is blocked.

Blood-Brain Barrier (BBB)

An anatomical adaptation made of endothelial cells and astrocytes that excludes harmful invaders from the brain.

Meninges

A series of three protective membranes (dura mater, arachnoid mater, pia mater) that encase the nervous system.

Dura mater

The thick, fibrous outermost layer of the meninges, meaning "tough mother."

Ventricles

A total of $4$ interconnected spaces in the brain (Lateral, Third, and Fourth) that produce and house CSF.

Cerebrospinal fluid (CSF)

A high-salt solution that allows the brain to float, reducing its effective weight from $\sim1.5\,kg$ to less than $50\,g$.