BN5.005 Mid-Semester Exam Study Guide (August 2025)

Vocabulary flashcards covering the key terms and concepts outlined in the BN5.005 mid-semester study guide, including nervous tissue, central and peripheral nervous systems, the autonomic nervous system, and special senses.

Axon

A long, slender projection of a nerve cell (neuron) that conducts electrical impulses away from the cell body toward target cells or effectors.

Dendrite

A branched extension of a neuron that receives incoming chemical and electrical signals from other cells and transmits them toward the cell body.

Basal nuclei

Clusters of grey matter located deep within the cerebral hemispheres that are involved in the subconscious control and regulation of voluntary motor activity.

Choroid plexus

A specialized vascular tissue found within brain ventricles composed of ependymal cells and capillaries that secretes and forms cerebrospinal fluid (CSF).

Resting membrane potential

The steady electrical potential difference (voltage) across the plasma membrane of an excitable cell, such as a neuron, when it is not actively conducting impulses.

Depolarisation

A shift in a neuron's membrane potential toward a less negative or positive value, typically triggered by an influx of sodium ions.

Repolarisation

The recovery of the resting membrane potential following depolarisation, primarily mediated by the opening of voltage-gated potassium channels and potassium efflux.

Hyperpolarisation

A change in a cell's membrane potential that makes it more negative than the resting potential, making it more difficult to generate an action potential.

Endoneurium

A delicate layer of connective tissue that wraps around each individual axon (nerve fiber) and its associated Schwann cells.

Perineurium

A protective middle sheath of connective tissue that groups multiple nerve fibers together into distinct bundles called fascicles.

Epineurium

The outermost, tough fibrous connective tissue sheath that encloses an entire peripheral nerve, surrounding all of its fascicles and blood vessels.

Ganglion

A distinct cluster or collection of neuronal cell bodies located within the peripheral nervous system (PNS).

Nucleus (in nervous tissue)

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

Tract

A bundle or collection of myelinated and unmyelinated axons traversing the central nervous system (CNS) that shares a common origin and destination.

Nerve

A cord-like peripheral nervous system structure containing bundles of axons, associated connective tissue coverings, and blood vessels.

Gray matter

Neural tissue containing high concentrations of neuronal cell bodies, dendrites, unmyelinated axons, and synapses, responsible for information processing and integration.

White matter

Neural tissue consisting predominantly of myelinated axons, specialized for the rapid propagation of electrical signals between different nervous system regions.

Interneuron

A neuron situated entirely within the central nervous system (CNS) that forms connections between sensory neurons and motor neurons to integrate signals.

Myelin

A lipid-rich insulating substance produced by neuroglial cells that covers nerve axons to accelerate electrical impulse conduction.

Neuroglia

Non-excitable supporting cells of the nervous system that nourish, protect, insulate, and structurally maintain neurons.

Neuron

The primary structural and functional excitable cell of the nervous system capable of generating and transmitting action potentials.

Neurotransmitter

An endogenous chemical agent stored in synaptic vesicles and released by a presynaptic cell to transmit signals across a synaptic cleft.

Synapse

The specialized junction where communication occurs between an axon terminal of a neuron and another neuron, muscle fiber, or gland cell.

Synaptic cleft

The narrow extracellular fluid-filled space between the presynaptic membrane and postsynaptic membrane at a chemical synapse.

Absolute refractory period

The time period following an action potential during which the initiation of a second action potential is completely impossible, caused by the inactivation of voltage-gated sodium channels.

Relative refractory period

The time interval following an action potential when an exceptionally strong stimulus can initiate a second impulse because sodium channels have reset, though potassium channels remain open.

Gyri

Elevated ridges or convolutions on the surface of the cerebral cortex that increase the surface area of the brain.

Sulci

Shallow grooves or depressions that separate adjacent gyri on the cerebral cortex.

Fissures

Deep, prominent clefts or grooves that divide major lobes or separate the cerebral hemispheres of the brain.

Limbic system

A functional collection of brain structures surrounding the upper brainstem that plays a central role in emotion, motivation, memory, and autonomic regulation.

Meninges

The three protective connective tissue membranes (dura mater, arachnoid mater, and pia mater) surrounding and safeguarding the brain and spinal cord.

Cerebrospinal fluid (CSF)

A clear, watery fluid derived from blood plasma that cushions the brain and spinal cord, provides buoyancy, and circulates essential nutrients.

Static equilibrium

The maintenance of body position and balance (primarily head orientation) in response to gravity when linear movement is absent.

Dynamic equilibrium

The maintenance of body balance and detection of head rotation in response to angular acceleration and sudden rotational movements.

Fovea

A tiny depression in the center of the retina containing an exceptionally high concentration of cone photoreceptors, providing the highest visual acuity.

Olfactory epithelium

A specialized sensory epithelial tissue lining the superior portion of the nasal cavity that contains receptor neurons dedicated to the sense of smell.

Auditory ossicles

The three tiny bones of the middle ear (malleus, incus, and stapes) that mechanically amplify and transmit acoustic vibrations from the tympanic membrane to the oval window.

Tympanic membrane

The eardrum; a thin, semitransparent fibrous membrane that separates the external acoustic meatus from the middle ear and vibrates in response to sound waves.

Otoliths

Microscopic calcium carbonate crystals embedded within the gelatinous otolithic membrane of the maculae that move under gravity to stimulate hair cells.

Macula

The sensory receptor organ located within the utricle and saccule of the inner ear, containing hair cells that monitor static equilibrium and linear acceleration.

Cristae ampulla

The receptor structures located within the ampullae of the semicircular canals consisting of hair cells that detect rotational (angular) head movements.

Cupula

A gelatinous cap overlying the hair bundle of the crista ampullaris that is displaced by endolymph fluid flow during head rotation.

Gustatory complex

The sensory pathway and cortical brain areas responsible for receiving, integrating, and interpreting chemical taste signals.

Pinna/auricle

The visible external cartilaginous flap of the ear that captures and channels sound waves into the external auditory canal.