ANSC 23000 - Physiology of Domestic Animals: The Nervous System

Vocabulary flashcards covering the structural divisions, cell types, action potentials, synaptic transmission, and gross anatomy of the central and peripheral nervous systems from Week 3 - Lecture 4.

Central Nervous System (CNS)

The structural division of the nervous system consisting of the brain and spinal cord that receives, integrates, processes, and coordinates sensory input while initiating motor commands.

Peripheral Nervous System (PNS)

All neural tissue located outside of the brain and spinal cord, functioning as the physical connection between the CNS and the rest of the body.

Afferent Division

The sensory division of the PNS that delivers information from peripheral sensory receptors to the central nervous system.

Efferent Division

The motor division of the PNS that carries outgoing commands from the central nervous system to peripheral organs and tissues.

Somatic Nervous System (SNS)

The branch of the efferent nervous system responsible for voluntary control of body movements by innervating skeletal muscle tissue.

Autonomic Nervous System (ANS)

The branch of the efferent nervous system responsible for involuntary, unconscious regulation of smooth muscle, cardiac muscle, glands, and adipose tissue.

Sympathetic Division

A subdivision of the autonomic nervous system responsible for the 'fight or flight' response, such as increasing heart rate and causing pupil dilation.

Parasympathetic Division

A subdivision of the autonomic nervous system responsible for the 'rest and digest' response, such as decreasing heart rate and increasing blood flow to the intestines.

Neuron

The structural and functional nerve cell of the nervous system responsible for transmitting and receiving electrical signals, consisting of a cell body, dendrites, and an axon.

Axon

A single long process of a neuron that conducts nerve impulses away from the cell body.

Dendrites

Neuronal processes that conduct nerve impulses toward the cell body and increase total cell surface area.

Glial Cells

Nonneuronal support cells of the nervous system that outnumber neurons 10-fold and include astrocytes, oligodendrocytes, Schwann cells, microglia, and ependymal cells.

Schwann Cells

Glial cells in the peripheral nervous system (PNS) that produce the insulating myelin sheath by wrapping around nerve cell axons.

Oligodendrocytes

Glial cells responsible for producing the insulating myelin sheath around nerve cell axons within the central nervous system (CNS).

Node of Ranvier

The unmyelinated gap between adjacent Schwann cells along a nerve axon.

Astrocytes

Star-shaped glial cells in the CNS that provide structural support and facilitate transport of molecules from blood capillaries to neurons, forming the blood-brain barrier.

Ependymal Cells

Simple columnar epithelial cells that line the ventricles of the brain and produce cerebrospinal fluid (CSF).

Microglia

Resident immune cells (macrophages) of the central nervous system that perform phagocytic functions.

Effectors

Peripheral target organs and tissues whose activities change in response to neural motor commands, including skeletal, smooth, and cardiac muscles, glands, and adipose tissue.

Resting Membrane Potential

The electrical potential difference across a cell membrane at rest (typically $-70\,mV$), caused by an unequal distribution of extracellular $Na^+$ and intracellular $K^+$ ions.

Na+/K+ ATPase Pump

An active transport pump that maintains resting membrane potential by moving $3 \times Na^+$ out of the cell and $2 \times K^+$ into the cell for every ATP consumed.

Depolarization to Threshold

The initial step of an action potential where mechanical or chemical stimuli induce a graded potential that depolarizes the membrane to its threshold of $-60\,mV$.

Rapid Depolarization

The phase of an action potential where voltage-gated $Na^+$ channels open, allowing $Na^+$ ions to rush into the cell and shifting the membrane potential to a positive value.

Repolarization

The phase of an action potential initiated when voltage-gated $Na^+$ channels close and voltage-gated $K^+$ channels open, allowing $K^+$ to rush out of the cell to restore negative potential.

Hyperpolarization

A brief drop in membrane potential to $-90\,mV$ caused by the delayed closing of voltage-gated $K^+$ channels before returning to the resting state of $-70\,mV$.

Continuous Propagation

The step-by-step conduction of an action potential along adjacent regions of an unmyelinated axon membrane.

Saltatory Propagation

The rapid transmission of an action potential along a myelinated axon where the electrical impulse jumps from one node of Ranvier to the next.

Synaptic Cleft

The narrow extracellular gap separating the presynaptic axon terminal from the postsynaptic cell membrane.

Acetylcholine (ACh)

A key neurotransmitter stored in presynaptic vesicles and released into the synaptic cleft to bind receptors on the postsynaptic membrane.

Acetylcholinesterase (AChE)

An enzyme present in the synaptic cleft that rapidly breaks down acetylcholine (ACh) to close $Na^+$ channels and terminate post-synaptic transmission.

White Matter

Regions of the central nervous system composed primarily of bundles of myelinated nerve axons.

Gray Matter

Regions of the central nervous system composed mainly of nerve cell bodies, dendrites, and unmyelinated processes, divided into dorsal and ventral horns.

Dorsal Root

The nerve root structure through which incoming afferent sensory nerves enter the spinal cord.

Ventral Root

The nerve root structure through which outgoing efferent motor nerves exit the spinal cord.

Cerebrum

The major brain region responsible for conscious thought, sensations, voluntary movement, intellectual functions, and memory storage and processing.

Cerebellum

The region of the brain responsible for the involuntary maintenance of posture, motor control, and coordination of balance.

Interbrain

The deep region of the brain comprising the epithalamus, thalamus, hypothalamus, and pituitary gland.

Brain Stem

The portion of the brain containing processing centers, relay stations, and autonomic functional centers, consisting of the midbrain, pons, and medulla oblongata.