Nervous System Lecture Review

Vocabulary flashcards generated from the lecture notes on the nervous system, covering anatomical divisions, cell structures, functions, and key brain regions.

Sensory Function

The function of the nervous system that detects internal and external stimuli.

Integrative Function

The function of the nervous system that processes sensory information and makes decisions for appropriate responses.

Motor Function

The function of the nervous system that elicits an appropriate response by activating effectors, such as muscles and glands, through cranial and spinal nerves.

Neurons

Nerve cells that possess electrical excitability.

Dendrites

Highly branched, tapering processes extending from the cell body (soma) of a neuron that conduct impulses toward the cell body and receive information via synapses.

Soma

The cell body of a neuron containing a nucleus surrounded by cytoplasm and organelles; receives incoming chemical signals and compiles them at the axon hillock to decide whether to fire an electrical impulse.

Axon

A single main neuronal process that joins the cell body at the axon hillock and propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell.

Axoplasm

The cytoplasm of an axon.

Axolemma

The plasma membrane of an axon.

Schwann Cell

A glial cell in the peripheral nervous system that forms the insulating myelin sheath around an axon.

Central Nervous System (CNS)

The structural division of the nervous system consisting of the brain and spinal cord located in the dorsal body cavity.

Peripheral Nervous System (PNS)

The structural division of the nervous system consisting of nerves, ganglia, and sensory receptors that link all parts of the body to the CNS.

Ganglia

Collections or small knots of nerve cell bodies located outside the Central Nervous System.

Sensory Division

Also known as the afferent division; conveys input into the CNS from somatic and special sensory receptors in the body.

Motor Division

Also known as the efferent division; conveys motor output from the CNS to effectors such as muscles and glands.

Somatic Nervous System

The voluntary component of the motor division that conveys output from the CNS exclusively to skeletal muscles.

Autonomic Nervous System

The involuntary component of the motor division that conveys output from the CNS to smooth muscle, cardiac muscle, and glands.

Parasympathetic Division

The branch of the ANS that promotes maintenance functions, conserves energy, and is referred to as the rest and digest system.

Sympathetic Division

The branch of the ANS that mobilizes the body during activity and is referred to as the fight-or-flight system.

Enteric Nervous System

The branch of the ANS that regulates the activity of smooth muscle and glands within the gastrointestinal (GI) tract.

Brain Stem

The region continuous with the spinal cord consisting of the midbrain, pons, and medulla oblongata, which produces automatic survival behaviors and contains nuclei for $10$ of the $12$ pairs of cranial nerves.

Midbrain

Also known as the mesencephalon; the brain stem section between the diencephalon and pons containing visual and auditory reflex centers and nuclei for cranial nerves III and IV.

Pons

The bulging brain stem region between the midbrain and medulla oblongata that contains nuclei for cranial nerves V–VII and cooperates with medullary respiratory centers to regulate breathing.

Medulla Oblongata

The most inferior portion of the brain stem containing nuclei for cranial nerves VIII–X and XII, functioning as an autonomic reflex center for heart rate, blood pressure, and breathing.

Decussation of Pyramids

The specific crossing point at the junction of the medulla oblongata and spinal cord where approximately $85\%$ to $90\%$ of motor nerve fibers cross over to the opposite side.

Cerebellum

The part of the brain dorsal to the pons and medulla that coordinates skilled movements and maintains posture and balance, constituting $11\%$ of total brain mass.

Thalamus

Bilateral egg-shaped nuclei comprising $80\%$ of the diencephalon, functioning as the principal relay station for sensory impulses reaching the cerebral cortex.

Hypothalamus

The part of the diencephalon inferior to the thalamus that regulates the ANS, hormone production, body temperature, circadian rhythms, and emotional behaviors.

Epithalamus

The most dorsal part of the diencephalon forming the roof of the third ventricle, containing the pineal gland which secretes melatonin.

Cerebrum

Known as the seat of intelligence; consists of cerebral cortex, white matter, and deep gray matter nuclei responsible for complex integrative functions like memory and reasoning.

Gyri

The folds or convolutions on the surface of the cerebral cortex formed as outer gray matter enlarges faster than deeper white matter.

Fissures

The deepest grooves located between folds of the cerebral cortex.

Sulci

The shallower grooves located between folds of the cerebral cortex.

Basal Nuclei

Gray matter nuclei deep within cerebral white matter that initiate and terminate movements, suppress unwanted movements, and regulate muscle tone.

Left Cerebral Hemisphere

The hemisphere responsible for receiving sensory signals from and controlling motor movements of the right side of the body, as well as handling speech, language, comprehension, analysis, calculations, and recognition of words and numbers.

Right Cerebral Hemisphere

The hemisphere responsible for receiving sensory signals from and controlling motor movements of the left side of the body, as well as handling creativity, spatial ability, context/perception, and recognition of faces, places, and objects.

Limbic System

Often termed the emotional brain; plays a primary role in emotions (pain, pleasure, docility, affection, anger), olfaction, and memory.

Cerebrospinal Fluid (CSF)

A clear, colorless liquid composed primarily of water that cushions and buoys the brain and spinal cord, protecting them from physical and chemical injuries.