Overview of Nervous System Function and Anatomy

Vocabulary flashcards covering the functions, cell types, divisions, electrical properties, and anatomy of the human nervous system based on lecture notes from chapters 10 and 11.

Sensory input

One of the three general functions of the nervous system that detects changes in and outside of the body.

Integration and processing

A general function of the nervous system responsible for making decisions.

Motor output

A nervous system function that stimulates muscles and glands to respond.

Central Nervous System (CNS)

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

Peripheral Nervous System (PNS)

Connects the CNS to other body parts and consists of cranial and spinal nerves.

Afferent (sensory) division

A subdivision of the PNS where impulses are conducted along peripheral nerves to the CNS for integration.

Efferent (motor) division

A subdivision of the PNS where neurons transmit impulses from the CNS to effectors.

Effectors

Muscles or glands outside the nervous system that perform motor functions.

Somatic Nervous System (SNS)

A subdivision of the efferent division that transmits voluntary commands to skeletal muscles.

Autonomic Nervous System (ANS)

A subdivision of the efferent division that transmits involuntary commands to viscera (organs).

Neurons

Specialized cells that react to environmental changes and can carry an electric impulse.

Neuroglia

Cells that support, protect, and nourish neurons but do not carry electric impulses.

Dendrites

Cytoplasmic extensions of the cell body that provide an increased surface area for the reception of cell signals.

Axon

The part of the neuron that carries the action potential (nerve impulse).

Synaptic knobs

Structures at the ends of axons that contain vesicles of neurotransmitters.

Interneurons

Types of neurons that connect different parts of the CNS.

Myelin sheath

A lipid-rich coating produced by Schwann cells in the PNS and Oligodendrocytes in the CNS.

Nodes of Ranvier

Spaces between the myelin on the axon that allow for faster signal conduction.

Saltatory conduction

Conduction that allows signals to skip down the Nodes of Ranvier, making it faster than unmyelinated axons.

White Matter

Groups of myelinated axons in the CNS.

Gray Matter

Clusters of cell bodies; called ganglia in the PNS and nuclei in the CNS.

Multipolar neurons

Neurons with many processes extending from the cell body (many dendrites, 1 axon), accounting for 99% of neurons.

Astrocytes

CNS neuroglia that connect neurons to blood vessels and form part of the Blood Brain Barrier.

Oligodendrocytes

CNS neuroglia that myelinate CNS axons and provide structural support.

Microglia

CNS neuroglia that act as phagocytic cells and provide structural support.

Ependyma

Cells that line the central canal of the spinal cord and ventricles of the brain to help regulate cerebrospinal fluid composition.

Schwann Cells

PNS neuroglia that produce the myelin sheath found on some peripheral axons.

Satellite Cells

PNS neuroglia that support ganglia, nourish neurons, and are vital for nerve regeneration.

Resting membrane potential

The electrical charge of a neuron at rest, measured at $-70\,mV$.

Threshold stimulus

The level of depolarization, specifically $-55\,mV$, required to stimulate an action potential at the trigger zone.

Axon hillock

The trigger zone where an action potential is stimulated if threshold is reached.

Depolarization

The phase of an action potential where Na+ enters the cell, making the inside more positive.

Repolarization

The phase of an action potential where K+ diffuses out of the cell, returning the membrane to a negative charge.

Absolute Refractory Period

Time during which a threshold stimulus cannot generate another action potential because voltage-gated Na+ channels are unresponsive.

Relative Refractory Period

Time when only a high-intensity stimulus can generate an action potential while the membrane is re-establishing resting potential.

Reuptake

A method of removing neurotransmitters from the synaptic cleft by pulling them back into the presynaptic neuron for reuse.

Convergence

A neuronal pool configuration where one neuron receives input from the axons of several neurons.

Divergence

A neuronal pool configuration where one neuron sends impulses to several neurons via axon branching to amplify an impulse.

The meninges

Membranes that protect the brain and spinal cord, consisting of the Dura mater, Arachnoid mater, and Pia mater.

Cerebrospinal Fluid (CSF)

A clear watery secretion (approx. $140\,mL$) produced by choroid plexuses that is nutritive and protective for CNS neurons.

Arachnoid granulations

Structures that absorb CSF after it has exchanged substances.

Frontal lobe

Brain region responsible for higher intellectual processes and personality.

Parietal lobe

Brain region responsible for sensory processing and integration.

Temporal lobe

Brain region responsible for language and auditory processing.

Occipital lobe

Brain region responsible for visual processing.

Corpus callosum

A structure that connects the two cerebral hemispheres.

Wernicke’s area

An area in the temporal/parietal lobe, usually the left hemisphere, responsible for understanding language.

Broca’s area

An area anterior to the primary motor cortex that controls muscles needed for speech.

Thalamus

The gateway for sensory impulses (except smell) ascending to the cerebral cortex.

Hypothalamus

Brain region that maintains homeostasis by regulating visceral activities like heart rate, body temperature, and hunger.

Limbic System

A group of brain structures that control emotional responses, feelings, and survival-oriented behavior.

Reticular formation

A network of nerve pathways in the brainstem that determines alertness and sleep/wake cycles.

Cerebellum

Integrates sensory information about body position and coordinates voluntary muscle activity and posture.

Conus medullaris

The tapering region below the lumbar enlargement forming the tip of the spinal cord.

Cauda equina

A group of lumbar and sacral nerves extending downward from the conus medullaris.

Reflex Arc

The pathway of a reflex consisting of a receptor, sensory neuron, interneuron, motor neuron, and effector.

Dermatome

A region of the skin innervated by a single spinal nerve.

Endoneurium

Loose connective tissue that surrounds individual axons.

Perineurium

Loose connective tissue that surrounds fascicles.

Sympathetic division

The part of the ANS that prepares the body for 'fight or flight' situations through short pre-ganglionic and long post-ganglionic fibers.

Parasympathetic division

The part of the ANS that prepares the body for 'rest and digest' activities through long pre-ganglionic and short post-ganglionic fibers.

Sympathetic tone

Constant low-level activity, such as smooth muscle stimulation in blood vessels, that maintains homeostasis.