Chapter 16 nervous system

CNS (Central Nervous System)

Includes the brain and spinal cord.

PNS (Peripheral Nervous System)

Includes nerves and sensory receptors.

Receptors

Receive stimuli and transmit information to effectors.

Effectors

Translate information into action; include mechanical and chemical types.

Mechanical Effectors

Muscles.

Chemical Effectors

Glands.

Neuroglia

Cells that support, nourish, and insulate neurons but do not transmit information.

Microglia

Cells that engulf foreign material and bacteria.

Oligodendrocytes

Cells in the CNS that insulate the axons of neurons.

Schwann Cells

Cells in the PNS that insulate the axons of neurons.

Ependymal Cells

Cells that line the central canals of the brain and spinal cord.

Astrocytes

Cells that pass nutrients between blood capillaries and neurons and help form the blood-brain barrier.

Neurons

Nerve cells that transfer information throughout the body via electrical stimuli.

Cell Body (Soma/Perikaryon)

One of the primary parts of a neuron.

Dendrites

Parts of a neuron that receive nerve signals.

Axons

Parts of a neuron that transmit nerve impulses.

(Pseudo)unipolar Neuron

A neuron with a single stem that divides into a dendrite and an axon.

Bipolar Neuron

A neuron with two processes: one dendrite and one axon.

Multipolar Neuron

A neuron with multiple dendrites and one axon.

Nerve

A bundle of axons located in the PNS.

Tract

A bundle of axons located in the CNS.

Ganglion

A collection of nerve cell bodies in the PNS.

Nucleus

A collection of nerve cell bodies in the CNS.

Myelin Sheath

Thick, whitish, fatty material wrapped around some axons to help insulate them.

Myelinated Neurons

Neurons or axons that possess a myelin sheath.

Unmyelinated Neurons

Neurons or axons that do not have a myelin sheath.

Nodes of Ranvier

Gaps or points along the axon (between myelin segments).

nerve regeneration and neuron generation (neurogenesis)

The PowerPoint lists the terms nerve regeneration and neuron generation (neurogenesis) as concepts related to neurons but does not provide specific explanatory definitions for them.

Nerve Impulse

The electrical signal transmitted by a neuron.

Graded Potential

A wave of electrical excitation.

Resting Potential

The electrical difference across a membrane when it is at rest.

Action Potential

An all-or-none phenomenon; the nerve impulse that sends the actual signal to other cells.

Synapse

The junction between a neuron and another cell.

Neurotransmitters

Stored chemical signals released by neurons in response to an action potential to stimulate another neuron.

Neurosecretory Cells

Specialized neurons that release secretions into the blood.

Somatic Nerves

Nerves that pass to or from somatic tissues, such as skeletal muscle and skin.

Visceral Nerves

Nerves that pass to or from viscera, including involuntary muscles and glands.

Sensory (Afferent) Neurons

Neurons that carry information to the CNS.

Motor (Efferent) Neurons

Neurons that carry information away from the CNS to effectors.

Somatic Nervous System

The part of the nervous system typically involving a one-neuron system to send signals.

Autonomic Nervous System

The part of the nervous system that presides over involuntary visceral activities and typically uses a two-neuron system.

Spinal Nerve

Nerves that come off the spinal column in pairs, named and numbered sequentially.

Dorsal Root

Carries afferent (sensory) fibers from nerves into the spinal cord.

Dorsal Root Ganglion

A collection of cell bodies located on the dorsal root.

Ventral Root

Carries efferent (motor) fibers from the spinal cord to the nerves.

Sympathetic Chain (Paravertebral Ganglia)

A chain of ganglia that peripheral nerves may interact with.

Dermatome

The region of skin innervated by a specific spinal nerve; also refers to the adjacent embryonic tissue a spinal nerve accompanies.

Cranial Nerves

Nerves with roots enclosed in the braincase, numbered by Roman numerals.

Lateral Line Cranial Nerves

Specific cranial nerves possessed by most anamniotes.

Occipitospinal Nerves

Anterior spinal nerves found outside the skull in cyclostomes.

Occipital Nerves

Anterior spinal nerves in fishes and amphibians that exit via foramina in the occipital region.

Hypobranchial Nerve

A composite nerve formed by the union of occipital nerves and cervical nerves to supply throat muscles.

I. Olfactory

Sensory; responsible for the sense of smell.

II. Optic

Sensory (technically a tract); responsible for the sense of vision.

III. Oculomotor

Motor and Parasympathetic; moves four eye muscles (superior, inferior, and medial rectus; inferior oblique), opens the eyelid, and controls pupil constriction.

IV. Trochlear

Motor; moves the superior oblique eye muscle.

V. Trigeminal

Mixed (Sensory/Motor); senses the skin of the face and the anterior 2/3rds of the tongue; moves muscles of mastication (biting/clenching).

VI. Abducens

Motor; moves the lateral rectus eye muscle.

VII. Facial

Mixed (Sensory/Motor/Parasympathetic); senses taste on the anterior 2/3rds of the tongue; moves muscles of facial expression; controls salivation and lacrimal (tear) glands.

VIII. Auditory (Vestibulocochlear)

Sensory; responsible for hearing and balance.

IX. Glossopharyngeal

Mixed (Sensory/Motor/Parasympathetic); senses taste/feeling on the posterior 1/3rd of the tongue and the pharynx; monitors the carotid sinus; moves one pharyngeal muscle; controls the parotid salivary gland.

X. Vagus

Mixed (Sensory/Motor/Parasympathetic); senses the pharynx, larynx, and thoracic/abdominal organs; moves the soft palate, pharynx, and voice muscles; controls thoracic and abdominal viscera.

XI. (Spinal) Accessory

Motor; moves the sternocleidomastoid and trapezius muscles (neck and shoulder).

XII. Hypoglossal

Motor; moves the intrinsic and extrinsic muscles of the tongue.

Somatic Reflex Arc

Typically includes a somatic sensory neuron, an interneuron, and a somatic motor neuron to establish simple reflexes.

Interneuron (Association Neuron)

A neuron within the reflex arc that may be used to connect sensory and motor neurons.

Visceral Reflex Arc

A more complex arc involving organs, requiring a minimum of four neurons.

Sympathetic Nervous System

Known as "fight or flight"; characterized by thoracolumbar outflow and adrenergic neurotransmitters.

Parasympathetic Nervous System

Known as "rest and digest"; characterized by craniosacral outflow and cholinergic neurotransmitters.

Enteric Nervous System

Exclusively located in the digestive tract; influenced by the other two systems and present in all vertebrate classes.

Adrenergic

Refers to the sympathetic system because it releases adrenaline (epinephrine) or noradrenaline (norepinephrine).

Cholinergic

Refers to the parasympathetic system because it releases acetylcholine.

Acetylcholine

The neurotransmitter for the parasympathetic system and the pre-ganglionic fibers of both autonomic systems.

Proprioceptor

Informs the CNS about limb position, joint bending, and muscle stretch.

Somatosensory System

An information-processing system including proprioceptors and surface skin receptors.

Diverging

Information pathways where a single signal branches out.

Converging

Information pathways where multiple signals come together.

Ventricles

Enlarged, fluid-filled connected spaces within the center of the brain.

Prosencephalon (Forebrain)

Becomes the cerebrum and diencephalon.

Mesencephalon (Midbrain)

Becomes the midbrain.

Rhombencephalon (Hindbrain)

Becomes the cerebellum, pons, and medulla oblongata.

Dura Mater

The tough, outermost layer of the meninges.

Arachnoid Mater

The weblike middle layer of the meninges.

Pia Mater

The inner layer of the meninges.

Cerebrospinal Fluid (CSF)

Viscous fluid found in brain ventricles, the subarachnoid space, and the central canal.

Choroid Plexus

Tufts of blood vessels with ependymal cells that produce most CSF.

Primitive Meninx

A single meninx found in fishes.

Secondary Meninx

An inner thin layer found in amphibians, reptiles, and birds, paired with an outer dura mater.

Gray Matter

Includes nerve cell bodies.

White Matter

Includes myelinated neurons.

Ascending/Descending Tracts

Pathways in the spinal cord and brain for information flow.

Medulla Oblongata

Houses cranial nerve nuclei, serves as a route for tracts, and contains autonomic centers for reflexes like respiration and heartbeat.

Pons

In mammals, contains nuclei that convey information to the cerebellum; initiates REM sleep and guides respiratory movements.

Cerebellum

Maintains equilibrium (balance) and muscle tone; refines and coordinates motor actions and muscle memory.

Midbrain

Receives visual and auditory input; roof is the tectum and floor is the tegmentum.

Telencephalon (Cerebrum)

Processes olfactory input, integrates all other input, and serves as the "thinking" part of the brain.

Diencephalon

Major coordinating center for sensory impulses (except smell) to the cerebral cortex.

Brainstem

Composed of the midbrain, pons, and medulla oblongata together.

Tectum

The roof of the midbrain; receives visual, auditory, and lateral line sensory information.

Superior/Inferior Colliculi

Specific structures within the tectum of mammals.