Bio 161 Exam 2 - Penn State

Vocabulary review flashcards covering neuroanatomy, neurophysiology, membrane potentials, and nervous system organization for Penn State Bio 161 Exam 2.

Current

Flow of charged particles from one point to another; requires an electrical potential (voltage).

Potential

Also called an electrochemical gradient.

Resting membrane potential

$$-70\,\text{mV}$$

Chemical gradient

Uneven distribution of molecules.

Electrical gradient

Uneven distribution of charge (because molecules are ions).

Large anions

Unable to penetrate the plasma membrane; give the cytoplasm a negative charge relative to the ECF.

Chemical diffusion

Requires concentration gradient for ions, molecules.

Leak channels

Channels that are always open and allow ions to move along their gradient.

Na+/K+ pump

Create chemical gradient of the ions.

Dendrite

Short extensions off the cell; site for receiving signals from other neurons.

Axon

Extension away from the cell body; some can be myelinated to improve conductivity.

Axon Hillock

Cone shaped region of an axon where it joins the cell body.

Axon terminal

The endpoint of a neuron where neurotransmitters are stored.

Synapse

Site of communication between neurons (in picture) or between a neuron and a target tissue.

Bipolar neurons

One axon and one dendrite.

Multipolar neuron

A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system.

Psuedounipolar neurons

Neurons whose cell bodies are found in the dorsal root.

Neuroglia

Supporting cells.

Oligodendrocytes

Type of glial cell in the CNS that wrap axons in a myelin sheath.

Schwann cells

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

Ganglia

Clusters of cell bodies in the PNS.

Nerves

Bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs.

Fascicles

Bundles of muscle fibers.

Endoneurium

Surrounds individual neurons.

Perineurium

Bundles neurons into fascicles.

Epineurium

Provides a touch, outer layer.

Cell body (soma)

Contains one nucleus.

Afferent neurons

Sensory neurons sometimes called receptors; start in PNS and travels to the CNS; detect stimuli, and deliver info about environment or condition of the body to the CNS.

Interneurons

Located in CNS, functions to receive and integrate information.

Efferent neurons

Send signals from the CNS to effectors (targets) Muscles, organs, glands.

Sensory neurons

Tracts of neuronal axons (white matter) or cell bodies (gray matter).

Motor neurons

Send signals from the CNS to effectors.

Dorsal

Toward the back.

Ventral

Belly side.

Vertebral column

A series of irregularly shaped bones called vertebrae that houses the spinal cord.

Spinal nerves

$31$ pairs of nerves arising from the spinal cord.

Cranial nerves

$12$ pairs of nerves that carry messages to and from the brain.

Dura

Hard, lasting.

Arachnoid

Middle layer of the meninges.

Pia

Tender.

Epidural space

Space between the dura mater and the wall of the vertebral canal.

Subarachnoid space

A space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid.

White matter

Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.

Gray matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.

Ventral horn

Somatic motor neurons whose axons exit the cord via ventral roots.

Dorsal root

The sensory branch of each spinal nerve.

Ventral root

Contains axons of motor neurons.

Dorsal root ganglion

Contains cell bodies of sensory neurons.

Gated channels

Ion movement during graded potentials is regulated by gated protein channels. They include chemical, voltage, or mechanical stimuli.

Chemical gated channels

Open and close in response to a specific chemical stimulus (ions, neurotransmitters, hormones).

Mechanical gated channels

Respond to physical changes.

Voltage gated channels

Open and close in response to changes in membrane potential.

Myelin sheath (importance)

Help insulate axons and with conductivity, fast propagation of signal.

Graded (local) potential

Triggered by receptors and neurotransmitters, depolarize or hyperpolarized, reversible.

Threshold potential

$$-55\,\text{mV}$$

Action potential

Always depolarize and are regulated by voltage-gated channels, irreversible.

Stimulus

A signal to which an organism responds.

Depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Hyperpolarization

More potassium leaves the cell than sodium enters.

Neurotransmitter

Synthesized in the cell body and transported in vesicles to the axon terminal. Many are derived from amino acids.

EPSP

Neurotransmitters cause depolarization of postsynaptic neuron.

IPSP

Neurotransmitters cause hyperpolarization of postsynaptic neuron.

Summation

The total of all local potential changes at the synapses of a postsynaptic cell.

Secretion

The process of converting the electrical signal to a chemical signal in the synapse and then back to an electrical signal.