Fundamentals of the Nervous System – Lecture 12

60 English fill-in-the-blank flashcards reviewing divisions of the nervous system, neuron anatomy, neuroglia, membrane potentials, action potentials, synapses, neurotransmitters, and information processing.

Nervous tissue contains two kinds of cells: neurons and __.

neuroglia

The anatomical divisions of the nervous system are the central nervous system (CNS) and the __.

peripheral nervous system (PNS)

The CNS is composed of the brain and __.

spinal cord

Bundles of axons in the PNS are called __.

nerves

The afferent division of the PNS carries __ information to the CNS.

sensory

Organs that respond to motor commands are known as __.

effectors

The sympathetic division of the ANS generally has a __ effect.

stimulating

Skeletal muscle contractions are controlled by the __ nervous system.

somatic

The enteric nervous system contains roughly __ million neurons in the digestive tract.

100

The cytoplasm of a neuron's cell body is called the __.

perikaryon

Dense areas of rough ER and ribosomes in neurons are called __ bodies.

Nissl

Fine projections on dendrites that receive information are __.

dendritic spines

The plasma membrane of the axon is known as the __.

axolemma

The thick region attaching the initial segment to the soma is the __.

axon hillock

The fine terminal extensions of an axon are the __.

telodendria

Movement of materials between soma and axon terminals is called __ transport.

axoplasmic

Neurons with one dendrite and one axon are structurally __ neurons.

bipolar

Most sensory neurons in the PNS are structurally __.

unipolar

All motor neurons that control skeletal muscles are structurally __ neurons.

multipolar

Neurons that connect sensory and motor neurons are called __.

interneurons

Receptors that monitor internal systems are __.

interoceptors

Glial cells that maintain the blood–brain barrier are __.

astrocytes

Cells that produce and monitor cerebrospinal fluid are __ cells.

ependymal

Myelin in the CNS is produced by __.

oligodendrocytes

Gaps between myelinated segments of an axon are called nodes of __.

Ranvier

Small phagocytic neuroglia in the CNS are __.

microglia

PNS glial cells that surround neuron cell bodies in ganglia are __ cells.

satellite

Myelinating cells of the PNS are __ cells.

Schwann

Degeneration of the distal axon after injury is called __ degeneration.

Wallerian

The typical resting membrane potential of a neuron is about __ mV.

−70

The sodium–potassium pump ejects 3 Na⁺ for every __ K⁺ it brings in.

2

Ion channels that open when a chemical ligand binds are __-gated channels.

chemically

Ion channels that respond to changes in membrane voltage are __-gated channels.

voltage

Small, localized changes in membrane potential are called __ potentials.

graded

Opening potassium channels typically causes __ of the membrane.

hyperpolarization

Any stimulus that reaches threshold will trigger an action potential according to the __ principle.

all-or-none

During the depolarization phase of an action potential, voltage-gated __ channels open.

sodium (Na⁺)

Repolarization of the membrane involves opening voltage-gated __ channels.

potassium (K⁺)

The period when no additional action potential can be generated is the __ refractory period.

absolute

Propagation along unmyelinated axons is called __ propagation.

continuous

Propagation that “jumps” from node to node in myelinated axons is __ propagation.

saltatory

Large-diameter, myelinated axons conducting about 120 m/s are classified as __ fibers.

Type A

The specialized site where a neuron communicates with another cell is a __.

synapse

Synapses in which cells are connected by gap junctions are __ synapses.

electrical

Chemical messengers that cross the synaptic cleft are called __.

neurotransmitters

Synapses that release acetylcholine are termed __ synapses.

cholinergic

The enzyme that breaks down acetylcholine is __.

acetylcholinesterase (AChE)

The brief 0.2–0.5 msec pause between arrival of an AP and postsynaptic effect is the __ delay.

synaptic

Neurotransmitters that depolarize the postsynaptic membrane are __.

excitatory

The CNS neurotransmitter associated with Parkinson’s disease is __.

dopamine

Small peptide neuromodulators that bind opiate receptors are collectively called __.

opioids

Adenylate cyclase produces the second messenger __.

cyclic-AMP (cAMP)

A graded depolarization of the postsynaptic membrane is an __.

excitatory postsynaptic potential (EPSP)

A graded hyperpolarization of the postsynaptic membrane is an __.

inhibitory postsynaptic potential (IPSP)

Rapid, repeated stimuli at one synapse lead to __ summation.

temporal

Simultaneous stimuli at several synapses cause __ summation.

spatial

Reduced neurotransmitter release by an axoaxonic synapse is presynaptic __.

inhibition

Enhanced neurotransmitter release by an axoaxonic synapse is presynaptic __.

facilitation

CNS regions rich in neuron cell bodies and unmyelinated axons are referred to as __ matter.

gray

Because the membrane is highly permeable to K⁺, the resting potential is closest to the equilibrium potential of __ ions.

potassium (K⁺)