Chapter 12: The Nervous System and Nervous Tissue

neurotransmitter

neurotransmitter

When this signal reaches the end bulbs, it causes the release of a signaling molecule called a

nonspecific channel

Some ion channels are selective for charge but not necessarily for size, and thus are called a

voltage-gated channel

is a channel that responds to changes in the electrical properties of the membrane in which it is embedded.

leakage channel

is randomly gated, meaning that it opens and closes at random, hence the reference to leaking.

Repolarization

meaning that the membrane voltage moves back toward the -70 mV value of the resting membrane potential.

postsynaptic potential (PSP)

is the graded potential in the dendrites of a neuron that is receiving synapses from other cells.

Spatial summation

is related to associating the activity of multiple inputs to a neuron with each other.

chemical synapse

a chemical signal—namely, a neurotransmitter—is released from one cell and it affects the other cell.

electrical synapse

there is a direct connection between the two cells so that ions can pass directly from one cell to the next.

biogenic amine

a group of neurotransmitters that are enzymatically made from amino acids.

neuropeptide

is a neurotransmitter molecule made up of chains of amino acids connected by peptide bonds.

metabotropic receptor

involves a complex of proteins that result in metabolic changes within the cell.

effector protein

is an enzyme that catalyzes the generation of a new molecule, which acts as the intracellular mediator of the signal.

Temporal summation

is the relationship of multiple action potentials from a single cell resulting in a significant change in the membrane potential.

mechanically gated channel

opens because of a physical distortion of the cell membrane.

ligand-gated channel

opens because a signaling molecule, a ligand, binds to the extracellular region of the channel.

electrochemical exclusion

meaning that the channel pore is charge-specific.

precentral gyrus of the frontal cortex

which has an axon that extends all the way down the spinal cord.

thermoreceptor

Found in the skin of your fingers or toes is a type of sensory receptor that is sensitive to temperature, called a

action potential

resulting electrical signal is called an

propagation

The action potential travels—a process known as

threshold

The voltage at which such a signal is generated is called the

graded potential

The amount of change is dependent on the strength of the stimulus (how hot the water is).

Schwann cell

which insulate axons with myelin in the periphery.

satellite cell

One of the two types of glial cells found in the PNS is the

choroid plexus

is a specialized structure in the ventricles where ependymal cells come in contact with blood vessels and filter and absorbcomponents of the blood to produce cerebrospinal fluid.

white matter

(the regions with many axons).

ganglion

In the PNS, a cluster of neuron cell bodies is referred to as a

tract

A bundle of axons, or fibers, found in the CNS is called a

initial segment

Because the axon hillock represents the beginning of the axon, it is also referred to as the

Microglia

as the name implies, smaller than most of the other glial cells.

oligodendrocyte

sometimes called just “oligo,” which is the glial cell type that insulates axons in the CNS.

pia mater

Those processes extend to interact with neurons, blood vessels, or the connective tissue covering the CNS that is called the

Multipolar

neurons are all of the neurons that are not unipolar or bipolar.

Bipolar

cells have two processes, which extend from each end of the cell body, opposite to each other.

Unipolar

cells have only one process emerging from the cell.

axon segment

The length of the axon between each gap, which is wrapped in myelin, is referred to as an

axoplasm

Within the axon hillock, the cytoplasm changes to a solution of limited components called

axon hillock

Where the axon emerges from the cell body, there is a special region referred to as the

synapses

The other processes of the neuron are dendrites, which receive information from other neurons at specialized areas of contact called

enteric nervous system (ENS)

is responsible for controlling the smooth muscle and glandular tissue in your digestive system.

autonomic nervous system (ANS)

is responsible for involuntary control of the body, usually for the sake of homeostasis (regulation of the internal environment).

somatic nervous system (SNS)

is responsible for conscious perception and voluntary motor responses.

stimulus

The sensory functions of the nervous system register the presence of a change from homeostasis or a particular event in the environment, known as a

nucleus

A localized collection of neuron cell bodies in the CNS is referred to as a

myelin

But white matter is white because axons are insulated by a lipid-rich substance called

Dendrites

are responsible for receiving most of the input from other neurons.

central nervous system (CNS)

is the brain and spinal cord

peripheral nervous system (PNS)

is everything else.

glial cell

is one of a variety of cells that provide a framework of tissue that supports the neurons and their activities.

axon

There is one important process that every neuron has called an

ependymal cell

is a glial cell that filters blood to make cerebrospinal fluid (CSF), the fluid that circulates through the CNS.