Bio 109: Chapter 48-49 Nervous System

Neurons

nerve cell; the fundamental unit of the nervous system, having structure and properties that allow it to conduct signals by taking advantage of the electrial charge across its plasma membrane

brain

Organ of the central nervous system where information is processed and integrated.

ganglion

A cluster (functional group) of nerve cell bodies in a centralized nervous system.

cell body

the part of a neuron that houses the nucleus and most other organelles

dendrites

branched extensions of a neuron that receives signals from other neurons

axons

a typically long extension, or process, of a neuron that carries nerve impulses away from the cell body toward target cells

axon hillock

The cone-shaped base of an axon, where signals that travel down the axon are generated.

synapse

The junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or an electrical coupling.

synaptic terminal

A bulb at the end of an axon in which neurotransmitter molecules are stored and released.

neurotransmitters

a molecule that is relased from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response

presynaptic cell

The transmitting neuron in a synapse.

postsynaptic cell

The neuron, muscle, or gland cell that receives the signal from a neuron.

glia/glial cell

Cells of the nervous system that support, regulate, and augment the functions of neurons.

sensory input, integration, motor output

What are the 3 functions of the nervous system?

sensory neuron

A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system.

interneruon

nerve cells that are resposnible for integration of sensory input; a nerve cell within the central nervous sytem that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output.

motor neurons

A nerve cell that transmits signals from the brain or spinal cord to muscles or glands.

Central, peripheral

What are the 2 divisions of the nervous system?

C. central nervous system

the portion of the nervous system where signal integration occurs; the brain and spinal cord is known as the:

A. Peripheral nervous system (PNS)

B. Right nervous system (RNS)

C. Central nervous system (CNS)

D. Left nervous system (LNS)

peripheral nervous system

the sensory and motor neurons that connect the central nervous system to the rest of the body

nerves

a fiber composed primarily of the bundled axons of neurons is known as _________

Nerve net

a netlike control system that sends signals to and from all parts of the body

membrane potential

What is the difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions. This affects the activity of excitable cells and the transmembrane movement of all charged substances.

resting potential

The membrane potential characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside.

action potential

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

B. K+

In most neurons, what ion has a higher concentration INSIDE the cell than outside?:

A. Na+

B. K+

C. Na-

D. K-

C. Na+

In most neurons, what ion has a higher concentration OUTSIDE the cell than inside?

A. Pb +

B. Fe -

C. Na+

D. Na -

A. sodium- potassium pump

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell is known as the:

A. sodium-potassium pump

B. Lead pump

C. Sodium pump

D. Potassium pump

D. ATP hydrolysis

The sodium potassium pump uses energy of what to actively transport Na+ out of the cell and K+ into the cell:

A. ADP hydrolysis

B. ADP dehydration synthesis

C. ATP dehydration synthesis

D. ATP hydrolysis

B. ion channels

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient is known as:

A. Sodium-potassium pump

B. Ion channels

C. Selective permeability

D. Protein gradient

equilibrium potential (Eion)

The magnitude of a cell's membrane voltage at equilibrium; cacluated using the Nernst equation is known as

A. Ion channels

B. Sodium - potassium pump

C. Resting potential

D. Equilibrium potential (Eion)

Gated ion channels

ion channels that open or close in response to stimuli are known as ____________ ___________

voltage-gated ion channels

A specialized ion channel that opens or closes in response to changes in membrane potential

hyperpolarization

A change in a cell's membrane potential such that the inside of the membrane becomes more negative relative to the outside. This reduces the chance that a neuron will transmit a nerve impulse.

depolarization

A change in a cell's membrane potential such that the inside of the membrane becomes more positive relative to the outside.

graded potential

a shift in the electrical charge in a tiny area of a neuron that decays as it spreads; it's magnitude varies with the strength of the stimulus

action potential

An electrical signal that travels along the membrane of a neuron or other excitable cell as a nongraded (all-or-none) depolarization.

threshold

the potential that an excitable cell membrane must reach for an action potential to be initiated

rising phase

The first part of an action potential, characterized by a rapid depolarization of the membrane.

falling phase

The part of an action potential characterized by a rapid fall of membrane potential from positive to negative.

undershoot

The part of an action potential when the membrane potential is more negative than at rest; also called after-hyperpolarization.

refractory period

The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of voltage-gated sodium channels.

myelin sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

C. Schwann cells

Which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS?

ANSWER:

A. astrocytes

B. oligodendrocytes

C. Schwann cells

D. Radial glia

b. oligodendrocytes

Which of these neuroglial cells forms the myelin sheath in the central nervous system?

A. astrocytes

B. oligodendrocytes

C. Schwann cells

D. Radial glia

Nodes of Ranvier

Gap in the myelin sheath of certain axons where an action potential may be generated. In saltatory conduction, an action potential is regenerated at each node, appearing to "jump" along the axon from node to node.

saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

D. Radial glia

Which of these neuroglia cells provide guidance for neurons migrating outward during brain development?

A. astrocytes

B. Oligodendrocytes

C. Schwann cells

D. Radial glia

A. Astrocytes

Which of these neuroglial cells form the blood brain barrier in the central nervous system?

A. Astrocytes

B. Oligodendrocytes

C. Schwann cells

D. Radial glia

electrical synapses

Synapses that transmit information via the direct flow of electrical current at gap junctions.

Chemical synapses

Synapses that transmit information via the secretion of chemical signals (neurotransmitters).

synaptic vesicle

storage site for neurotransmitters

Ca2+

In chemical synapses, what causes the synaptic vesicles to fuse with the terminal membrane and release the neurotransmitter

synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

ligand-gated ion channel

A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions; also called an ionotropic receptor.