Chapter 6A

The predominant ions in the extracellular fluid are ______, and the predominant ions in the intracellular fluid are ______.

Na+ and Cl-; K+ and phosphate compounds

Neurons that convey information from the tissues and organs of the body toward the CNS are classified as ____________neurons.

Afferent

The entire nervous system is divided into two anatomical regions: the ______________nervous system and the ______________________nervous system.

Central and Peripheral

Two fluid-filled experimental chambers are separated by a plasma membrane that has open Cl- channels but no other ion permeability. Into side 1 you put 200 mM NaCl and into side 2 you put 100 mM KCl. Which of the following will occur? Multiple choice question. Cl- will flow from side 1 to side 2 until the two compartments have the same Cl- concentrations. Cl- will flow from side 1 to side 2 and the membrane will develop a membrane potential that is positive on side 1 and negative on side 2. No membrane potential will develop, because the electrical attraction of Na+ and K+ ions will keep Cl- from moving through the membrane. The higher concentration of Cl- on side 1 will make the membrane have a resting membrane potential that is negative on side 1 and positive on side 2.

Cl- will flow from side 1 to side 2 and the membrane will develop a membrane potential that is positive on side 1 and negative on side 2.

The ______ exchange Na+ ions that leak into the cell for K+ ions that had leaked out of the cell, thus maintaining the resting potential. Multiple choice question. Na+/K+-ATPase pumps ligand-gated channels voltage-gated channels leak channels

Correct Answer: Na+/K+-ATPase pumps Incorrect: ligand-gated channels voltage-gated channels leak channels Reason: The Na+/K+-ATPase pump exchanges ions that have leaked, putting them back where they were and thus maintaining ion gradients and the resting potential.

Which is a true statement regarding the voltage-gated Na+ and K+ channels that mediate neuronal action potentials? Multiple choice question. The K+ channels have inactivation gates, but the Na+ channels do not. The Na+ channels have inactivation gates, but the K+ channels do not. Neither Na+ nor K+ channels have inactivation gates. Both Na+ and K+ channels have inactivation gates.

Correct Answer: The Na+ channels have inactivation gates, but the K+ channels do not. Incorrect Answer: The Na+ channels have inactivation gates, but the K+ channels do not. Reason: The Na+ channels have inactivation gates, but the K+ channels do not. Neither Na+ nor K+ channels have inactivation gates. Reason: The Na+ channels have inactivation gates, but the K+ channels do not. Both Na+ and K+ channels have inactivation gates. Reason: The Na+ channels have inactivation gates, but the K+ channels do not.

The part of the neuron that carries information toward the cell body is the ______.

Dendrite

Neurons that carry information from the CNS toward the tissues and organs of the body are known as _____________neurons.

Efferent

True or false: Graded potentials are "all-or-none," meaning that the change in the membrane potential is the same size regardless of the size of the stimulating event.

False

The non-neuronal cells of the nervous system that provide physical and metabolic support to neurons are collectively called ___________cells.

Glial

Channels in the membrane of a cell that are always open and passively allow the movement of K+ ions that makes the inside of the cell negative with respect to the outside are called _______________ K+ channels.

Leak

The resting potential of a cell is largely generated by the movement of potassium and sodium down their concentration gradients through ion channels that are always open in the membrane. These channels are called ______ channels. aquaporin leak active pump voltage-gated ligand-gated

Leak

The ______ exchange Na+ ions that leak into the cell for K+ ions that had leaked out of the cell, thus maintaining the resting potential. Multiple choice question. ligand-gated channels Na+/K+-ATPase pumps voltage-gated channels leak channels

Na+/K+-ATPase pumps

The specialized cells of the nervous system that conduct electrical signals are called_____________.

Neuron

The specialized cells of the nervous system that conduct electrical signals are called____________.

Neurons

The nerves that connect the brain and spinal cord with the body's muscles, glands, and sense organs make up the general anatomic division known as the ___________________nervous system.

Peripheral

Which ion species are in higher concentration in the cytosol of neurons than in the extracellular fluid? Multiple select question. Na+ Phosphate ions Cl- K+ Ca2+

Phosphate ions K+

All inactive cells in the body maintain a voltage difference across their membrane, called the ______________________ ____________________ ______________________ , in which the inside of the cell is negatively charged in comparison to the outside of the cell.

Resting Membrane Potential

The ions that enter a neuron and cause the depolarization phase of a typical action potential are _________________ions.

Sodium

Which of the following is true about graded potentials? Multiple choice question. They are "all-or-none," meaning they are always of the same size regardless of the size of the stimulus. The flow of charge decreases with distance. The flow of charge is propagated the entire length of the axon. They are only generated by voltage-gated ion channels.

The flow of charge decreases with distance.

Consider an experimental set-up with two fluid-filled chambers that are separated by a plasma membrane with open K+ channels but no other ion permeability. If you were to add 100 mM of NaCl into side 1 and 100 mM of KCl into side 2, what would you expect to happen? Multiple choice question. K+ will flow from side 2 to side 1 until it is in equal concentrations in the two compartments. No K+ will flow through the membrane because the charged Na+ on side 1 will repel any K+ from moving. The membrane will develop a membrane potential that is positive on side 2 compared to side 1. The membrane will develop a membrane potential that is positive on side 1 compared to side 2.

The membrane will develop a membrane potential that is positive on side 1 compared to side 2.

Which two statements are true about neurons? Multiple select question. They are epithelial cells lining the ventricles of the brain that regulate the production of cerebrospinal fluid. They are cells responsible for the basic functioning of the nervous system. They are also called neuroglia. They operate by generating electrical signals that move from one part of the cell to another part of the cell.

They operate by generating electrical signals that move from one part of the cell to another part of the cell. They are cells responsible for the basic functioning of the nervous system.

True or false: Action potentials in neurons are very brief events, and may repeat at high frequencies-up to several hundred per second.

True

True or false: Graded potentials can either depolarize or hyperpolarize the membrane potential.

True

True or false: Most cells have resting membrane potentials that are negative on the inside compared to the outside.

True

Ion channels that are closed when the cell is at its resting potential but open when the cell's membrane potential changes are categorized as ___________-_____________ ion channels.

Voltage-Gated

Large, rapid, all-or-none depolarizations of neuron membrane polarity are called _________ ______________.

action potential

The glial cells of the nervous system ______. are neurons with cell bodies in the central nervous system and long axons that extend into the peripheral nervous system are non-neuronal cells that provide physical and metabolic support to neurons are neurons that are found in the outer layer of the brain are neurons with cell bodies in the peripheral nervous system and long axons that extend into the central nervous system

are non-neuronal cells that provide physical and metabolic support to neurons

The long process that carries information away from a neuron's cell body is called a(n)

axon

The long process that carries information away from a neuron's cell body is called a(n) ____________________.

axon

The part of the neuron that carries information toward the cell body is the ______. Multiple choice question. axon terminal hillock dendrite

dendrite

A subthreshold stimulus to a neuron ______. Multiple select question. does not generate an action potential depolarizes the local membrane potential briefly before it returns to the resting potential hyperpolarizes the membrane potential of the axon thus activating only a few voltage-gated ion channels generates a weak action potential

does not generate an action potential depolarizes the local membrane potential briefly before it returns to the resting potential

The repolarization phase of a neuronal action potential is produced primarily by the ______. Multiple choice question. influx of Na+ influx of K+ efflux of K+ efflux of Na+

efflux of K+

Threshold stimuli ______. Multiple choice question. elevate the membrane potential sufficiently to generate an action potential lower the membrane potential below threshold cause the opening of leak K+ channels cause the opening of only voltage-gated K+ channels

elevate the membrane potential sufficiently to generate an action potential

The ability of cells with voltage-gated ion channels to produce electrical signals is called ______. Multiple choice question. impedance conductivity excitability extensibility reactivity

excitability

The capability of a cell to produce electrical signals through the action of a voltage-gated ion channels is called ________________.

excitability

An action potential ______. Multiple select question. is conducted without decrement is an all-or-none event can function as a signal only over a very short distance occurs very rapidly increases in amplitude if the initiating stimulus is stronger

is conducted without decrement is an all-or-none event occurs very rapidly

The resting membrane potential of body cells ______. is negative, with values varying from -100 to -200 mV is negative, with values varying from -5 to -100 mV is positive, with values varying from 100 to 200 mV is positive, with values varying from 5 to 100 mV

is negative, with values varying from -5 to -100 mV

The resting potential of a cell is largely generated by the movement of potassium and sodium down their concentration gradients through ion channels that are always open in the membrane. These channels are called ______ channels. Multiple choice question. aquaporin ligand-gated voltage-gated active pump leak

leak

The Na+/K+-ATPase pump in the cell membrane ______. Multiple select question. initiates the action potential moves sodium into the cell and potassium out of the cell moves potassium ions into the cell and sodium ions out of the cell maintains the concentration gradients that ultimately determine the resting potential of the cell

moves potassium ions into the cell and sodium ions out of the cell maintains the concentration gradients that ultimately determine the resting potential of the cell

The closing of voltage-gated K+ channels during repolarization of an action potential is an example of ______ feedback; the opening of Na+ channels during the depolarizing phase of an action potential is an example of ______ feedback. Multiple choice question. positive; negative negative; negative negative; positive positive; positive

negative; positive

By convention, when describing a cell's membrane potential the ______ of the cell is assigned a value of zero, and the voltage is defined as the positive or negative charge on the ______ of the cell. Multiple choice question. cytoplasm; cytosol inside; outside outside; inside nucleus; cytoplasm

outside;inside

The permeability of a resting plasma membrane is greater for ______ than it is for ______; therefore, a net negative membrane potential develops. Multiple choice question. sodium; potassium potassium; sodium sodium; chloride

potassium; sodium

All cells under resting conditions have a voltage difference between the inside and outside of their plasma membranes, which is referred to as the ______. baseline ionic permeability background leak current action potential resting membrane potential

resting membrane potential

A stimulus that causes a graded depolarization that is too small to generate an action potential is called a(n) _____________stimulus.

subthreshold

A stimulus that is just strong enough to trigger the voltage-gated channels of the initial segment of an axon to open and begin the action potential is called a(n)_______________ stimulus.

threshold

Afferent neurons convey information ______ the CNS, while efferent neurons convey information ______ the CNS.

toward; away from

An ion channel that opens in response to a change in the membrane potential of the cell is called a __________ channel. Multiple choice question. voltage-gated leaky ligand-gated fair-weather mechanically gated

voltage-gated

While K+ ions move through both leakage and voltage-gated channels, Na+ ions move predominantly through ______ during an action potential. Multiple choice question. endocytosis leak or leakage channels voltage-gated channels

voltage-gated channels