Biopsychology chapter 1

neuron

information processing and information transmitting cells of the nervous system

Nodes of Ranvier

interruptions in myelin sheeths

Potassium ions are mostly ____ (extra or intracellular)

intracellular

Cytoplasm

jelly-like substance that fills the cell

The speed of nerve impulse ranges from

less than 1 meter/second to 100 meters/seconds

membrane

lipid bilayer that defines the boundary of cell

multipolar neuron

most common neuron in the CNS

diffusion (aka concentration gradient)

movement of molecules from regions of high concentrations to regions of low concentrations

Once the threshold of excitation is reached, a subsequent _______ occurs (effect is for even more sodium/ Na+ to rush in)

nerve impulse

Depolarization

reduction of the membrane potential from its normal resting potential (move towards zero/ goes up/ less negative)

neuron cell membrane

semi-permeable: some, but not all, particles cna pass through it -proteins anchored in the membrane allow certain things to pass through

Fluid surrounding the outside of the cell

sodium and chloride

An unusually rapid series of action potentials can lead to a buildup of _____ within the axo which can be toxic (rare instances such as stroke for example)

sodium ions

Resting potential

state of a neuron prior to sending a nerve impulse (electron charge of a neuron)

CNS

the brain and spinal cord

Refractory periods

the neuron resists the production of another action potential after the first action potential

relative refractory period

the second part, right after neuron fires, in which is takes a stronger than usual stimulus to trigger an action potential (after this its difficult to start another action potential)

The brain is not set up to register small differences in the time of arrival of touch messages, except in the case of

vision (movements must be detected as accurately as possible. in some cases time matters with other senses, in others it doesnt)

Sodium and potassium channels' permeability depends upon the __________ across the membrane

voltage difference

Threshold of excitation

voltage level that triggers an action potential

The threshold of excitation occurs when the charge reaches about ______, although this can differ between neurons (the charge in 1 single neuron is always the same though)

-65mV

The resting potential inside a neuron is approximately

-70mV

Local neurons

Have short axons, exchange info with only close neighbors, and do not produce action potentials (special case)

What does an efferent axon do? a. it controls involuntary behavior. b. it controls voluntary behavior c. it carries output from a structure d. it brings information into a structure

It carries output from a structure

Does the nerve impulse travel directly down the axon?

No. It is regenerated at points along the axon so that it is not weakened (signal strength and speed maintained throughout the impulse)

When the neuron is at rest, the ____ (inside/ outside) of a neuron is more positively charged than the ______

Outside; inside (the neuron has more sodium ions outside than inside and sodium channels are closed)

Which of these can easily cross the blood-brain barrier by active transport? a. Oxygen, water, and fat-soluble molecules b.. Glucose and amino acids c. Proteins d.. Viruses

Oxygen, small uncharged molecules, psychoactive drugs, water and fat-soluble molecules

Sensory neuron

Specialized at one end to be highly sensitive to a particular type of stimulation such as light, sound, or touch.

Which of the following is a function of astrocytes? a. Conduct impulses over long distances b. Build myelin sheaths that surround and insulate axons c. Create the blood-brain barrier. d. Synchronize activity for a group of neurons.

Synchronize activity for a group of neurons

Saltatory conduction

The jumping of the action potential from node to node

polarization

The maintaining of a membrane's electrical gradient (a difference in electrical charge inside and outside the cell)

Which part of a neuron has its own genes, separate from those of the nucleus? a. The ribosomes b. The mitochondria c. The axon d. The dendrites

The mitochondria

presynaptic terminal

The swelling end of each axon branch (aka button or bulb)

What is most distinctive about neurons, compared to other cells? a. Their temperature b. Their shape c. Their internal components, such as ribosomes and mitochondria d. Their color

Their shape

Which of these do dendritic spines do? a. They synthesize proteins. b. They increase the surface area available for synapses c. Their internal components such as ribosomes and their mitochondria d. They metabolize fuels to provide energy for the rest of the neuron

They increase the surface area available for synapses

Interneuron (intrinsic neuron)

a cell's dendrites and axon are entirely contained within a single structure

Microelectrode

a very fine electrode that can be used to electrically stimulate or record from a neuron (placed in the soma and axon of a neuron)

What causes potassium ions to leave the axon just after the peak of the action potential? Select one: a. A continuing concentration gradient and the opening of the potassium gates b. Binding of potassium ions to proteins that leave at this time c. An increased tendency of the sodium-potassium pump to push potassium out d. An increase in the concentration gradient across the membrane

a. A continuing concentration gradient and the opening of the potassium gates

n efferent axon carries information away from a structure. Select one: a. True b. False

a. True

The major disadvantage of a blood-brain barrier is that ____. Select one: a. certain required chemicals must be actively transported b. so much glucose is required to maintain it c. many chemicals can easily diffuse into the brain d. viruses cannot escape

a. certain required chemicals must be actively transported

The tree-like branches of a neuron that receive information from other neurons are called _____. Select one: a. dendrites b. axons c. soma d. myelin

a. dendrites

During the relative refractory period, the ____. Select one: a. sodium gates are reverting to their usual state b. sodium gates are wide open c. potassium gates are firmly closed d. sodium gates are firmly closed

a. sodium gates are reverting to their usual state

After ______ occurs, sodium (Na+) channels are quickly closed

action potential

Presynaptic terminal

at the end points of an axon release chemicals to communicate with other neurons

What type of glia helps to synchronize the activity of axons? Select one: a. Radial glia b. Astrocytes c. Oligodendrocytes d. Schwann cells

b. Astrocytes

What term describes the difference in voltage that typically exists between the inside and the outside of a neuron? Select one: a. Generator potential b. Resting potential c. Shock gradient d. Concentration gradient

b. Resting potential

When the neuronal membrane is at rest, the potassium channels ____. Select one: a. prohibit any movement of potassium ions b. permit potassium ions to pass slowly c. permit potassium ions to pass quickly and easily d. help to open up the sodium channels

b. permit potassium ions to pass slowly

Afferent axon

brings info into a structure (sensory neuron)

Which type of glia builds myelin sheaths around axons in the periphery of the body? Select one: a. Radial glia b. Oligodendrocytes c. Schwann cells d. Astrocytes

c. Schwann cells

When the potential across a membrane reaches threshold, the sodium channels ____. Select one: a. open to let sodium exit the cell rapidly b. close to prevent sodium from exiting the cell c. open to let sodium enter the cell rapidly d. close to prevent sodium from entering the cell

c. open to let sodium enter the cell rapidly

When a neuron's membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell. Select one: a. out of; out of b. into; into c. out of; into d. into; out of

c. out of; into

Efferent axon

carries info away from a structure (motor neuron)

Potassium ions flow out due to the ____________ and take with them their positive charge

concentration gradient

Saltatory conduction

conserves energy for the cell (requires fewer Na+/K+) pumps -larger/ longer axons= greater conduction speed

bipolar neuron

conveys sensory info to CNS (esp changes in environment like temperature, movement, placement in environment)

unipolar neuron

conveys sensory info to CNS (esp relevant in sensation of touch)

Dr. Ruggs is giving a lecture about the all-or-none-law. What would she tell the class? Select one: a. That all neurons produce an action potential at the same time or none produce one. b. That all ion channels open at the same time or none at all. c. That all neurons are active at the same time or none at all. d. That after reaching threshold, the amplitude and velocity of the action potential is the same each time.

d. That after reaching threshold, the amplitude and velocity of the action potential is the same each time

What type of glial cells myelinate axons in the brain and spinal cord? Select one: a. Schwann cells b. astrocytes c. radial glia d. oligodendrocytes

d. oligodendrocytes

When sodium channels are opened and they rush in, this _____ (hyper or depolarizes?) the neuron

depolarizes (increases the charge)

A cell membrane's charge is produced by a balance between the forces of ____ and ______

diffusion; electrostatic pressure

Nerve impulse

electrical message transmitted down the axon of neuron

Chloride ions are mostly ____ (extra or intracellular)

extracellular

Sodium ions are mostly _____ (extra or intracellular)

extracellular

At each node of Ranvier, the axon is exposed to _______ and ____ from node to node

extracellular fluid; jumps

myelin sheath

fatty insulating substance that prevents messages from escaping the axon

action potential of a neuron

image of AP

Hyperpolarization

increase in the membrane potential relative to the normal resting potential (more negative, goes down)

Chemicals that are actively transported into the brain through the blood-brain barrier include

- glucose (the brain's main fuel) - amino acids (the building blocks of proteisn) - purines - choline - a fewvitamins - iron - hormones

radial glia

-Guide the migration of neurons and their axons and dendrites during embryonic development -after embryonic development, radial glia differentiate into neurons/ usually astrocytes/ oligodendrocytes sometimes

oligodendrocytes

-In the brain and spinal cord, build/produce myelin sheaths that surround and insulate certain vertebrate axons and supply axons with nutrients for functioning

Basic functions of Glia

-Provide physical and chemical buffers to isolate neurons (make sure only firing at targeted neurons) -surround neurons and hold them in place (not free-floating) -Control supply of chemicals to/ from neurons -Insulate neurons from each other so that neural signals dont get scrambled -Housekeepers: destroy and remove dead cells

Which ions come in and out of a neuron's protein channels/ membrane?

-Sodium (Na+) -Potassium (K+) -chloride (Cl-)

Why is the blood-brain barrier necessary in the brain?

-The immune system destroys damaged or infected cells throughout the body - neurons in the brain generally dont regenerate, so its important for the blood brain barrier to block harmful material from entering

sodium-potassium pump

-a protein complex embedded in the cell membrane - helps to maintain the electrical gradient -uses active transport (requires ATP)

microglia

-act as part of immune system -remove viruses and fungi and dead or damaged neurons and weakened synapses from the brain -smallest glia cells -protect the brain from microorganisms -inflammatory response when there is brain damage

Two forces that move ions

-diffusion -electrostatic pressure

Molecules reliant on active transport to get through the blood-brain barrier

-glucose -thiamine -amino acids -certain hormones

Blood-brain barrier

-mechanism that excludes most chemicals from the vertebrate brain

Cell body (soma)

-most of a neurons metabolic work occurs here -contains the nucleus, ribosomes, and mitochondria

Schwann Cells

-only in the periphery of the body - build myelin sheaths that surround and insulate a single vertebrate axon -can guide regrowth in case of axon damage

Organic anions

-only intracellular -too big to ass through membrane

The sodium-potassium pump continually pumps ____ sodium ions out of the cells while drawing ___ potassium ions into the neuron

3; 2

Dendrites

Branching fibers that get narrower near their ends and their surface is lined with specialized synaptic receptors that receive info from other neurons

Diffusion pushes ______ (which ion?) into the cell and electrostatic pressure pushes it out of the cell (it has no net movement at rest)

Chloride

What is the brain's main source of fuel? a. Glucose b. Glutamate c. Choline d. Proteins

Glucose

PNS

Has two divisions: -Somatic: sensory organs and skeletal muscles -Autonomic: Regulation of smooth and cardiac muscle and glands

Thiamine

Needed for the body/ brain to use glucose

Endoplasmic reticulum

Network of thin tubes that store or transport newly synthesized proteins to other locations through the cell

Does action potential travel both directions on a neuron?

No because it -starts at initial segment at the edge of the soma -has a refractory period for Na+ channels (which tend to close rapidly after opening)

Axoplasmic Transport

Process by which substances are transported up and down the axon (active process- requires energy/ ATP)

motor neuron

Receives excitation through its dendrites and conducts impulses along its axon to a muscle (soma in spinal cord)

The _____ prevents too many action potentials from firing at once

Refractory period

Which of the following is the function of the microglia? a. Remove dead cells and weak synapses b. Build myelin sheaths that surround and insulate axons c. Dilate blood vessels to increase blood supply to active brain areas d. synchronize activity for a group of neurons

Remove dead cells ad weak synapses

Dendritic spines

Short outgrowths that increase the surface area available for synapses

Diffusion pushes ______ (which ion?) into the cell and electrostatic pressure pushes it into the cell (It is ready for action and therefore has no net movement at rest- there are certain conditions where is rushes into the cell)

Sodium

Saltatory conduction

The myelin sheath of axons are interrupted by short, unmyelinated sections called nodes of Ranvier

Santiago Ramon y Cajal was responsible for which of these discoveries? a. the human cerebral cortex has many specializations to produce language b. The brain's left and right hemispheres control different functions. c. The nervous system is composed of separate cells. d. Neurons communicate at specialized junctions called synapses

The nervous system is composed of separate cells

PNS

The part of the nervous system outside of the brain and spinal cord including attached nerves

For the brain to use its main source of fuel, what does it also need? a. Steroid hormones b. Vitamin C c. Thiamine d. Acetylsalicyclic acid

Thiamine

Local neurons

When stimulated, produce membrane potentials that vary in magnitude and don't follow the all-or-none law -they depolarize and hyperpolarize in proportion to the stimulation

Does the action potential remain at equal strength throughout the transmission down the axon?

Yes. Behind each area of sodium entry, potassium ions exit, restoring the resting potential

As an action potential occurs at 1 point on the axon, enough sodium enters to depolarize the next point to its threshold, producing a __________ at that point

action potential

catabolic enzymes

aids with breakdown of different substances

metabolic enzymes

aids with synthesis of different substances

action potential

an abrupt depolarization (increase in charge) of the membrane that allows the neuron to communicate over long distances and last 2 ms (how the neuron sends a message)

There are two types of glial cells that produce myelin sheath. In the central nervous system, Schwann cells fulfill this role and, in the periphery, oligodendrocytes produce it. Select one: a. True b. False

b. False

When a neuron's membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell. Select one: a. out of; into b. into; into c. into; out of d. out of; out of

b. into; into

Gaps in the insulating material that surrounds axons are known as ____. Select one: a. myelin synapses b. nodes of Ranvier c. interpeduncular nuclei d. presynaptic terminals

b. nodes of Ranvier

Which type of glia release chemicals that modify the activity of neighboring neurons? Select one: a. Schwann cells b. Oligodendrocytes c. Astrocytes d. Radial glia

c. Astrocytes

Which type of glia remove waste material in the nervous system? Select one: a. Radial glia b. Oligodendrocytes c. Astrocytes d. Schwann cells

c. Astrocytes

Which action would depolarize a neuron? Select one: a. Decreasing membrane permeability to calcium b. Increasing membrane permeability to potassium c. Increasing membrane permeability to sodium d. Decreasing membrane permeability to sodium

c. Increasing membrane permeability to sodium

If all of a neuron's dendrites or axons were contained within the spinal cord, it would be considered a(n) ____ neuron. Select one: a. Purkinje b. efferent c. intrinsic d. afferent

c. intrinsic

The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____. Select one: a. concentration gradient b. phospholipid bilayer c. refractory period d. sodium potassium pump

c. refractory period

Axon

conducts/ transmitstHE an impulse toward other neurons, an organ, or a muscle

cytoskeleton

consists of microtubules which are strands of proteins linked together to give the cell shape

unipolar neuron

contains a single axon that leaves the soma and divides into 1 branch

Multipolar neuron

contains one axon and many dendritic trees branching from soma

bipolar neuron

contains one axon and one dendritic tree at opposite ends of the soma (2 axons in total)

What mechanism prevents or slows some chemicals from entering the brain, while allowing others to enter? Select one: a. An endoplasmic wall b. A threshold c. A differential-drug inhibitor d. A blood-brain barrier

d. A blood-brain barrier

Dr. O'Reilly is trying to produce hyperpolarization in the neurons in her laboratory. What should she do? Select one: a. Add a drug that will increase the membrane's permeability to sodium b. Add a drug that will decrease the membrane's permeability to potassium c. Use a microelectrode to apply a positive charge d. Use a microelectrode to apply a negative charge

d. Use a microelectrode to apply a negative charge

Many dendrites contain short outgrowths called spines that _____. Select one: a. eliminate cell waste products b. increase the speed of transmission c. increase the symmetry of the soma d. increase the surface area available for synapses

d. increase the surface area available for synapses

In order to produce an action potential, the collective amount of depolarization must exceed the _____ Select one: a. energy required to open the potassium channels b. resting membrane potential c. absolute refractory period d. threshold of excitation

d. threshold of excitation

Within the nervous system, a given neuron is ______ from one structure and ______ to another

efferent; afferent

_____ and _____ work to pull sodium ions into the neuron

electrical gradient; concentration gradient

The rate of entry and voltage of sodium into the neuron is ______ (slower/faster and higher/lower?) than the rate of exit of potassium from the neuron

faster and higher/ more positive voltage

intracellular fluid

fluid inside the neuron cell

extracellular fluid

fluid outside the neuron cell

Electrostatic pressure (:aka electrostatic gradient)

force of attraction/ repulsion between ions

terminal buttons

form synapses with other neurons

The only time an action potential travels backwards is when

its right at the starting point, it can back-propagate into the soma, which leads to some of the structural changes involved in learning

Oscilloscope

measures and shows voltage over time (good way for researchers to get info on neural threshold/ action potential)

Golgi apparatus

membrane that packages products to be secreted by the cell

In saltatory conduction along the axon, the action potential is regenerated by a chain of _________ pushed along by the previous segment

positively charged ions

Diffusion pushes ______ (which ion?) out of the cell and electrostatic pressure pushes it into the cell (it has no net movement at rest)

potassium

The neuron is returned to its resting state by the opening of _____ channels

potassium (K+)

The neuron has more _____ ions inside than outside, and _____ channels are partially closed (allowing for very slow passage)

potassium (K+) ions

The ions surrounding the inside of the Cytoplasm are

potassium ions and other organic anions

electrical gradient tends to pull ______ into the neuron also, even though they also slowly leak out, carrying a _____ charge with them

potassium; positive

Active Transport

protein-mediated process that expends energy to pump chemicals form the blood into the brain

Saltatory conduction

provides rapid conduction of impulses, which enables fast thinking/ response time

a touch on the ____ reaches the brain more quickly than a touch on the ____

shoulder; foot

The resting potential of a neuron remains stable until the neuron is _______

stimulated

Glia

support cells of the nervous system -support and protect neurons in the CNS -More limited role in the PNS

The greater the ___ of a dendrite, the more info it can recieve

surface area

All-or-none law

the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it (an action potential, once triggered, is transmitted w/ out decreasing in size to the end of the neuron/ axon)

Absolute refractory period

the first part of the period in which the membrane cannot produce an action potential

Astrocytes

type of glia that shields synapses from chemicals circulating in the surroundings (make sure neurons firing where they should) -helps synchronize closely related neurons -dilate the blood vessels to bring more nutrients into brain areas that have heightened activity -aid in controlling extracellular chemical environment -maintain the blood-brain barrier

Enzymes

type of protein that controls a chemical rxn

Glucose

vertebrate neurons depend almost entirely on this